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| February 10, 2012
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Circulation Over 51,000
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December 7, 2009
SMT Component Lead Oxidation
How do you suggest we remove oxidization from SMT component leads?
The component leads are seriously oxidized due to long time storage.
E. W.
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Re-tinning by dipping into fairly aggressive flux then into molten solder is the positive method of removing oxide (and unwanted platings).
If these are fine pitch QFPs (less than 1mm centers) this becomes a challenge.
I know that Fancort offers a service to do this. Check out their website.
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Alan Cable
President
ACE Production Technologies
Alan Cable, the principle owner of ACE production technologies Inc. has over 40 years experience in the electronics manufacturing arena. Alan's expertise is high production manufacturing automation, equipment design and process engineering. For the past 25 years Alan has focused specifically on soldering issues relating to component solderability, lead tinning and selective soldering, owning several companies with this focus.
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The answer is to retin the leads to remove the oxidation and prepare the leads for the SMT operation. A wetting balance test can be performed to insure the leads meet solderability.
The leads can be dipped in either lead free or leaded flowing solder pot.
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Mark McMeen
VP Engineering Services
STI Electronics Inc.
Mark T. McMeen is STI Electronics Inc.ʼs Vice President of Engineering Services. He oversees the daily operations of the Engineering Services division of STI. He has over 18 years experience in the manufacturing and engineering of PCBs.
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To answer a question like this you need to know what the original finish was on the leads. If this is only a few components perhaps a simple flux operation may remove the oxide.
You may also want to consider flux and solder dip, to tin the leads.
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Steven Adamson
Market Specialist
Nordson ASYMTEK
Market Specialist for Nordson ASYMTEK. Mr. Adamson worked for Kodak, Motorola and Plessey, ICL in the UK with 5 US and 2 UK patents. He was awarded a HNC in electrical engineering and was 2008 President of IMAPS. Mr. Adamson was a respected mentor in the electronics industry. He passed away October, 2011. Learn about the Steve Adamson Memorial Annual Scholarship Fund.
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I would suggest you contact your solder supplier. They can evaluate the solderability of your components and recommend a suitable flux.
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Edward Zamborsky
Regional Sales Manager
OK International Inc.
Mr. Zamborsky serves as one of OK's technology advisers to the Product Development group. Ed has authored articles and papers on topics such as; Low Volume SMT Assembly, Solder Fume Extraction, SMT Rework, BGA Rework, Lead Free Hand Soldering, Lead Free Visual Inspection and Lead Free Array Rework.
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This kind of depends on the termination style - leaded components can be pre-tinned using more active flux if necessary to break down the oxide layer. Chip components are trickier and replacement with new components should be considered.
Prevention, of course, is the preferred route and if long term storage is likely then vacuum packing is a good option to prolong solderability shelf life.
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Bryan Kerr
Principal Engineer - CMA Lab
BAE Systems
Bryan Kerr has 35 years experience in providing technical support to PEC assembly manufacturing. His experience ranges from analysis of materials and components to troubleshooting and optimizing, selecting reflow, cleaning, coating and other associated processes.
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Since you had observed the oxidationin SMT Component you have to check the Moisture sensitive level of the component.
The JDEC standard deeply explain the self life of the SMT components as well as the storage condition. If the component is to old (i.e the component stored for long time more than the self life), I would suggest not to use the component.
The JDEC standard will help you more in this issue.
The JDEC standard also explain how to increase the self life of the component.
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Sandip Thakor
Quality Engineer
Matrix Telecom Solution P Ltd
Sandip Thakor has 9 years of experience in electronics industry specializing in soldering technology. Thakor has experience in lead free installation, process optimization and developing quality standards.
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