Bowl hole double-sided circuit board and manufacturing method

Abstract

The present invention relates to a bowl-hole double-sided circuit board and a manufacturing method thereof. Specifically, a single-sided copper-clad plate is etched to produce a front circuit, a solder resist is made, and then a middle glue layer is formed on the back side. A hole is punched with a mold at a place where a bowl hole is required, and the hole simultaneously penetrates the front solder resist layer, the front circuit layer, the middle insulating layer and the middle glue layer. The other single-sided circuit board is used as the back circuit, and the back circuit board is aligned and attached to the glue-coated surface of the front circuit board with an existing hole. At the hole, the bottom of the hole is the back circuit layer, and the hole wall is the front solder resist layer, the front circuit layer, the middle insulating layer and the glue coating layer to form a bowl hole. The present invention is characterized in that the front solder resist layer, the front circuit layer and the middle insulating layer of part or all of the bowl hole are holes formed by pasting together, and the front circuit layer is not exposed when viewed from a top view, thereby solving the problems of poor appearance caused by the bowl hole having no multiple steps and poor soldering caused by chaotic tin flow during soldering.

Description

Technical Field

[0001] The invention relates to the field of circuit boards, and in particular to a bowl-hole double-sided circuit board and a manufacturing method thereof. Background Art

[0002] In traditional double-sided circuit boards, the conduction of double-sided circuits is generally achieved by drilling or punching through holes on the double-sided copper-clad board, and then using a copper electroplating process to form a conductive layer on the inner wall of the through holes on the double-sided circuit board to conduct electricity on both sides of the circuit. This process causes serious pollution to the environment due to the need for electroplating.

[0003] The inventor has previously invented a series of patents for double-sided circuit boards with bowl holes, for example: Patent No.: 200920260552.0, Patent Name: Double-sided Circuit Board, Patent No.: 200920215983.5, Patent Name: Double-sided Circuit Board with Components, Patent No.: 201020514646.9, Patent Name: Double-sided Circuit Board and Combined Pads Thereof, etc., all involve processing holes at the positions where the double-sided circuits need to be turned on before solder masking on the front single-sided boards, and then performing front solder masking, which results in uneven front solder masking and the middle insulating layer at the hole wall, and multiple steps between the front solder masking, the front copper, the middle insulating layer and the bottom of the bowl hole, resulting in poor appearance and the inability to produce high-end products. At the same time, the front copper at the bowl hole is exposed when viewed from above, and when soldering, the copper at the bottom of the hole and the front copper expand on the surface after the tin melts, resulting in chaotic tin flow, resulting in poor solder connection.

[0004] In order to overcome the above defects and shortcomings, the present invention covers the front copper with a front solder resist at the bowl hole, coats the back with glue, and then punches or drills holes at the same time, and then presses the back circuit together with the glue layer. The bowl-shaped bottom of the bowl hole is the back copper, and the front copper is not exposed from a top-down perspective, thereby solving the problem of poor appearance of multiple steps at the bowl hole and the poor soldering caused by the front circuit copper and the back circuit copper competing for tin during soldering. Summary of the invention

[0005] The invention relates to a bowl-hole double-sided circuit board and a manufacturing method thereof. Specifically, a single-sided copper-clad plate is etched to produce a front circuit, a solder resist is made, and then a middle glue layer is formed by coating the back surface with glue. A mold is used to punch holes where bowl holes are required, and the holes penetrate the front solder resist layer, the front circuit layer, the middle insulating layer and the middle glue layer at the same time. Another single-sided circuit board is used as a back circuit, and the back circuit board is aligned and pasted to the glue-coated surface of the front circuit board with a hole. At the hole, the bottom of the hole is the back circuit layer, and the hole wall is the front solder resist layer, the front circuit layer, the middle insulating layer and the glue layer to form a bowl hole. The invention is characterized in that the front solder resist layer, the front circuit layer and the middle insulating layer of part or all of the bowl hole are holes formed by pasting together, and the front circuit layer is not exposed when viewed from a top view, thereby solving the problems of poor appearance caused by the bowl hole not having multiple steps and poor soldering caused by chaotic tin flow during soldering.

