发明名称 |
BOHRER AUS HARTMETALL ZUM BOHREN VON KONTAKTLOECHERN IN LEITERPLATTEN U.DGL. |
摘要 |
A hard metal drill is disclosed for drilling contact holes in multi-legend printed circuit boards formed of synthetic resin. The drill has a diameter of not more than 1.5 mm. and has main and secondary cutting edges and spiral-shaped flutes lying opposite the drill longitudinal axis. At least one of these edges has a different angle or a different legend with respect to a corresponding other edge. The amount of difference of the two cutting angles or lengths to be compared is selected such that a gap between the drill and an edge of the drill hole is at least 20 mu m and not more than 50 mu m. In order to produce such holes more readily, the two spiral-shaped flutes have different depths. |
申请公布号 |
DE2742104(A1) |
申请公布日期 |
1979.03.29 |
申请号 |
DE19772742104 |
申请日期 |
1977.09.19 |
申请人 |
SIEMENS AG |
发明人 |
BRABETZ,BERNHARD,DIPL.-ING.;HACKL,HELMUT,DIPL.-PHYS. |
分类号 |
B23B51/02;H05K3/00;(IPC1-7):H05K3/36 |
主分类号 |
B23B51/02 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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