CN106793574A - A kind of PCB back drilling methods - Google Patents

Abstract

The invention discloses a PCB back-drilling method. The method removes the short pile part of the PCB board through corrosion to realize the PCB back-drilling. By stuffing the solder resist ink into the hole that needs to be back drilled, the solder resist ink only fills the signal transmission part in the hole, and the short pile part is not filled with solder resist ink; then plug the hole that needs to be back drilled into the hole of the solder resist ink Corrosion, because the line of the short pile is not protected by ink, so in a corrosive environment, this section of copper will be corroded directly, and finally the short pile stub will be removed to form the back drilling we need. The method of the invention can easily realize the back-drilling of the PCB without using expensive back-drilling equipment, so that the back-drilling technology becomes simple and easy.

Description

A PCB back drilling method

technical field

The invention relates to the technical field of PCB boards, in particular to a PCB back-drilling method.

Background technique

After electronic equipment adopts PCB (printed circuit board or printed board), due to the consistency of similar printed boards, manual wiring errors are avoided, and electronic components can be automatically inserted or mounted, automatic soldering, automatic Testing ensures the quality of electronic equipment, improves labor productivity, reduces costs, and facilitates maintenance.

Printed boards have developed from single-layer to double-sided, multi-layer and flexible, and still maintain their own development trends. Due to the continuous development in the direction of high precision, high density and high reliability, continuous reduction in size, cost reduction and performance improvement, printed boards still maintain strong vitality in the development of future electronic equipment.

Discussions on the future development trend of printed board manufacturing technology at home and abroad are basically consistent, that is, to high density, high precision, fine aperture, thin wire, fine pitch, high reliability, multi-layer, high-speed transmission, light weight, thin Develop in the direction of production, and at the same time increase productivity, reduce costs, reduce pollution, and adapt to the direction of multi-variety and small-batch production. The technical development level of printed circuits is generally represented by the line width, aperture, and board thickness/aperture ratio of the printed circuit board.

With the high speed of signal transmission, the high density of printed circuit boards, and the low loss of signals have gradually become a development trend of printed circuit boards.

As shown in Figure 1, it is a schematic cross-sectional view of a 6-layer printed circuit board, in which:

101 is a circuit: the function of the circuit is equivalent to a wire, which can connect different components to each other to form an electrical network;

102 is a hole: the function of the hole is to connect the lines of different layers to each other, so that the different layers of the PCB are interconnected into an electrical network;

103 is an insulating layer: the function of the insulating layer is to isolate different lines, isolate different holes, and ensure that no short circuit occurs in the lines;

104 is a signal transmission route, and 104 shows that a signal is transmitted from the L6 layer to the L3 layer through holes;

105 is the distance from the drill hole to the inner circuit. In order to ensure that the drill hole and the inner circuit are not short-circuited, a certain distance is required for 105, which has different values according to the different processing capabilities of different companies;

106 is STUB (short stub), which is a redundant part in signal transmission, but it must appear in the process of PCB processing due to the needs of the process;

At present, the PCB industry drills out redundant stubs through back drilling to reduce signal loss.

As shown in Figure 2, it is a schematic cross-sectional view of the PCB after back drilling, where:

201 is back-drilling, when back-drilling, the drilling machine can control the depth of the drilling to drill off the redundant short piles without damaging the required layers;

202 is the distance from the hole before back drilling to the inner layer copper, 202 is equivalent to 105 in Figure 1;

203 is the distance from the edge of the hole after back drilling to the inner layer copper. In order to ensure that the redundant short piles can be completely drilled off, 202 is generally 0.05mm larger than 203 in the industry;

204 is an inner circuit.

Back-drilling requires special back-drilling equipment. At present, the key high-precision stepping motor and high-precision optical ruler technology involved in this equipment are controlled by foreign companies. Domestic companies need to pay a lot of money if they want to get involved in this field.

Contents of the invention

The technical problem to be solved by the present invention is: the present invention provides a PCB back-drilling method aiming at the above problems.

The technical scheme adopted in the present invention is:

A PCB back-drilling method, the method removes the short pile part of the PCB board by means of corrosion, so as to realize the PCB back-drilling.

The implementation process of the method is as follows: the solder resist ink is inserted into the hole that needs to be back-drilled, the solder resist ink only fills the signal transmission part in the hole, and the short pile part is not filled with the solder resist ink;

Then plug the hole that needs to be back drilled into the hole of the solder resist ink for corrosion. Since the circuit of the short pile is not protected by the ink, in a corrosive environment, the copper of this section will be corroded directly, and finally the short pile STUB will be removed. Form the back drill we need.

In the method, a layer of solder resist ink is also covered on the surface of the PCB to expose only the holes that need to be back-drilled, and then the corrosive liquid is sprayed on the surface of the PCB, and the back-drilling operation is performed on all short piles on the surface of the PCB at the same time.

The beneficial effects of the present invention are:

The method of the invention can easily realize the back-drilling of the PCB without using expensive back-drilling equipment, so that the back-drilling technology becomes simple and easy.

Description of drawings

Figure 1 is a schematic cross-sectional view of a PCB to be backdrilled, and the PCB has relatively large short piles;

Figure 2 is a schematic cross-sectional view of the PCB after back drilling;

Fig. 3 is a schematic diagram of stuffing solder resist ink into a hole to be back-drilled.

detailed description

The present invention will be further described below in conjunction with specific embodiments according to the accompanying drawings of the description:

Example 1

A PCB back-drilling method, the method removes the short pile part of the PCB board by means of corrosion, so as to realize the PCB back-drilling.

Example 2

As shown in Figure 3, on the basis of Example 1, this embodiment inserts solder resist ink into the hole that needs to be back-drilled. The solder resist ink only fills the signal transmission part in the hole, and the short pile part is not filled with solder resist ink. ;

Then plug the hole that needs to be back drilled into the hole of the solder resist ink for corrosion. Since the circuit of the short pile is not protected by the ink, in a corrosive environment, the copper of this section will be corroded directly, and finally the short pile STUB will be removed. Form the required back drill.

Example 3

On the basis of Example 2, the method described in this example covers the surface of the PCB with a layer of solder resist ink, exposing only the holes that need to be back-drilled, and then spraying the corrosive liquid on the surface of the PCB, which can damage the PCB. All short pile sections on the surface are backdrilled simultaneously.

The embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those of ordinary skill in the relevant technical field can also make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent The technical solution also belongs to the category of the present invention, and the scope of patent protection of the present invention should be defined by the claims.

Claims (3)

1. a kind of PCB back drilling methods, it is characterised in that methods described is gone to the stub part of pcb board by way of corrosion Fall, realize PCB back drills.

2. a kind of PCB back drilling methods according to claim 1, it is characterised in that methods described implementation process is as follows：

Solder mask is filled in the hole for need back drill, solder mask is filled only with signal transmission part in full hole, and stub part is not Filling solder mask；

Then the stopple of back drill will be needed to enter the hole of solder mask corroded.

3. a kind of PCB back drilling methods according to claim 2, it is characterised in that methods described is by pcb board surface One layer of solder mask of covering, only exposing needs the hole of back drill, and corrosive liquids then is sprayed into pcb board face, to pcb board face institute There is stub part while carrying out back drill operation.