PCB Backdrilling Technology

What is backdrilling?

In the high speed signal transmission printed circuit board, part copper of vias becomes the signal transmission”tail” (Stubs),adverse effects on signal transmission,in order achieve better signal integrity, it is necessary to reduce the length of the Stubs in vias,shorter length of the residual Stubs is better for integrity of the signal.

Backdrilling is the way to remove PTH and Stubs without any connection or transmission in vias by the second drilling.This Stubs will distort the signal caused by the reflection, scattering, delay, etc. of the signal.

Difficulties in backdrilling technology

1.Back drilling depth control

The backdrilling is the processing of blind holes by the depth control function of the drilling machine. The tolerance is influenced by the precision of the drilling equipment and the tolerance of dielectric thickness.Besides, its accuracy is easily influenced by external factors, such as the resistance of drilling tool, the angle of drill tool tip, the contact effect between the cover plate and the measuring unit, the bow and twist of PCB, etc.Therefore, more attention should be paid to selecting more suitable drilling materials and drilling methods to control the accuracy to the best.

2.Precision control of backdrilling

The back hole is formed by the second drilling afer first drilling, and the accuracy of the second drilling is critical.PCB material harmomegathus, precision equipment, drilling, drill size will affect the accuracy of the second drilling,it’s very importance to the quality control at end process of PCB manufacturers.

The backdrilling capability of King Sun PCB

King Sun PCB has accumulated rich technical experience for many years backingdrilling process.Its technical ability has been in the forefront of the industry. The next figure is a 16 – layer five deep – back drilling technology, with a depth control tolerance +/-0.05mm.