Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Imm Silver and Voiding

Views: 4779

Gman

#42362

Imm Silver and Voiding | 22 June, 2006

Hello, Has anyone had issues with voiding while using Imm Silver PCB finish. Does thickness of silver, contamination of the plating bath or other factors if you come point out cause voids due to the plating.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#42368

Imm Silver and Voiding | 22 June, 2006

do you mean microvoids or macrovoids??

reply »

#42390

Imm Silver and Voiding | 22 June, 2006

First, we expect voiding in imm silver to be similar to ENIG. We expect more voiding in OSP than other common solderability protection.

Second, choosing a solder paste, which does not contain resins and activators that decompose at higher temperatures, is the primary factor in void reduction.

Third, tell us more about your: * Solder paste * Thermal recipe measured at voiding site * Breadth and scope of problem

reply »

Gman

#42402

Imm Silver and Voiding | 23 June, 2006

Some amount of voiding was always seen on sites where solder paste is printed. These voids are much smaller. However the site where a flip chip is flux dipped has never had problems with voiding. Macro voids (and huge ones at that)across the board surfaced recently, both on sites with solder paste and on the flux only Flip chip. So this is not limited only to the solder paste. 2 different pastes were also tried (kester 244 and SMQ 92 J), with different profiles.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#42415

Imm Silver and Voiding | 26 June, 2006

It does make you think the immersion coating is causing the voiding, doesn't it? We never have seen that.

reply »

KEN

#42434

Imm Silver and Voiding | 26 June, 2006

We saw this condition over 3 years ago. It sometimes is called "champagne bubbles". The intemetalic formation is interrupted due to the micro voiding reducing mechanical strength. I discovered this on lead free test vehicles for a major computer manufacturer. I had BGA's popping off boards during HALT testing (literally).

Funny how plating manufacturers don't admit there is a problem but 6 months later they have a new and improved process to eliminate this problem? But I thought you said there was no problem? Check out the Cookson silver process....there should be some good info there.

reply »

GMan

#42452

Imm Silver and Voiding | 27 June, 2006

Yes it does seem like a plating issue and analysis is being done. Thank you for your inputs.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

Board House

#42457

Imm Silver and Voiding | 27 June, 2006

There was a good artical on this in Assembly Magazine October 5, 2005 by Donald P. Cullen, Director of OEM and Assembly Applications, MacDermid Inc., Waterbury, CT

Heres the Link http://www.assemblymag.com/CDA/Archives/56840a86f06c9010VgnVCM100000f932a8c0____

Might give some ideas,

also ask your board house a couple of questions, What chemisty are they using, is the process in house, does the process share any rinse tanks with anything else.

We have had sucess with Macdermid silver, we have tried others but the Macdermid was easier to control the chemisty and has been requested by many of our assembly houses.

Try to use a board shop that has the process in house, typically we have tighter controlls than the Job shops.

Regards,

Mike

reply »

Loco

#42463

Imm Silver and Voiding | 28 June, 2006

Wow, great article there mike! Thanks for digging it up for us!

Kind regards, Loco.

reply »

Gman

#42474

Imm Silver and Voiding | 28 June, 2006

Good article. Would EDX analysis of the cross-section at the void joints be a good method to determine any plating contamination or solder mask issues?

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#42478

Imm Silver and Voiding | 28 June, 2006

Yes, it would. That you are asking this question makes us wonder if you would be better advised to contract with a independent FA laboratory to help you baseline your analysis.

Among the fine labs to consider are: * Robisan Laboratory 6502 East 21 St Indianapolis, IN 46219 317-353-6249 fax 357-1270 Susan Mansilla, Technical Director robisan1@aol.com * Trace Laboratories - East 5 North Park Dr Hunt Valley, MD 21030 410.584.9099 Fax 9117 tracelab@connext.net http://www.tracelabs.com * American Competitiveness Institute One International Plaza Suite 600 Philadelphia, PA 19113 610-362-1200 Fax 1290 info@aciusa.org

reply »

SMT Equipment Online Auctions

Real-time PCB X-ray Inspection System