Won't a thin flex attached on aluminum do the same job? If it must be
cheap, I think Ruwel can use LCP instead. We made some sort of battery
charge/control circuit this way.
(I don't say this to make John Burke crazy)
Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Nila Young
Skickat: den 15 juni 2007 16:57
Till: [log in to unmask]
Ämne: Re: [TN] MCPCB finish questions
Good Morning Steve,
Yes, your pictures are very similar looking as far as materials used,
but instead of green soldermask we are specifying black soldermask. When
I looked at the ThermalClad information, this is pretty much exactly
what we are wanting.
I am not sure about what vendor our EE is thinking of, but will forward
your email to him.
Thanks,
Nila
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Friday, June 15, 2007 7:33 AM
To: [log in to unmask]
Subject: Re: [TN] MCPCB finish questions
Hi Nila!
Your board sounds a lot like one that I built a while back. It was a
tiny little power supply that generated a lot of heat and it was built
on a aluminum substrate called Thermal Clad made by a company named
Bergquist. I've got a sample of the material that I had laying
around...here's some photos:
http://stevezeva.homestead.com/files/ThermalClad.jpg
http://stevezeva.homestead.com/files/ThermalClad_2.jpg
This sample is 1.6mm thick too. I didn't have many problems reflowing
the assembly. We built it in a 8-up fixture because it was so small, and
it stayed in the fixture from screen print, through pick and place, and
reflow. The only thing was that we had to be careful of was when the
fixture came out of the reflow oven because the assemblies would stay
liquidous for a few minutes after they came out.
What I'm about to say happened a while ago, so things may have changed
since then. But we had a terrible time with Bergquist. Thermal Clad is a
licensed and patented substrate, and Bergquist was the only ones that
built something like it for quite a while. They were constantly late on
delivery, which in turn really upset our delivery to our customer. We
were stuck with them for a while because the assemblies had qualified on
this substrate (it was a military assembly). Tyco came out with
something similar and we finally built some assemblies with their
substrate which were able to qualify...for the life of me I can't
remember what they called their substrate.
All of Tyco's PCB divisions was sold last fall to TTM Technologies, and
I don't know if they continued to make the substrate or not...
Steve Gregory
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: Thursday, June 14, 2007 5:46 PM
To: [log in to unmask]
Subject: Re: [TN] MCPCB finish questions
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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