CN116471740A - A high-reliability through-hole copper plating structure and its manufacturing method - Google Patents

Abstract

The invention discloses a high-reliability through hole copper plating structure and a manufacturing method thereof. The invention can improve the connection strength of the hole copper and the base copper and improve the production quality of the PCB.

Description

A high-reliability through-hole copper plating structure and its manufacturing method

technical field

The invention belongs to the technical field of PCB board manufacturing, and relates to a highly reliable through-hole copper plating structure and a manufacturing method thereof.

Background technique

With the development of science and technology and the improvement of people's lives, people have higher and higher requirements for the intelligentization of electronic equipment, which makes the design of the cornerstone PCB board of electronic equipment more and more complicated, with smaller and smaller volumes and denser circuits. The production methods of conventional thin lines include copper reduction method (thinning the surface copper thickness to facilitate etching lines), vacuum etching method (enhancing etching ability), hole electroplating method (only plating holes but not plate surface, reducing surface copper thickness) and so on.

However, the above technologies have different limitations. The copper reduction method or vacuum etching method cannot overcome the change in etching accuracy caused by uneven surface copper thickness, resulting in extremely poor yields when making dense and fine lines; while the hole electroplating method only plated holes without increasing the surface copper thickness, which can overcome the problem of uniformity of line etching, but there is a problem of weak connection between hole copper and base copper, and it is easy to break when electronic products are subjected to cold and heat shocks.

Contents of the invention

The object of the present invention is to overcome the deficiencies in the prior art, provide a highly reliable through-hole copper plating structure and its manufacturing method, which can improve the connection strength between hole copper and base copper, and improve the production quality of PCB boards.

In order to achieve the above object, the present invention is achieved by adopting the following technical solutions:

A high-reliability through-hole copper plating structure, comprising a circuit board, the circuit board is provided with a through hole, the two board surfaces of the circuit board are respectively provided with base copper, the hole wall of the through hole is provided with hole copper, and the hole copper and the base copper are provided with a mortise and tenon structure for strengthening the connection.

Optionally, the mortise and tenon structure includes a connection protrusion and a connection groove for installing the connection protrusion, the connection protrusion is provided on the hole copper at both ends of the through hole, and the connection groove is provided on the base copper at both ends of the through hole.

A method for manufacturing a highly reliable through-hole copper plating structure, comprising the following steps:

Pressing several core boards together to obtain circuit boards;

Cover the two sides of the circuit board with dry film;

Expose and develop the circuit board covered with dry film once, so that the dry film on the position where the window needs to be opened on the circuit board is developed, and the base copper is exposed;

Etching the exposed base copper to reduce copper;

Remove the dry film on both sides of the circuit board;

Drilling the base copper at the place where the copper is etched and reduced to obtain a through hole;

Metal coating on the hole wall of the through hole;

Cover the dry film on both sides of the circuit board again;

Perform secondary exposure and development on the circuit board covered with dry film, so that the dry film on the position where the window needs to be opened on the circuit board is developed, and the base copper and the through hole where the copper is etched and reduced are exposed;

Copper electroplating is carried out on the wall of the through hole after metal plating to obtain hole copper, so that the electroplated copper at both ends of the through hole is connected to the base copper at the etching copper reduction place;

Remove the dry film on both sides of the circuit board again;

The traces are etched on the circuit board from which the dry film has been removed again.

Optionally, also include:

After removing the dry film on the two surfaces of the circuit board again, the electroplated copper is leveled so that the electroplated copper at both ends of the through hole is level with the surface of the base copper.

Optionally, a ceramic brush is used to lightly brush the bumps on the electroplated copper surface at both ends of the through hole to smooth the electroplated copper.

Optionally, the exposed area of the base copper is greater than the cross-sectional area of the via hole during one exposure and development.

Optionally, metal plating is performed on the wall of the through hole by using a polymer conductive film, sputtering or electroless copper deposition.

Optionally, the area of the dry film developed by the first exposure is greater than the area of the dry film developed by the second exposure.

Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

The invention provides a highly reliable through-hole copper plating structure and a manufacturing method thereof. A mortise and tenon structure is provided between the hole copper and the base copper. The mortise and tenon structure can increase the contact surface between the hole copper and the base copper at the opening of the through hole, enhance the connection strength between the hole copper and the base copper, and prevent the connection fracture between the hole copper and the base copper;

The mortise and tenon structure can be completed by two times of exposure and development, etching of base copper and copper plating of through holes. The whole process is simple and convenient, without the need for thickening of copper plating, which greatly improves the accuracy and uniformity of the circuit.

