Drilling bit

Abstract

This invention provides a drill bit that is long in length and has a small diameter, at the same time, features a high strength capable of advancing straight forwards. In addition, this invention provided a drill bit capable of drilling holes with excellent inner wall roughness so as to enhance the applicability of the drill. According to this invention, plural chip discharge grooves 2 are helically provided on a peripheral surface. A margin section 1 is provided between the chip discharge grooves 2. In addition, the drill 3 is provided at its tip with a cutting edge 8. The chip discharge grooves 2 are provided at the bottoms with plural chip guiding grooves 6, 7 extending towards the chip discharge grooves 2.

Description

technical field [0001] The invention relates to a drill bit for drilling precision holes on workpieces. Background technique [0002] A printed circuit board (hereinafter referred to as a printed circuit board) on which electronic components are mounted is formed by laminating copper foil on a fiber-reinforced resin. A metal plating layer is formed on the inner wall, and the copper foil on the surface of the printed substrate is etched to form a printed circuit, and the printed circuit and the copper foil of the lower layer are conducted through the metal plating layer, and electronic soldering such as LSI is soldered to the through hole. components to form a printed circuit board. [0003] However, in recent years, along with the improvement in performance and miniaturization of electronic equipment, there has been an increasing demand for high-density mounting on printed circuit boards. Due to this requirement, while the thickness of the printed circuit board is thinner,...

AI Technical Summary

Problems solved by technology

[0014] If the chip discharge performance is degraded, the drill 33 will pierce while the chip flute 32 is full of chips, and the part where the chips are stored will roughen the inner wall surface of the through hole to become a concave-convex surface. The load acting on the drill bit 33 is increased, and the drill bit 33 is damaged

[0015] Therefore, in the conventional examples, there is a limit to increasing the core thickness of the drill bit 33, and the above-mentioned conditions (small diameter, very long, high strength, excellent straightness, and excellent drill bit) required for printed circuit board processing are fully satisfied. Good inner wall roughness of the exiting hole) is very difficult, especially it is impossible to achieve the two aspects of straightness and good inner wall roughness of the pierced hole at the same time

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