TWI661758B - Circuit board structure and manufacturing method thereof - Google Patents

Abstract

A circuit board structure includes a multilayer board, a protective layer, and a conducting layer. The multilayer board includes an upper plate surface and a lower plate surface on opposite sides, and the multilayer plate is formed with a through hole penetrating the upper plate surface and the lower plate surface. The multilayer board is recessed from a lower plate surface portion corresponding to the through hole, and a pre-back drilled hole that is not penetrated to the upper plate surface is formed, and the pre-back drilled hole diameter is larger than the through-hole diameter. The protective layer is disposed in the pre-drilled hole and is connected to at least part of the hole wall of the pre-drilled hole. The protective layer is cut into a hole wall of the through hole. The conductive layer is plated on the hole wall of the through hole and the protective layer portion cut in parallel. In addition, the invention further provides a circuit board structure and a manufacturing method thereof.

Description

Circuit board structure and manufacturing method thereof

The invention relates to a circuit board, in particular to a circuit board structure and a manufacturing method thereof.

In the existing circuit board structure, a back hole is often formed on the back of the part corresponding to the through hole, and a conductive layer is formed at the through hole. However, the interface between the back hole and the conductive layer is often re-welded ( After reflow), due to the mismatch of thermal expansion coefficients (CTE) between different materials, stress concentration and cracks occurred. Furthermore, after the conventional circuit board structure is plugged into the back hole, the interface between the back hole and the through hole is more likely to generate cracks due to stress concentration.

Therefore, the present inventor believes that the above-mentioned defects can be improved, and with special research and cooperation with the application of scientific principles, he finally proposes an invention with a reasonable design and effective improvement of the above-mentioned defects.

Embodiments of the present invention provide a circuit board structure and a manufacturing method thereof, which can effectively improve defects that may occur in the existing circuit board structure.

An embodiment of the present invention discloses a method for manufacturing a circuit board structure, including: implementing a pre-drilling step: drilling a multilayer board to form a pre-through through a board surface and a lower board surface of the multilayer board; Hole; performing a pre-drilling step: drilling a hole from the lower plate surface portion corresponding to the pre-through hole to form a pre-back hole that does not penetrate to the upper plate surface, and the pre-drilling hole Back-drilled hole having a larger hole diameter than the pre-through hole A pre-plugging step: filling a pre-plugging resin in the pre-through hole and the pre-drilled hole; implementing a drilling step: drilling a hole in the multilayer board to remove a part The pre-plugged resin forms a through hole penetrating the upper plate surface and the lower plate surface, and leaves the pre-plugged resin to leave only a part attached to the wall of the pre-drilled hole; wherein, A portion left by the pre-plugged hole resin in the drilling step is defined as a buffer layer; an electroplating step is performed: a conductive layer is formed by electroplating on the wall of the through hole; and a back drilling step is performed: self-corresponding Drilling at the lower plate surface portion of the through hole to remove a portion of the buffer layer and a portion of the conductive layer to form a back hole, and leaving the buffer layer only connected to the buffer layer A part of the pre-drilled hole wall and the conducting layer; wherein the part of the buffer layer left in the back-drilling step is defined as a protective layer.

The embodiment of the invention also discloses a circuit board structure, which is made by the manufacturing method of the above circuit board structure.

An embodiment of the present invention further discloses a circuit board structure, including: a multilayer board including an upper board surface and a lower board surface on opposite sides, and the multilayer board is formed to penetrate the upper board surface and the lower board surface A through-hole, the multilayer board is recessed from the lower plate surface portion corresponding to the through-hole, and a pre-back drilling hole not penetrated to the upper plate surface is formed, and the pre-back drilling hole diameter is larger than that The through hole diameter; a protective layer disposed in the pre-drilled hole, the protective layer is connected to at least part of the hole wall of the pre-drilled hole, and the protective layer is cut into the through hole A hole wall; and a conducting layer, which is plated on the hole wall of the through hole and the protective layer portion that is aligned with the hole wall.

In summary, the circuit board structure and the manufacturing method thereof disclosed in the embodiments of the present invention can absorb the stress by forming the above-mentioned protective layer, thereby effectively avoiding the circuit board structure at the interface between the back drilling and the through hole. The problem of cracks due to stress concentration.

In order to further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention, but these descriptions and drawings are only used to illustrate the present invention, and not to make any limitation to the scope of the present invention limit.

