SAE GEIA-HB-0005-3-2008 Rework Repair Handbook to Address the Implications of Lead-Free Electronics and Mixed Assemblies in Aerospace and High Performance Electronic Systems (Forme.pdf

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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/GEIAHB0005_3 TECHNICAL REPORT Issued 2008-09 Reaffirmed 2015-09 Rework/Repair Han

5、dbook to Address the Implications of Lead-Free Electronics and Mixed Assemblies in Aerospace and High Performance Electronic Systems RATIONALE GEIA-HB-0005-3 has been reaffirmed to comply with the SAE five-year review policy. NOTICE This document has been taken directly from the original TechAmerica

6、 document and contains only minor editorial and format changes required to bring it into conformance with the publishing requirements of SAE Technical Standards. The release of this document is intended to replace the original with the SAE International document. Any numbers established by the origi

7、nal document remain unchanged. The original document was adopted as an SAE publication under the provisions of the SAE Technical Standards Board (TSB) Rules and Regulations (TSB 001) pertaining to accelerated adoption of specifications and standards. TSB rules provide for (a) the publication of port

8、ions of unrevised specifications and standards without consensus voting at the SAE committee level, and (b) the use of the existing specification or standard format. GEIA-HB-0005-3 TechAmerica Engineering Bulletin Rework/Repair Handbook to Address the Implications of Lead-Free Electronics and Mixed

9、Assemblies in Aerospace and High Performance lectronic Systems EGEIA-HB-0005-3 September 2008 GEIA-HB-0005-3NOTICE TechAmerica Engineering Standards and Publications are designed to serve the public interest by eliminating misunderstandings between manufacturers and purchasers, facilitating intercha

10、ngeability and improvement of products, and assisting the purchasers in selecting and obtaining with minimum delay the proper product for their particular needs. Existence of such Standards and Publications shall not in any respect preclude any member or nonmember of TechAmerica from manufacturing o

11、r selling products not conforming to such Standards and Publications, nor shall the existence of such Standards and Publications preclude their voluntary use by those other than TechAmerica members, whether the standard is to be used either domestically or internationally. Standards and Publications

12、 are adopted by TechAmerica in accordance with the American National Standards Institute (ANSI) patent policy. By such action, TechAmerica does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Standard or Publication. Technical Publicat

13、ions are distinguished from TechAmerica Standards in that they contain a compilation of engineering data or information useful to the technical community and represent approaches to good engineering practices that are suggested by the formulating committee. This Bulletin is not intended to preclude

14、or discourage other approaches that similarly represent good engineering practice, or that may be acceptable to, or have been accepted by, appropriate bodies. Parties who wish to bring other approaches to the attention of the formulating committee to be considered for inclusion in future revisions o

15、f this publication are encouraged to do so. It is the intention of the formulating committee to revise and update this publication from time to time as may be occasioned by changes in technology, industry practice, or government regulations, or for other appropriate reasons. (Formulated under the co

16、gnizance of the TechAmerica (APMC) Avionics Process Management Committee and the (G-12) Solid State Devices Committee. This is a joint activity of the Aerospace Industries Association (AIA), Avionics Maintenance Conference (AMC), and TechAmerica, to address aerospace issues related to the global eli

17、mination of lead from electrical and electronic equipment put on the market after July 1, 2006. Formed in 2004, this coalition includes all stakeholders (market segments, supply chain, geographic regions.) Published by 2010 TechAmerica Standards ” February 2004, ver. 1.0 Altera Corporation Applicati

18、on Note 353, “Reflow Soldering Guidelines for Lead-Free Packages,” July 2004, ver.1.0 Peter Biocca (Kester) White Paper, “Lead-free hand-soldering - ending the nightmares,” http:/ Altera Corporation Application Note 81, “Reflow Soldering Guidelines for Surface-Mount Devices,” June 2002, ver. 4 3.0 T

19、erms and Definitions For purposes of this document, the following terms and definitions apply: Alloy Composition is stated as weight in percent. For instance 63Sn-37Pb corresponds to a mixture of 63% by weight of Tin (Sn) and 37% by weight of Lead (Pb). Assemblies are electronic items that require e

