2017年3月8日星期三

Reduce PCB Fabrication Cost


The PCB is the centerpiece of a design. To reduce PCB fabrication cost, here are some specific techniques to keep in mind:

A blind via connects an outer layer of the PCB with exactly one inner layer. A buried via connects two inner layers, and contains no contact with outside layers. These techniques are characteristic of high density circuit boards, and add greatly to their expense. 

A minimum of three board fiducials shall be provided located in a triangular pattern as far apart as possible on the PCB. Fiducials located near the corners of the PCB are preferred.

Aim for the smallest board dimension and the fewest number of layers. Minimize the amount of gold and copper. 

Allow the board fabricator to design the multi-up pallet for smaller boards.

Ensure that the fabricator knows the material specifications of the PCB laminate by indicating this in the fabrication drawing. For RoHS assemblies, the laminate must have a Tg greater than or equal to 175 degrees C. 

Not every fabricator will be able to replicate a particular laminate stack-up. Up front, define the minimum trace width, the minimum distance between traces, and the smallest hole diameter.

Placing fiducials on the top copper layer of a board allows pick-and-place vision systems to detect boards more accurately.

To be continued…

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