Been away
So my next question would have been [and still is] and it furthers the
thoughts below:...
Have you run a profiler through your oven and determined the actual
temperatures Delta T on the PCB and suspect area?
--
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: Wednesday, July 29, 2015 2:50 PM
To: [log in to unmask]
Subject: Re: [TN] Soldering NiPdAu finish components with low melt solder
Brilliant. I have seen this several times before especially with customer
supplied kits. Most parts look great one or two specific parts don't. At
first glance, looks like cold solder. This can be a serious problem when
there are two reflow cycles. If he can find those parts in the oven maybe
he can confirm, missing end caps.
Guy
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Tuesday, July 28, 2015 5:51 PM
To: [log in to unmask]
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]> 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
> Peregrine Semiconductor
>
>
> -----Original Message-----
> From: Mike Fenner [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
> T: +44 [0] 1865 522 663
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Mumtaz Bora
> Sent: Thursday, July 23, 2015 3:46 PM
> To: [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
> Peregrine Semiconductor
>
>
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