A stacked laser hole structure and manufacturing method thereof

Abstract

The present invention discloses a stacked laser hole structure and a manufacturing method thereof. The present invention adopts a mechanical through hole stacked first laser hole structure. Compared with a traditional HDI board, the structure is more compact. Compared with a traditional anylayer board, the laser hole is easier to align. In addition, a metal boss is arranged between the first laser hole and the mechanical through hole to ensure the reliability of the through hole joint surface, and can withstand extreme environments or long-term impacts encountered in industries such as aerospace, military industry, and automobiles.

Description

Technical Field

[0001] The invention relates to a stacked laser hole structure and a manufacturing method thereof, and belongs to the field of PCB preparation. Background Art

[0002] In recent years, circuit boards have been developing in the direction of being small and dense, and the corresponding vias on the circuit boards have also become smaller and smaller, thus developing high-density interconnect circuit boards, or HDI boards. Conventional HDI boards use staggered designs of through holes and laser holes or use an anylayer design with full laser hole stacking (called "anylayer boards"), but there are the following problems: 1. The staggered design has the problem of complex circuits and large volumes; 2. Full laser stacking is extremely demanding on the alignment capability of laser holes and the production capacity of thin boards. Generally, it is difficult to control the alignment when stacking to 4 layers. Summary of the invention

[0003] The present invention provides a stacked laser hole structure and a manufacturing method thereof, which solves the problems disclosed in the background technology.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A stacked laser hole structure comprises a substrate, a mechanical through hole is punched on the substrate, the top surface of the substrate, the bottom surface of the substrate and the inner wall of the mechanical through hole are all plated with metal layers, a filler is plugged in the mechanical through hole plated with the metal layer, the top and bottom ends of the filler are both plated with metal bosses, a dielectric layer is pressed on the metal layer on the top surface of the substrate and the metal boss, a first laser hole is punched on the dielectric layer, the first laser hole and the mechanical through hole are on the same straight line, the bottom end of the first laser hole is in contact with the metal boss, the aperture of the bottom end opening of the first laser hole and the mechanical through hole are both smaller than the diameter of the metal boss, the top surface of the dielectric layer is plated with a metal layer, and the metal layer on the top surface of the dielectric layer fills the first laser hole.

[0006] The filling material is resin or metal.

[0007] Circuits are etched on the metal layers on the top and bottom surfaces of the substrate, and the etching depth extends to the metal base layer of the substrate; circuits are etched on the metal layer on the top surface of the dielectric layer, and the etching depth extends to the metal base layer of the dielectric layer.

[0008] A second laser hole is also drilled on the dielectric layer. There is no mechanical through hole below the second laser hole. The bottom of the second laser hole is in contact with the metal layer on the top surface of the substrate. The metal layer on the top surface of the dielectric layer also fills the second laser hole.

[0009] A method for manufacturing a stacked laser hole structure, comprising:

[0010] Step 1, making a substrate and drilling mechanical through holes on the substrate;

[0011] Step 2, metallizing the substrate after drilling the mechanical through hole, and plating a metal layer on the top surface of the substrate, the bottom surface of the substrate and the inner wall of the mechanical through hole;

[0012] Step 3, filling the mechanical through hole plated with the metal layer with a filler;

[0013] Step 4, metallizing the substrate after being filled with fillers again, and plating a metal layer covering the fillers on the top and bottom surfaces of the substrate;

[0014] Step 5, pressing a dry film on the top and bottom surfaces of the re-metallized substrate, and opening a hole in the dry film facing the mechanical through hole, wherein the hole diameter is larger than the hole diameter of the mechanical through hole;

[0015] Step 6, plating a metal boss in the opened hole and removing the dry film;

[0016] Step 7, laminating a dielectric layer on the metal layer on the top surface of the substrate and the metal boss;

[0017] Step 8, drilling a first laser hole on the dielectric layer, wherein the first laser hole and the mechanical through hole are on the same straight line, the bottom end of the first laser hole is in contact with the metal boss, and the diameter of the metal boss is larger than the bottom end opening of the first laser hole and the aperture of the mechanical through hole;

[0018] Step 9: Plate a metal layer on the top surface of the dielectric layer, and fill the first laser hole with the metal layer on the top surface of the dielectric layer.

[0019] Before the substrate is metallized again, the uneven surface of the filler is ground off and the surface of the filler is roughened.

[0020] Before pressing the dry film, etching circuits on the metal layers on the top and bottom surfaces of the substrate, the etching depth extending all the way to the metal base layer of the substrate;

[0021] or,

[0022] Before laminating the dielectric layer, circuits are etched on the metal layers on the top and bottom surfaces of the substrate from which the dry film has been removed, and the etching depth extends all the way to the metal base layer of the substrate.

