Basic knowledge of the backing plate for drilling

Phenolic resin laminates are used for PCB drilling pads, insulation, and bakelite boards for mold fixtures. The backing plate and the bakelite boards have the same characteristics of high temperature resistance and resistance to deformation, high flatness,can be used in advanced PCB drilling technology, the principle is to use processed paper (insulation paper) to immerse in phenolic resin and press together by a hot press to form a plate-like laminate. Among them, the main products of the backing plate are divided into upper cover plate and lower backing plate. The former type includes pure aluminum plate, soft and hard aluminum plate alloy, bakelite boards and LE series; the latter includes melamine veneer phenolic board, phenolic resin board, melamine veneer wood pulp board, wood pulp board, etc. 

The purpose of the upper cover plate is to:

1. Protect the board surface when the PCB is drilled;
2. At the same time, the drill bitis fixed to reduce the offset;
3. Prevent to occurburrs on the substrate;
4. Assist the drill bit to dissipate heat;
5. Assists toclean the groove of the drill bit.

Under the above purpose, the upper cover also has five major requirements, including sufficient softness, excellent thickness tolerance, flatness, high temperature resistance, low hygroscopicity and not easy to deform.

The purpose of the lower backing plate is to:

1. Prevent to occurburrs down the substrate;
2. Drill through the PCB board;
3. Protect the drilling machine;
4. Ensure substrate quality.

Its characteristics are required to be good in flatness, excellent dimensional tolerance, easy to cut, hard and flat surface, high temperature material without stickiness or release of chemical substances to contaminate the hole wall or drill bit, and drill cuttings that are soft so that they will not scratch the hole wall.