I am looking for an IPC spec for intentional PCB warp

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My customer made a process change to overcome a design flaw.... - Dec 22, 2014 by ProcEng1

Basically the contract comes first, then the design drawings... - Dec 22, 2014 by adam

I know the contract rules, but this is idiotic. I did find ... - Dec 23, 2014 by ProcEng1

ProcEng1

#73260

I am looking for an IPC spec for intentional PCB warp | 22 December, 2014

My customer made a process change to overcome a design flaw. The PCB assembly mounts in a plastic housing. The PCB mounts to the front housing via plastic stand-offs. They had to change a connector on the back side of the assembly due to long term availability. This cause a small clearance issue with the rear housing.

To fix this, they have instructed us to trim one of the 4 stand-offs shorter by .160" to pull that corner down to clear the rear housing. So 3 corners of the PCB are the same height, and one corner is 0.160 lower, intentionally bowing the PCB. We can't shorten all 4 due to a clearance on the front side.

The mounting hole pattern is 2.7" x 3.4". Diagonally to the lower post is 4.35" from the opposite corner.

I'd like to be able to quote an IPC Spec against doing this to hopefully encourage a better solution from them, or at least give me an "I told ya so" to cover my own butt should problems arise later.

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adam

#73262

I am looking for an IPC spec for intentional PCB warp | 22 December, 2014

Basically the contract comes first, then the design drawings then IPC. if your costumer is asking you to bend the PCB then it becomes apart of the design drawings. as for looking for a cover, get it in writing that that's what they want you to do. IPC610-E 1.2 "if the assembly does not comply with these or equivalent requirements, the acceptance criteria shall be defined between the customer and the supplier."

otherwise..

IPC-TM-650, 2.4.22 https://www.ipc.org/TM/2.4.22c.pdf

Or IPC-610-E 10.2.6 They say should not exceed 1.5% for PTH or 0.75% for SMT

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ProcEng1

#73267

I am looking for an IPC spec for intentional PCB warp | 23 December, 2014

I know the contract rules, but this is idiotic. I did find the 10.2.6 spec already, but I had not looked at the TM-650. I'll check that out, thanks.

I also may have found another part that has a better clearance, so I also hope to use these specs to encourage changing the part again. We'll see how it goes.

Thanks Adam

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