20、lectrical attachments, including soldering of wires or piece part terminations; examples include circuit cards and wire harnesses. 2 GEIA-HB-0005-3 Backwards Compatibility refers to Pb-free materials compatible with a SnPb process. Ball Grid Array (BGA) is a surface mount package type that uses a gr

21、id of solder balls arranged in an array to provide direct electrical interconnection between the part substrate and the circuit board. Coefficient of Thermal Expansion (CTE) is the linear dimensional change of a material per unit change in temperature. Conductive refers to the use of a contact heat

22、source such as a soldering iron, hot bar, or resistance to transfer heat to the assembly. Convective refers to the use of a non-contact heat source usually heated air, Nitrogen or infrared light to transfer heat to the assembly. Copper Dissolution is the excessive loss of copper from plated-through-

23、hole barrels and pads caused by wave or solder fountain processing primarily with high Tin (Sn) content solders. Critical item or function, if defective, will result in the systems inability to retain operational capability, meet primary objective, or affect safety. Customer refers to an entity or o

24、rganization that (a) integrates a piece part, soldered assembly, unit, or system into a higher level system, (b) operates the higher level system, or (c) certifies the system for use. For example, this may include end item users, integrators, regulatory agencies, operators, original equipment manufa

25、cturers (OEMs), and subcontractors. Delamination is a separation between plies within a base material, between a base material and a conductive foil, or any other planar separation with a printed board that may propagate under thermal stress. Depot Level Maintenance (D) is maintenance requiring majo

26、r overhaul or a complete rebuilding of parts, assemblies, subassemblies, and end items, including the manufacture of parts, modifications, testing, and reclamation as required. Depot maintenance serves to support lower categories of maintenance by providing technical assistance and performing that m

27、aintenance beyond their responsibility. Dissolution is the process in which one substance is dissolved in another by chemical action. Electroless Nickel / Immersion Gold (ENIG) is a two technology process for the application of a desired finish where Nickel is applied using Electroless plating, requ

28、iring the presence of a proper reducing agent in a plating bath that converts the metal salts into metal and deposits them onto the substrate. The immersion plating process deposits a new metal surface (Gold) by replacing the base metal; in this process, plating stops when the surface of the base me

29、tal is completely covered, thus only a limited coating thickness can be obtained through the immersion process. The control of the kinetics associated with both processes is vital to plating results. 3 GEIA-HB-0005-3 Eutectic (Solder) is the alloy composition at which a solder alloy melts/freezes co

30、mpletely without going through a pasty (partially solid) phase. High Performance System requires continued performance or performance on demand, or equipment down time cannot be tolerated, or end-use environment may be uncommonly harsh, and the equipment must function when required, such as life sup

31、port or other critical systems. Intermediate Level Maintenance (I) includes limited repair of commodity-orientated piece parts and end items, job shop, bay, and production line operations for special mission requirements; repair of printed circuit boards, software maintenance, and fabrication or man

32、ufacture of repair parts, assemblies, piece parts. Intermediate maintenance consists of repair of aircraft and engine components, WRAs, and LRUs forwarded to the Intermediate level Navy (AIMD) or USAF Back Shops by the organizational level flight-line activities. WRA and LRU repair is accomplished b

33、y the removal, troubleshooting, and replacement of faulty SRA and SRU, pieces, and parts within the WRA/LRU. Lead (Pb) in this document, if the element “Lead” is implied, it will be stated as either Pb or as Lead (Pb). Lead-Free (Pb-free) is defined as less than 0.1% by weight of Pb in accordance wi

34、th Waste Electrical and Electronic Equipment (WEEE) guidelines. Lead-Free Control Plan (LFCP) refers to an aerospace or military system suppliers document that defines the processes that assure the plan owners, their customers, and all other stakeholders that aerospace and high performance high-reli

35、ability electronics systems containing Pb-free solder will continue to be reliable, safe, producible, affordable, and supportable. Technical guidance for a LFCP can be found in GEIA-HB-0005-1. Line Replaceable Unit (LRU) is a black box of electronics removed and replaced at the flight-line level. Li

