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Pb. Crane Division, Naval Surface Warfare Center Lead Free. LEAP-WG 10 April 2008. Distribution Statement A: Approved for Public Release; distribution is unlimited. Presenter. Gary S Latta 2M Program 812-854-1973 E-mail: [email protected] Crane Division, Naval Surface Warfare Center.

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Crane division naval surface warfare center lead free

Pb

Crane Division, Naval Surface Warfare CenterLead Free

LEAP-WG10 April 2008

Distribution Statement A: Approved for Public Release; distribution is unlimited


Presenter

Presenter

Gary S Latta

2M Program

812-854-1973

E-mail: [email protected]

Crane Division, Naval Surface Warfare Center


Lead free control plan

Lead-Free Control Plan


What it is

What it is

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • A Risk Management tool

  • A Pb-free policy document

  • Identifies what can/cannot be done

  • An education tool

  • An implementing document


What it is not

What it is not

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • A 100% solution

  • “The” answer to Pb-free


Structure

Structure

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

1. SCOPE

2. REFERENCES

3. TERMS AND DEFINITIONS

4. SYMBOLS AND ABBREVIATED TERMS

5. OBJECTIVES

6. TECHNICAL REQUIREMENTS

7. ADMINISTRATIVE REQUIREMENTS


Structure1

Structure

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

0. BACKGROUND

1. SCOPE

2. REFERENCES

3. TERMS AND DEFINITIONS

4. SYMBOLS AND ABBREVIATED TERMS

5. OBJECTIVES

6. TECHNICAL REQUIREMENTS

7. ADMINISTRATIVE REQUIREMENTS


0 background

0. Background

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • RoHS and other mandates

  • Commercial market impact on military electronics

  • Increased reliability risks

  • No drop in replacement for SnPb solder


0 background1

0. Background

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • For over fifty years, the electronics industry has relied on tin-lead (SnPb) solder as the primary means of interconnection between electronic devices. The reliability of SnPb interconnections is well known, well studied, and well documented. The European Union’s (EU) Restriction of Hazardous Substances[1] (RoHS) directive and other international and domestic mandates to eliminate materials deemed hazardous has forced the electronics industry to adopt solders free of lead (Pb). While military electronics have received exclusions from these Pb-free imperatives, the reality is that the consumer marketplace drives the electronic industry, not the military. To remain competitive electronics companies and their suppliers worldwide must change to solders and materials compatible with Pb-free assembly. Electronics for high reliability applications, such as the military, rely heavily on commercial components, and, in some cases, circuit boards, assemblies, and equipment, the majority of which have been or will be transitioned to Pb-free. Based on the scientific information available today, there are increased reliability risks due to the implementation of Pb-free into military electronics. These risks are the spontaneous formation of tin whiskers from pure tin (Sn) finishes, reduced Pb-free solder joint reliability, limited rework opportunities from copper dissolution, cross-contamination between the different alloys, and the potential damage from higher Pb-free processing temperatures. Because there is no drop-in replacement for SnPb solder, the conversion of the commercial supply chain to Pb-free components, circuit boards, and assemblies requires due diligence to ensure that the reliability of military electronics is maintained and not adversely impacted from the unwitting introduction of Pb-free. This Lead Free Control Plan (LFCP) for the Crane Division, Naval Surface Warfare Center (NSWC Crane) provides such due diligence. [1] Sometimes referred to as Reduction of Hazardous Substances (RoHS)


1 scope

1. Scope

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • Policies, processes, documentation

  • Inherent risks to Pb-free

  • Risk management processes

  • Implementation of Pb-free is limited

  • Other Pb-free uses are prohibited


1 scope1

1. Scope

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • This LFCP describes the policies, authorized soldering processes, and reference documents NSWC Crane uses to ensure that its deliverable electronic products will satisfy the applicable requirements for performance, reliability, safety, and certifiability throughout the lifecycle as the global electronics industry transitions to Pb-free. This LFCP addresses the inherent risks with Pb-free, defines the limited acceptable uses of Pb-free, and provides risk management processes relating to new product build, rework, repair, component acquisition, and commercial-off-the-shelf (COTS) procurement, as well as the flow-down of these processes and requirements to all lower-tier suppliers.

  • All electronic assemblies, equipment, and systems supplied by NSWC Crane shall meet the reliability and product lifecycle requirements of the applicable program specification. Introduction of Pb-free is limited to the authorized soldering processes (SnPb, 1, 2, 3, or 4) described below in paragraph 6.2.3. This LFCP prohibits uses of Pb-free solders for assembly, rework, and repair unless there is sufficient documented data to indicate continued reliable performance as defined by the program specification. For COTS procurements where Pb-free is likely to be unavoidable, processes 5 and 5a in paragraph 6.2.3. apply.

  • This LFCP is a baseline document in that it describes policies, authorized processes, and reference documents that are common to most NSWC Crane products and programs. Some applications may have unique requirements that exceed the scope of this baseline LFCP. In those cases, modifications will be negotiated with the customer and formally documented as an addendum to this LFCP.


1 1 exclusions

1.1 Exclusions

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • Specialized solder alloys

  • Non-tactical equipment

  • COTS NOT excluded when in critical applications


1 1 exclusions1

1.1 Exclusions

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • This LFCP does not preclude the use of specialized solder alloys other than Sn37Pb eutectic solder required for high operating temperature, low temperature step soldering, RF applications, etc. as required by program specification.