Description of drawings

Fig. 1 shows the flow chart of high reliability through-hole copper plating structure and manufacturing method thereof of the present invention;

Fig. 2 shows the cross-sectional view of the circuit board in the first step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 3 shows the cross-sectional view of the circuit board in the second step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 4 shows the cross-sectional view of the circuit board in the third step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 5 shows the cross-sectional view of the circuit board in the fourth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 6 shows the cross-sectional view of the circuit board in the fifth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

FIG. 7 is a cross-sectional view of the circuit board in the sixth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 8 is a cross-sectional view of the circuit board in the seventh step of the highly reliable through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 9 is a cross-sectional view of a circuit board in the eighth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

FIG. 10 is a cross-sectional view of a circuit board in the ninth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

FIG. 11 is a cross-sectional view of a circuit board in the tenth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 12 is a cross-sectional view of a circuit board in the eleventh step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

Fig. 13 is a cross-sectional view of a circuit board in the twelfth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention;

FIG. 14 is a cross-sectional view of a circuit board in the thirteenth step of the high-reliability through-hole copper plating structure and its manufacturing method of the present invention.

In the figure: 1, circuit board; 11, core board; 2, through hole; 3, base copper; 4, hole copper; 5, connection convex; 6, connection groove; 7, dry film.

Implementation

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

Neither the endpoints nor any values of the ranges disclosed herein are limited to that precise range or value, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed herein.

For the purposes of this specification and the appended claims, unless otherwise stated, all figures expressing amounts, percentages or ratios and other numerical values used in this specification and the appended claims are understood to be modified in all instances by the term "about". Furthermore, all ranges disclosed herein are inclusive of endpoints and independently combinable.

Embodiment one

As shown in Figure 2, a highly reliable through-hole copper plating structure includes a circuit board 1, a through hole 2 is provided on the circuit board 1, base copper 3 is provided on the two board surfaces of the circuit board, and a hole copper 4 is provided on the hole wall of the through hole 2, and a mortise and tenon structure for strengthening the connection is provided between the hole copper 4 and the base copper 3.

The mortise and tenon structure includes a connecting protrusion 5 and a connecting groove 6 for installing the connecting protrusion 5. The connecting protrusion 5 is arranged on the hole copper 4 at both ends of the through hole 2, and the connecting groove 6 is arranged on the base copper 3 at both ends of the through hole 2. The connecting protrusion 5 and the connecting groove 6 are connected.

Embodiment two

As shown in FIG. 1 and FIG. 2, based on the high-reliability through-hole copper plating structure provided by Embodiment 1, this embodiment provides a manufacturing method for a high-reliability through-hole copper plating structure, including the following steps:

S1, pressing several core boards 11 to obtain a circuit board 1;

S2, covering the two board surfaces of the circuit board 1 with the dry film 7;

S3, exposing and developing the circuit board 1 covered with the dry film 7 once, so that the dry film on the position where the window needs to be opened on the circuit board 1 is developed, and the base copper 3 is exposed;

S4, etching the exposed base copper 3 to reduce the copper to obtain the connection groove 6;

S5, removing the dry film 7 on both board surfaces of the circuit board 1;

S6, drilling the bottom of the connecting groove 6 to obtain the through hole 2;

S7, performing a copper metal coating on the hole wall of the through hole 2 by using a polymer conductive film, sputtering or electroless copper deposition;

S8, covering the two board surfaces of the circuit board 1 with the dry film 7 again;

S9, performing secondary exposure and development on the circuit board covered with the dry film 7, so that the dry film 7 on the position where the window needs to be opened on the circuit board 1 is developed, and the connection groove 6 and the through hole 2 are exposed;

S10, electroplating copper on the wall of the through hole 2 after metal plating to obtain hole copper 4, so that the connection protrusions 5 at both ends of the through hole 2 are connected to the connection groove 6;

S11, remove the dry film 7 on the two board surfaces of the circuit board 1 again;

S12, etching lines on the circuit board 1 after removing the dry film 7 again.

One exposure and development reveals that the circle diameter of the base copper 3 is 0.4mm~2mm larger than the hole diameter of the through hole 2 .

The circle diameter of the dry film 7 developed by the single exposure is 0.05 mm to 0.1 mm larger than the circle diameter of the dry film 7 developed by the second exposure.

