Hi John, As for the process, yes, I think you have it right on what we want to do. But, I have to be able to actually state it on the drawings so that there are no questions asked when we send it to what ever printed circuit board vendor that purchasing specifies. Here is where the problem occurs. Purchasing folks want to use our supplier in China, not our sister company's supplier because of cost and lead time. There is a supplier here in the USA that can do this for us, but again, purchasing folks are not wanting engineering to pursue this alternative for cost savings reasons. Sigh. I did get the notes directly from our sister company as they have a similar pcb that has more LEDs on it than what we want. So not much help there as to improving things as that is the only mcpcb that they have. Now why to assemble directly on aluminum.... The LEDs that we want to use need to be in a very confined area so not enough room for a separate heat sink or to use plane layers to act as a heat sink as the pcb would then not fit in the housing. By mounting them directly onto aluminum, the heat sink and the pcb are one, and the pcb area can then be greatly decreased. Thanks :-) Nila -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke Sent: Thursday, June 14, 2007 4:46 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 -----------------------------------------------------