  • This LFCP excludes commercial non-tactical equipment, such as oscilloscopes, cameras, and personal computers etc., that support ongoing work activities in non-critical environments. This exclusion does not apply to any commercial equipment used in mission critical systems and/or safety of flight circumstances.


Inclusions exclusions

Inclusions/Exclusions

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

Non-Tactical Equipment

MissionCriticalSafety ofFlight


2 references

2. References

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • NAVSURFWARCENDIVCRANEINST 4855.10

  • NAVSURFWARCENDIVCRANEINST 4855.18B

  • IPC-A-610

  • J-STD-001

  • IPC-7711/7721

  • NAVAIR 01-1A-23NAVSEA SE004-AK-TRS-010/2M


2 references1

2. References

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • J-STD-609

  • GEIA-STD-0005-2

  • GEIA-STD-0005-3

  • GEIA-STD-0006-1


3 terms and definitions

3. Terms and Definitions

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • IPC T-50


4 symbols and abbreviated terms

4. Symbols and Abbreviated Terms

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • HSD – hot solder dip

  • Pb – lead

  • Sn – tin

  • Sn37Pb – 63% tin 37% lead eutectic solder


5 objectives

5. Objectives

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • To meet the reliability and product lifecycle requirements of the specific program specification and produce high reliability military (Class III) electronic products

  • To maintain control of the configurations of all systems, equipment, assemblies, and sub-assemblies, as required by the specific program

  • To avoid, transfer, or mitigate the increased risks factors for military high-reliability electronics that the global transition to Pb-free has introduced


5 objectives1

5. Objectives

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • To introduce no additional limitations of use for the electronic assemblies bought, built, reworked, or repaired in accordance with this LFCP

  • To require the repair, maintenance, and support activities under NSWC Crane comply with this LFCP

  • To apply the requirements of this LFCP to any outsourced products procured by NSWC Crane, except as excluded in paragraph 1.1


5 objectives2

5. Objectives

N S W C C r a n e L e a d F r e e C o n t r o l P l a n

  • To meet the reliability and product lifecycle requirements of the specific program specification and produce high reliability military (Class III[1]) electronic products

  • To maintain control of the configurations of all systems, equipment, assemblies, and sub-assemblies, as required by the specific program

  • To avoid, transfer, or mitigate the increased risks factors for military high-reliability electronics that the global transition to Pb-free has introduced

  • To introduce no additional limitations of use for the electronic assemblies bought, built, reworked, or repaired in accordance with this LFCP

  • To require the repair, maintenance, and support activities under NSWC Crane comply with this LFCP

  • To apply the requirements of this LFCP to any outsourced products procured by NSWC Crane, except as excluded in paragraph 1.1

  • [1] Per J-STD-001 and IPC-A-610.


  • 6 technical requirements

    6. Technical Requirements

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.1 Risks and Limitations of Use

    • 6.2 Risk Management

    • 6.3 Reliability

    • 6.4 Processes and Materials

    • 6.5 Configuration Control and Product Identification

    • 6.6 Aircraft Wiring


    6 1 risks and limitations of use

    6.1 Risks and Limitations of Use

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.1.1 Tin whiskers

    • 6.1.2 Solder joint reliability

    • 6.1.3 Copper dissolution

    • 6.1.4 Cross-contamination

    • 6.1.5 Processing temperatures


    6 1 risks and limitations of use1

    6.1 Risks and Limitations of Use

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • The transition to Pb-free in military high-reliability electronics has introduced a number of increased risk factors; including:

      • Tin Whiskers—Pure Sn finishes have a propensity to whisker

      • Solder Joint Reliability—Largely unknown for Pb-free used in military environments

      • Copper Dissolution—Limits rework and repair opportunities

      • Cross-Contamination—The reliability impact of mixing Pb-free alloys with other Pb-free alloys and/or SnPb is largely unknown

      • Higher Processing Temperatures—Greater potential for damage to the circuit boards and/or components can exist

    • The authorized soldering processes (SnPb, 1, 2, 3, or 4) identified in paragraph 6.2.3. avoid these risk factors except for in some cases tin whiskers, which require mitigation per GEIA-STD-0005-2. For COTS bought per processes (5 or 5a), these risk factors must be accepted except for tin whiskers, which can be mitigated per GEIA-STD-0005-2.

    • The authorized soldering processes (SnPb, 1, 2, 3, or 4) defined in paragraph 6.2.3. introduce no additional limitations of use for the electronic assemblies bought, built, reworked, or repaired in accordance with this LFCP. For COTS bought per processes (5 or 5a), no such assertion is made.


    6 1 1 tin whiskers

    6.1.1 Tin Whiskers

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Electrically conductive, crystalline structures

    • Can grow to lengths of several millimeters


    6 1 1 tin whiskers1

    6.1.1 Tin Whiskers

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Tin whiskers are pure tin crystal conductive filaments which can result in pin to pin or pin to trace shorting. The formation of tin whiskers is a means of stress relief of compressive forces within the tin. Contributing conditions are known, but not well understood. The exact event or sequence of events that result in the start of a tin whisker is being researched. Driven by the transition to Pb-free products, tin whiskers pose major safety, reliability, and potential liability threats to all makers and users of high reliability electronics and associated hardware. Hardware manufacturers do not have many options. The primary means of mitigation are component termination retinning and conformal coating. Retinning is required when addressing safety of flight where loss of aircraft or injury to flight crew may exist. Retinning brings with it the possible introduction of latent component defects as well as the associated increased material costs. Determination of the risk is established through a platform risk analysis. All conformal coating will likely require a change to existing processes. The appropriate selection of conformal coating may also change. Issues of rework or method of application are driving factors that must likewise be addressed. None of the existing approaches are totally sufficient to control tin whiskering in high-reliability systems.


