Hi Dave, Thank-you for your email and pointers .Yes , we are doing root cause analysis for the solderability issues and trying to optimize the reflow profile using SAC alloys to avoid change of solder. Appreciate all you r insight into the passive solderablty issues.
Thank-you
Mumtaz
858-795-0112
Peregrine Semiconductor
From: David Hillman [mailto:[log in to unmask]]
Sent: Tuesday, July 28, 2015 2:51 PM
To: TechNet E-Mail Forum; Mumtaz Bora
Subject: Re: [TN] Soldering NiPdAu finish components with low melt solder
Hi Mumtaz - just my opinion but I would not go to a low temperature alloy for the issue you detailed as there should be other root causes that are the problem. My guess is that you have a solderability or pad geometry or some other contributing issue. One possible root cause would be that the passive components being soldered do not have a termination barrier layer. Lead-free solders are have aggressive dissolution rates and if your passive components don't have a termination barrier layer (typically copper or nickel) then the soldering process may be leaching the termination finish completely into the solder joint allowing for the issue you are seeing. A simple fix would be to use a better quality part and not have a complex soldering process with two alloys.
Dave
On Tue, Jul 28, 2015 at 12:26 PM, Mumtaz Bora <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hello Mike, Thank-you for your pointers regarding low melt solders. Much appreciated .
The soldering is using reflow oven, not hand soldering. The concern is some passives are not soldering very well and falling off the board with the SAC alloys, so one recommendation is to switch to low melt solders.
Thank-you
Mumtaz
858-795-0112<tel:858-795-0112>
Peregrine Semiconductor
-----Original Message-----
From: Mike Fenner [mailto:[log in to unmask]<mailto:[log in to unmask]>]
Sent: Sunday, July 26, 2015 8:44 AM
To: 'TechNet E-Mail Forum'; Mumtaz Bora
Subject: RE: [TN] Soldering NiPdAu finish components with low melt solder
Are you hand soldering or possibly have an oven with small number of zones?
I assume the driver here is difficulty of getting the joints to flow because of the heat sinking effect of the ground plain, and possible concerns for heat damage through prolonged heating times.
Low melting alloys such as SN/Bi [and its modified variants] may not improve matters. It's the tin that does the work in solder joint formation and in these low melting alloys it's relatively dilute so lower to work. In addition there is less energy due to the lower temperatures so the rate of joint formation is slow compared to eutectic and SAC types. If you then add NiPdAu to the mix that is decidedly not going to help. That stuff can be pretty close to wood in soldering terms.
Flux performance can be similarly impaired. If you are hand soldering by all means have a go, but you might find it is better to adjust tool performance so that you get a rapid rise to soldering temperatures before the heat sinking flattens you and/or to have some background heating to reduce the burden on local heating.
Don't forget that if choosing a lower MP alloy you are reducing the operating temperature range of your product and possibly reducing its life if it sees a lot of temperature cycling in service.
--
Regards
Mike Fenner
Bonding Services & Products
M: +44 [0] 7810 526 317<tel:%2B44%20%5B0%5D%207810%20526%20317>
T: +44 [0] 1865 522 663<tel:%2B44%20%5B0%5D%201865%20522%20663>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf Of Mumtaz Bora
Sent: Thursday, July 23, 2015 3:46 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [TN] Soldering NiPdAu finish components with low melt solder
Dear All, Good Morning, Looking for some knowledge base on soldering
NiPdAu finished components with low melt solder such as Sn42.0Bi57.6Ag0.4 to avoid wetting issues on a heavy copper plane board. Any insight and advise will be appreciated.
Thank-you
Mumtaz
858-795-0112<tel:858-795-0112>
Peregrine Semiconductor
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