Embodiment Three

As shown in FIG. 1 and FIG. 2, based on the high-reliability through-hole copper plating structure provided by Embodiment 1, this embodiment provides a manufacturing method for a high-reliability through-hole copper plating structure, including the following steps:

S1, pressing several core boards 11 to obtain a circuit board 1;

S2, covering the two board surfaces of the circuit board 1 with the dry film 7;

S3, exposing and developing the circuit board 1 covered with the dry film 7 once, so that the dry film on the position where the window needs to be opened on the circuit board 1 is developed, and the base copper 3 is exposed;

S4, etching the exposed base copper 3 to reduce the copper to obtain the connection groove 6;

S5, removing the dry film 7 on both board surfaces of the circuit board 1;

S6, drilling the bottom of the connecting groove 6 to obtain the through hole 2;

S7, performing a copper metal coating on the hole wall of the through hole 2 by using a polymer conductive film, sputtering or electroless copper deposition;

S8, covering the two board surfaces of the circuit board 1 with the dry film 7 again;

S9, performing secondary exposure and development on the circuit board covered with the dry film 7, so that the dry film 7 on the position where the window needs to be opened on the circuit board 1 is developed, and the connection groove 6 and the through hole 2 are exposed;

S10, electroplating copper on the wall of the through hole 2 after metal plating to obtain hole copper 4, so that the connection protrusions 5 at both ends of the through hole 2 are connected to the connection groove 6;

S11, remove the dry film 7 on the two board surfaces of the circuit board 1 again;

S12, after removing the dry film 7 on the two board surfaces of the circuit board 1 again, lightly brush the protrusions on the surface of the connection protrusion 5 at both ends of the through hole 2 with a ceramic brush, and smooth the connection protrusion 5, so that the connection protrusion 5 at both ends of the through hole 2 is level with the surface of the base copper 3;

S13, etching lines on the circuit board 1 after removing the dry film 7 again.

One exposure and development reveals that the circle diameter of the base copper 3 is 0.4mm~2mm larger than the hole diameter of the through hole 2 .

The circle diameter of the dry film 7 developed by the single exposure is 0.05 mm to 0.1 mm larger than the circle diameter of the dry film 7 developed by the second exposure.

The above is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principles of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be considered as protection scope of the present invention.

Claims (8)

1. A high-reliability through-hole copper plating structure, comprising a circuit board, the circuit board is provided with a through hole, the two board surfaces of the circuit board are respectively provided with base copper, the hole wall of the through hole is provided with hole copper, it is characterized in that: a mortise and tenon structure for strengthening connection is provided between the hole copper and the base copper. 2. The highly reliable through-hole copper plating structure according to claim 1, characterized in that: the mortise and tenon structure includes a connection protrusion and a connection groove for installing the connection protrusion, the connection protrusion is provided on the hole copper at both ends of the through hole, and the connection groove is provided on the base copper at both ends of the through hole. 3. A method for manufacturing the high-reliability through-hole copper plating structure described in any one of claims 1-2, characterized in that, comprising the following steps: Pressing several core boards together to obtain circuit boards; Cover the two sides of the circuit board with dry film; Expose and develop the circuit board covered with dry film once, so that the dry film on the position where the window needs to be opened on the circuit board is developed, and the base copper is exposed; Etching the exposed base copper to reduce copper; Remove the dry film on both sides of the circuit board; Drilling the base copper at the place where the copper is etched and reduced to obtain a through hole; Metal coating on the hole wall of the through hole; Cover the dry film on both sides of the circuit board again; Perform secondary exposure and development on the circuit board covered with dry film, so that the dry film on the position where the window needs to be opened on the circuit board is developed, and the base copper and the through hole where the copper is etched and reduced are exposed; Copper electroplating is carried out on the wall of the through hole after metal plating to obtain hole copper, so that the electroplated copper at both ends of the through hole is connected to the base copper at the etching copper reduction place; Remove the dry film on both sides of the circuit board again; The traces are etched on the circuit board from which the dry film has been removed again. 4. The manufacturing method of the high-reliability through-hole copper-plated structure according to claim 3, further comprising: After removing the dry films on the two surfaces of the circuit board again, the electroplated copper is leveled so that the electroplated copper at both ends of the through hole is level with the surface of the base copper. 5 . The manufacturing method of the highly reliable through-hole copper-plated structure according to claim 4 , characterized in that: use a ceramic brush to lightly brush the bumps on the electroplated copper surface at both ends of the through-hole to smoothen the electroplated copper. 6 . 6 . The manufacturing method of the highly reliable through-hole copper-plated structure according to claim 3 , wherein the exposed area of the base copper is larger than the cross-sectional area of the through-hole through one exposure and development. 7 . 7. The manufacturing method of the highly reliable through-hole copper-plated structure according to claim 3, characterized in that: metal plating is performed on the hole wall of the through-hole by polymer conductive film, sputtering or electroless copper deposition. 8 . The manufacturing method of the highly reliable through-hole copper plating structure according to claim 3 , wherein the area of the dry film developed by the first exposure is larger than the area of the dry film developed by the second exposure.