I first got involved doing this in the late 60's and early 70's doing
military MLB's. Some experiences good as attaching sink after fab not really
making the sink part of the board. Bad meant laminating the sinks, either
copper or aluminum, as part of the board. Bad because of obvious warpage issues.

Either aliminum or copper may be bonded to the MLB using "no-flow" prepreg
or some other adhesive. This method does not allow plated through holes as
part of the structure as does the laminated types.

We "etched" features in sinks up to 60 mils thick. Beyond that, "chem
milling," done outside, or machined sinks were made and attached.

You work in the heart of where most of this started many years ago. I don't
know what Methode/Bureau of Engraving is called now but they used to be up
your street not more than a couple of miles. Ambitech also resides there as
some others. All these folks did this at one time and should provide details
of the adventure.

A better way to get the heat out of some boards is to sandwich the sinks
internal to the board (up to ten ounce copper can be done this way) as part
of the MLB structure. This becomes a better solution as a balanced
construction is assured and heat pipes, as plated through holes, can be used
to get the heat to the edges and cold wall contacts, if required.

MoonMan

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------