Printed circuit board milling

High-resolution boards using the wet process are hard to achieve and still, when done, one still has to drill and eventually cut out the PCB from the base material.

[6] In mass production, milling is unlikely to replace etching although the use of CNC is already standard practice for drilling the boards.

A PCB milling system is a single machine that can perform all of the required actions to create a prototype board, with the exception of inserting vias and through hole plating.

Most of these machines require only a standard AC mains outlet and a shop-type vacuum cleaner for operation.

[10] Typically this drive system comprises non-monitored stepper motors for the X/Y axis, an on-off non-monitored solenoid, pneumatic piston or lead screw for the Z-axis, and a DC motor control circuit for spindle speed, none of which provide positional feedback.

The lead screw is in turn linked to the gantry or milling head by a special precision machined connection assembly.

The rate of descent as well as the amount of force exerted on the spring stop must be manually set by mechanically adjusting the position of the solenoid's plunger.

Due to the small cylinder size and the amount of air pressure used to drive it there is little range of control between the up and down stops.

The final type of Z-axis control uses a stepper motor that allows the milling head to be moved in small accurate steps up or down.

Since conventional etching techniques rely on optical masks that sit right on the copper layer they can conform to any slight bends in the material so all features are replicated faithfully.