CN116367429A - Manufacturing method of power circuit board with blind buried holes - Google Patents

Abstract

The invention provides a manufacturing method of a power circuit board with blind buried holes, which is characterized in that a conduction butt joint mode of an inner layer and an outer layer is optimized, a residual copper layer left at the bottom after deep drilling of blind holes on an L3-L4 ultra-thick copper core board is directly used for replacing a copper covering layer, then the deep drilling blind holes are metallized through copper deposition and VCP electroplating, laser drilling is carried out after lamination, a laser blind hole is drilled on the residual copper layer left when the deep drilling of the blind holes is carried out, and then hole filling is carried out through electroplating, so that conduction between the inner layer and the outer layer can be realized; meanwhile, the time-controlled deep blind hole pressing glue filling is free of resin hole filling, so that the manufacturing process is effectively shortened, the efficiency is improved, and meanwhile, the cost is saved.

Description

Manufacturing method of power circuit board with blind buried holes

Technical Field

The invention relates to the field of circuit board manufacturing, in particular to a method for manufacturing a power supply circuit board with blind buried holes.

Background

The power panel is mainly applied to a plurality of fields such as a photovoltaic inverter, a guide rail power supply, an industrial power supply, a medical power supply, an automobile power management system, a power distribution system, an energy storage and charging pile power supply control main board and the like.

At present, the design of copper thickness is mainly mainstream with 2oz to 4oz, and in the future, the requirements of high heat resistance, high heat dissipation and other characteristics such as high-power and high-current server power boards are more prone to be designed into thicker copper PCBs, and under the condition of a certain line width, increasing copper thickness is equivalent to increasing the cross-sectional area of a circuit, and the power board has the characteristics of carrying large current, reducing thermal strain, good heat dissipation and voltage breakdown resistance. The PCB structure of the part high heat resistance and high heat dissipation power supply can adopt inner layer ultra-thick copper and outer layer 2OZ, and the inner layer and the outer layer are communicated through blind buried holes, so that the aim of network conduction is fulfilled, and meanwhile, the high heat resistance and high heat dissipation of the PCB are met.

At present, the general method in the industry is to manufacture buried holes on an ultra-thick copper core board, manufacture a copper-covered layer by electroplating and filling (POFV process) after resin is plugged, manufacture an inner layer circuit, laminate the inner layer circuit, and then conduct an outer layer and an inner layer by laser blind hole drilling and hole filling electroplating; however, this procedure has the following disadvantages:

(1) The process is long, the buried holes are required to be filled with resin and then electroplated and filled (POFV process), so that the production time is prolonged;

(2) The manufacturing cost is increased, and as the laser blind holes on the secondary outer layer are required to be communicated with the inner layer, the buried holes are required to be subjected to a resin hole plugging process and an electroplating filling process (POFV process) to manufacture the copper-covered layer. The resin hole plugging process needs resin hole plugging, resin curing and resin polishing, the electroplating filling process needs copper deposition 2 and VCP electroplating 2, and both the processes need manpower and material resources investment, so that the manufacturing cost is greatly increased.

Disclosure of Invention

The invention provides a manufacturing method of a power circuit board with blind buried holes, which aims to solve at least one technical problem.

In order to solve the above problems, as one aspect of the present invention, there is provided a method for manufacturing a power circuit board including blind buried vias, comprising:

step 1, cutting:

cutting the copper-clad plate into a designed size by a blanking machine to obtain an L3-L4 ultra-thick copper core plate with the thickness of 0.1mm8/8OZ (without copper);

step 2, deep drilling of blind holes:

processing a depth control blind hole with the aperture of 0.45mm, the depth of 0.45mm and the bottom residual copper layer thickness of 0.15+/-0.05 mm on the laminated middle two-layer plate (the depth of the depth control blind hole and the aperture ratio are less than or equal to 1:1);

step 3, hole metallization;

step 4, internal light imaging;

step 5, etching the inner layer;

step 6, superposing the L1 layer and the L4 layer on the outer sides of the middle two layers in a laminating mode;

step 7, brown oxidation copper reduction:

reducing the thickness and the brown copper of copper on the surface to 7-9 mu m by means of uniform chemical copper biting;

step 8, laser drilling:

processing laser blind holes on the plate subjected to the brown copper reduction by using a laser drilling machine;

step 9, copper deposition 2:

hole metallization treatment is carried out on the plate subjected to laser drilling, so that a conductive layer is formed in a substrate area in the middle of the plate;

step 10, electroplating and hole filling:

thickening a copper deposition layer of the plate after copper deposition 2 in an electroplating mode, filling up laser blind holes, and conducting three layers of networks of L1, L2 and L3 and three layers of networks of L2, L3 and L4.