    6 1 2 solder joint reliability

    6.1.2 Solder Joint Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Little long-term field reliability data on LF in military environments

    • Reliability of solder joint indications

      • LF more than SnPb in low stress conditions

      • LF less than SnPb in high stress conditions


    6 1 2 solder joint reliability1

    6.1.2 Solder Joint Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Insufficient data exist to validate whether Pb-free solder is reliable enough to sustain military hardware through the lifecycle of the system. The existing data from controlled studies indicates that Pb-free solder typically outperforms Sn37Pb solder under low stress conditions (For example for SAC305 was able to out perform SnPb with stress level below 5% of the ultimate strength) and SnPb solder outperforms Pb-free solder under higher stress conditions. With no drop-in replacement for Sn37Pb solder, a multitude of alternative Pb-free alloys are available. The general trend of the commercial industry has been SAC305. Due to the demand for higher mechanical shock/vibration performance SAC105 is now being considered. A low level of indium (In) is also being assessed to lower the melting point for rework/repair applications and devices where significant thermal mass influences the required dwell-time during assembly process.


    6 1 3 copper dissolution

    6.1.3 Copper Dissolution

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Dissolution of copper as a result of exposure to molten solder

    30.64μm

    0.00μm


    6 1 3 copper dissolution1

    6.1.3 Copper Dissolution

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • The higher Sn content and increased temperatures used in Pb-free soldering processes greatly increase the dissolution rate of copper from traces, plated-through holes, and pads exposed to the liquid solder during assembly and rework/repair. Under common conditions, the dissolution rates may be so high that plated-through-holes and pads are almost completely dissolved within 20 to 30 seconds using solder fountain methods. Multiple studies have identified that the copper dissolution rate of SnCu and SnAgCu alloys soldered through-hole circuit boards is so great that an assembly can be reworked a maximum of one time using the solder fountain method, an unacceptable consequence for military hardware with a lifecycle of 20-30 or more years.


    6 1 4 cross contamination

    6.1.4 Cross-Contamination

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Alloy Proliferation

    • One study shows 0.5% Pb in Pb-free solder reduces reliability by 50%

    • Placing a SnPb component in a Pb-free CCA could cause serious reliability issues

    • Compatibility between alloys is unknown


    6 1 4 cross contamination1

    6.1.4 Cross-Contamination

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • As Pb-free COTS hardware is introduced into legacy SnPb systems, the potential for cross-contamination of metallurgies during rework is greatly increased. This will be complicated further by the replacement of SnPb finished piece-parts with Pb-free finishes. During the rework process, mixing metallurgy is a major concern for the long-term reliability of the product. A Pb-free BGA placed in a SnPb assembly using SnPb rework procedures will result in significantly reduced reliability and premature failure. A SnPb finished piece-part placed in a COTS Pb-free assembly containing a Bismuth alloy will also have reduced reliability. The intentional or unintentional mixing of SnPb and Pb-free solder and piece-part finishes will increase the risk of cross-contamination throughout a products service life and during each rework cycle.

  • 6.1.4.1 Pb-free Terminations in SnPb Joints

    • The variety and compositions of the Pb-free surface finishes being delivered into the electronics industry is extensive. From a solder joint reliability viewpoint, most Pb-free piece-part finishes are compatible with SnPb solder and processes. The exceptions are area array BGA and CSP components whose attachment spheres do not fully melt when processed using SnPb procedures. While the impact is not universal, the causes for these solder joint integrity issues must be prevented through piece-part and assembly alloy validation prior to rework. This LFCP prohibits the introduction of Pb-free area array components into assemblies containing SnPb solder alloys.


  • 6 1 4 cross contamination2

    6.1.4 Cross-Contamination

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.1.4.2 SnPb Terminations in Pb-free Joints

      • The introduction of SnPb terminated components in a Pb-free solder system is likely during the early stages of Pb-free assembly processing while the piece-part supply stream still contains SnPb terminated components. In addition, fine pitch leaded components <0.65mm (0.025”) have been granted an EU exemption and may continue to be available with SnPb finish. Concerns exist when SnPb finished components are introduced into Pb-free solder alloys containing Bismuth.

    • 6.1.4.3 Bismuth

      • The addition of bismuth (Bi) to SAC yields a solder joint with improved reliability. However, when Bi and Pb are intermixed in the solder joint, a low melting point SnBiPb ternary alloy can form under certain situations. The melting point of the ternary alloy is 96°C causing the solder joint to be susceptible to partial reflow during hot mission environments.


    6 1 4 cross contamination3

    6.1.4 Cross-Contamination

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.1.4.4 SnPb Finish in SnBi Solder Alloy

      • Trace amounts of Pb have a detrimental effect on solder life of SnAg and SAC solders containing 3-5% Bi in the solder alloy and resulted in catastrophic failure of Sn58Bi solder joints. Since the repair infrastructure may have both SnPb and Pb-free alloy configurations for a significant amount of time, it is imperative that parts screening be conducted to identify component termination finish. SnPb finished components shall not be used to assemble or rework Pb-free assemblies containing Bi in the solder alloy.

