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First time with press fit assembly

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mtwieg

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I'm working on a PCB design in which I'll need to use press fit connectors for the first time. I'm seeking some advice on making sure I turn out a design which can actually be manufactured.

First of all, at what point are press fit components usually mounted during an assembly process? Before or after SMT component placement and reflow?
What supplementary materials does the assembly house typically need for working with press fit connectors? I've read that the press fit assembly often involves a PCB template (which is specific for the PCB layout) and a stamp (which is specific to the press fit component). Are these things an assembly house normally creates themselves, or do they need to be supplied with designs or actual parts, and instructions on how to use this?

Unfortunately I can't call up the fab house to ask them, since I have no idea what fab house will be selected for the task (it isn't up to me, and probably won't be until I complete the layout). But I'm still trying to get an idea of what I'm in for.
 

barry

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I used a press-fit DIN connector a number of years ago, and had to acquire a tool/fixture from the connector mfr. for pressing it into the board. It was quite expensive, as I recall, but depending on how many boards you're making, it might not matter. I was only making a few and was able to get the local rep lend me the tool. You could probably make your own, depending on time/cost etc. When you layout the board, you may have to allow some clearance for the tool; hopefully the connector mfr will give you this info.

I think it might be up to the board assembler to decide at what point they want to install the connector.
 
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mstrghettorigg

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I did couple of them while back also. The fixture was provided by the customer so I'm not sure what the cost is, but it was fairly simple metal plate with holes for the connectors so you can use a press to just push the connector together.

I think only problem I ran into was not specifying the tolerance of the hole good enough the first time around. I think it would be best to specify the tolerance of those holes as specified by the data sheet and don't use the default tolerance due to the nature of the connector.

We press fit the connector after SMT assembly. We did at the very end, but it was very low quantity and I don't have that much experience with it so there might be better solution or process for this.

Hope this helps.
 
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mtwieg

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Thanks for the replies.

The parts I'm intending to us are these power element connectors from Wurth. There's a small slideshow on using them here (on slide 14), but it's pretty vague.
Looking at the pictures, I assume the "template" is there so that you can put a PCB on a press with SMT components already assembled, and do the press without crushing the SMT components, right? So it has holes that match up with the locations of SMT components? In general, does the template need to cover a very large area, or just the area very near the press fit component? One of the documents on these parts suggests a clearance of 4mm, and I'm wondering if that's because that's how much room the template/stamp are supposed to take. If so that is pretty small.

What about if you have multiple instances of the same press fit component? Do you have one template for the entire PCB, with all the different instances together? Or do you just use on small template with one component, and just switch its location for each of the components?

From the shape of the connectors, it looks like both the template and stamp could be trivial things for a good machinist to make.
 

mstrghettorigg

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The board I worked on had press fit on upper and lower edge so the template was for the entire board. I think as long as the SMT components near the press fit is not too tall them the recommended clearance is probably fine, but it all depends on how the template is made too.

I am not an expert in this subject so please make sure to do some more research, but this is what I have encountered in the past.
 

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