[0023] After a metal layer is plated on the top surface of the dielectric layer, a circuit is etched on the metal layer on the top surface of the dielectric layer, and the etching depth extends all the way to the metal base layer of the dielectric layer.

[0024] When drilling the first laser hole, a second laser hole is drilled on the dielectric layer, wherein there is no mechanical through hole below the second laser hole, the bottom of the second laser hole is in contact with the metal layer on the top surface of the substrate, and the metal layer on the top surface of the dielectric layer also fills the second laser hole.

[0025] The beneficial effects achieved by the present invention are as follows: the present invention adopts a mechanical through hole stacked with a first laser hole structure, which is more compact than the traditional HDI board, and the laser hole is easier to align than the traditional anylay board. In addition, the present invention arranges a metal boss between the first laser hole and the mechanical through hole, which can ensure the reliability of the through hole joint surface and can withstand the extreme environment or long-term impact encountered in the aerospace, military, automotive and other industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a stacked laser hole structure;

[0027] Figure 2 Flowchart made for stacked laser hole structure;

[0028] Figure 3 is a schematic diagram of the structure of the substrate;

[0029] Figure 4 It is a schematic diagram of the structure of the substrate after drilling mechanical through holes;

[0030] Figure 5 is a schematic diagram of the structure of the substrate after metallization;

[0031] Figure 6 It is a schematic diagram of the structure of the substrate after plugging the filler;

[0032] Figure 7 It is a schematic diagram of the structure of the substrate after re-metallization;

[0033] Figure 8 It is a schematic diagram of the structure of the substrate after the film is pressed and the holes are opened;

[0034] Fig. 9 It is a schematic diagram of the structure of the substrate after the metal boss is plated;

[0035] Fig.10 It is a schematic diagram of the structure of the substrate after etching the circuit;

[0036] Fig.11 It is a schematic diagram of the structure after the semi-solid sheet is pressed;

[0037] Fig.12 This is a schematic diagram of the structure after laser drilling;

[0038] Fig.13 Schematic diagram of the structure after metallization on the top surface of the dielectric layer. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0040] like Figure 1As shown, a stacked laser hole structure includes a substrate 1, which is formed by laminating a double-sided board or a multi-layer board, and a mechanical through hole 2 is punched on the substrate 1. The top surface of the substrate 1, the bottom surface of the substrate 1 and the inner wall of the mechanical through hole 2 are all plated with a metal layer 8, and the metal is specifically copper. The mechanical through hole 2 plated with the metal layer 8 is filled with a filler 3, and the filler 3 can be made of resin or metal, and resin is used here. The top and bottom ends of the filler 3 are plated with metal bosses 7, and circuits are etched on the metal layer 8 on the top and bottom surfaces of the substrate 1, and the etching depth extends all the way to the metal base layer of the substrate 1.

[0041] A dielectric layer 4 is pressed onto the metal layer 8 on the top surface of the substrate 1 and the metal boss 7. The dielectric layer 4 is punched with a first laser hole 5 and a second laser hole 6. The first laser hole 5 and the mechanical through hole 2 are on the same straight line. The bottom end of the first laser hole 5 is in contact with the metal boss 7. The bottom opening of the first laser hole 5 and the aperture of the mechanical through hole 2 are both smaller than the diameter of the metal boss 7. There is no mechanical through hole 2 below the second laser hole 6. The bottom end of the second laser hole 6 is in contact with the metal layer 8 on the top surface of the substrate 1. The top surface of the dielectric layer 4 is plated with a metal layer 8, and the metal layer 8 on the top surface of the dielectric layer 4 fills the first laser hole 5 and the second laser hole 6. The metal layer 8 on the top surface of the dielectric layer 4 is also etched with circuits, and the etching depth extends to the metal base layer of the dielectric layer 4. All etched circuits are not directly opposite the mechanical through hole 2 and the laser hole.

[0042] The traditional HDI board laser hole is next to the mechanical through hole 2, and the alignment error must be reserved. The present invention adopts a mechanical through hole 2 stacked first laser hole 5 structure, which does not require reserved alignment error and has a more compact structure. The traditional anylay board needs to be aligned repeatedly, and each level upgrade must be aligned on the basis of the previous time. Each time the layer is increased, the laser hole must be punched on the laser hole of the previous layer. The higher the level, the greater the alignment difficulty and the lower the product yield. For example, if there are 4 layers of laser holes, then 3 alignments are required. The present invention samples the mechanical through hole 2 stacked first laser hole 5 structure and uses mechanical holes instead of the laser holes of the first 3 layers. Only one alignment is required, and alignment is easier.

[0043] If the present invention does not set the metal boss 7 between the first laser hole 5 and the mechanical through hole 2, due to the inconsistency in the expansion coefficients of the resin in the mechanical through hole 2 and the material of the plate body solidification sheet, and the mechanical through hole 2 is a whole copper-plated structure that runs through the entire substrate 1, when subjected to cold or hot shock or extreme environment, the transverse shear stress and longitudinal expansion stress will cause the joint surface of the mechanical through hole 2 and the laser hole to break easily.

[0044] Figure 1Among them, F1 is the longitudinal expansion and contraction stress of the material, F2 is the transverse expansion and contraction stress of the material, F3 is the weakened transverse expansion and contraction stress, h1 is the thickness of the laser hole dielectric layer 4 with the metal boss 7, h2 is the thickness of the laser hole dielectric layer 4 without the metal boss 7, h1 < h2, and due to the tearing effect blocked by the metal boss 7, F3 < F2. Therefore, by setting the metal boss 7 between the first laser hole 5 and the mechanical through hole 2, the reliability of the through hole joint surface can be ensured, and it can withstand the extreme environments or long-term impacts encountered in industries such as aerospace, military, and automotive.

[0045] Based on the above structure, the present invention also discloses a corresponding manufacturing method, a manufacturing method for a stacked laser hole structure, as shown in Figure 2 , including the following steps:

[0046] Step 1: Fabricate the substrate 1, and drill the mechanical through hole 2 on the substrate 1, as shown in Figure 3 and 4 .

[0047] Step 2: Metallize the substrate 1 after drilling the mechanical through hole 2, and deposit a metal layer 8 on the top surface of the substrate 1, the bottom surface of the substrate 1, and the inner wall of the mechanical through hole 2, as shown in Figure 5 .

[0048] Step 3: Fill the mechanical through hole 2 plated with the metal layer 8 with the filler 3, grind off the uneven parts on the surface of the filler 3, and roughen the surface of the filler 3, as shown in Figure 6 .

[0049] Step 4: Re-metallize the substrate 1 after filling with the filler 3, and deposit a metal layer 8 covering the filler 3 on the top surface and the bottom surface of the substrate 1, as shown in Figure 7 .

[0050] Step 5: Press dry film on the top surface and the bottom surface of the substrate 1 after re-metallization. The dry film is a photosensitive dry film for ordinary PCB, and openings are made in the part of the dry film facing the mechanical through hole 2. The diameter of the openings is larger than the diameter of the mechanical through hole 2, as shown in Figure 8 .

[0051] Step 6: Deposit the metal boss 7, that is, the copper boss, in the openings, and remove the dry film, as shown in Fig. 9 .

[0052] Steps 5 and 6 are the process of pressing dry film on the whole surface for pattern electroplating, and the metal boss 7 is fabricated on the mechanical through hole 2 through pattern electroplating.

[0053] Step 7: Etch the circuit on the metal layer 8 on the top surface and the bottom surface of the substrate 1 after removing the dry film. The etching depth extends all the way to the metal base layer of the substrate 1, as shown in Fig.10 .

[0054] The circuit etching on the substrate 1 may also be performed before the film is pressed dry, which may be determined according to the actual situation.

[0055] After the metal boss 7 is made by pattern electroplating, the board surface is uneven. When the photosensitive film is pressed and etched again, a special photosensitive film is required. Generally, a photosensitive wet film coating or a thick photosensitive dry film with a high glue content is used to prevent the etching solution from penetrating the gap after pressing the film.

[0056] Step 7, laminating the dielectric layer 4 on the metal layer 8 on the top surface of the substrate 1 and the metal boss 7, see Fig.11 .

[0057] Step 8, punching a first laser hole 5 and a second laser hole 6 on the dielectric layer 4, wherein the first laser hole 5 and the mechanical through hole 2 are on the same straight line, the bottom end of the first laser hole 5 is in contact with the metal boss 7, the diameter of the metal boss 7 is larger than the bottom opening of the first laser hole 5 and the aperture of the mechanical through hole 2, there is no mechanical through hole 2 below the second laser hole 6, and the bottom end of the second laser hole 6 is in contact with the metal layer 8 on the top surface of the substrate 1, as shown in FIG. Fig.12 .

[0058] Step 9, a metal layer 8 is plated on the top surface of the dielectric layer 4, and the metal layer 8 on the top surface of the dielectric layer 4 fills the first laser hole 5 and the second laser hole 6. Fig.13 .

[0059] Further, a circuit can be etched on the metal layer 8 on the top surface of the dielectric layer 4 obtained in step 9, and the etching depth extends to the metal base layer of the dielectric layer 4. Figure 1 .