    • 6.1.4.5 SnBi Finish in SnPb Solder Alloy

      • In the transition to Pb-free electronics, some piece-parts are now only available with a SnBi termination finish. Testing shows that a SnBi termination finish containing 2-4% Bi is not detrimental to SnPb solder life. The use of SnBi termination finishes where the Bi content is ≤4% is permissible in SnPb soldered assemblies.


    6 1 5 processing temperatures

    6.1.5 Processing Temperatures

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Pb-free alloys melt ~30° C over SnPb

    • Potential damage to piece parts and circuit boards


    6 1 5 processing temperatures1

    6.1.5 Processing Temperatures

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Pb-free solders typically have melting points 30-40°C higher than SnPb solder, require a longer dwell time to acquire fully liquidous state, and require changes to the flux properties. This requires a significant process change from the traditional SnPb methods. For systems designed and produced using SnPb, a major concern in the switch to Pb-free solders is the impact higher reflow temperatures have on materials designed and qualified for SnPb processing. Pb-free soldering processes impart significant stress on laminate and component materials. Common problems include board delamination and warping, popcorn cracking, and molding compound delamination from the lead frame. For new system acquisition, the issue of material selection must be actively addressed to avoid like situations.


    6 2 risk management

    6.2 Risk Management

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    6.2.1 Risk Assessment

    6.2.2 Risk Response Strategies

    6.2.3 Risk Management for Pb-free

    6.2.4 Commercial-Off-The-Shelf (COTS) Equipment


    6 2 1 risk assessment

    6.2.1 Risk Assessment

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    6 2 risk management1

    6.2 Risk Management

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Employment of risk management and risk management principals is required to deal with the identified Pb-free risk factors to eliminate or at least minimize any potential negative impact on the performance and reliability of military electronics performing in military environments.

  • 6.2.1 Risk Assessment

    • The most effective form of risk assessment is quantitative. Unfortunately, at this time there is little in the way of meaningful data with respect of Pb-free performing in military environments from which to conduct such a quantitative analysis. No one can say with any certainty that because of tin whiskers (or any other risk factor) the reliability of a system will be reduced by a specific percentage. Therefore, a qualitative risk assessment is in order. Figure 1 is a qualitative analysis of the probability and impact of each risk factor identified previously.

    • The probability that tin whiskers will form approaches certainty when 100%Sn component termination finishes are used. However, for the various tin whisker variables, the probability is much less sure: the number of whiskers that will form; the lengths to which will grow; will any reach and short adjacent terminations; will any fracture, fall off, and cause shorts; etc. This makes the potential impact range for tin whiskers from moderate to quite high. The assessment of copper dissolution is similar to tin whiskers with the probability of occurrence being high and the potential impact ranging from moderate to high. The risk factor, cross-contamination, differs with respect that its potential impact ranges from very low to moderate. Processing temperatures has similar impact range as cross-contamination, but its probability of occurrence is moderate. Finally, the risk factor, solder joint reliability, has a moderate probability of occurrence, but its potential impact covers the whole spectrum from low to high.


  • 6 2 2 risk response strategies

    6.2.2 Risk Response Strategies

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Acceptance

    • Avoidance

    • Transfer

    • Mitigation


    6 2 risk management2

    6.2 Risk Management

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.2.2 Risk Response Strategies

      • There are four types of response strategies to manage or counter risks having negative impacts:

        • Accept—do nothing and deal with the impact should it occur

        • Avoid—eliminate the threat or the possibility of having any impact

        • Transfer—shift responsibility to another party, (i.e. warranties)

        • Mitigate—reduce the probability of occurrence and/or reduce the impact if it does occur

    • 6.2.3 Risk Management for Pb-free

      • As described previously, the increased risk factors resulting from the transition to Pb-free in military high-reliability electronics are tin whiskers, solder joint reliability, copper dissolution, cross-contamination, and increased processing temperatures. Table 1 shows the limited introduction of Pb-free at NSWC Crane and how risk management will be accomplished through the risk response strategies employed. The columns first categorize the solder, component, and board finish variables; followed by the risk response strategy for each of the risk factors identified; and finally, name the column with a solder process identifier. For the risk response strategy blocks, the green (avoid) blocks denote no increased risk; the yellow-green (mitigate/accept) show little increased risk; the yellow (mitigate) show low to moderate increased risk; and the red (accept) blocks show moderate to high increased risk.


    Risk factors

    Risk Factors

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Tin Whiskers

    • Solder Joint Reliability

    • Copper Dissolution

    • Cross Contamination

    • Processing Temperatures

    • Component Reliability


    6 2 3 risk management for pb free

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    6 2 3 risk management for pb free1

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    6 2 3 risk management for pb free2

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    6 2 risk management3

    6.2 Risk Management

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.2.3 Risk Management for Pb-free

      • One of the potential risk management techniques hot solder dipping (HSD) does itself create an additional risk factor–component reliability. HSD reprocesses pure Sn component terminations by adding at least 3% Pb. Because HSD does reheat the component, there is potential for introducing latent defects.

      • Of the seven processes identified above in Table 1, the standard and preferred soldering process in use at NSWC Crane for all applications is:

      • SnPb process—Sn37Pb solder/SnPb board finish/SnPb component termination finishes. The SnPb Process consists of the Sn37Pb[1] solder alloy[2]; the board finish contains a minimum of 3% Pb; and the component termination finishes also contain a minimum of 3% Pb.


