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 ************************************** See what's free at http://www.aol.com. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------