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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.



Checklist | 23 February, 2003

Anyone has the Front End Checklist (From printing, chip placement up to reflow and post solder inspection)to share? I am planning to introduce the checklist to Production line. What are the some of the to do list to watch?

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Checklist | 25 February, 2003

This might be a little more that you've bargained for, but have you had a look at IPC-S-816? Obviously it needs to be tailored to your process, your quality needs, etc.

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Jon Fox


Checklist | 26 February, 2003

1. First and foremost is paste alignment. If you start out of the gates with a bad paste/pad relationship, it will be nothing but problems down the line. AOI is not required, but dial in the alignment, QC if necessary, then introduce the boards to the line for placement. 2. Second step only applies to epoxy applications whe mixed with solder paste. (yes, I've seen it done and it is used more than you think on bottom side assemblies. Why? I think its overkill if you ask me, but some ME just feel better about it for some a teddy bear to hold if you need one) Inspect to ensure that epoxies have not mixed with paste or make sure that the solder pads are free of epoxy as this can be an issue come time for the wave. 3. Component placement. QC first runs of everything, even if you ran it yesterday. Someone might have changed a reel or a matrix tray and put it in the wrong location or replaced it with the wrong part. Most machines these days have intelligence or what not built in, but humans are humans and we all make mistakes. Once an assembly has been verified, run with it. 4. Production verification. Reel changes, changeovers (machine feeder setups), and program changes need to be verified. Its easier to catch an issue at the root of its cause than to try to figure out wy you have 500 boards that all failed test three days from now. Most operators see these things as finger pointing tools, so educate them. 5. Reflow. QC first piece out of the oven, if it looks good, run with it.

These are probably the most important steps for ensuring a quality product is being produced and that the process itself is repeatable. There's a lot of fancy stuff out there to replace a QC person (AOI), but if you take the extra 15-20 minutes up front to ensure a clean start (depending on population time of course) you can be pretty sure that things are going to be fine for the rest of the run using these steps.

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 Reflow System

Used SMT machines