    6 2 3 risk management for pb free3

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    6 2 3 risk management for pb free4

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    Au

    NiPd

    NiPdAu

    ENIGImAg

    OSP


    6 2 3 risk management for pb free5

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    HotSolder

    Dip


    6 2 3 risk management for pb free6

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    Pure Tin


    6 2 3 risk management for pb free7

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    Authorized soldering processes

    Authorized Soldering Processes

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    Process 1

    • Sn37Pb solder

    • non-Sn Pb-free component termination finishes

    • non-Sn or SnPb board finish

  • Requires written customer approval


  • Authorized soldering processes1

    Authorized Soldering Processes

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    Process 2

    • Sn37Pb solder

    • reprocessed Pb-free Sn termination finishes

    • non-Sn or SnPb board finish

  • Requires tin whisker mitigation

  • Requires written customer approval


  • Authorized soldering processes2

    Authorized Soldering Processes

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    Process 3

    • Sn37Pb solder

    • pure Sn component termination finishes

    • non-Sn or SnPb board finish

  • Requires tin whisker mitigation

  • Requires written customer approval


  • Authorized soldering processes3

    Authorized Soldering Processes

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    Process 4

    • Sn37Pb solder

    • pure Sn component termination finishes

    • pure Sn board finish

  • Requires tin whisker mitigation

  • Requires written customer approval


  • 6 2 risk management4

    6.2 Risk Management

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.2.3 Risk Management for Pb-free

      • The soldering processes authorized by NSWC Crane for assembly, rework, and repair relative to Pb-free are as follows:

      • Process 1—Sn37Pb solder/non-Sn or SnPb board finish/non-Sn Pb-free component termination finishes. Process 1 consists of the Sn37Pb5solder alloy6; the board finish is non-Sn or contains a minimum of 3% Pb; and/or the component termination finishes are non-Sn (e.g. gold, nickel palladium, nickel palladium gold). The use of process 1 requires written customer approval.

      • Process 2—Sn37Pb solder/non-Sn or SnPb board finish/reprocessed Pb-free Sn component termination finishes. Process 2 consists of the Sn63Pb37 solder alloy; the board finish is non-Sn or contains a minimum of 3% Pb; and the component termination finishes are reprocessed [hot solder dipped (HSD)] per GEIA-STD-0006 to contain a minimum of 3% Pb. Because of potential reliability issues, the use of process 2 requires written customer approval. Process 2 mandates using tin whisker mitigation per GEIA-STD-0005-2.


    6 2 risk management5

    6.2 Risk Management

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.2.3 Risk Management for Pb-free

      • Process 3—Sn63Pb37 solder/non-Sn or SnPb board finish/pure Sn component termination finishes. Process 3 consists of the Sn63Pb37 solder alloy6; the board finish is non-Sn or contains a minimum of 3% Pb; and the component termination finishes are pure Sn. Because of potential reliability issues, the use of process 3 requires written customer approval. Process 3 mandates utilizing tin whisker mitigation per GEIA-STD-0005-2.

      • Process 4—Sn63Pb37 solder/pure Sn board finish/pure Sn component termination finishes. Process 4 consists of the Sn63Pb37 solder alloy6 with the board finish and the component termination finishes are pure Sn. Because of potential reliability issues, the use of process 4 requires written customer approval. Process 4 mandates utilizing tin whisker mitigation per GEIA-STD-0005-2.

      • Note: Components, circuit boards, and assemblies that are no longer available in SnPb will trigger a process change..


    6 2 3 risk management for pb free8

    6.2.3 Risk Management for Pb-free

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    6 2 4 cots equipment

    6.2.4 COTS Equipment

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n


    Cots soldering processes

    COTS Soldering Processes

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    Process 5

    • Pb-free solder

    • Pb-free component finish

    • Pb-free board finish

  • Requires tin whisker mitigation

  • Requires written customer approval

    Process 5a

  • No tin whisker mitigation

  • Requires written customer approval


  • 6 2 4 cots equipment1

    6.2.4 COTS Equipment

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • The use of COTS is being mandated as part of acquisition reform and is becoming increasingly prevalent in military electronic equipment. In some cases, this equipment may be in mission critical systems and/or in safety of flight situations. Being commercial, COTS is more than likely to be Pb-free, as the commercial manufacturers are being forced to Pb-free as part of RoHS and other legislative mandates. This creates a huge burden on the DoD acquisition community as Pb-free is unproven in military environments. The same reliability concerns addressed herein apply to COTS used in military equipment.

    • Special care must be taken to understand and address the reliability concerns that Pb-free presents for COTS equipment. The use of COTS in mission critical and/or in safety of flight circumstances requires an addendum to this LFCP to address the inclusion of Pb-free.

    • The remaining two processes identified above in Table 1 are reserved for COTS procurements where there is no viable alternative to Pb-free:

    • Process 5—Pb-free solder/board finish/component termination finishes. Process 5 consists of no Pb in the solder alloy, the board finish, and the component termination finishes. Because of potential reliability issues, the use of process 5 requires written customer approval. Process 5 mandates utilizing tin whisker mitigation per GEIA-STD-0005-2.

