Hi Susan,

Aside from long-term reliability, the issue is how well your board suppliers
can produce 4 mil lines and spaces.  If your suppliers can not produce these
features with high yields there may be delays in the delivery of the boards.
Furthermore, there are questions on how well your board suppliers maintain
line width control.

For example, when you request 4 mil lines with specification limits of ±
10%, a supplier without the necessary capability may deliver boards with
lines that average 3.2 mils in width, with a range of 2.2 mils to 4.3 mils,
substantially missing the target.

Line width control is process dependent and some suppliers have their
processes controlled better than others.

We offer a testing and analysis service that provides process capability
data on PCB manufacturing capabilities.  If you need help in understanding
you board suppliers capabilities please feel free to contact me.

Tim Estes
Conductor Analysis Technologies Inc.
Phone: 505-294-6936
Fax: 505-294-6596
Email: [log in to unmask]
Web: http://biz.swcp.com/cat

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