According to the invention, the conduction butt joint mode of the inner layer and the outer layer is optimized, a residual copper layer (with the thickness of 0.15+/-0.05 mm) remained at the bottom after deep drilling of the blind holes on the L3-L4 ultra-thick copper core plate is directly used for replacing a cover copper layer, then the deep drilling blind holes are metallized through copper deposition 1 and VCP electroplating 1, laser drilling is carried out after lamination, the laser blind holes are drilled on the residual copper layer remained when the blind holes are deep drilled, and then electroplating is carried out for filling holes, so that the conduction between the inner layer and the outer layer can be realized; meanwhile, the time-controlled deep blind hole pressing glue filling is free of resin hole filling, so that the manufacturing process is effectively shortened, the efficiency is improved, and meanwhile, the cost is saved.

Drawings

FIG. 1 schematically shows a schematic structure of the middle two layers;

FIG. 2 schematically shows a schematic structural view of the deep blind hole;

FIG. 3 schematically shows a schematic structural diagram after hole metallization;

FIG. 4 schematically shows a schematic structural view after internal light imaging;

FIG. 5 schematically shows a schematic view of the structure after etching of the inner layer;

fig. 6 schematically shows a schematic structural view after lamination;

FIG. 7 schematically shows a schematic view of the structure after laser drilling;

fig. 8 schematically shows a schematic structural view after electroplating of the via holes.

Detailed Description

The following describes embodiments of the invention in detail, but the invention may be practiced in a variety of different ways, as defined and covered by the claims.

The invention provides a production method of a high heat-resistant and high heat-dissipation power supply PCB (printed circuit board) with blind buried holes, which is characterized in that a conduction butt joint mode of an inner layer and an outer layer is optimized, a residual copper layer (thickness of 0.15+/-0.05 mm) remained at the bottom after deep drilling of blind holes on an L3-L4 ultra-thick copper core plate is directly used for replacing a cover copper layer, then the deep drilling blind holes are metallized through copper deposition 1 and VCP electroplating 1, laser drilling is carried out after lamination, a laser blind hole is drilled on the residual copper layer remained when the blind holes are drilled in the deep drilling, and then hole filling is carried out through electroplating, so that the conduction of the inner layer and the outer layer can be realized; meanwhile, the time-controlled deep blind hole pressing glue filling is free of resin hole filling, so that the manufacturing process is effectively shortened, the efficiency is improved, and meanwhile, the cost is saved.

Referring to FIG. 8, FIG. 8 is a graph showing the effect of 4 layers of substrates after electroplating and hole filling, wherein 1 is a depth-controlled blind hole (aperture 0.45mm, depth-controlled blind hole depth and aperture ratio less than or equal to 1:1); 2 is a hole copper layer with the thickness of 20-25 mu m after the deep control blind hole is metallized; 3 is a laser blind hole after electroplating and hole filling; 4 is an L1-L2 laminar flow prepreg; 5 is an L3-L4 laminar flow prepreg; 6 is VCP plating 1 copper plating layer with the thickness of 25-35 mu m;7 is a residual copper layer (the thickness of the residual copper layer is 0.15mm, and the tolerance is +/-0.05 mm) remained at the bottom after deep drilling of blind holes on the L3-L4 ultra-thick copper core plate; 8 is the base copper thickness of the L3-L4 ultra-thick copper core plate, and the copper thickness is more than or equal to 8OZ.

The invention relates to a manufacturing method of a power circuit board with blind buried holes, which comprises the following steps:

1. cutting material

The copper-clad plate is cut into a designed size by a blanking machine, and an L3-L4 ultra-thick copper core plate with the thickness of 0.1mm8/8OZ (without copper) is manufactured.

2. Depth-controlled drilling blind hole

And processing the laminated plate by using a high-speed drilling machine to form a depth-control blind hole with the aperture of 0.45mm and the depth of 0.45mm and the thickness of the residual copper layer at the bottom of 0.15+/-0.05 mm (the depth of the depth-control blind hole is less than or equal to 1:1).

3. Hole metallization (copper deposition 1, VCP plating 1):

copper deposition 1: hole metallization treatment is carried out on the drilled plate, and the main purpose of the treatment is to enable a base material area in the middle of the plate to form a conductive layer, wherein the generated copper layer is about 0.02 um;

VCP plating 1: the plate after copper deposition is thickened by electroplating, the thickness of copper on the surface is about 25-35um, the thickness of copper on the blind hole is about 20-25um, and the L2 layer and the L3 layer are conducted.

4. Internal light imaging

And (3) pasting a dry film on the plate surface at a certain temperature and under a certain pressure, aligning by using a negative film, finally utilizing ultraviolet irradiation on an exposure machine to enable the non-shaded dry film of the negative film to react, forming a required circuit pattern on the plate surface, dissolving the film which is not irradiated by light under the action of a developing solution through a developing section, etching the exposed copper under the action of an acid etching solution through an etching section, and finally removing the film under the action of a film removing solution through a film removing section to expose an inner layer circuit pattern.

