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On 20/07/16 09:28, Brad Rogers wrote:
On Wed, 20 Jul 2016 08:52:42 +0100 Tom <madtom1999@xxxxxxxxxxxxxx> wrote: Hello Tom,automating that should help. Gordon mentioned registration for double sided stuff but that shouldnt be too hard to work out...Easy; Make a registration mask (a hole in each corner[1][2], say 1mm dia) and etch that first then drill. Make a front and rear mask that include the registration holes to allow you to achieve the correct alignment. [1] These holes are often later drilled out to accommodate mounting pillars. [2] They don't have to be the corners of a rectangle. Sometimes it's helpful to have one hole offset, since that makes it harder to flip an etch mask inadvertently. I was going to choose the furthest NSEW holes to use as registration points. When doing chip design 'in the old days' we used to have special registration designs that were used to automate optical alignment of the masks with the dies used in processing which is another possible solution - assuming there is enough space left on the pcb to drill a pattern. Tom te tom te tom |
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