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How are you reworking high mass LED pcb's?

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#77905

How are you reworking high mass LED pcb's? | 23 June, 2017

I have a few LED pcb's that have an aluminum substrate that are ridiculous to rework. They heat-sink like crazy and I can't reflow the bad LED's, no matter how much heat I apply. Any suggestions on techniques or equipment to use?

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#77906

How are you reworking high mass LED pcb's? | 23 June, 2017

I haven't tried doing these, personally...but...

- Try a pre-heater? - IR rework station?

Off the top of my head, that's all I've got.

Cheers, ..rob

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#77954

How are you reworking high mass LED pcb's? | 24 June, 2017

Here's a good IR preheater that you should look at:

www.paceworldwide.com/products/smt-rework-systems-and-preheaters/preheaters/ph-100-low-profile-pcb-preheater

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#78141

How are you reworking high mass LED pcb's? | 7 July, 2017

Are you reflowing them and they are coming out of the oven bad? If so, what kind of oven are you using? What kind of LEDs? What kind of solder? Mass of substrate?

Have you ran a profiler through your oven and compared the plot to the solder's spec sheet? Note: You really need to do this to have even a remote idea of what the conditions are in your oven. We run a primarily lighting products here, and it's pretty much a requirement that aluminum boards come out of the oven perfect, because they are such a pain to rework. I would start with your oven-- try and save yourself from having to do the rework, don't look for solutions to make it easier.

That being said, if you're looking for a cheap solution-- just get a hot plate to pre-heat.

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#78143

How are you reworking high mass LED pcb's? | 7 July, 2017

I have worked with a few of my customers to rework heavy LEDs. One technique that has worked; use a large flat soldering tip, apply the tip to the back side of the PCB directly under the LED. I have seen the soldering iron handle mounted in a table vise to hold it in an upright position. The PCB is held/placed onto the tip and reworked. I have reworked high wattage brake light LED on tail light PCB with this technique.

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#78146

How are you reworking high mass LED pcb's? | 7 July, 2017

A picture shows more than a thousand words. If you show us the LED and PCB if possible, I am sure people here will come up with some ideas.

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#78149

How are you reworking high mass LED pcb's? | 7 July, 2017

We had very little success reworking these type of boards. We used a BGA repair station and still was a major hassle.

Are these shifted LED's or defective?

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#78150

How are you reworking high mass LED pcb's? | 7 July, 2017

Defective LED's that I need to replace.

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#78151

How are you reworking high mass LED pcb's? | 7 July, 2017

Sounds interesting CAPSE, but unwieldy. Thanks.

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#78154

How are you reworking high mass LED pcb's? | 7 July, 2017

Hi jchri,

Evtimocv is correct.

I think there is somebody or manufacturer can help if the problem is found with a picture.

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#78156

How are you reworking high mass LED pcb's? | 7 July, 2017

I agree ... I'll get a photo off on Monday when I get back to the office.

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#78179

How are you reworking high mass LED pcb's? | 10 July, 2017

Just a random thought, but we had an issue with having to replace faulty LED's on a PCB, and the solution turned out to be pre-baking the LED's prior to build. Just put them in an oven at 40C for 24 hours, then build. Result was zero defective LED's.

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#78283

How are you reworking high mass LED pcb's? | 12 July, 2017

> I have a few LED pcb's that have an aluminum > substrate that are ridiculous to rework. They > heat-sink like crazy and I can't reflow the bad > LED's, no matter how much heat I apply. Any > suggestions on techniques or equipment to use?

> I have a few LED pcb's that have an aluminum > substrate that are ridiculous to rework. They > heat-sink like crazy and I can't reflow the bad > LED's, no matter how much heat I apply. Any > suggestions on techniques or equipment to use?

I have used a hot plate in the past. Like the Hakko FR860-02C. The only problem is it brings everything up to the same temperture.

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#78284

How are you reworking high mass LED pcb's? | 12 July, 2017

Not much help for what you have manufactured but you could try using a lower melting point solder paste?

Sn/Bi/Cu

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#78354

How are you reworking high mass LED pcb's? | 13 July, 2017

We are using hot-plate. It is the safest method to rework aluminum substrate PCB's.

http://www.martin-smt.de/en/rework/products/pre-heater-hotbeam.html

"For efficient rework on heavy electrical systems with flat bottom surface and LED PCBs the powerful under heater HOTPLATE-04 with 700W is recommended."

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