CN103179805A - Metal half-hole forming method and printed circuit board manufacturing method - Google Patents

Abstract

The invention provides a metal half hole molding method. A metal half hole of a printed circuit board (PCB) is molded through a board milling procedure before the procedures of film removing, alkaline etching and tin removing in the manufacture process of the PCB. A manufacture method of the PCB is further provided. The manufacture method includes the metal half hole molding method which is used for manufacturing the metal half hole of the PCB. By means of the metal half hole molding method and the manufacture method of the PCB, the metal half hole is molded by milling the board before the procedures of film removing, alkaline etching and tin removing, the problem of residual copper wire burr is solved, and the effect of improving molding quality of the metal half hole is achieved.

Description

Metal half-hole forming method and printed circuit board manufacturing method

technical field

The invention relates to the field of printed circuit boards (PCBs), in particular to a metal half-hole forming method and a PCB manufacturing method.

Background technique

Metal half hole is also called half PTH (plating through hole, plated through hole). FIG. 1 shows a PCB with metal half-holes arranged on all four sides of a unit according to the related art, and FIG. 2 shows an enlarged schematic diagram of part A in FIG. 1 . As shown in the figure, the so-called metal half hole refers to the metallized hole (or groove) that only half is left on the edge of the PCB shape, and the other half will be milled off during the shape processing.

The general mechanical processing method of circuit board forming is CNC forming machine milling. A metal half-hole forming method in the related art is to directly form metal half-holes in the process of milling the shape of the PCB after printing characters. The specific process is as follows:

Lamination→drilling→electroless copper→electroplating copper→outer layer dry film→electroplating copper tin→removing film/alkaline etching/sn stripping→wet film→electroless nickel gold→printing characters→milling (shape forming and metal Half-hole forming) → E/T (electrical test) → FQC (final quality inspection) → QA AUDIT (quality assurance) → packaging.

Fig. 3 shows a schematic diagram of milling a metal half hole according to the related art. As shown in the figure, in the direction of travel of the milling cutter, it is easy to leave copper wire burrs in the holes of the metal half holes. These metal half-holes are to be soldered to the pins of the components. If copper wire burrs remain in these metal half-holes, problems such as weak soldering feet, false soldering, and bridging short circuits will occur during soldering.

In order to solve the problem of residual copper wire burrs in the metal half hole, the related technology provides a solution. Before milling, the metal hole is drilled twice in the direction of the milling cutter. The specific process is as follows:

Lamination→drilling→electroless copper→electroplating copper→outer layer dry film→electroplating copper tin→removing film/alkaline etching/sn stripping→wet film→electroless nickel gold→printing characters→secondary drilling→milling (shape forming and metal half-hole forming) → E/T (electrical test) → FQC (final quality inspection) → QA AUDIT (quality assurance) → packaging.

However, as shown in FIG. 4 , the inventors have found that the secondary drilling is prone to misalignment. The inventor found that due to the tolerance of the secondary drilling and milling in the forming process, the center line of the milling plate does not fall on the position of the secondary drilling. When cutting the copper in the hole, it will inevitably lead to residual copper on the section of the remaining part of the copper-plated hole. The copper wire burrs shown in Figure 3 below, and even the copper skin on the hole wall are seriously lifted.

In order to solve the problem of residual copper wire burrs in the metal half-hole, the related technology also provides a solution. The metal half-hole forming is canceled in the process, and the specific process is as follows:

Lamination→drilling→electroless copper→electroplating copper→outer layer dry film→electroplating copper tin→removing film/alkaline etching/sn stripping→wet film→electroless nickel gold→printing characters→V-CUT→milling ( Forming)→E/T→FQC→QA AUDIT→Packaging.

As PCB boards tend to be short, small, light, and thin, the half-hole diameter required by many designs is only 0.5mm. However, as shown in Figure 5, the inventors found that when the metal half hole < 0.5mm, the V-CUT caused the quality problem of the metal half hole < 1/3 of the aperture, that is, the V-CUT design method did not reach the metal half hole. Hole ≥ 0.2mm requirements.

Contents of the invention

The present invention aims to provide a metal half-hole forming method and a PCB manufacturing method to form high-quality metal half-holes.

In an embodiment of the present invention, a metal half-hole forming method is provided. In the process of manufacturing PCB, before the film removal/alkaline etching/soldering process, the process of milling the printed circuit board is formed. Metal half hole.

In an embodiment of the present invention, a PCB manufacturing method is provided, including the metal half-hole forming method of the above-mentioned embodiment, which is used to manufacture the metal half-hole of the PCB.

The metal half-hole forming method and the PCB manufacturing method of the above-mentioned embodiments of the present invention overcome the problem of residual copper wire burrs in the metal half-hole because the metal half-hole is formed by milling before the film removal/alkaline etching/soldering process, and achieve The effect of improving the forming quality of metal semi-holes.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 shows a PCB with metal half-holes in the entire four sides of the unit according to the related art;

Figure 2 shows an enlarged schematic view of part A in Figure 1;

Fig. 3 shows the schematic diagram according to the milling plate forming metal half hole of related art;

Fig. 4 shows the schematic diagram of secondary drilling forming metal half hole according to the related art;

Fig. 5 shows the schematic diagram according to the V-CUT molding metal half hole of related art;

Fig. 6 shows a schematic diagram of forming metal half holes in the milling process according to an embodiment of the present invention;

Fig. 7 shows a schematic diagram of the metal half hole after the milling process according to an embodiment of the present invention;

Fig. 8 shows a schematic diagram of a metal half-hole after a film removal/alkaline etching/sn stripping process according to an embodiment of the present invention;

Fig. 9 shows a schematic diagram of forming metal half-holes in the milling process according to a preferred embodiment of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

Fig. 6 shows a schematic diagram of forming a metal half hole in the milling process according to an embodiment of the present invention. In the process of manufacturing PCB, before the film removal/alkaline etching/soldering process, the printing process is formed by the milling process. Metal half hole for circuit board.

