A process for manufacturing a heat-dissipating circuit board with inlaid copper pillars and an article thereof

Abstract

The application discloses a preparation process of a heat-dissipating circuit board with inlaid copper columns and a product thereof, and comprises the following steps: (1) drilling; (2) copper plating; (3) placing copper columns and plating copper again. The application provides a preparation process of a heat-dissipating circuit board with inlaid copper columns and a product thereof, wherein holes are drilled in the area of the circuit board that needs heat dissipation, the hole wall is made conductive by copper plating, and copper columns are inlaid to achieve excellent heat-dissipating effect. The application adopts hole-filling electroplating technology to make the gap filling more sufficient by optimizing the process flow, and the adhesion between the copper column and the copper base material is not realized by glue but by electroplated copper adhesion.

Description

Technical Field

[0001] This invention relates to the field of H05K3 / 00, and more specifically to a manufacturing process and product of a heat dissipation circuit board with embedded copper pillars. Background Technology

[0002] With the increasing application of high-power components, the demand for heat dissipation substrates is also increasing. Conventional heat dissipation substrates mostly use metal substrates or ceramic substrates.

[0003] The method for manufacturing a circuit board with embedded copper pillars provided by CN113038689A ensures the flatness of the final circuit board with embedded copper pillars after lamination by setting a first opening and filling the first opening with a first colloid. The provided circuit board with embedded copper pillars has a heat sink and a heat dissipation channel directly connected to the heat sink, achieving a rapid heat dissipation effect. However, the heat dissipation performance of the metal substrate is generally less than 10W due to the limitation of the insulating layer.

[0004] CN105430924A provides a method for manufacturing a high-frequency, high-speed circuit board with embedded heat sinks, including processes such as pressing, drilling, first routing, copper plating, board electroplating, outer dry film plating, and circuit electroplating. This method prevents breakage during drilling and routing due to the high brittleness of the high-frequency, high-speed circuit board, resulting in a stable circuit board with excellent heat dissipation performance. However, ceramic substrates are expensive, unsuitable for double-sided or multi-layer fabrication, and have low circuit processing precision.

[0005] Multilayer circuit boards are a product of the development of electronic information technology towards high speed, multi-functionality, large capacity, small size, thinness and lightweight. Polymer materials have a stronger advantage in this field, but their disadvantage lies in their poor heat dissipation performance. Summary of the Invention

[0006] To address the aforementioned problems, this invention discloses a fabrication process for a heat dissipation circuit board with embedded copper pillars, comprising the following steps:

[0007] (1) Drilling;

[0008] (2) Copper plating;

[0009] (3) Place the copper pillar in and plate it with copper again.

[0010] In one embodiment, step (1) drilling specifically involves drilling holes on the circuit board.

[0011] In one embodiment, the circuit board is a multilayer circuit board with 2-30 layers.

[0012] Preferably, the multilayer circuit board is any one of FR-4 multilayer circuit board, Teflon multilayer circuit board, CAM-3 multilayer circuit board, hydrocarbon resin multilayer circuit board, BT resin multilayer circuit board, and polyimide multilayer circuit board.

[0013] More preferably, the multilayer circuit board is a Teflon multilayer circuit board.

[0014] In one embodiment, the hole is a heat dissipation hole.

[0015] In one embodiment, the hole is selected from any one of square holes, round holes, triangular holes, and irregularly shaped holes.

[0016] Preferably, the hole is a circular hole.

[0017] In one embodiment, the aperture D of the hole is 0.1-5 mm.

[0018] Preferably, the aperture D of the hole is 0.12 mm.

[0019] In this invention, when the hole is square or triangular, the hole diameter is equal to the side length of the cross-section; when the hole is round, the hole diameter is equal to the diameter of the cross-section; when the hole is irregularly shaped, the appropriate hole size can be measured by the cross-sectional area.

[0020] In one embodiment, step (2) copper plating specifically involves: in order to ensure the circuit connectivity in the circuit board, copper plating is required on the hole wall, and conductivity is achieved through the contact between the copper layer and the copper pillar.

[0021] Preferably, the thickness d of the copper layer on the hole wall is 0.01-0.1 mm.

[0022] More preferably, the thickness d of the copper layer on the hole wall is 0.02 mm.

[0023] In one embodiment, step (3) of placing a copper pillar and then plating copper again specifically involves placing a suitable copper pillar in the hole and then using a hole-filling electroplating technique. The copper pillar and the copper hole of the substrate are connected into a whole by electroplating copper, and the gap in the middle is completely filled by the copper plating layer.

[0024] In one embodiment, the shape of the copper pillar corresponds to the hole and is selected from one of square copper pillars, round copper pillars, triangular copper pillars, and irregular copper pillars.

[0025] Preferably, the diameter of the copper pillar is equal to the hole diameter minus the thickness of the copper layer on the hole wall minus 0.01 mm.

[0026] In one embodiment, the via-filling electroplating technology includes the following steps:

[0027] Step 1: Prepare the pre-impregnation solution;

[0028] Step 2: Immerse the multilayer circuit board in the prepreg solution, ensuring that the holes are fully wetted by the prepreg solution;

[0029] Step 3: Use an electroplating solution to fill the holes in the multilayer circuit board with electroplating to smooth them out.

[0030] In one embodiment, the pre-impregnation solution comprises: 40-60 g / L sulfuric acid, 150-200 g / L copper sulfate pentahydrate, 40-80 mg / L chloride ions, 50-80 mg / L sodium N,N-dimethylthiocarbamoylpropanesulfonate, and 30-60 mg / L sodium dodecyl sulfate, with water as the solvent.

