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Ag/Pd Component Finish

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AR

#42479

Ag/Pd Component Finish | 29 June, 2006

We are experiencing some difficulties with reflow soldering a 1210-sized MOV with silver/palladium finish. The PCB finish is SAC. When inspecting the board after reflow it seems that nearly all solder is gone both from the pads and the component terminations. The component is only soldered underneath the termination, no evidence of meniscus of any kind. All the other types of components solder just fine, including some ferrite-core inductors. The paste composition is Sn/Ag/Cu 95.5/3.8/0.7

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#42480

Ag/Pd Component Finish | 29 June, 2006

Hi I manufacture a range of components with Ag,Pd,Pt terminatons. Has the solder wetted to the componet and is the termination still left on the component? I would expect the solder to remain on the pad though, if all your other devices on the pcb are soldering ok it should still be there. One good thing, for leach resistance and wetability i would recomend SAC387 anyway.

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AR

#42487

Ag/Pd Component Finish | 29 June, 2006

Hi Slaine,

The terminations are still present on the component but all the solder (including the pad finish) has coalesced on to the terminations. The termination that normally is shiny and bright in colour has turned matte grey on that zone where the solder from the paste and the pads has crept up the termination. There is no solder left on the pads at all save a few solder balls and an untidy-looking blotch of flux. It is as if the pad had been cleaned with solder wick. The component does sit firmly on the pads although there is no meniscus so I assume that some soldering effect has occurred. But it certainly isn't conforming to any IPC standards.

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RDR

#42491

Ag/Pd Component Finish | 29 June, 2006

Any possiblity that there are vias in the affected pads?

Russ

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AR

#42500

Ag/Pd Component Finish | 29 June, 2006

No, no vias anywhere near the affected area

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#42509

Ag/Pd Component Finish | 30 June, 2006

Hi If all the solder has collected onto the component termination then it sounds more of a PCB problem then a component problem. Some times all the temination can be stripped off the ceramic with high tin content solders and leave a gray finish behind (glass frit). To check this if you give it a scrape it should be bright and shiny underneath if it not the metalisation has been applied incorrectly.But if this had happened i would expect the solder to be on the pad. Have you tried soldering to some of the componets with an Iron to see what happens?

Pehaps you could post some photos or sent them to me?

hope this helps Slaine

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AR

#42510

Ag/Pd Component Finish | 30 June, 2006

Hi

All the other components on the PCB solder just fine, including resistors, ceramic capacitors, inductors, SOT23 etc. etc. so I do not think that it is a PCB problem. It is clearly focussed on this single component.

Haven't yet tried scraping or soldering with an iron. Will do it soon, thanks for the hint.

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visitor

#42573

Ag/Pd Component Finish | 6 July, 2006

I have question,is this the only Ag/Pd component in your board? If yes then concentrate on this component, I would suggest evaluating other component of the same value with Tin terminations. If I am not mistaken Ag/Pd plated components termination are more costly the Tin plated ones and this might be a good justification besides the soldering issue.

I hope this would help.

Kind regards

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AR

#42594

Ag/Pd Component Finish | 7 July, 2006

Hi

Yes, this is the only component with Ag/Pd finish. I found that by applying a copious amount of solder on the pad (we are using a dispenser) the component will be soldered. Although most of the solder coalesces on the terminations of the component there still is a sufficient amount of solder left on the pads for some kind of meniscus formation. Not pretty though.

I have ordered samples with different finish, I expect them to rectify the situation.

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