36、quidus is the minimum temperature at which all components of a mixture (such as an alloy) can be in a liquid state. Below liquidus, the mixture will be partly or entirely solid. Measling is a condition that occurs in laminated base material in which internal glass fibers are separated from the resin

37、 at the weave intersection. This condition manifests itself in the form of discrete white spots or “crosses” that are below the surface of the base material. Organic Solderability Preservative (OSP) is a thin organic compound that selectively bonds with Copper (Cu) used to preserve the solderability

38、 of bare Cu on printed wiring boards (PWBs). Organizational Level Maintenance (O) is maintenance normally performed by an operating unit on a day-to-day basis in support of its own operations. Organizational-level maintenance typically includes “inspections,“ “servicing,“ “handling,“ and “preventive

39、 maintenance” and is limited to the replacement of electronics assemblies at the WRA and LRU (black box) level of 4 GEIA-HB-0005-3 major aircraft and engine components. An exception is U.S. Navy ships, where troubleshooting and piece parts level repair are accomplished at the Organizational level. P

40、b-free Tin is any Tin alloy with 95% wt Sn) used in through-hole wave soldering has created rework/repair issues with solder fountain methods. Solder fountain rework/repair of connectors and other multi-termination piece parts is causing excessive dissolution of the PWB pad and barrel. In some cases

41、 where prolonged time in the solder wave can occur, one Pb-free rework/repair can completely dissolve the plated hole at the knee. Under common conditions, the dissolution rates may be so high that traces are almost completely dissolved within 20 to 30 seconds. Stabilized alloys composed of Sn, Cu,

42、and small amounts of Ni have proven to offer several advantages for wave soldering applications, including 10 GEIA-HB-0005-3 brighter solder joints, low Copper Dissolution rates comparable to SnPb, good flow characteristics, and reduced defects such as bridges and icicles. Due to the high probabilit

43、y of Copper Dissolution in high Sn content Pb-free alloys, solder fountain rework/repair using these alloys should be avoided. Continuous vacuum extraction methods should be employed to maximize plated-through-hole integrity allowing for potential future rework/repair. Separate solder fountains shou

44、ld be maintained in situations where rework/repair is being performed on legacy SnPb and Pb-free assemblies. See Paragraph 7.2 for additional solder fountain details. 6.0 Materials 6.1 Solder Some examples of solder alloy types are listed below. 6.1.1 Solder Alloys IPC/JEDEC J-STD-609 designations (

45、e0 e9) are listed after some of the common Pb-free alloys: Contains Pb 0.1 Wt % e0 Tin-Silver-Copper (SAC) family of alloys; e1 Tin-Copper; e2 Tin-Copper-Nickel “Stabilized”; e2 Other alloys containing Bismuth; e6 Tin-Silver-Copper-Bismuth (SACB); e6 Solders containing Indium; e7 Melting temperature

46、 is less than 302F (150C) Other Pb-free alloys Currently over 200 different formulations exist 6.1.2 Solder Forms Pb-free solder is available in many of the same forms as SnPb solder including wire, paste, spheres, ribbon or foil, ingot or bar, and preforms. Pb-free solders may not be easily disting

47、uishable from SnPb solders or other Pb-free alloys so it is important for technicians to keep all solder alloy materials clearly marked in the manufacturers original packaging. Wire solder or solder paste with missing labels may render the material unidentifiable without testing. It is especially im

48、portant to maintain 100% control of solders where multiple alloys are present at the rework/repair station and cross contamination could occur if mixed. 6.1.2.1 Solder Wire A wide range of solid and flux-cored Pb-free solder wire is commercially available. The diameters for rework/repair have not ch

49、anged with standard sizes between 0.062” and 0.015” 11 GEIA-HB-0005-3 being common. Due to the inherent stiffness of Pb-free solder wire, some Pb-free alloys are difficult or impossible to extrude in the 0.010” diameter. 6.1.2.2 Solder Paste In appearance Pb-free and SnPb solder paste look identical. At least one manufacturer has tinted the flux