Luxeon Star base conductivity -- Insulation Ques

lemlux · Mar 20, 2003

The Lumileds data sheet for the 5W stars cautions in Note 3 on Page 2 that: "Electrical insulation between neighboring stars is required -- aluminum board is not electrically neutral."

Artic Silver says: "Caution! Even though Artic Silver Thermal Adhesive is specifically engineered for high electrical resistance, you should keep it away from processor, memory, and motherboard traces, pins and leads. The cured adhesive is slightly capacitive and can cause problems if it bridges two close-proximity electrical paths."

It sounds like a small degree of connectivity in the LS base is further diluted by the largely resistive Artic Silver.

Has anyone mounted multiple stars to the same aluminum heat sink with Artic Silver? I would really like to mount four LS Stars on a Zalman SM80A-HP VG heat pipe cooler. (http://www.zalmanusa.com) This quadruple finned surface unit would be shorter and no deeper than the head unit of the small lantern battery light that it will replace. The battery chamber can hold either 8D cells or 1 lantern battery providing room for a 9.6 V 4.0 A C cell rechargeable battery pack and four separate Power Pucks to deliver a regulated 700 mA to each separate LS.

ufokillerz · Mar 20, 2003

i dumped 5 1watt LD stars on a TT Dragon Orb 3. But i used Artic Alumina because i didn't find the price difference justifiable for use with LS. I think its a safer bet to use Artic Alumina, and there shouldn't be any noticable temperature differences. maybe 1-3c.

Slick · Mar 20, 2003

While I choose to use Arctic Alumina, no epoxy can be expected to provide "insulation" to a conductive ground plane.

If you are using "red family" Luxeons, it WON'T work because the die slugs for those LED's are positive. If you are using "white family" Luxeons, you will be OK as long as the LED's are wired in parallel, but NOT in series..

lemlux · Mar 20, 2003

I'll be using white 5W LS. Each will be separately wired to a separate powerpuck. If the 5W bases are negative I would hope there wouldn't be a problem. I don't want to destroy anything finding out, though.

MR Bulk · Mar 21, 2003

[ QUOTE ]
lemlux said:
I don't want to destroy anything finding out, though.

[/ QUOTE ]

Clark,

Why not? Then you could join The Club! Now whenever I need a quick reference to check for Luxeon mounting clearances or similar, I have ready-made measuring jigs (just grab one from my pile of burned-out LS emitters).

lemlux · Mar 21, 2003

Charlie:

As you know, I've already joined the club by overpowering my original ARC LS and my Mr. Bulk Nexneedle which has lost about half of its original luminoscity.

I've also recently discovered that 4 @ Panasonic 4/5 A 2000 mAh NiMHs overdrive a P61 to a life of < 3 hours. (I learned that lesson twice.) On the other hand, 4 @ Sanyo 2450-2700 mAh A NiMHs underdrive the P61. Go figure.

When I have time, I'll test to see if Slick's observation that the 1W White Stars have a negative base holds true for the 5W. I'll gamble if the slug is negative.