    • Process 5a—Pb-free solder/board finish/component termination finishes. Process 5a differs from process 5 in that there is no tin whisker mitigation. Because of potential reliability issues, the use of process 5a requires written customer approval.


    6 3 reliability

    6.3 Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    6.3.1 Reliability tests and analyses

    6.3.2 Environmental and operating conditions

    6.3.3 Sources of reliability data

    6.3.4 Conversion of results from available data

    6.3.5 Reliability by similarity

    6.3.6 System reliability


    6 3 reliability1

    6.3 Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • All equipment supplied by NSWC Crane shall meet the reliability and product life requirements of the program specification. The authorized soldering processes (SnPb, 1, 2, 3, or 4) identified in paragraph 6.2.3. assure meeting these reliability requirements. The use of non-Sn (e.g. gold, nickel palladium, nickel palladium gold) as a termination finish is permitted (process 1) and presents no tin whisker risk. The use of hot solder dipping (process 2); pure Sn as a termination finish (process 3); and pure Sn as a termination and board finish (process 4) present reliability risks due to tin whiskering, but are permitted provided tin whisker mitigation per GEIA-STD-0005-2 has been utilized. Because of the acceptance of the reliability risks factors inherent with Pb-free, the use of Pb-free solders and finishes (processes 5 & 5a) for the procurement of COTS requires written customer approval.

  • 6.3.1 Reliability tests and analyses

    • Because there is increased reliability risks with HSD, reliability tests and/or analyses per GEIA-STD-0006 will be conducted on components that have had Pb-free termination finishes hot solder dipped adding a minimum of 3% Pb. Additional analyses may be conducted as directed by customer to validate reliability of the product in its intended environment. These reliability tests shall be in accordance with MIL-STD-883 (method 5004), MIL-STD-19500, MIL-STD-202, IPC 9701, GEIA-STD-0005-3, and/or other approved document as appropriate.


  • 6 3 reliability2

    6.3 Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.3.2 Environmental and operating conditions

      • The lifecycle environmental and operating conditions of a given piece of equipment shall be determined according to the requirements as defined in the customer’s statement of work (SOW), specification control drawings, and/or request for quotation. In the absence of definitive lifecycle environmental and operating conditions, the assumed default condition shall be Class III3.

    • 6.3.3 Sources of reliability data

      • The following Pb-free datasets are the basis for NSWC Crane’s Lead-Free Solder Joint Integrity Knowledge Base.

        • University of Maryland CALCE studies

        • Joint Group on Pollution Prevention/Joint Council on Aging Aircraft (JG-PP/JCAA)

        • IPC Solder Products Value Council Report

        • iNEMI studies

        • HDPUG studies

        • Internal studies


    6 3 reliability3

    6.3 Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.3.4 Conversion of results from available data

      • NSWC Crane’s electronics assemblies bought, built, reworked, or repaired in accordance with the authorized soldering processes (SnPb, 1, 2, 3, or 4) defined in paragraph 6.2.3. assures that all equipment supplied by NSWC Crane will meet the reliability requirements of the program specification. COTS bought per processes (5 or 5a) have no such assurance. Should the customer direct additional analyses through the conversion of results from one set of environmental or operating conditions to another, these analyses shall be in accordance with MIL-STD-883 (method 5004), MIL-STD-19500, MIL-STD-202, IPC 9701, GEIA-STD-0005-3, and/or other approved document, as appropriate.


    6 3 reliability4

    6.3 Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.3.5 Reliability by similarity

      • NSWC Crane’s electronics assemblies bought, built, reworked, or repaired in accordance with the authorized soldering processes (SnPb, 1, 2, 3, or 4) defined in paragraph 6.2.3. assures that all equipment supplied by NSWC Crane will meet the reliability requirements of the program specification. COTS bought per processes (5 or 5a) have no such assurance. Should the customer direct additional analyses through the comparison of similar equipment for which reliability has been demonstrated through testing, analysis, or in-service performance, these analyses shall be in accordance with MIL-STD-883 (method 5004), MIL-STD-19500, MIL-STD-202, IPC 9701, GEIA-STD-0005-3, and/or other approved document, as appropriate, and demonstrate similarity according to the following criteria:

        • Circuit board properties

        • Circuit board final finish before solder assembly

        • Component termination finish being identical

        • Assembly operation time/temperature profile being similar

      • Other similarity criteria will be agreed upon on a case-by-case basis with the customer. Operating environment is a key consideration for agreeing on similarity claims.


    6 3 reliability5

    6.3 Reliability

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.3.6 System reliability

      • NSWC Crane’s electronics assemblies bought, built, reworked, or repaired in accordance with the authorized soldering processes (SnPb, 1, 2, 3, or 4) defined herein assures that all equipment supplied by NSWC Crane will meet the system reliability requirements of the program specification. COTS bought per processes (5 or 5a) have no such assurance.


