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

Printed Circuit Board Assembly & PCB Design Forum

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Igmar

#12429

Pre-heat for Ceramic Capacitors | 4 March, 1999

Can someone please advise me to the rework procedure for removal and replacing Ceramic Chip Capacitors (e.g. 0805, 1206, etc.)?

Is it necessary to pre-heat ceramic capacitors before soldering them onto a PCB with a soldering iron? Is this just a recommendation or is it absolutely necessary? Thanks for any advice.

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Scott Cook

#12430

Re: Pre-heat for Ceramic Capacitors | 6 March, 1999

| Can someone please advise me to the rework procedure for removal and replacing Ceramic Chip Capacitors (e.g. 0805, 1206, etc.)? | | Is it necessary to pre-heat ceramic capacitors before soldering them onto a PCB with a soldering iron? Is this just a recommendation or is it absolutely necessary? | Thanks for any advice. | | Igmar,

The true issue here is Thermal ramping, and micro fractures in the dielectric composition of the R's & C's. It's been several years since I visited this issue, but a short time ago most passive vendors would only stand behind a 2 degree C per second ramp.

For an interesting experiment, mount a thermocouple onto a ceramic passive, and have your best rework operator remove and reattach it with a soldering iron. The thermal ramp will SCARE you.

I've seen many methods tried; two irons at once, one at each termination (to level the thermal "hit" out), selective solder, tweezer type rework, etc.

The best solution I've personally seen is a hot air pencil. Mask the surrounding area with kapton tape, flood with flux, hit with the pencil, remove with tweezers. reverse for reattach.

Maybe someone else out there can help with newer ideas here.

Question: Why are you reworking passives?

Process issue? Wrong part? Wrong profile in the wave / Reflow oven?

I'd suggest diving into your root cause, or you will be in misery forever.

Scott Cook scook@nettally.com

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#12431

Re: Pre-heat for Ceramic Capacitors | 8 March, 1999

| Can someone please advise me to the rework procedure for removal and replacing Ceramic Chip Capacitors (e.g. 0805, 1206, etc.)? | | Is it necessary to pre-heat ceramic capacitors before soldering them onto a PCB with a soldering iron? Is this just a recommendation or is it absolutely necessary? | Thanks for any advice. | | Igmar: Look at the following thread:

Re: Handsoldering ceramic capacitor's - Bill Chrisitian 18:41:23 06/24/1998

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