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A stacked laser hole structure, characterized in that: The invention comprises a substrate, a mechanical through hole is punched on the substrate, the top surface of the substrate, the bottom surface of the substrate and the inner wall of the mechanical through hole are all plated with a metal layer, a filler is plugged in the mechanical through hole plated with the metal layer, the top and bottom ends of the filler are both plated with metal bosses, the metal boss at the top end of the filler protrudes upward from the metal layer on the top surface of the substrate, and the metal boss at the top end of the filler and the metal layer on the top surface of the substrate form a step structure in the longitudinal direction, the metal boss at the bottom end of the filler protrudes downward from the metal layer on the bottom surface of the substrate, and the metal boss at the bottom end of the filler and the metal layer on the bottom surface of the substrate form a step structure in the longitudinal direction, a dielectric layer is pressed on the metal layer on the top surface of the substrate and the metal boss, a first laser hole is punched on the dielectric layer, the first laser hole and the mechanical through hole are on the same straight line, the bottom end of the first laser hole is in contact with the metal boss, the bottom end opening of the first laser hole and the aperture of the mechanical through hole are both smaller than the diameter of the metal boss, the top surface of the dielectric layer is plated with a metal layer, and the metal layer on the top surface of the dielectric layer fills the first laser hole.

2. The stacked laser hole structure according to claim 1, characterized in that: The filling material is resin or metal.

3. The stacked laser hole structure according to claim 1, characterized in that: Circuits are etched on the metal layers on the top and bottom surfaces of the substrate, and the etching depth extends all the way to the metal base layer of the substrate; Circuits are etched on the metal layer on the top surface of the dielectric layer, and the etching depth extends all the way to the metal base layer of the dielectric layer.

4. The stacked laser hole structure according to claim 1, characterized in that: A second laser hole is also drilled on the dielectric layer. There is no mechanical through hole below the second laser hole. The bottom of the second laser hole is in contact with the metal layer on the top surface of the substrate. The metal layer on the top surface of the dielectric layer also fills the second laser hole.

5. A method for manufacturing a stacked laser hole structure, characterized in that: include: Step 1, making a substrate and drilling mechanical through holes on the substrate; Step 2, metallizing the substrate after drilling the mechanical through hole, and plating a metal layer on the top surface of the substrate, the bottom surface of the substrate and the inner wall of the mechanical through hole; Step 3, filling the mechanical through hole plated with the metal layer with a filler; Step 4, metallizing the substrate after being filled with fillers again, and plating a metal layer covering the fillers on the top and bottom surfaces of the substrate; Step 5, pressing a dry film on the top and bottom surfaces of the re-metallized substrate, and opening a hole in the dry film facing the mechanical through hole, wherein the hole diameter is larger than the hole diameter of the mechanical through hole; Step 6, plating a metal boss in the opened hole and removing the dry film; wherein the metal boss at the top of the filler protrudes upward from the metal layer on the top surface of the substrate, and the metal boss at the top of the filler and the metal layer on the top surface of the substrate form a step structure in the longitudinal direction, and the metal boss at the bottom of the filler protrudes downward from the metal layer on the bottom surface of the substrate, and the metal boss at the bottom of the filler and the metal layer on the bottom surface of the substrate form a step structure in the longitudinal direction; Step 7, laminating a dielectric layer on the metal layer on the top surface of the substrate and the metal boss; Step 8, drilling a first laser hole on the dielectric layer, wherein the first laser hole and the mechanical through hole are on the same straight line, the bottom end of the first laser hole is in contact with the metal boss, and the diameter of the metal boss is larger than the bottom end opening of the first laser hole and the aperture of the mechanical through hole; Step 9: Plate a metal layer on the top surface of the dielectric layer, and fill the first laser hole with the metal layer on the top surface of the dielectric layer.

6. The method for manufacturing a stacked laser hole structure according to claim 5, characterized in that: Before the substrate is metallized again, the uneven surface of the filler is ground off and the surface of the filler is roughened.

7. The method for manufacturing a stacked laser hole structure according to claim 5, characterized in that: Before pressing the dry film, etching circuits on the metal layers on the top and bottom surfaces of the substrate, the etching depth extending all the way to the metal base layer of the substrate; or, Before laminating the dielectric layer, circuits are etched on the metal layers on the top and bottom surfaces of the substrate from which the dry film has been removed, and the etching depth extends all the way to the metal base layer of the substrate.

8. A method for manufacturing a stacked laser hole structure according to claim 5, characterized in that: After a metal layer is plated on the top surface of the dielectric layer, a circuit is etched on the metal layer on the top surface of the dielectric layer, and the etching depth extends all the way to the metal base layer of the dielectric layer.

9. A method for manufacturing a stacked laser hole structure according to claim 5, characterized in that: When drilling the first laser hole, a second laser hole is drilled on the dielectric layer, wherein there is no mechanical through hole below the second laser hole, the bottom of the second laser hole is in contact with the metal layer on the top surface of the substrate, and the metal layer on the top surface of the dielectric layer also fills the second laser hole.

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