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metal core/clad pcb

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#62423

metal core/clad pcb | 11 August, 2010

Anyone work with or have knowledge about metal core/clad boards? The board I'm working with is approximately 2" X 3/4" aluminum core pcb, in a 56 up array. There are 3 LED placements per board.

I'm having trouble getting a consistent screen print. I contribute most of this problem to bowed/twisted/warped panels. I have the maximum support available for the screen printer. These panels are warped so much, sometimes I have a hard time getting them to stay on the tooling pins.

What are the possible causes for this much bow/twist/warp in aluminum pcb's?

Is there anything the board supplier can do about this?

Is there anyway to straighten/flatten the boards we have?

Would some sort of fixture help?

Any thoughts/suggestions/random facts about aluminum core pcb's would be very much appreciated.

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#62426

metal core/clad pcb | 12 August, 2010

Without seeing a picture, my first instinct would be first and foremost some fixturing that provides full support for your print process. After that, since you are citing bow and twist, consider that the fixturing might as well travel through the oven with the product. Now your fixturing must be light enough to not adversely affect the reflow profile,(think honeycomb) while not confining the boards and allowing for some expansion while heating...

again...just first instinct based on your description. As far as metal clad boards, not my expertise, but the 'rubber meets the road' at the solder joint in our business, and profiling is profiling, mass is mass.

'hege

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#62428

metal core/clad pcb | 12 August, 2010

You might reduce your panel size, cut it in half and rotate to better utilize your edge clamping/board supports. Tape off your current stencil and see if it improves the print. A new stencil and a little extra handling may be cheaper than tooling.

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