100‧‧‧Circuit board structure

1‧‧‧multilayer board

11‧‧‧ Upper plate surface

12‧‧‧ lower plate surface

13‧‧‧Pre-Through Hole

13a‧‧‧through hole

14‧‧‧ Pre-drilled

14a‧‧‧Back drilling

2‧‧‧pre-plugged resin

21‧‧‧ buffer layer

22‧‧‧ protective layer

2a‧‧‧ plug hole resin

3, 3a‧‧‧ conduction layer

σ ‧‧‧ angle

FIG. 1 is a schematic diagram of step S110 of a manufacturing method of a circuit board structure according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of step S120 of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram of step S130 of a manufacturing method of a circuit board structure according to a first embodiment of the present invention.

FIG. 4 is a schematic diagram of step S140 of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram of step S150 of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram of step S160 (including step S210 and step S220) of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 7A is a schematic diagram of step S170 (including step S230) of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 7B is a partially enlarged schematic diagram of FIG. 7A.

FIG. 8 is a schematic diagram of step S240 of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 9 is a schematic diagram of step S250 of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 10 is a schematic diagram of step S260 of the method for manufacturing a circuit board structure according to the first embodiment of the present invention.

FIG. 11 is a schematic diagram of step S160 of the method for manufacturing a circuit board structure according to the second embodiment of the present invention.

FIG. 12A is a schematic diagram of step S170 of the method for manufacturing a circuit board structure according to the second embodiment of the present invention.

FIG. 12B is a partially enlarged schematic diagram of FIG. 12A.

Please refer to FIG. 1 to FIG. 12B, which are embodiments of the present invention. It should be noted that this embodiment corresponds to the related quantities and appearances mentioned in the drawings, and is only used to specifically describe the embodiments of the present invention. In order to facilitate understanding of the content of the present invention, it is not intended to limit the protection scope of the present invention.

[Example 1]

As shown in FIG. 1 to FIG. 10, it is a first embodiment of the present invention. This embodiment discloses a circuit board structure 100 and a manufacturing method thereof. In order to facilitate understanding of the circuit board structure 100 of this embodiment, a manufacturing method of the circuit board structure 100 will be described below, and then the circuit board structure 100 will be described.

Wherein, the manufacturing method of the circuit board structure 100 in this embodiment includes the following steps, but in actual application, the order of the steps and the actual operation method in this embodiment can be adjusted according to requirements (such as: (The above steps can be reasonably used or added or deleted), and is not limited to the content or order contained in this embodiment.

As shown in FIG. 1, a pre-drilling step S110 is performed: a multi-layer board 1 is drilled to form a pre-through hole 13 penetrating the upper board surface 11 and the lower board surface 12 of the multi-layer board 1. Wherein, the multi-layer board 1 in this embodiment is composed of a multi-layer board structure that is sequentially stacked from top to bottom, and the board structure of each layer is composed of a copper foil substrate (such as two plates on an insulating substrate). A copper foil is laid on each surface) after being cut to a suitable size and formed by an inner-layer circuit etching process, and an insulating layer (such as a resin film) is sandwiched between each layer of the plate structure and its adjacent plate structure. The pre-through holes 13 pass through each layer structure of the multilayer board 1.

As shown in FIG. 2, a pre-backdrilling step S120 is performed: drilling is performed on the lower plate surface 12 corresponding to the pre-through hole 13 to form a hole that does not penetrate the upper plate surface 11. A pre-drilled hole 14, and a diameter of the pre-drilled hole 14 is larger than a diameter of the pre-through hole 13. Wherein, the central axis of the pre-drilled hole 14 is preferably overlapped with the central axis of the pre-through hole 13, but the present invention is not limited thereto.

As shown in FIG. 3, a pre-plugging step S130 is implemented: a pre-plugging hole resin 2 is filled in the pre-through hole 13 and the pre-back hole 14. Wherein, the two ends of the pre-plugged hole resin 2 (such as the top and bottom ends of the pre-plugged hole resin 2 in FIG. 3) may be subjected to a planarization operation (such as grinding using an eight-axis grinder) to separate the The upper plate surface 11 and the lower plate surface 12 of the multilayer board 1 are disposed in a coplanar manner.

As shown in FIG. 4, a drilling step S140 is performed: a hole is drilled in the multilayer board 1 to remove a part of the pre-plugged hole resin 2 to form a passage through the upper plate surface 11 and the lower plate surface 12. Hole 13a, and leaving the pre-plugged hole resin 2 to leave only the portion (that is, the buffer layer 21 described below) attached to the hole wall of the pre-drilled hole 14.

Further, the central axis of the through-hole 13a in this embodiment is preferably overlapped with the central axis of the pre-through-hole 13, but the present invention is not limited to this; and in the drilling step S140, The drilling hole diameter is not smaller than the drilling hole diameter in the above-mentioned pre-drilling step S110, so that the pre-plugged hole resin 2 only leaves a portion attached to the wall of the pre-drilled 14 hole. Wherein, the part of the pre-plugged hole resin 2 left in the drilling step S140 is defined as a buffer layer 21.

