CN101626662A - Process for removing flash of half PTH hole by dry film etching method - Google Patents

Abstract

The invention discloses a manufacturing method for removing a flash of a half PTH hole by a printed circuit board, which adopts the technical implementation scheme that the method comprises the following steps: not removing tin-lead after etching a circuit in the production of an alkaline etching process, and milling the half PTH hole by a numerical control milling machine, wherein a flash residue is left at a tangent plane of the half PHT hole and meanwhile the flash at the tangent plane exposes a copper layer; covering a dry film on a printed circuit board, only exposing the half PTH hole after performing exposure and development on the dry film, and protecting the circuit on the board surface by the dry film and a tin-lead layer, wherein the tin-lead layer also can protect the wall of the hole; and then removing the flash left at the tangent plane of the half PTH hole by an etching method. The new process flow can solve the quality problem caused by disqualification of the flash of the half PTH hole, and improve the process yield of a half PTH hole plate.

Description

Removing flash of half PTH hole by dry film etching method technology

Technical field

Belong to printed wiring board flow process manufacturing technology, be applicable to the making flow process that contains half of PTH orifice plate.

Background technology:

Hole wall copper sheet perk behind the half of PTH hole forming, residual burr problem is a difficult problem in the wiring board machining always.Remain in copper wire burr in the half of PTH hole in the welding process of the SMT in downstream producer, occur problems such as solder joint is insecure, rosin joint, the short circuit of bridge knot easily.Industry is milled the generation of the method minimizing burr of plate with CNC milling machine behind the general employing secondary drilling when making half of PTH hole at present, but the method can't thoroughly be removed burr, majority also needs artificial place under repair, and production cycle and processing cost are caused very big influence." removing flash of half PTH hole by dry film etching method technology " is exactly the special control technology of the half of PTH of the solution of developing under this background hole burr. can effectively solve the bad problem of half of PTH hole burr.

Summary of the invention:

Make the printed wiring board in half of PTH hole at needs, do not take off tin lead after in the production process of alkali etching operation, etching circuit, mill out half of PTH hole with CNC milling machine, this moment, to have burr residual tangent plane place, half of PTH hole, and tangent plane place burr can expose the copper layer simultaneously.Cover dry film then on printed wiring board, will only expose half of PTH hole behind the dry film exposure imaging, utilize dry film and tin lead layer baffle upper thread road, tin lead layer also can be protected hole wall simultaneously, then removes the burr at tangent plane place, half of PTH hole with engraving method.

Embodiment:

1, make flow process:

Last operation → circuit etching (not taking off tin lead) → secondary drilling → mill half of PTH hole → subsides dry film, exposure imaging → etching (removing burr) → take off dry film → take off tin lead → following operation

2, process description:

1., circuit etching (not taking off tin lead): etch the circuit that printed wiring board is done, do not take off tin lead and be in order to protect half of PTH hole hole wall copper when tangent plane place, the half of PTH hole of the etching burr.

2., secondary drilling: for the half of PTH hole of aperture φ 〉=0.6mm, bore to chew to add with the SLOT of diameter 0.6mm and bore a hole, get rid of copper sheet and batch cutting edge of a knife or a sword to reduce half of PTH hole in feed place of milling half of PTH hole; The half of PTH hole of aperture φ＜0.6mm does not add boring.

3., mill half of PTH hole: make and mill the plate program, half of PTH hole is milled out.

4., paste dry film, exposure imaging: whole plate pastes dry film and exposure imaging, is used for baffle upper thread road when half of PTH pitting is carved except that burr.

The design of the exposure film: half of PTH does the design of being in the light in the hole site, the used monolateral big 4mil of bit diameter when hole than half of PTH in the zone of being in the light, and printing opacity is done in all the other zones.

5., etching (removing burr): the burr of removing tangent plane place, half of PTH hole with alkali etching liquid medicine.

6., take off dry film: with concentration is that the special use of 20-25% is taken off film liquid (main component: potassium hydroxide) dry film that will be attached on the pcb board face is taken off wash clean;

7., take off tin lead: take off the plumbous liquid medicine of tin with special use and remove tin lead layer in plate face and the hole.

Claims (1)

1. A kind of technological process method that solves the half of PTH of printed wiring board hole burr problem, it is characterized in that: do not take off tin lead after in the production process of alkali etching operation, etching circuit, earlier mill out half of PTH hole with CNC milling machine, this moment, to have burr residual tangent plane place, half of PTH hole, and tangent plane place burr can expose the copper layer simultaneously.Cover dry film then on printed wiring board, will only expose half of PTH hole behind the dry film exposure imaging, utilize dry film and tin lead layer baffle upper thread road, tin lead layer also can be protected hole wall simultaneously, then removes the burr at tangent plane place, half of PTH hole with engraving method.