Reflow Damage to Capacitors

Hello All :

I recently returned a batch of thirty PCB's to a supplier for re-work - the BGA devices had some intermittent connections on a couple of boards and I wanted them all to be re-reflowed on a re-work station and re-tested.

It seems that they just put the whole board back through a reflow oven. Even those components that had been hand fitted after the initial reflow.

So now I see a slight discoloration in the cans of the through hole electrolytics.

I want them to replace all the through hole electrolytics, believing there is at least a chance that the reflow damaged them. The cap manufacturers (Panasonic and Nichicon) don't specify anything like reflow temperature withstand for through hole parts, just for SM parts.

Does anybody have any experience of what happens if through-hole can electrolytics are reflowed in this way ?

Am I unnecessarily concerned, given that leg seals etc are already rated for wave soldering, and that SM electrolytics are rated for reflow and are pretty much the same design ?

Thanks. Gary

Reply to
Gary Pace
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You're getting to picky, most people don't care what the components look like in side, the internals is not a show and tell. If they are working then leave them a lone..

That's just my opinion.

--
"I\'d rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:
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Reply to
Jamie

Wavesoldering preheat and dwell temperatures can be more severe than reflow, but concentrate on the board and leads.

You should be concerned about film capacitors, but electrolytics are not damaged by temporary controlled skin temperatures that may split their pvc jackets.

RL.

Reply to
legg

Just a discoloration should not be a problem. However, 6-7 years ago, when I did my first board with some BGAs on it, which I subjected to countless reflow cycles, I did damage a 1000 uF electrolytic cap. It was visibly damaged, though, it had leaked because of the pressure. After that (it happened during one of the first reflows) I removed it - being just 1 - prior to reflow and reattached it manually afterwards. I had to do the same with a quarz oscillator (those in the large metal can), which was mounted on the board bottom - apparently things got detached inside during reflow (I even managed to heal one once, by reflowing it alone this time belly _down_....:-) ).

Dimiter

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Gary Pace wrote:

Reply to
Didi

Hi,

IMHO, electrocytic caps are very temperature sensitive devices. A reflow cycle is about 200 degrees, which can boil the liquid in the caps.

Each and every process start with reflow, and then comes the big caps.

I'd convince the house to replace the elcos. And stay away from them from now on...

-- Levente

Reply to
Levente

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