Also, I remembered you are soldering with Sn37, and that is also more forgiving.
Had it been lead-free, then there is a much higher rate of copper dissolution into the molten solder, and a more likely problem with diminishing/disappearing through-hole pads.
So you should be OK.
dean
From: Steve Gregory [mailto:[log in to unmask]]
Sent: Monday, March 25, 2019 10:12 AM
To: Stadem, Richard D
Cc: TechNet E-Mail Forum
Subject: Re: [TN] HDSP-2502 Smart Display through hole Solder Joints Failing
Hi Richard,
Thank you for confirming my suspicions. It's curious that not all displays fail, in fact it is a small but irritating percentage. We were just recently made aware of the issue. Observations made during the actual soldering operation and subsequent inspections revealed no issues, good barrel fill and good top side and bottom side fillets, and as I said we do a functional test before we ship the assemblies. I think we will adjust our KISS program to slow it down and increase dwell time over the display leads. We were hitting them at 1- 1.5-sec. dwell and we will increase that to 2-2.5-sec.
Thanks Odin!
Steve
On Mon, Mar 25, 2019 at 7:08 AM Stadem, Richard D <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hi, Steve
In looking at the data sheet, you are correct, these are Olin C194 pins, which is a very hard copper alloy that is 97% hardened and annealed copper, with 2.5% iron and .5% phosphate bronze finish for oxidation resistance. I have soldered these before in automotive and industrial applications. It may take a longer dwell time to achieve a good IMF with the hardened base copper. This, along with the fact that you have two rows of these pins encased in a silicon chip makes the package extremely stiff. These are common in applications such as automotive connectors, etc. where good resistance to corrosion is required. But they do need extra care when soldering to ensure you get a good IMF, or they crack if there is a significant CTE delta between the board and the part and they are in a harsh environment (thermal cycling and vibration during operation). I suspect that is what is happening.
I would recommend pre-tinning the leads first to get a good IMF established, then assembling and soldering the parts. That way you do not need to worry about annular ring erosion and/or damage to the component itself during normal selective/wave solder processing.
Odin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf Of Steve Gregory
Sent: Friday, March 22, 2019 2:11 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [TN] HDSP-2502 Smart Display through hole Solder Joints Failing
Hi All,
This just a shot in the dark, but have any of you used this display in a
board that experiences vibration and have the solder joints fail?
We have a board that we're building using leaded solder, and use a
selective solder to solder it into the board. We electrically test it here
before we ship it. It goes out in the field and then the display will stop
working at some point. We've gotten the boards back, and discovered that it
usually is a cracked solder joint. In fact, you can pull the display
completely out of the board, the leads pull out of the solder joints. None
of the other through hole components have any issues, and there's quite a
few other through hole components on the board.
The leads are very stiff, they are some sort of copper alloy I think.
Olin194, does that sound right? I've had a hard time finding what they are
actually made from, or what the lead finish is. Supposedly they are ROHS
compliant. They've changed names a few times, started out as Agilent, then
Avago, now Broadcom.
Like I said this is a shot in the dark...
Thanks,
Steve
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Steve Gregory
Kimco Design and Manufacturing
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