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range decreases. SAC performs better than Sn-Pb at the less extreme cycling conditions. Another advantage of SAC is that it appears to be more resistant to gold embrittlement than Sn-Pb. In test results, the strength of the joints is substantially higher for the SAC alloys than the Sn-Pb alloy. Also,
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The process requirements for (Pb-free) SAC solders and Sn-Pb solders are different both materially and logistically for electronic assembly. In addition, the reliability of Sn-Pb solders is well established, while SAC solders are still undergoing study, (though much work has been done to justify the
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In 2003, tin-silver-copper was being used as a lead-free solder. However, its performance was criticized because it left a dull, irregular finish and it was difficult to keep the copper content under control. In 2005, tin-silver-copper alloys constituted approximately 65% of lead-free alloys used in
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microstructures that are not as thoroughly studied as current tin-lead solder microstructures. These concerns are magnified by the unintentional use of lead-free solders in either processes designed solely for tin-lead solders or environments where material interactions are poorly understood. For
88:. For example, the common "SAC305" solder is 3.0% silver and 0.5% copper. Cheaper alternatives with less silver are used in some applications, such as SAC105 and SAC0307 (0.3% silver, 0.7% copper), at the expense of a somewhat higher melting point.
175:, and older style plastic components. However, a number of companies have started offering 260 °C compatible components to meet the requirements of Pb-free solders. iNEMI has proposed that a good target for development purposes would be around 260
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203:(CBGA) systems, which are ball-grid arrays with a ceramic substrate. The CBGA showed consistently better results in thermal cycling for Pb-free alloys. The findings also show that SAC alloys are proportionately better in
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properties, strength, and wettability. Lead-free solder is gaining much attention as the environmental effects of lead in industrial products is recognized, and as a result of Europe's
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One important difference is that Pb-free soldering requires higher temperatures and increased process control to achieve the same results as that of the tin-lead method. The
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example, the reworking of a tin-lead solder joint with Pb-free solder. These mixed-finish possibilities could negatively impact the solder's reliability.
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and other hazardous materials from electronics. Japanese electronics companies have also looked at Pb-free solder for its industrial advantages.
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349:"The Impact of Reflowing A Pb-free Solder Alloy Using A Tin/Lead Solder Alloy Reflow Profile On Solder Joint Integrity"
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Also, SAC solders are alloyed with a larger number of metals so there is the potential for a far wider variety of
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the failure mode is changed from a partially brittle joint separation to a ductile tearing with the SAC.
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104:(WEEE). These initiatives resulted in tin-silver-copper alloys being considered and tested as lead-free
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In 2000, there were several lead-free assemblies and chip products initiatives being driven by the
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of the eutectic tin-lead (63/37) alloy. This requires peak temperatures in the range of 235–245
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Please help update this article to reflect recent events or newly available information.
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to be present in a solder joint. These more complex compositions can result in
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Can lead-free solder joints be good looking? (and give better sounds quality?)
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the industry and this percentage has been increasing. Large companies such as
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switched from using lead-containing solder to a tin-silver-copper alloy.
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Some of the components susceptible to SAC assembly temperatures are
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SAC solders have outperformed high-Pb solders C4 joints in ceramic
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use of SAC solders, such as the iNEMI Lead Free Solder
Project).
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STATS picks pure-tin solder as best lead-free packaging solution
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Lead-Free
Defects in Reflow Soldering – How to Prevent Them
270:"Difference Between Various Sn/Ag/Cu Solder Compositions"
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David
Hillman; Matt Wells; Kim Cho; Rockwell Collins.
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Lead-free SMT Soldering
Defects: How to Prevent Them
102:
Waste
Electrical and Electronic Equipment Directive
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Japan
Electronic Industries Development Association
332:Lead-free Solder Assembly: Impact and Opportunity
268:Sawamura, Tadashi; Igarashi, Takeo (2005-06-29).
57:(SMT) assembly in the industry, as it is near
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108:alternatives for array product assemblies.
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355:. American Competitiveness Institute.
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49:commonly used for electronic
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394:This article needs to be
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255:October 15, 2006, at the
124:Constraints and tradeoffs
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319:, T. DeBonis, Intel 2007
136:of SAC alloys is 217–220
76:Typical alloys are 3–4%
55:surface-mount technology
295:, eetimes, Nov 24, 2000
165:electrolytic capacitors
317:"Getting the Lead Out"
250:Lead-Free Solder FAQ’s
240:, emsnow, Feb 17, 2005
69:legislation to remove
437:Brazing and soldering
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63:thermal fatigue
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100:(JEIDA) and
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275:. Almit Ltd
106:solder ball
80:, 0.5–0.7%
427:Tin alloys
421:Categories
279:2016-08-24
236:, mirror:
216:References
195:Advantages
169:connectors
406:July 2016
39:lead-free
253:Archived
59:eutectic
37:), is a
396:updated
361:2678802
207:as the
158:wicking
154:wetting
92:History
43:Pb-free
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82:copper
78:silver
51:solder
357:S2CID
273:(PDF)
118:Intel
47:alloy
179:°C.
156:and
116:and
114:Sony
71:lead
67:RoHS
86:tin
35:SAC
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30:Cu
26:Ag
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