    6 4 processes and materials

    6.4 Processes and Materials

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    6.4.1 Assembly

    6.4.2 Repair, rework, maintenance, and support

    6.4.3 Cleaning

    6.4.4 Handling and storage


    6 4 processes and materials1

    6.4 Processes and Materials

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.4.1 Assembly

      • The assembly processes conducted and materials used shall be in accordance with the following standards:

        • NSWCDIVINST 4855.18BElectrostatic Discharge (ESD) Control Program

        • NSWCDIVINST 4855.10Soldering Program

        • J-STD-001 Requirements for Soldered Electrical and Electronic Assemblies

        • J-STD-002 Solderability Tests for Component Leads, Terminations, Lugs, Terminals and Wires

        • J-STD-003 Solderability Tests for Printed Boards

        • J-STD-004 Requirements for Soldering Fluxes

        • J-STD-005 Requirements for Soldering Pastes

        • J-STD-006 Requirements for Electronic Grade Solder Alloys and Fluxed and Non-Fluxed Solid Solders for Electronic Soldering Applications

        • IPC-4101 Specification for Base Materials for Rigid and Multilayer Printed Boards

        • IPC-4202 Flexible Base Dielectrics for Use in Flexible Printed Wiring

        • GEIA-STD-0006 Requirements for Using Solder Dip to Replace the Finish on Electronic Components


    6 4 processes and materials2

    6.4 Processes and Materials

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.4.2 Repair, rework, maintenance, and support

      • All data, information, and procedures required to conduct repair and rework shall be incorporated into this LFCP as addendum(s) and made available to those responsible for repair, rework, maintenance, and support.

      • Repair and rework of sub-assemblies shall be conducted according to the processes documented in NSWCDIVINST 4855.18B. Processes for repair and rework of sub-assemblies not covered in NSWCDIVINST 4855.18B, IPC-7711/7721 // IPC-A-610 or NAVAIR 01-1A-23 // NAVSEA SE004-AK-TRS-010/2M shall be documented and incorporated into this LFCP as addendum(s).

    • 6.4.3 Cleaning

      • The cleaning processes shall be done and materials selected per the manufacturers’ recommendations or in accordance with J-STD-001.

    • 6.4.4 Handling and storage

      • Handling and storage of solder materials and of assemblies and sub-assemblies shall be done according to NSWCDIVINST 4855.10 and NSWCDIVINST 4855.18B.


    6 5 configuration control identification

    6.5 Configuration Control & Identification

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    6.5.1 Termination material and finish alloy

    6.5.2 Solder alloys used

    6.5.3 Surface finish on bare circuit boards

    6.5.4 PCB base material categories

    6.5.5 Conformal coating

    6.6 Aircraft wiring


    6 5 configuration control identification1

    6.5 Configuration Control & Identification

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • The use of the authorized Pb-free soldering processes (SnPb, 1, 2, 3, or 4) identified in paragraph 6.2.3. does not constitute a configuration control change unless dictated by customer requirements. Any other change (different components, etc.) may invoke the customer’s configuration change process.

    • The use of the assembly, rework, or repair processes in this LFCP may drive part number changes. Any requests for part number changes shall be made to and approved by the cognizant engineering authority.

    • All components, circuit boards, and assemblies are required to be labeled in accordance with J-STD-609 as per the following paragraphs.


    6 5 configuration control identification2

    6.5 Configuration Control & Identification

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.5.1 Termination material and finish alloy

      • NSWC Crane shall identify the types of termination materials and finish alloy compositions of components using X-ray fluorescence (XRF), Energy Dispersive X-ray analysis (EDX) or similar methodologies. Lot sampling verses 100% inspection is acceptable. A vendor’s Certificate of Compliance does not eliminate the requirement for XRF or EDX verification. Compliant parts will be marked in such a manner that users, maintainers, and repairers of the equipment have sufficient information to perform their functions reliably.

      • Termination material and finish alloy compositions of components shouldbe labeled per J-STD-609, as space permits. NSWC Crane will identify the Material Category (MC) designation on the topside of individual components (if space permits) with the MC enclosed within a circle, ellipse, underlined, or in parentheses. If the second level interconnect termination finish or material is removed and replaced on a component, the original ‘e’ code marking on that physical component shall be obscured and the component shall be remarked with the new applicable ‘e’ code.

      • Where possible, component termination finishes that do not whisker shall be selected for use.


    6 5 configuration control identification3

    6.5 Configuration Control & Identification

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.5.2 Solder alloys used

      • For new build products, the solder authorized and used on sub-assemblies shall be labeled per J-STD-609. If two or more solder alloy categories are used, the solder categories will be shown in the following sequence: reflow, wave, and other.

      • When performing rework, NSWC Crane shall maintain the correct category codes and marking sequences as part of rework, repair, or modification where markings were included as part of the manufacturing process. If alternate solder alloys are approved for use, the original solder category code shall be permanently obscured as part of the rework procedure.

      • For COTS products, the solder authorized and used on sub-assemblies should be labeled per J-STD-609.


    6 5 configuration control identification4

    6.5 Configuration Control & Identification

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.5.3 Surface finish on bare circuit boards

      • NSWC Crane shall identify the surface finish used on bare circuit boards in such a manner that users, maintainers, and repairers of the equipment have sufficient information to perform their functions reliably. Alloy identification shall be verified using XRF, EDX or similar methodologies.

      • For new build products, NSWC Crane shall provide board assembly markings. Surface finish used on bare circuit boards shall be labeled per J-STD-609. The preferred location for marking of the categories is on circuit board layer 1 (topside) at the lower right hand segment, next to the board part/serial number or next to the company logo. The marking sequence should be clearly identifiable and separate from other board markings.

      • For COTS products, the circuit board surface shouldbe labeled per J-STD-609.


    6 5 configuration control identification5

    6.5 Configuration Control & Identification

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.5.4 PCB base material categories

      • NSWC Crane will identify the PCB base material used in circuit boards using the Specification Sheet (“slash-sheet”) number classification system found in IPC-4101 in such a manner that users, maintainers, and repairers of the equipment have sufficient information to perform their functions reliably. For new build products, PCB base material used shall be labeled per J-STD-609.