[0006] According to the present invention, a method for manufacturing a bowl-hole double-sided circuit board is provided. Specifically, after etching a single-sided copper-clad board to manufacture a front circuit, a front solder resist is manufactured, and at the position where the bowl hole needs to be manufactured, a solder resist layer is partially or completely covered, and then glue is applied to the back to form an intermediate glue layer, and holes are engraved with a laser, or holes are drilled with a drilling machine, or holes are punched with a mold, and the holes simultaneously penetrate the front solder resist layer, the front circuit layer, the intermediate insulating layer and the intermediate glue layer. According to the design, another single-sided circuit board is manufactured as the back circuit, and the back circuit board is aligned and attached to the glue-coated surface of the front circuit board with the hole, with the metal of the back circuit facing the glue surface, and after pressing The middle glue layer overflows to the bottom of the bowl hole, and the overflow amount is greater than 0mm and less than or equal to 0.8mm. The glue is cured by heating to make a bowl-hole double-sided circuit board. At the position where the hole is located, the hole and the back circuit at the bottom of the hole form a bowl hole, and the back circuit exposed at the bottom of the bowl hole forms a bowl hole pad. The front solder mask layer and the middle insulating layer of part or all of the bowl holes are flush with the hole wall. The front circuit copper of part or all of the bowl holes is at the bowl hole and is not exposed from a top-down perspective. The back circuit metal is exposed at the bottom of the bowl hole when viewed from the front top-down perspective. The glue layer overflows on the metal at the bottom of the hole when viewed from the front top-down perspective, and the overflow amount is greater than 0mm and less than or equal to 0.8mm.

[0007] According to the present invention, there is also provided a bowl-hole double-sided circuit board, comprising: a front solder resist layer; a front circuit layer; an intermediate insulating layer; an intermediate glue layer; a back circuit layer; a back insulating layer; a bowl hole; characterized in that the bottom of the bowl hole is the back circuit layer, and the front solder resist of part or all of the bowl holes covers the front circuit metal at the bowl hole, and when viewed from the front, the back circuit metal is exposed from the front of the bottom of the bowl to form a bowl hole solder pad, and the front circuit metal is not exposed at part or all of the bowl holes when viewed from the front, and the front circuit layer metal is exposed or not when viewed from the side of the hole wall, and there is an intermediate glue layer at the bottom of the bowl hole that overflows on the back circuit layer, and the overflow amount is greater than 0mm and less than or equal to 0.8mm, and the front solder resist layer and the intermediate insulating layer of part or all of the bowl holes are flush at the hole wall.

[0008] According to a preferred embodiment of the present invention, the bowl-hole double-sided circuit board is characterized in that, in the back circuit layer and the back insulating layer, at the position where the bowl hole is set, it is already recessed when viewed from the back of the circuit board, and when viewed from the front of the circuit board, the back circuit in the bowl hole has bulged upward, and the pads formed by the back circuit in the bowl hole are close to the same plane as the pads of the front circuit, and the pad surface on the front circuit is used as the reference plane of the plane, and the upper and lower ranges of the pad surface formed by the back circuit in the bowl hole and the reference plane are lower than the reference plane and not lower than 0.5 mm, and higher than the reference plane and not higher than 0.5 mm.

[0009] According to a preferred embodiment of the present invention, the bowl-hole double-sided circuit board is characterized in that the front solder resist layer is an ink solder resist layer or a cover film solder resist layer.

[0010] According to a preferred embodiment of the present invention, the bowl-hole double-sided circuit board is characterized in that the covering film solder resist layer is a PI film or a PET film.

[0011] According to a preferred embodiment of the present invention, the bowl-hole double-sided circuit board is characterized in that the bowl-hole pads are pads for welding components, board pads, and welding power line pads.

[0012] According to a preferred embodiment of the present invention, the bowl-hole double-sided circuit board is characterized in that, on the soldering pad of a welding component provided with a bowl hole, part of the soldering feet of the component are soldered to the back circuit through the bowl hole, and the other part of the soldering feet are soldered to the front circuit, so that the front circuit and the back circuit are connected through the component.

[0013] According to a preferred embodiment of the present invention, the bowl-hole double-sided circuit board is characterized in that on a welding power line pad provided with a bowl hole, the power line is welded to the back circuit through the bowl hole.

[0014] According to a preferred embodiment of the present invention, the bowl-hole double-sided circuit board is characterized in that when multiple circuit boards are soldered together on the board pads provided with bowl holes, they are connected by soldering to the back circuit through the bowl holes.

[0015] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the detailed description below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The features, objects and advantages of the present invention will become more apparent by reading this specification in conjunction with the following drawings, a brief description of which is as follows.

[0017] Figure 1 This is a plan view of the front circuit after etching the single-sided flexible copper-clad laminate.

[0018] Figure 2 This is a plan view of the front circuit after printing the front solder mask.

[0019] Figure 3 This is a plan view of a single-sided circuit board after punching holes on the front circuit.

[0020] Figure 4 For Figure 3 Schematic diagram of the cross section at 1.3c of ″.

[0021] Figure 5This is a plan view of the back circuit.

