How are you reworking high mass LED pcb's?

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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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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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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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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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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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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> 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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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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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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Thanks for all of your suggestions. I ended up borrowing a Pace Worldwide PH100 Preheater, which worked like a charm. I'm in the process of purchasing one for our own shop. I had to place the aluminum pcb directly onto the PH100's ceramic heating plate, then preheat until the top of board obtained 125°C temp. Once the board was saturated with heat, I was able to remove the LEDs with a Pace MT-100 Thermal Tweezer and resolder with a standard iron. If you would like to check out the PH100, go to this website:

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

There 's a nice video on the same page that explains the system.

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