TECHNICAL ARTICLE

What are the properties of Bakelite sheets used for CNC punching machines?

2021-09-17 16:32  |  By: ZTELEC  |  62click

The Bakelite sheet, also known as phenolic laminated paper board, is manufactured from cellulosic paper as the reinforcement, impregnated with phenolic resin by hot pressing technique. Its colors are orange, orangey-red and black. The Bakelite sheet is mainly used for CNC punching machine, electrical insulating parts, molds, and jigs etc. Its excellent characteristics such as high heat resistance, good mechanical strength, wear resistance, flat surface, and electrical properties make it possible to be the backing board for CNC hole punching and cutting in manufacturing PCBs.

 

picture of PCB hole punching with the Bakelite sheet as the backing board

The Bakelite backing board used for punching PCBs contains the upper cover plate and the lower pad plate. The purpose of the upper cover plate is to protect the surface of PCB when punching holes, and additionally to fix the punching needle, reduce the position error, prevent the PCB from generating burrs on the upper surface, as well as helping accelerate heat dissipation from the punching needle and the clearance of its groove. The upper cover plate material requires a certain softness, good thickness tolerance, flat surface, high temperature resistance, low water absorption and not easy to deform. The lower pad is used to avoid the burrs on the back side, protect the punching machine, and ensure the punching quality of the PCB. The lower pad material requires high hardness, good flatness, small dimensional tolerance and cutting easiness. And besides, materials used as the pad plate should not produce stickiness or release chemicals at high temperature that are likely to contaminate the hole wall or punching needle. Also, the scraps generated during the hole punching should be soft to avoid scratching the hole wall. Therefore, Bakelite sheets can exactly meet the requirements of being the backing boards.

ZTelec Group is equipped with CNC sheet cutting machine and automatic sealing and packing machine with waterproof film, which ensures the customized sheet cutting service. Our Bakelite sheets used as the backing boards in PCB fabrication have the following advantages:

1. Flat surface without impurities, low warping rate.

2. Uniform thickness, which corresponds to the common requirements of the manufacturing industry.

3. No hole clogging and rough edges when punched and machined.

4. Suitable hardness does not affect the service life of the punching needle.

In conclusion, the comprehensive mechanical and electrical properties of the Bakelite sheet determine its use as the PCB backing board.

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