[0022] Figure 6 This is a plan view of a bowl-hole double-sided circuit board.

[0023] Figure 7 This is a cross-sectional diagram of a bowl-hole double-sided circuit board at the bowl hole 1.3c position.

[0024] Figure 8 This is a cross-sectional schematic diagram of a bowl-hole double-sided circuit board at the bowl hole 1.3a position.

[0025] Fig. 9 This is a schematic cross-sectional view of a bowl-hole double-sided circuit board at the bowl hole 1.3b position.

[0026] Fig.10 It is a cross-sectional schematic diagram showing that the back circuit layer and the back insulation layer bulge upward at the bowl hole 1.3c. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below by taking preferred embodiments as examples.

[0028] However, those skilled in the art should understand that the following descriptions are merely examples and descriptions of some preferred embodiments and do not impose any limitations on the claims of the present invention.

[0029] Using the traditional circuit board manufacturing process, the single-sided flexible copper clad board is made into a front circuit 1 (such as Figure 1 As shown), the solder mask 2 is printed on the front circuit 1, exposing the solder pads 1.2 for soldering components and the solder pads 1.1 for soldering power lines, and then the characters are printed on the screen to make a single-sided circuit board (as shown). Figure 2 As shown), then glue is applied on the back of the single-sided circuit board, that is, the middle insulating layer 3, to form the middle glue layer 4, and then holes 1.3a, 1.3b and 1.3c are punched out at the positions where the bowl holes need to be set in the double-layer circuit using the designed mold on the punching machine, and the holes penetrate the front solder mask 2, the front circuit 1, the middle insulating layer 3 and the middle glue layer 4 (as shown). Figure 3 , Figure 4 shown).

[0030] The conventional circuit board manufacturing process is used to make a single-sided flexible copper-clad board through the processes of screen printing circuit anti-corrosion ink, baking and curing, etching, and film stripping to produce a back circuit 5 (such as Figure 5 (shown)

[0031] The metal surface of the back circuit 5 is aligned and attached to the middle glue layer 4 of the punched single-sided circuit board, and pressed together to form bowl holes at holes 1.3a, 1.3b and 1.3c. The bottom of the bowl hole is the back circuit 5. Looking down at the bottom of the bowl from the front, the metal of the back circuit is exposed from the front. At the bottom of the bowl hole, the glue overflowed from the middle glue layer 4 due to pressing is on the back circuit 5, and the overflow amount is greater than 0 to 0.8 mm (such as Figure 6 , Figure 7 , Figure 8 , Fig. 9 shown).

[0032] At the bowl hole 1.3c, from the cross-section, the hole wall is the front solder mask 2, the front circuit 1, the middle insulating layer 3 and the middle glue layer 4, and the front solder mask 2 is flush with the front circuit 1 and the middle insulating layer 3 at the hole wall (such as Figure 7 shown).

[0033] At the bowl hole 1.3a, from the cross-section, the hole wall is the front circuit 1, the middle insulating layer 3 and the middle rubber layer 4, and the front circuit 1 and the middle insulating layer 3 are flush at the hole wall (such as Figure 8 shown).

[0034] At the bowl hole 1.3b, from the cross-section, the hole wall is the front solder resist 2, the middle insulating layer 3 and the middle glue layer 4, and the front solder resist 2 and the middle insulating layer 3 are flush at the hole wall (such as Fig. 9 shown).

[0035] Then, it is baked and cured, OSP anti-oxidation surface treated, formed and FQC processed to make a bowl hole double-sided circuit board (such as Figure 6 , Figure 7 , Figure 8 , Fig. 9 shown).

[0036] like Fig.10 As shown, the back circuit 5 and the back insulating layer 6 protrude toward the front circuit 1 at the position of the bowl hole 1.3c, and the back circuit 5 in the bowl hole 1.3c forms a soldering pad, with the soldering pad on the front circuit as the reference plane of the plane, that is, the position of the reference line 7.1. The upper and lower ranges of the plane position of the soldering pad of the back circuit opening toward the front are: downwardly lower than the reference plane, not lower than 0.5mm of the reference plane, that is, the position of the reference line 7.3, and upwardly higher than the reference plane, not higher than 0.5mm of the reference plane, that is, the position of the reference line 7.2.

[0037] The present invention applies glue to the back side after the front side solder resist is applied to cover the front side copper at the bowl hole, and then punches or drills holes at the same time, and then the back side circuit is glued and pressed together through the glue layer, so that the bowl-shaped bottom of the bowl hole is the back side copper, and the front side copper is not exposed when viewed from a top view, thereby solving the problem of poor appearance of multiple steps at the bowl hole and poor soldering caused by the front side circuit copper and the back side circuit copper competing for tin during soldering.