The related technology is to form the metal half hole at the same time when the milling board is forming the shape of the PCB, so the purpose of adding the second drilling process is to avoid the copper wire burr when the milling board is forming the metal half hole. In this embodiment, the process of milling the metal half hole is advanced before the film removal/alkaline etching/sn stripping process, so that the milling process can be removed by the film removal/alkaline etching/sn stripping process to form the metal half hole. Copper wire burrs (especially alkaline etching can ensure that the copper wire burrs are etched away).

As shown in FIG. 7 , after the milling process of this embodiment is performed, copper wire burrs will be formed in the metal half-hole. As shown in FIG. 8 , after the film removal/alkaline etching/sn stripping process is performed, the copper wire burr formed in the metal half hole can be etched away.

That is, the difference between this embodiment and related technologies is that this embodiment does not try to avoid the formation of burrs in the metal half-holes in the milling process, but uses the subsequent film removal/alkaline etching/sn stripping process in the later stage Removes burrs formed in metal half-holes. In this embodiment, by simply adjusting the execution sequence of the processes, the forming quality of the metal half-hole is improved, and the problem of deviation in the secondary drilling is solved.

Preferably, the milling process is performed between the copper-tin electroplating process and the film removal/alkaline etching/sn stripping process. The relevant technology is to perform the milling process after the tin stripping process, but in this preferred embodiment, the milling process is performed between the electroplating copper tin process and the film removal/alkaline etching/tin stripping process, so that tin plating can be used to protect Metal half hole.

Fig. 9 shows a schematic diagram of forming a metal half hole in the milling process according to a preferred embodiment of the present invention, wherein the milling strip width range of the milling process can be 0.8mm to 2.0mm. For example, the milling strip width of the milling process can be 1.2mm. Preferably, the PCB is fixed by the connecting bridge when the milling process is performed. Preferably, the width of the connecting bridge is ≥ 4 mm. Preferably, no less than 4 connection bridges are set on each PCS (unit) in the PCB manufacturing process.

The inventor has verified and obtained the parameters of the above preferred embodiment through a large number of experiments, and the setting of the above parameters can further improve the forming quality of the metal half hole.

Preferably, between the milling process and the film removal/alkaline etching/sn stripping process, a high-pressure cleaning process is also included to clean the residue generated in the milling process.

Preferably, the process of manufacturing PCB includes: lamination→drilling→electroless copper plating→copper electroplating→outer layer dry film→copper tin electroplating→milling process→high pressure cleaning→film removal/alkaline etching/sn stripping process →Wet film→Immersion Nickel Gold→Printing characters→Milling (shape)→E/T→FQC→QA AUDIT→Packaging.

An embodiment of the present invention also provides a method for manufacturing a PCB, including the metal half-hole forming method of any one of the above-mentioned embodiments, for manufacturing a metal half-hole of a PCB.

Preferably, the PCB manufacturing method includes: lamination→drilling→electroless copper plating→copper electroplating→outer layer dry film→copper tin electroplating→milling process→high pressure cleaning→film removal/alkaline etching/tin stripping process →Wet film→Immersion Nickel Gold→Printing characters→Milling (shape)→E/T→FQC→QA AUDIT→Packaging.

As can be seen from the above description, compared with the related technology, the above embodiment of the present invention has the following obvious advantages after changing the execution order of the milling process:

First: The metal half hole is milled and formed at one time, without the need for secondary drilling, which reduces additional costs;

Second: It can effectively remove the burrs in the metal half hole to ensure the quality of the metal half hole;

Third: It can make metal half-holes with a diameter of ≤0.6mm, and can ensure that the diameter of the metal half-holes is ≥0.2mm.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A metal half-hole forming method is characterized in that, in the process of manufacturing a printed circuit board, before the film removal/alkaline etching/sn stripping operation, the metal half of the printed circuit board is molded by the operation of milling board hole. 2. The method according to claim 1, wherein the milling process is performed between the copper-tin electroplating process and the film removal/alkaline etching/sn stripping process. 3. The method according to claim 1, characterized in that, the width of the strip milling in the milling process is 0.8 mm to 2.0 mm. 4. The method according to claim 1, characterized in that, when performing the milling process, the printed circuit board is fixed by connecting bridges. 5. The method according to claim 4, characterized in that the width of the connecting bridge is ≥ 4mm. 6 . The method according to claim 4 , wherein no less than four connecting bridges are provided on each unit of the printed circuit board manufacturing process. 7 . 7. The method according to claim 1, characterized in that, between the milling process and the film removal/alkaline etching/sn stripping process, a high-pressure cleaning process is also included for cleaning the milling process Process residues. 8. The method according to claim 7, wherein the process of manufacturing a printed circuit board comprises: Lamination→drilling→electroless copper plating→copper electroplating→outer layer dry film→copper tin electroplating→the milling process→high pressure cleaning→the film removal/alkaline etching/tin stripping process→wet film→chemical Immersion nickel gold→printing characters→milling (outline)→electrical testing→final quality inspection→quality assurance→packaging. 9. A method for manufacturing a printed circuit board, characterized in that it comprises the metal half-hole forming method according to any one of claims 1-7, for manufacturing the metal half-hole of the printed circuit board. 10. The method of claim 9, comprising: Lamination→drilling→electroless copper plating→copper electroplating→outer layer dry film→copper tin electroplating→the milling process→high pressure cleaning→the film removal/alkaline etching/tin stripping process→wet film→chemical Immersion nickel gold→printing characters→milling (outline)→electrical testing→final quality inspection→quality assurance→packaging.

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