As requested, 3 XM-L Driver/Emitter module DIY

Almost There!

BareBoards

PPtk

Oh, wow. Man, you are such a tease. :)

That wasn't a tease.. This is a tease :)

Hehe..

PPtk

I can actually SEE the dirty smile on your face right now!

Haha, That's great :) Look really closely into the 24 karat gold pads and you're probably right, I'm sure I'm reflected in one of them :-)

PPtk

For those who are intending on purchasing a DIY Kit, here is the assembly drawing - shows which part goes where. All of this information is on the Silk-Screen of the board, but I find it much easier to build when I can look at a reference (and possibly even make notes on it).

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PDF Copy

PPtk

Pilot:

I'm in for this one: Cool white U2 Flux 1C Tint, fully assembled module. Can't wait to review this bad boy.

Just tell me where to send the Paypal and when.

Foy

I thought you were NeutraWhiteLovingFoy ? ?

Gold plating for solder pads can be a bad thing! Gold tends to form intermetallic compounds with lead/tin/aluminum (google "purple plague" for a well known example). These can be brittle and poorly conductive. Components have been known to fall of circuit boards...

He'll buy both versions anyway, we know the Foy, dont we? ;)

looking great Pilot, can't wait to see these in action.

About the programming - can the controller chips be supplied programmed off the board for self-assemblers or can they only be programmed after assembly using the pads on the board?

I am . . . but I'm going for lumens on this deal, or . . . will these neutrals be as bright as the 1C?

Foy

U2 Cool is going to be a bit brighter than a Neutral, but we are talking about 3 FULLY driven XM-L's. It's a lot of light no matter which exact emitter you choose.

I can supply them pre-programmed. It will be a no-cost option.

PPtk

The ENIG (Electroless Nickel, Immersion Gold) process has been perfected over the years, and solder joint quality on ENIG is excellent. "Purple Plague" is really a reference to brittle joints between aluminum and gold and is seen when gold is used inside of a chip package where a wire-bond takes place. Wire bonding and soldering are very different processes. "Black-Pad" can be a problem if electro-plated Nickel is used as the base, but circuit board finishes use electroless nickel to avoid that problem. Even NASA and the U.S. Military approve of the use of ENIG PCBs - And I promise that neither of those agencies would tolerate random components falling off of their assemblies. Components won't be falling off of these boards.

PPtk

These boards look so nice, I bet that fully assembled modules ,would be a real turn on (ok, that sounded a bit weird )

I'm so because I c'not afford something like this...

Purple plague is the aluminum-gold intermetallic. It is the most common/notorious. There are also gold-lead and and gold-tin intermetallics.

See the wikipedia article on gold plating. last section on soldering issues:

You are probably better off masking the gold from the component pads. There are also some indications that, under the right conditions, gold may help catalyze the formation of tin whiskers from lead-free solder. And gold can grow its own whiskers. But it sure is pretty...

Wikipedia is cute and all, but I think I'll reference something with a little more qualification..

NASA Jet Propulsion Laboratories, for instance..

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/20708/1/98-1767.pdf

These are the conclusions after testing the way that solder joints fail on a variety of different component packages and a variety of different PCB finishes.

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Conclusions

For plastic packages, crack initiation, propagation, and failure occurred at either the package or

board interfaces for sections with or without voids. This was true for A or B cycle conditions.

Generally, voids were concentrated near the package interfaces. There appeared to be no crack

propagation among the voids, except for the voids interconnected at the interface.

For a ceramic assembly failure (See Comment Below), brittle failure was observed for Nickel-Gold surface finishes. OSP and

HASL showed ductile failure through eutectic solder joints. For plastic packages, there was no

distinction between the three surfaces

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The ceramic packages tested were very odd - from the document:

Ceramic packages with 625 I/Os and 361 I/Os were also included in our evaluation. Ceramic

packages had high melting solder balls (90Pb/lOSn) with 0.035 inch diameters. These balls were

attached to the 'ceramic substrate with eutectic solder (63Sd37Pb). At reflow, package side eutectic

solder and the PWB side eutectic paste was reflowed to provide the electro-mechanical interconnects.

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The high melting point solder is nothing like standard leaded or lead-free. It's VERY heavy in gold content. Nothing like that is used on the 3 XM-L Board

PPtk

I recently built some boards for the military and was expressly forbidden to use solder-on-gold. Also forbidden to use lead-free solder for that matter. In their environment, every little detail matters immensely. Things that don't matter in a benign, short life consumer environment can quickly turn into nasty problems. I can also show you some gold plated circuit boards out of some HP test equipment that failed because of the problem.