[0038] The present invention is described in detail above with reference to the accompanying drawings by using a specific embodiment of a bowl-hole double-sided circuit board and a manufacturing method. However, those skilled in the art should understand that the above description is only an example to illustrate and describe some specific implementation methods, and does not limit the scope of the present invention, especially the scope of the claims.

Claims

1. A method for manufacturing a bowl-hole double-sided circuit board, specifically, after etching a single-sided copper-clad board to make a front circuit, a front solder mask is made, and at the position where the bowl hole needs to be made, a solder mask layer is partially covered or completely covered, and then the back is coated with glue to form an intermediate glue layer, and holes are engraved with a laser, or holes are drilled with a drilling machine, or holes are punched with a mold, and the holes simultaneously penetrate the front solder mask layer, the front circuit layer, the intermediate insulating layer and the intermediate glue layer. According to the design, another single-sided circuit board is made as the back circuit, and the back circuit board is aligned and attached to the glue-coated surface of the front circuit board with a hole, with the metal of the back circuit facing the glue surface, and the middle glue is pressed after The layer overflows to the bottom of the bowl hole, and the overflow amount is greater than 0mm and less than or equal to 0.8mm. The glue is cured by heating to make a bowl-hole double-sided circuit board. At the position of the hole, the hole and the back circuit at the bottom of the hole form a bowl hole, and the back circuit exposed at the bottom of the bowl hole forms a bowl hole pad. The front solder mask layer and the middle insulating layer of part or all of the bowl holes are flush with the hole wall. The front circuit copper of part or all of the bowl holes is at the bowl hole and is not exposed from a top-down perspective. The back circuit metal is exposed at the bottom of the bowl hole when viewed from the front top-down perspective. The glue layer overflows on the metal at the bottom of the hole when viewed from the front top-down perspective, and the overflow amount is greater than 0mm and less than or equal to 0.8mm.

2. A bowl-hole double-sided circuit board, comprising: Front solder mask; Front circuit layer; Intermediate insulation layer; Middle glue layer; Back side circuit layer; Back insulation layer; Bowl hole; It is characterized in that the bottom of the bowl hole is the back circuit layer, the front solder mask of some or all of the bowl holes covers the front circuit metal at the bowl hole, and the back circuit metal is exposed from the front of the bottom of the bowl when viewed from the front to form a bowl hole solder pad, and the front circuit metal is not exposed at some or all of the bowl holes when viewed from the front, and the front circuit layer metal is exposed or not exposed when viewed from the side of the hole wall. There is an intermediate glue layer overflowing on the back circuit layer at the bottom of the bowl hole, and the overflow amount is greater than 0mm and less than or equal to 0.8mm. The front solder mask and the intermediate insulating layer of some or all of the bowl holes are flush with the hole wall.

3. The bowl-hole double-sided circuit board according to claim 2, characterized in that: In the back circuit layer and the back insulating layer, at the position where the bowl hole is set, it is already sunken when viewed from the back of the circuit board, and when viewed from the front of the circuit board, the back circuit in the bowl hole has bulged upward, and the pads formed by the back circuit in the bowl hole are close to the same plane as the pads of the front circuit, and the pad surface on the front circuit is used as the reference plane of the plane. The upper and lower ranges of the pad surface formed by the back circuit in the bowl hole and the reference plane are lower than the reference plane and not lower than 0.5 mm, and higher than the reference plane and not higher than 0.5 mm.

4. A bowl-hole double-sided circuit board according to claim 1 or 2, characterized in that: The front solder resist layer is an ink solder resist layer or a cover film solder resist layer.

5. The bowl-hole double-sided circuit board according to claim 4, characterized in that: The cover film solder resist layer is a PI film or a PET film.

6. A bowl-hole double-sided circuit board according to claim 1 or 2, characterized in that: The bowl hole pad is a pad for welding components, a pad for connecting a board, or a pad for welding a power line.

7. The bowl-hole double-sided circuit board according to claim 6, characterized in that: On the soldering pad of a soldering component provided with a bowl hole, part of the soldering feet of the component are soldered to the back circuit through the bowl hole, and the other part of the soldering feet are soldered to the front circuit, so that the front circuit and the back circuit are connected through the component.

8. The bowl-hole double-sided circuit board according to claim 6, characterized in that: On the welding power line pad provided with a bowl hole, the power line is welded to the rear circuit through the bowl hole.

9. The bowl-hole double-sided circuit board according to claim 6, characterized in that: When a plurality of circuit boards are welded and connected to each other on a connecting plate pad provided with a bowl hole, they are welded to the back circuit through the bowl hole for connection.

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