How do you remove emitter epoxied to board?

[Turbo DV8]

I have a K2 Stunner that was obsolete before I took delivery of it, with the Cree's and SSC's coming out at the same time. I want to swap the eight K2 emitters for SSC P4's. The K2's are epoxied to the board with a very small bit of thermal epoxy. Is there any way to gingerly remove the emitters from the board without completely destroying the board? Perhaps get some thin, sharp blade and gently tap it between the emitter and board? Just want to know if anybody else has successfully done this sort of thing and how you accomplished it. Thanks.

 

[DonShock]

I find I get the most damage when trying to "pry up" something that has been epoxied down. What seems to work best is if I can appply force from the side so I am trying to move the parts in a moton parallel to the surface where they are joined. Sometimes a twising motion works too.

 

[AlexGT]

I had luck using a Dental Pick and removing small pieces of epoxy, it's slow but works.

AlexGT

 

[greenLED]

Heat up the board a little to soften the epoxy, then use a thin blade (wear eye protection). Sometimes that works, but most often I've ended up destroying the old emitter.

 

[Turbo DV8]

I had luck using a Dental Pick and removing small pieces of epoxy, it's slow but works.

AlexGT

... times 8 emitters... ugh! So I think I'll try the "hybrid" approach: heat, dental pick, slidy, twisty. I am not too concerned with damaging the K2 emitters. It is the board that I am concerned with saving. So on the subject of heat, would you suggest a heat gun applied to the surface of the board opposite the emitters?

 

[Changchung]

... times 8 emitters... ugh! So I think I'll try the "hybrid" approach: heat, dental pick, slidy, twisty. I am not too concerned with damaging the K2 emitters. It is the board that I am concerned with saving. So on the subject of heat, would you suggest a heat gun applied to the surface of the board opposite the emitters?

With the heat gun you can kill the Led, check this out, check below...

http://home.mchsi.com/~testlight/miniprokit2.htm

I do like that with good results...

 

[greenLED]

What kind of "board" do you have? Is it populated with other electronics, or are we talking a metal heatsink only?

If it's a heatsink only I'd just heat the whole thing (put it on your range for a few minutes). If it's a populated board things get trickier and may require you to apply heat locally (as close to the emitter as possible) with your soldering iron.

 

[Turbo DV8]

What kind of "board" do you have? Is it populated with other electronics, or are we talking a metal heatsink only?

It's just metal with some sort of coating on most of it, along with various traces and a 1 ohm surface mount resistor near each emitter.

Which brings up a question I will run into later. Wayne mentioned he tried using the K2's with no resistance, but they ran a little too hot using three NiMH D cells... bright, but even with the light's massive finned heatsinked head, it still got real hot. So for most orders he used 1 ohm resistors for each LED. I am wondering with the SSC's if I can run them with a shunt around each resistor, or if I need to retain the 1 ohm resistors, or perhaps even higher? I have not been able to get any comment from Wayne on this.

 

[richdsu]

Heat up a scalpel blade with a gas stove.
When moderately hot enough ( testing it on masking tape ), gently slice it
through the epoxied board.

 

[TexLite]

I find I get the most damage when trying to "pry up" something that has been epoxied down. What seems to work best is if I can appply force from the side so I am trying to move the parts in a moton parallel to the surface where they are joined. Sometimes a twising motion works too.

+1 on what DonShock said.Twisting has worked best for me,prying is usually a bad idea.

 

[uk_caver]

I've had very good success [destructively] removing Luxeon I/III emitters from mounted stars by use of a soldering iron, though I'm not sure if it would work for K2s.

Anyway, My method is to chop the leads, and then scrunch off the LED dome and black plastic with pliers.
Once down to the aluminium 'pillar', I use my 50W soldering iron with a large bit fitted, set to ~350C, and apply a large blob of solder to the bit to improve contact area and speed heating.
Then, I press the bit down on top of the pillar for ~5 seconds, remove the iron and immediately try to gently twist the pillar off with pliers. If it doesn't work, I just try again.

This has worked on >20 stars so far with no failures, and hasn't damaged the mounting of the star.