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Questions relating to designing PCBs
By peskywinnets
#134726
I'm looking to order some of these up. Size seem to be 1.6mm 2.2mm 2.4mm & 2.8mm - I'll probably get a couple of each, but just wondered what size diameter chip breaker the pcb fab houses typically use for cutting out the pcb shape?

If it varies...then what's the most popular diameters?
By InactiveUser001
#134921
The routings bits most commonly used that I know of are 2mm.

AFAIK it is standard to leave a 2mm gap between boards in a panel for this, smaller bits means less panels can be done at the same time.
By rolmix
#136861
peskywinnets wrote:I'm looking to order some of these up. Size seem to be 1.6mm 2.2mm 2.4mm & 2.8mm - I'll probably get a couple of each, but just wondered what size diameter chip breaker the pcb fab houses typically use for cutting out the pcb shape?

If it varies...then what's the most popular diameters?
39...98mil

http://www.mctinfo.net/lpkf-tools/cat_21.html
http://www.thinktink.com/stack/volumes/ ... chmill.htm
By InactiveUser001
#136942
AFAIK... The smaller the bit used, the less the number of boards that can be stacked, the more operations the manufacturer has to do the higher the cost. I have always found that in the UK & Europe, 2mm is the preferred size of routing bit, coming down to 1mm only when necessary. Always one for making the manufacturers job easier and hence keeping prices down I opt for the larger spacing, it has never caused any form of problem.

(We are talking about the gap between boards in a panel ?)
By lwhodson
#138797
Most PCB shops don't use the "Chipbreaker" style router bits. The "Diamond Cut" style is much more popular by a factor of 10 to 1. The variety of sizes is also more generally available with the "Diamond Cut" style. Another benefit to the “Diamond Cut” is that they can machine carbon composite materials much better.

PCB shops in the US use a 3/32"(2.40mm) bit and can route a stack 3 or 4 deep assuming the individual board thickness is .062 (1.60mm). A 1/16"(1.60mm) bit can be used to route a stack 2-3 high. 1/32"(.80mm) and .040(1.0mm) can be stacked 2 high. Keep in mind the board shops are using production equipment with high speed spindles and stable granite bases that help with accuracy and lessens tool breakage. Most breakaway arrays tend to based on the 1/16"(1.60m) tool path, of course that is stateside, the European shops may differ.

Generally you are also better off choosing a “Fishtail” (FT) end style as well. They tend to be a little more forgiving if you haven’t set your Z depth correctly and they cut a larger vacuum path.

http://mctinfo.net/router-bits/cat_20.html