Hole quality

Drilled hole quality is also important. With respect to CAF performance, minimizing resin-to-glass fracturing that can result in excessive wicking of plating chemistries is critical. 

Undercut drill bits generally provide better hole quality with these materials. Other drill process variables must also be examined, and include ... 

Repointed Drill Bits. Drill bits are typically repointed for reasons of economics. The cost of repointing a tool may be as low as 15 percent of the cost of a new tool. The number of times a drill is repointed varies anywhere from 1 to as many as 10 times or more and typically depends on the drill diameter. The smaller the drill, the fewer times it is normally repointed. The reason is that smaUer-diameter holes are more critical and require better hole quality. 

The first is to specify a certain number of times the tool is to be repointed before being discarded. This number typically varies between one to three for smaller-diameter tools depending on hole quality experienced after repointing. 

Laminate Type Entry Material Backup Materiai Hole Quality... 

Effects. Excessive backup penetration depth increases drill wear and the occurrence of breakage of small-diameter drill bits, adversely affects hole quality, and increases process time per load. Insufficient backup penetration depth results in incompletely drilled holes. This impiies that thickness variations of the backup material are very important, meaning that minimai variations are a much desired characteristic of the backup and need to be considered when choosing a material suitable for your application. 

Permanganate is also nsed as a second step in conjunction with the other methods to enhance hole quality. ... 

However, appropriate backing boards and drilling conditions should be determined to achieve good hole quality. A suitable combination of the NC drilling machine and drilling bit can generate smaller holes than 100 microns diameter. 

Hole quality Excellent Good Fair Fair Fair... 

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