Solder vendors: 'no difference' in tested SAC alloys.Bannockburn, IL -- A group of leading vendors of solder in November released white paper findings that "no significant difference" exists between a trio of heavily researched lead-free alloys. The lead-free pastes were found to result in less bridging but more voiding than a tin-lead eutectic control. In a 16-page report, the IPC (1) (InterProcess Communication) The exchange of data between one program and another either within the same computer or over a network. It implies a protocol that guarantees a response to a request. Solder Products Value Council (ipc.org) announced results of a down-select process of six tin-silver-copper solder pastes and subsequent PCB PCB: see polychlorinated biphenyl. PCB in full polychlorinated biphenyl Any of a class of highly stable organic compounds prepared by the reaction of chlorine with biphenyl, a two-ring compound. assembly comparing three of the alloys and a tin-lead solder paste. [TEXT NOT REPRODUCIBLE IN ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. ] The SVPC SVPC Single Variable Per Constraint SVPC Scroll View Page Counter is made up of 17 solder vendors who aim to achieve worldwide consensus on a standard lead-free alloy. The paper details the second of a three-phase, $1 million program testing tin-silver-copper alloys. Five solder manufacturers submitted paste samples for the anonymous testing anonymous testing Public health The testing of an individual for certain infections, in particular, HIV, providing the results to public health departments without identifying that person by name, but rather by a number. Cf Named reporting. , which was conducted by an independent party. The pastes studied: 96.5/3.0/0.5 tin/silver/copper, 95.5/3.8/0.7 tin/silver/copper and 95.5/4.0/0.5 tin/silver/copper. Engent AAT Alpha-1-antitrypsin (AAT) A blood component that breaks down infection-fighting enzymes such as elastase. Mentioned in: Chronic Obstructive Lung Disease (engentaat.com) tested one alloy per vendor using tin-lead eutectic paste as a control. Testing was performed on FR-4 boards using surface finishes of immersion silver, OSP (Online Service Provider) See online service. OSP - Optical Signal Processor , electroless nickel/immersion gold (ENIG ENIG Electroless Nickel Immersion Gold (printed circuit board manufacturing process) ) and bare copper and components with tin and tin-silver-copper finishes. Tests performed included: reproducibility of printed paste volume, solder paste wetting and spread, and interconnect voiding. Next, two major EMS companies, Flextronics and Solectron, built a total of 200 assemblies each, using the three alloys and a tin-lead control. The companies then studied the three pastes for testability, rework and repair, handling and storage, printing, reflow and cleaning. There was "no significant difference" between the lead-free solders, they found. However, in general the tin-lead paste outperformed the lead-free alloys. According to the report, "Submitted samples ... showed that, in general, the lead-free pastes were not as well-defined or as repeatable as tin-lead solder paste nor was their slump performance as good as tin-lead solder paste. This was most likely due to the use of a generic print process that was not optimized for each material." The lead-free pastes also resulted in less bridging but more voiding than the control paste, the paper notes. The final report is due in early 2005 and will include results and analysis of long-term and thermal-shock reliability testing. Edited by Mike Buetow |
|
||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion