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Reflow soldering through hole parts

BScholl

#5079

Reflow soldering through hole parts | 29 January, 2001

I have been told that is is possible to reflow solder through hole components. Can anyone confirm this is being done reliably? If so, what are the required equipment, steps and processes? What is the reliability of the solder joints? Is this a generally accepted practice?

Thanks in advance for your help!

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#5082

Reflow soldering through hole parts | 29 January, 2001

It's common. We've talked about it here several times. Hopefully the fine SMTnet Archive that are available are helpful. If there not talk back.

Other sites that are sources of information are: * SMT Magazine * Bob Willis * Phil Zarrow * Amp[connectors]

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#5083

Reflow soldering through hole parts | 30 January, 2001

Bill,

We do solderpaste reflow on through-hole here every day on plated-thru-holes. We do it on connectors only. It is a reliable process. We use no special profile. The stencil apertures must be modified for this process. Check out the IPC-7525 "Stencil Design Guidelines". The stencil ap mods are in there. The joints can be as reliable as any other solder method provided the stencil ap mods are done to get the correct volume of paste and you have a good process. There's only one little thing we're wotking on correcting. When the lead is inserted thru the hole it displaces the paste that covers the hole to the end of the lead. After reflow there is a solder bead at the tip of the lead. Its just a "visual" thing. Its not a problem provided you've got a good fillet in the hole barrel per IPC-A-610 Rev. C.

Pete

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#5090

Reflow soldering through hole parts | 30 January, 2001

Pete,

I'm wondering how much optimisation you needed (or were allowed) to do with respect to connector design. The first one we evaluated had a row of leads that I can only describe as "crescent" shaped in cross section. Impossible to get even 50% fill with the stencil that we started with, and further paste volume analysis provided us with requirements for aperture diameters that exceeded the lead pitch of the connector.

Even stepping up the stencil thickness wasn't going to give us what we needed. Design was commited to this connector, so we commited to waving it.

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Dason C

#5093

Reflow soldering through hole parts | 30 January, 2001

You can also check Alpha Metals web site for some information.

http://www.alphametals.com/products/pin-in-pasteprocess.html

Rgds. Dason

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#5101

Reflow soldering through hole parts | 31 January, 2001

Steve,

I have no influence over conn design. We paste print-reflow solder two types of connectors. One is a 50 pin IDC w/ 0.5mm lead dia @ 2.54mm lead pitch and a chamfered pointed lead tip. The other is 32 pin DIP w/ 0.36mm lead dia @ 2.54mm pitch and a rounded lead tip. As you can see both these connectors are large pitch so the enlarged apertures do not cause bridging. There is good solder flow thru the hole usually just meeting the solder land on the bottom side. No solder "climbing" up the lead on the bottom side. Other important elements are PCB holes that are at least 0.4mm larger in dia than the lead dia as well as proper sized solder lands as per IPC guideline. Hope this helps.

Pete

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#5105

Reflow soldering through hole parts | 31 January, 2001

Thanks, Pete. In our case I think the device is just too much of a challenge to take on as a first try at the process. The reduction in lead volume from the optimum round lead to the "crescent" shape pretty much sunk us from the get-go. Just couldn't get enough paste in the hole to make up for that skinny lead.

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