5. Inner layer etching

The copper layer is firstly etched by chemical liquid medicine, and the liquid medicine does not corrode the dry film. And after etching, the dry film is removed to expose the required circuit pattern.

6. Lamination

Through stacking prepregs, under the action of certain temperature and pressure, lines, base materials and depth control blind holes are filled through resin flow of the prepregs, and when the temperature reaches a certain degree, solidification occurs to bond the layers together.

7. Brown copper reduction

The copper thickness and the brown of the surface copper are reduced to 7-9 mu m by means of uniform chemical biting of copper.

8. Laser drilling

And processing laser blind holes on the plate after the copper reduction by brown oxidation by using a laser drilling machine. And (3) drilling the laser to the depth of the interlayer L2\L3 layer.

9. Copper deposition 2: hole metallization treatment is carried out on the plate after laser drilling, and the main purpose of the treatment is to enable a base material area in the middle of the plate to form a conductive layer, wherein the generated copper layer is about 0.02 um.

10. Electroplating filling hole

Thickening a copper deposition layer of the plate after copper deposition 2 in an electroplating mode, filling up laser blind holes, and conducting three layers of networks of L1, L2 and L3 and three layers of networks of L2, L3 and L4.

In the technical scheme, the conduction mode of the inner layer and the outer layer is changed from the conduction mode of the buried hole and the laser blind hole in a butt joint mode to the conduction mode of the depth-controlled blind hole and the laser blind hole in a butt joint mode, so that the cost and the production efficiency are both greatly improved, and a technical foundation is laid for mass production.

According to the invention, the conduction butt joint mode of the inner layer and the outer layer is optimized, a residual copper layer (with the thickness of 0.15+/-0.05 mm) remained at the bottom after deep drilling of the blind holes on the L3-L4 ultra-thick copper core plate is directly used for replacing a cover copper layer, then the deep drilling blind holes are metallized through copper deposition 1 and VCP electroplating 1, laser drilling is carried out after lamination, the laser blind holes are drilled on the residual copper layer remained when the blind holes are deep drilled, and then electroplating is carried out for filling holes, so that the conduction between the inner layer and the outer layer can be realized; meanwhile, the time-controlled deep blind hole pressing glue filling is free of resin hole filling, so that the manufacturing process is effectively shortened, the efficiency is improved, and meanwhile, the cost is saved.

The invention has the following advantages:

(1) The conduction mode of the inner layer and the outer layer does not need to manufacture a copper-covered layer (which is formed by embedding holes in L2-L3 layers with resin and then depositing copper 2 and VCP electroplating 2) to enable laser blind holes to be in butt joint conduction, and the copper-covered layer is directly replaced by a residual copper layer left at the bottom after deep drilling of the blind holes on the L3-L4 ultra-thick copper core board, so that the manufacturing flow is shortened, the efficiency is improved, and the cost is saved;

(2) The depth-control blind hole pressing glue filling does not need to be filled with resin, so that the manufacturing process is shortened, the efficiency is improved, and the cost is saved.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (1)

1. A manufacturing method of a power circuit board with blind buried holes is characterized by comprising the following steps:

step 1, cutting:

cutting the copper-clad plate into a designed size by a blanking machine to obtain an L3-L4 ultra-thick copper core plate with the thickness of 0.1mm8/8OZ (without copper);

step 2, deep drilling of blind holes:

processing a depth control blind hole with the aperture of 0.45mm, the depth of 0.45mm and the bottom residual copper layer thickness of 0.15+/-0.05 mm on the laminated middle two-layer plate (the depth of the depth control blind hole and the aperture ratio are less than or equal to 1:1);

step 3, hole metallization;

step 4, internal light imaging;

step 5, etching the inner layer;

step 6, superposing the L1 layer and the L4 layer on the outer sides of the middle two layers in a laminating mode;

step 7, brown oxidation copper reduction:

reducing the thickness and the brown copper of copper on the surface to 7-9 mu m by means of uniform chemical copper biting;

step 8, laser drilling:

processing laser blind holes on the plate subjected to the brown copper reduction by using a laser drilling machine;

step 9, copper deposition 2:

hole metallization treatment is carried out on the plate subjected to laser drilling, so that a conductive layer is formed in a substrate area in the middle of the plate;

step 10, electroplating and hole filling:

thickening a copper deposition layer of the plate after copper deposition 2 in an electroplating mode, filling up laser blind holes, and conducting three layers of networks of L1, L2 and L3 and three layers of networks of L2, L3 and L4.

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