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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Immersion silver leaching.

Dougie

#27939

Immersion silver leaching. | 7 April, 2004

Hi,

We are Scottish manufacturing company considering a move to Immersion Silver finished PWB's from HASL. The driver behind it being the RoHS and WEEE legislation in Europe at present.

My question is...

We plan on using a Sn/Cu/Ni solder bar in our wave process. Does anyone out there have any experience of using Immersion silver boards with a similar/silver free wave soldering material?

My fear is that leaching will occur over time and the bath will have to be treated for silver impurities.

Any help much appreciated.

Dougie.

reply »

Dougie

#27940

Immersion silver leaching. | 7 April, 2004

Hi,

We are Scottish manufacturing company considering a move to Immersion Silver finished PWB's from HASL. The driver behind it being the RoHS and WEEE legislation in Europe at present.

My question is...

We plan on using a Sn/Cu/Ni solder bar in our wave process. Does anyone out there have any experience of using Immersion silver boards with a similar/silver free wave soldering material?

My fear is that leaching will occur over time and the bath will have to be treated for silver impurities.

Any help much appreciated.

Dougie.

reply »

#27941

Immersion silver leaching. | 7 April, 2004

In addition to your concerns about leaching, why aren't you concerned about: * Tin whiskers * Total absence of in use reliability information about no-lead, especially given that creep is significantly different between SnPb and no-leads.

While they have nothing to do with in-use [they report results of accelerated laboratory testing], there are reports about leaching of silver in no-leads on the net, for instance: http://eerc.ra.utk.edu/ccpct/lfsp-docs/Solder_Leachate_Report1.doc

reply »

Dougie

#27965

Immersion silver leaching. | 8 April, 2004

We are concerned about the issues you mentioned and more, however we have no option but to change over due to legislation. A high percentage of our market share is in Europe and Japan, who of course have already embraced the no-lead change. We simply won't be able to function as a business without going ahead with this. You'd also be surprised how much reliability information is available. Indium, Alpha, Kester et al have rafts of data as they have been running lead free processes globally for a number of years now.

Thanks for the link.

Dougie.

reply »

Ken

#27982

Immersion silver leaching. | 9 April, 2004

I have experience in this. My company offers Lead free SMT and Wave soldering. I have processed ImSn, ImAg, Enig, OSP in both smt and wave.

Yes, silver leaching will occur. Yes, copper leaching will occur. High tin content solders disolve everything readily with the exception of titanium, tungsten etc.

what is your end market? Consumer, industrial, high reliability?

reply »

Dougie

#28026

Immersion silver leaching. | 13 April, 2004

Hi Ken,

Our product is consumer, although our product is sold on it's reliability. We run a low volume high mix throughput. Any ideas on timescale for the Ag leaching?

Sounds like it could be a safer bet to use Imm Sn boards with the Sn/Cu/Ni bar we intend to use in the wave.

Dougie.

reply »

SMT Services - STI Electronics

table top X-ray inspection