As shown in FIG. 5, a plating step S150 is performed: a conductive layer 3 (such as a metallic copper layer) is formed on the hole wall of the through hole 13 a by electroplating. According to this, the conducting layer 3 can make the layers of the multilayer board 1 conductive with each other. Wherein, the electroplating step S150 preferably includes processes such as removing slag, chemical copper, and electroplated copper, but the present invention is not limited thereto.

As shown in FIG. 6, a back-drilling step S160 is performed: corresponding to the through hole 13 a (or The bottom plate surface 12 corresponding to the conducting layer 3 and the buffer layer 21) is drilled to remove part of the buffer layer 21 and part of the conducting layer 3 to form a back hole 14a and make the buffer The layer 21 only leaves a part connected to the hole wall of the pre-drilled hole 14 and the conducting layer 3a.

Furthermore, the central axis of the back hole 14a is preferably overlapped with the central axis of the through hole 13a, but the present invention is not limited thereto. And the drilling hole diameter in the back-drilling step S160 is preferably not less than the drilling hole diameter in the pre-drilling step S120, but in actual application, the drilling hole diameter in the back-drilling step S160 ( That is, the hole diameter of the back-drilled hole 14a) may be 80% to 100% of the hole diameter (that is, the hole diameter of the back-drilled hole 14) in the pre-drilling step S120, but it is not limited to this embodiment. Set.

According to this, after the back-drilling step S160 is performed, the buffer layer 21 may only leave the wall wall connected to the pre-drilled hole 14 (eg, the end of the wall of the pre-drilled hole 14 in FIG. 6) and A part of the conductive layer 3a. The portion of the buffer layer 21 left in the back drilling step S160 is defined as a protective layer 22. It should be noted that the thickness of the protective layer 22 can be adjusted and changed according to the designer's needs, and the thickness of the protective layer 22 is controlled as follows: the drilling depth in the back-drilling step S160 is smaller than the pre-drilling depth. The difference between the drilling depths in the back drilling step S120 is 50 μm to 150 μm.

In addition, during the implementation of the above-mentioned back-drilling step S160 of the multilayer board 1, another pre-drilling step S210 and another pre-drilling step S220 may be simultaneously performed at another part of the multilayer board 1. The implementation of the pre-drilling step S210 and the pre-drilling step S220 is substantially the same as the pre-drilling step S110 and the pre-drilling step S120 described above, and details are not described herein.

It should be additionally noted that, in other embodiments not shown in this embodiment, the manufacturing method of the circuit board structure 100 can also only implement the above steps S110 to S160, which can improve or overcome the existing circuit board structure in The problem of cracks due to stress concentration at the interface between the back hole and the through hole.

As shown in FIG. 7A and FIG. 7B, a plugging step S170 is implemented: a through-hole resin 2a is filled in the through hole 13a and the back hole 14a; and the plug hole resin corresponding to the back hole 14a is filled. The part 2a is connected to the protective layer 22. Furthermore, both ends of the plug-hole resin 2a (such as the top and bottom ends of the plug-hole resin 2a in FIG. 7A) may be subjected to a planarization operation (for example, grinding with an eight-axis grinder) to separate from the The upper plate surface 11 and the lower plate surface 12 of the multilayer board 1 are disposed in a coplanar manner.

In more detail, the plugging resin 2a and the preplugging resin 2 in this embodiment are mainly based on the matching coefficient of thermal expansion coefficient between the plugging resin 2a and the preplugging resin 2, that is, the plugging resin 2a and the preplugging resin 2 The same or different materials can be used according to the designer's needs. For example, the material of the plug hole resin 2a or pre-plug hole resin 2 can be, for example, Shanrong PHP-IR series, Sun THP series, or Kedingxin TP series.

In addition, in the process of performing the above-mentioned hole plugging step S170 on the multilayer board 1, another pre-plugging step S230 may be simultaneously performed on another part of the multilayer board 1. The implementation of the pre-plugging step S230 is substantially the same as the pre-plugging step S130 described above, and details are not described herein.

As shown in FIG. 8 to FIG. 10, another part of the multilayer board 1 is sequentially subjected to another drilling step S240, another electroplating step S250, and another back drilling step S260. The implementation of the drilling step S240, the plating step S250, and the back-drilling step S260 are substantially similar to the above-mentioned drilling step S140, the plating step S150, and the back-drilling step S160, and are not described herein.

