Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


SMT

cman

#23606

SMT | 3 March, 2003

In a short time, I will be manufacturing a mixed board. On the primary side, I have through hole and SMT combination. On the secondary side, I have SMT only. I produced Through hole and SMT in the past, but not in the same board. What is the best process to use? Thanks.

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MA/NY DDave

#23612

SMT | 3 March, 2003

Hi

I have seen a few different ways to do this, including hand solder for certain PIH (pin in hole) components as the last operation.

Search the archives would be one place for you to look Buy or Borrow one of the SMT Books out in the market. There are a pile of them. Obtain some IPC documents, they might even have a video. One caution is that IPC can be pricey sometimes.

YiEng, MA/NY DDave

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Matherat

#23658

SMT | 5 March, 2003

Our company does not assemble boards but our customers do and 2 side smd with through hole is pretty common in our experiences.Our customers usually have already decided to glue the bottom side components and fuse them during the wave solder process. The drill goes like this.

Paste and place (or ssd) the top side, go through reflow

Flip the board, glue the bottom side, run through low temp bake to set glue. Usually around 125C for 60-90 seconds I think but check with your vendor to be sure.

Flip again, insert the through hole parts and wave solder where the bottom side smt components pick up their solder.

If you prefer to reflow both sides at once you can ssd on both sides minus the adhesive flux. Bring the boards in, glue the bottom side components onto the ssd's. Flip it over, print adhesive flux (much easier than printing paste) place components, spray flux the bottom side and single pass reflow both sides at once.

mkehoe@sipad.net

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#23701

SMT | 7 March, 2003

Hi,what do you use? Reflow oven or wave?

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cman

#23746

SMT | 10 March, 2003

We have both, reflow and wave solder. Planning on PTH and secondary SMT through Wave solder; then reflow primary SMT.

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Stephen

#23747

SMT | 10 March, 2003

May I be the first to ask, how you plan on applying paste to the primary SMT? You won't be able to stencil it on as is typical. Do you have a paste dispenser? Also a lot of PTH parts can not take reflow temperatures, not even all SMT parts can. (been there done that, oops)

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#23750

SMT | 11 March, 2003

Ok. The best ways: 1.Wave A.Secondary side(SMD only)with glue. B.Primary side (smd+TH) c.Wave both sides(or wave and reflow)

2.If you can't solder the primary side or you don't use dispenser use classic way with reflow and trough hole at the end of the process.

Your idea is near the first way which I think is better,but it depends on your equipment at all(using dispenser or not).There might be problems with reflow primary side after wave secondary. Wish you good luck!

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Essemtec Spider SMT Fluid Dispenser

Heller Industries Mark 5获得了 2015年中国SMT远见奖 - 回焊炉领域