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Soldering PTH Card stiffeners



Soldering PTH Card stiffeners | 13 August, 2002

Hi Folk's,

a quick and easy? question. Got a card with PTH edge stiffeners fitted to it so we need to flow solder them. Having problems getting hole fill, mainly I think due to 2 things, poor pin to hole ratio and also a bit of oxide. The question is how do these fit into IPC 610C in term's of hole fill requirements. I Think that it just fall's into the same as a std PTH hole and need's 75% min (class 2), one of my collegues say's that it doesn't matter as its non electrical so isn't covred by IPC 610 C, I can't believe this is correct, anyone got any opinions?


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Soldering PTH Card stiffeners | 13 August, 2002

A bit of gray area for you. consider the application over the specmanship. Why are the stiffeners there in the first place? Is the rigidity requirement a high function i.e. very necessary due to potential shock and vibration , etc.?

The soldering is a process decision, any variety of fasteners could have been used. Consider what force the mechanical bond is designed for, then determine how much solder is really needed. The IPC spec is not just for an electrical connection, it is conjunctive for all the reasons solder is placed in a through hole. Consider that without a well formed miniscus of top solder, the possibility of dust, liquids, etc, can be entrapped (over time) in the below grade well around the pin and cause an oxidation or premature failure of the joint.

Consider what may happen if you pull test that joint. Will the stiffener break first before the solder? Will you pull the plated barrel out of the fab with minimum solder?

Be practical first, then apply specs to set a standard, if necessary.

By the way, if you are building this assembly for a customer, what do they want? Can clear up any unnecessary academic debates if you get their spin on the issue.

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Soldering PTH Card stiffeners | 13 August, 2002

Gesh, you back from vacation already?

First the �quick and easy� part, your colleague�s argument: Get a towel. A-610, 4 - Mechanical Assembly deals with things like threaded fasteners, lock washers, burrs on screws, cable ties, lacing, and the like. There is nothing electrical about those things. They all have to do with producing a reliable product.

Now your problem: Bad, board warp or flex => stuffener <= mechanical strength, good

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