The above is the description of the manufacturing method of the circuit board structure 100 according to the present invention. The following briefly describes the structural features of the circuit board structure 100; that is, some structural features that overlap with the above manufacturing methods will not be described below. The description of the circuit board structure 100 is repeated. It should be noted that the circuit board structure 100 of this embodiment is made by the manufacturing method of the circuit board structure 100 described above, but the present invention is not limited thereto. and also That is, in other embodiments not shown in the present invention, the circuit board structure 100 may also be made in other ways.

Please refer to FIGS. 7A and 7B. The circuit board structure 100 includes a multilayer board 1, a protective layer 22 disposed in the multilayer board 1, and a conductive layer disposed in the multilayer board 1 and connected to the protective layer 22. 3a, and a plug resin 2a filled in the multilayer board 1 and connected to the protective layer 22 and the conductive layer 3a. Wherein, the circuit board structure 100 of this embodiment is described by using the above-mentioned components, but in practical applications, the circuit board structure 100 may also omit the plugging resin 2a. Each component structure and connection relationship of the circuit board structure 100 will be described below.

The multilayer board 1 includes an upper plate surface 11 and a lower plate surface 12 located on opposite sides. Wherein, the multilayer board 1 is formed with a through hole 13a penetrating the upper plate surface 11 and the lower plate surface 12, and the multilayer plate 1 is recessed from the lower plate surface 12 at a position corresponding to the through hole 13a. A pre-drilled hole 14 penetrates to the upper plate surface 11. The diameter of the pre-drilled hole 14 is larger than the diameter of the through hole 13a.

The protective layer 22 is substantially annular and is disposed in the pre-drilled hole 14 of the multilayer board 1. Wherein, the protective layer 22 is connected to at least part of the hole wall of the pre-drilled hole 14 (for example, the end of the hole wall of the pre-drilled hole 14 in FIG. 7A), and the protective layer 22 is cut into the through hole. 13a hole wall. Further, the portion of the pre-drilled hole 14 after deducting the protective layer 22 is defined as a back-drilled hole 14a, and the depth of the back-drilled hole 14a is preferably smaller than the depth of the pre-drilled hole 14. The value is 50 μm to 150 μm, and the hole diameter of the back-drilled hole 14 a is preferably 80% to 100% of the hole diameter of the pre-drilled hole 14.

To put it another way, in this embodiment, the protective layer 22 is connected to the hole wall portion of the pre-drilled hole 14 far from the lower plate surface 12, and the protective layer 22 and the unconnected The above-mentioned back-drilled holes 14a are formed by surrounding the hole wall portions of the pre-drilled back holes 14, but the present invention is not limited thereto.

The conducting layer 3a is plated on the hole wall of the above-mentioned through hole 13a and the cut-outs The protective layer 22 (eg, the inner edge of the protective layer 22 shown in FIG. 7B). Wherein, the conducting layer 3a is substantially tubular, and the (inner edge) of the protective layer 22 is connected to the end of the conducting layer 3a obliquely. Furthermore, the bottom edges of the protective layer 22 and the conductive layer 3a are aligned with each other, and in the cross-section of the protective layer 22 and the conductive layer 3a, the mutually aligned bottom edges of the protective layer 22 and the conductive layer 3a together define the mediator. An angle σ between 110 degrees and 165 degrees.

The plug hole resin 2a fills the through hole 13a and the back hole 14a formed in the multilayer board 1, so that the plug hole resin 2a is connected to the hole walls of the conductive layer 3a and the back hole 14a. Furthermore, two ends of the plug-hole resin 2 a (such as the top and bottom ends of the plug-hole resin 2 a in FIG. 7A) are disposed in a plane with the upper plate surface 11 and the lower plate surface 12 of the multilayer board 1, respectively.

[Example 2]

Please refer to FIG. 11 to FIG. 12B, which is a second embodiment of the present invention. This embodiment is similar to the first embodiment, so the same points between the two embodiments are not described again, and this embodiment is similar to the above embodiment. The main differences are as follows.

Specifically, as shown in FIG. 11, when the back drilling step S160 is performed, the center axis of the back drilling 14 a is preferably overlapped with the center axis of the through hole 13 a, and the back drilling step S160 is performed. The drilling hole diameter in the hole is slightly smaller than the drilling hole hole in the pre-drilling step S120 described above, so that the protective layer 22 left by the buffer layer 21 is connected to all hole walls of the pre-drilled hole 14 and is conductive. Layers 3, 3a.

