OK this is driving me crazy.

In 1985 I printed a Budweiser can with a clear coat followed by conductive
traces and stuck down led's using conductive epoxy, this worked really well.
The same year I assembled enamel coated steel boards with LED's

For your LED board I strongly suggest you use the same approach - treat it
like you would a hybrid and print down the circuitry.

And if you want to get right down to it pick up the phone to your sister
company and ask where they get them made.........8-).

And I guess the question everyone would be thinking is why you would want to
assemble onto aluninium?


 
 
John Burke
 
(408) 515 4992

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Nila Young
Sent: Thursday, June 14, 2007 3:31 PM
To: [log in to unmask]
Subject: Re: [TN] MCPCB finish questions

Werner,

The sample I have from our sister company does not have metal surrounded
by 2 pcbs. It is a real metal pcb that is intended to act as a heat sink
for the leds and is not surrounded by any FR-4. (Yep, a soldering
nightmare that I am sure plenty of assembly personel will be happy to
work on...) It is just a piece of aluminum that has a coating on one
side with traces laid on top of that followed by a soldermask. We will
not be putting the leds on ourselves, but will look for a cm to assemble
it. I believe that our sister company may have a CM that is hand
soldering the leds to the mcpcb. The only other part that goes on this
is a connector that will connect a FR-4 pcb to drive the leds. 

As for your White Paper, I have not read it as our pcbs are typically
all through hole and our engineers are just now in the process of
converting to RoHS compliance. 

Nila

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Thursday, June 14, 2007 4:18 PM
To: [log in to unmask]
Subject: Re: [TN] MCPCB finish questions

Hi Nila,
Your PCB sounds like a "challenge"-not to say nightmare in this brave
new LF-world of ours.
I sure hope you are planning on using vapor phase for your solder
assembly process, otherwise the thermal requirements are going to be
"hellish".
When you say 'metal core', do you mean a real metal-core substrate, or a
PCB 
with a heat sink   in the middle surrounded by 2 FR-4 PCBs?
What are you doing to make your PCB survive the LF-assembly process?
Did you read my White Paper on the subject?

Werner



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