Drilling process (3)

Continuing from our previous session, let's further explore the PCB drilling process.

 

Drilling Process

 

1. Principles of Drilling Process

The process of machining PTH (Plating Through Hole) for interlayer circuit connectivity in the stacked panels and NPTH (Non Plating Through Hole) for alignment marks and assembly of fixtures.

CNC (Computer Numerical Control) Drilling involves the use of automation devices such as computers to control the movement in the X, Y, Z axes with high precision, following the specified coordinates in the data to perform the machining.

Machining of holes is achieved by utilizing the rotational force of the bit inserted into the Spindle, creating holes at designated positions.

 

2. Key Factors in Drilling

 

Spindle Run-out: The degree of vibration generated by the rotation of the bit.

 

Maxhit: The maximum number of times the bit hits.

 

Offset: Correction value for the Down Limit.

 

Speed: Spindle's rotational speed in rotations per minute (RPM).

 

Chip Load: Depth the drill bit descends in one rotation.

 

Infeed: Speed at which the Spindle descends.

 

RTR (Return to Reference): Speed at which the Spindle rises.

 

Up Limit: Height the Spindle goes up from the reference point during the Spindle's upward and downward movement.

 

Formula: Thickness of backup board + Stacking thickness * Number of stacked panels + Entry Board thickness + 3.5mm

 

Down Limit (DN Value): Height of the Spindle from the reference point when it descends.

 

Formula: Thickness of backup board - 0.6~0.5 (depth of bit penetrating the backup board)