Furthermore, as shown in FIG. 12A and FIG. 12B, when the plug hole step S170 is performed, the outer edge of the plug hole resin 2a filled in the through hole 13a and the back hole 14a is completely connected to the protective layer. 22 and the conductive layers 3 and 3a, and the two ends of the plug hole resin 2a (such as the top and bottom ends of the plug hole resin 2a in FIG. 11 or FIG. 12) are respectively connected to the upper plate surface 11 and The lower plate surface 12 is disposed in a coplanar manner.

[Technical effect of the embodiment of the present invention]

In summary, the circuit board structure and the manufacturing method thereof disclosed in the embodiments of the present invention can absorb the stress by forming the above-mentioned protective layer, thereby effectively avoiding the circuit board structure at the interface between the back drilling and the through hole. The problem of cracks due to stress concentration.

Further, the circuit board structure can absorb the stress through the formation of the above-mentioned protective layer regardless of whether the plug-hole resin is filled in the through-hole and the back-drilled hole, thereby effectively avoiding the circuit board. The structure has a problem of cracks at the interface between the back hole and the through hole due to stress concentration.

The above description is only the preferred and feasible embodiments of the present invention, and is not intended to limit the protection scope of the present invention. Any equivalent changes and modifications made according to the patent scope of the present invention shall fall within the protection scope of the claims of the present invention.

Claims (10)

A method for manufacturing a circuit board structure includes: implementing a pre-drilling step: drilling a multilayer board to form a pre-through hole penetrating a board surface and a lower board surface of the multi-layer board; Back drilling step: drilling a hole from the lower plate surface portion corresponding to the pre-through hole to form a pre-back hole that does not penetrate to the upper plate surface, and the hole diameter of the pre-back hole Larger than the diameter of the pre-through hole; implementing a pre-plugging step: filling a pre-plugging resin in the pre-through hole and the pre-back drilling; implementing a drilling step: performing on the multilayer board Drilling a hole to remove a part of the pre-plugged resin to form a through hole penetrating the upper plate surface and the lower plate surface, and leaving the pre-plugged resin to remain only attached to the pre-drilled hole A portion of the hole wall; wherein the portion of the pre-plugged hole resin left in the drilling step is defined as a buffer layer; performing a plating step: forming a conductive layer on the through hole hole wall by electroplating; and A back drilling step: drilling from the lower plate surface portion corresponding to the through hole to remove Dividing the buffer layer and a part of the conductive layer to form a back hole, and leaving the buffer layer to only a portion connected to the pre-drilled hole wall and the conductive layer; wherein the buffer The layer left in the back drilling step is defined as a protective layer. The method for manufacturing a circuit board structure according to claim 1, further comprising implementing a plug hole step: filling the through hole and the back hole with a plug hole resin; wherein, corresponding to the back hole The plugging resin part of the hole is connected to the protective layer. The method for manufacturing a circuit board structure according to claim 1, wherein the difference between the drilling depth in the back-drilling step and the drilling depth in the pre-drilling step is 50 micrometers (μm) to 150 Microns. The method for manufacturing a circuit board structure according to claim 1, wherein the drilling hole diameter in the back-drilling step is 80% to 100% of the drilling hole diameter in the pre-drilling step. A circuit board structure manufactured by the method for manufacturing a circuit board structure according to claim 1. A circuit board structure includes a multi-layer board including an upper board surface and a lower board surface on opposite sides, and the multi-layer board is formed with a through hole penetrating the upper board surface and the lower board surface. The multi-layer board is recessed from the lower plate surface portion corresponding to the through hole, and a pre-back hole is formed which does not penetrate the upper plate surface, and the pre-back hole diameter is larger than the through-hole diameter; A protective layer disposed in the pre-drilled hole, the protective layer is connected to at least part of the hole wall of the pre-drilled hole, and the protective layer is cut to the hole wall of the through hole; and a conduction Layer, which is plated on the hole wall of the through hole and the protective layer portion that is aligned with the hole wall. The circuit board structure according to claim 6, wherein the portion of the pre-back drilling after deducting the protective layer is defined as a back drilling, and the depth of the back drilling is smaller than the difference between the depth of the pre-back drilling. The value is 50 μm to 150 μm; the hole diameter of the back-drilled hole is 80% to 100% of the hole diameter of the pre-drilled hole. The circuit board structure according to claim 6, wherein the protective layer is connected to an end of the conductive layer obliquely. The circuit board structure according to claim 6, wherein the protective layer is connected to a hole wall portion of the pre-drilled hole remote from the lower board surface, and the protective layer and the unconnected The back wall of the pre-drilled hole is surrounded by a hole wall. The circuit board structure according to claim 9, further comprising a plug hole resin, and the plug hole resin fills the through hole and the back hole so that the plug hole resin is connected to the via. Layer and the hole wall of the back-drilled hole.