      • If the base materials used in making the bare circuit boards are halogen-free, the label/marking “HF” shall be noted on the bare board. If no “HF” is present, a halogen-containing base resin and reinforcement matrix are assumed. This marking applies only to the PCB base material and is not to be interpreted as an indication of a halogen-free (HF) assembly.

      • For COTS products, the circuit board base material should be labeled per J-STD-609.


    6 5 configuration control identification6

    6.5 Configuration Control & Identification

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 6.5.5 Conformal coating

      • NSWC Crane shall identify the conformal coating category used on circuit boards found in IPC-CC-830 in such a manner that users, maintainers, and repairers of the equipment have sufficient information to perform their functions reliably. For new build products, Conformal coating material used shall be labeled per J-STD-609.

      • When performing rework, NSWC Crane shall maintain the correct category codes and marking sequences as part of rework, repair, or modification where markings were included as part of the manufacturing process. If alternate conformal coatings are approved for use, the original conformal coating category code shall be permanently obscured as part of the rework procedure.

      • For COTS products, the conformal coating material code should be labeled per J-STD-609.


    6 6 aircraft wiring

    6.6 Aircraft wiring

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Aircraft wiring shall be in accordance with the program’s contractual requirements as defined in the customer’s SOW.


    7 administrative requirements

    7. Administrative Requirements

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    7.1 LFCP focal authority

    7.2 LFCP applicability

    7.3 LFCP implementation

    7.4 LFCP acceptance

    7.5 LFCP modifications

    7.6 Requirements for suppliers and subcontractors

    7.7 Verification

    7.8 Renewal


    7 administrative requirements1

    7. Administrative Requirements

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 7.1 LFCP focal authority

      • The focal authority for this LFCP is the NSWC Crane Chief Technology Officer who is responsible for maintaining, updating, executing, and communicating all issues related to the document. The identity of the focal authority will be made known to all internal and external stakeholders.

    • 7.2 LFCP applicability

      • This LFCP shall apply to all electronic products in any stage of processing at NSWC Crane except for the specified exclusions identified herein.

      • The requirements of this LFCP shall be imposed on all applicable subcontracts, assembly drawing(s), documentation, and purchase orders. When it is unclear where flow-down should stop, it is the responsibility of the manufacturer to establish that determination with the customer. Unless otherwise specified, the requirements of this LFCP are imposed on the procurement of COTS assemblies or subassemblies used in fielded military systems.


    7 administrative requirements2

    7. Administrative Requirements

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 7.3 LFCP implementation

      • NSWC Crane shall implement only the authorized soldering processes documented in this LFCP.

      • The introduction of Pb-free will cause changes to the acquisition processes to ensure that the components, circuit boards, and assemblies are of the alloy(s) intended. The acquisition and management processes adopted by NSWC Crane with respect to Pb-free are as follows:

        • Train purchasing, receiving and assembly personnel on handling procedures to avoid confusion between Pb and Pb-free components.

        • Verify finish on all Bill of Material components.

        • Require a part number change for all components no longer available in SnPb.

        • Require a Certificate of Conformance with all purchases.

        • Impose J-STD-609 labeling of all acquired components, circuit boards, and assemblies.

        • Perform 100% inspection of components provided without a Certificate of Conformance.

        • Perform random inspection of all components unless sampling inspection is defined as part of a documented process control plan.

    • 7.4 LFCP acceptance

      • Upon signature of the Commanding Officer, this LFCP becomes the policy of NSWC Crane.


    7 administrative requirements3

    7. Administrative Requirements

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • 7.5 LFCP modifications

      • This LFCP may be modified by adding, deleting, or changing one or more clauses. In the event that this baseline LFCP is modified to satisfy the requirements of an individual product, program, or customer, the baseline LFCP shall remain in effect, and identified according to its current document and revision number. The modified LFCP is considered an addendum and shall be given a new, unique document designation. An addendum requires signature by the focal authority.

      • In the event that this baseline LFCP is permanently modified, it shall be superseded by the modified LFCP, which then becomes the new baseline LFCP.

    • 7.6 Requirements for suppliers and subcontractors

      • The requirements of this LFCP apply to all NSWC Crane suppliers and subcontractors.

    • 7.7 Verification

      • The soldering processes described herein are verified and approved by the focal authority for use at NSWC Crane for the assembly, rework, or repair of circuit boards and sub-assemblies.

    • 7.8 Renewal

      • This LFCP shall be reviewed annually and updated as necessary by the focal authority.


    Acquisition process

    Acquisition Process

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Train purchasing, receiving and assembly personnel

    • Verify finish on all piece parts

    • Require a part number changes when no longer SnPb

    • Require a Certificate of Conformance

    • Impose J-STD-609 labeling

    • Perform 100% inspection

    • Perform random inspection of all piece parts


    What needs to be done

    What Needs to be Done

    N S W C C r a n e L e a d F r e e C o n t r o l P l a n

    • Inspection criteria and process(es)

    • Acquisition process


    Summary

    Summary

    • Who we are

    • What we do

    • Why we are involved with Pb-free

    • LFCP


    Conclusions

    Conclusions

    • The decisions made today will affect sailors, airmen, and soldiers for many years to come


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