[0031] Preferably, the pre-impregnation solution comprises: 55 g / L sulfuric acid, 180 g / L copper sulfate pentahydrate, 60 ml / L chloride ions, 60 mg / L N,N-dimethylthiocarbamoylpropanesulfonate sodium salt, and 40 mg / L sodium dodecyl sulfate, with water as the solvent.

[0032] In one embodiment, ultrasonic vibration is applied to the preimpregnation liquid to remove air bubbles in the pores through vibration, thereby ensuring that the pores are fully wetted by the preimpregnation liquid. The duration of ultrasonic vibration is controlled between 10 and 40 seconds.

[0033] In one embodiment, the electroplating solution comprises: 230-280 g / L copper sulfate pentahydrate, 50-80 g / L sulfuric acid, 40-70 mg / L chloride ions, 10-20 ml / L sodium N,N-dimethylthiocarbamoylpropanesulfonate, 5-15 ml / L sodium dodecyl sulfate, and 10-15 ml / L N-methylthiourea, with water as the solvent.

[0034] In one embodiment, the current density during the hole-filling electroplating is 1-2 ASD, and the electroplating time is 0.5-1.5 h.

[0035] Preferably, the current density during the hole-filling electroplating is 1.8 ASD and the electroplating time is 1 hour.

[0036] This invention optimizes the process flow, bonding the copper pillar to the copper substrate not with adhesive, but with electroplated copper bonding. It employs a hole-filling electroplating technique, which allows for more thorough filling of gaps. Before electroplating, a pre-impregnation solution is used to pre-impregnate the holes. Under the action of sodium N,N-dimethylthiocarbamoyl propane sulfonate and sodium dodecyl sulfate, copper ions in the pre-impregnation solution are adsorbed and fill the pores. During the hole-filling electroplating process, the addition of N-methylthiourea, sodium N,N-dimethylthiocarbamoyl propane sulfonate, and sodium dodecyl sulfate to the electroplating solution inhibits the growth of surface-plated copper and results in a smoother, less void-filled electroplating within the holes, achieving rapid hole-filling and improving the quality of hole filling. Pre-impregnation ensures uniform distribution within the holes, and then increasing the copper ion content before electroplating further improves the quality of hole filling and reduces costs.

[0037] Beneficial effects

[0038] This invention provides a manufacturing process and product of a heat dissipation circuit board with embedded copper blocks. By drilling holes in areas of the circuit board requiring heat dissipation, copper plating is applied to make the hole walls conductive, and then the copper blocks are embedded, achieving excellent heat dissipation. This invention optimizes the process flow; the bonding between the copper pillars and the copper substrate is not achieved through adhesive, but through electroplated copper bonding, employing a hole-filling electroplating technique, which allows for more thorough filling of gaps. Detailed Implementation

[0039] Example 1

[0040] This embodiment 1 discloses a fabrication process for a heat dissipation circuit board with embedded copper pillars, the steps of which are as follows:

[0041] (1) Drilling: Drilling holes on a circuit board.

[0042] The circuit board is a Teflon multilayer circuit board, 10 layers, purchased from Shenzhen Chongda Multilayer Circuit Board Co., Ltd.

[0043] The hole is a round hole.

[0044] The diameter D of the hole is 0.12 mm.

[0045] (2) Copper plating: In order to ensure the continuity of the circuit in the circuit board, copper plating is required on the hole wall to achieve conductivity through the contact between the copper layer and the copper pillar.

[0046] The thickness d of the copper layer on the hole wall is 0.02 mm.

[0047] (3) Insert copper pillars and plate copper again: Insert suitable copper pillars into the holes, and then use the hole-filling electroplating technology. The copper pillars and the copper holes of the substrate are connected into a whole by electroplating copper, and the gaps in the middle are completely filled by the copper plating layer.

[0048] The copper pillar is circular and has a diameter of 0.09 mm.

[0049] The hole-filling electroplating technology involves the following steps:

[0050] Step 1: Prepare the pre-impregnation solution: The pre-impregnation solution includes: 55 g / L sulfuric acid, 180 g / L copper sulfate pentahydrate, 60 ml / L chloride ions, 60 mg / L sodium N,N-dimethylthiocarbamoylpropanesulfonate, and 40 mg / L sodium dodecyl sulfate, with water as the solvent.

[0051] Step 2: Immerse the multilayer circuit board in the prepreg solution, ensuring that the holes are fully wetted: Apply ultrasonic vibration to the prepreg solution to remove air bubbles in the holes through vibration, thus ensuring that the holes are fully wetted by the prepreg solution. The ultrasonic vibration time is controlled between 10-40 seconds.

[0052] Step 3: Use an electroplating solution to fill the holes in the multilayer circuit board. The electroplating solution includes: 270 g / L copper sulfate pentahydrate, 60 g / L sulfuric acid, 50 mg / L chloride ions, 15 ml / L sodium N,N-dimethylthiocarbamoylpropanesulfonate, 10 ml / L sodium dodecyl sulfate, and 12 ml / L N-methylthiourea, with water as the solvent.

[0053] The current density during the hole-filling electroplating was 1.8 ASD, and the electroplating time was 1 hour.

[0054] Example 2

[0055] The difference between this embodiment and Embodiment 1 is that the via-filling electroplating technology steps are as follows: using an electroplating solution to perform via-filling electroplating on the multilayer circuit board to fill the holes, the electroplating solution includes: 270g / L copper sulfate pentahydrate, 60g / L sulfuric acid, 50mg / L chloride ions, 15ml / L sodium N,N-dimethylthiocarbamoylpropanesulfonate, 10ml / L sodium dodecyl sulfate, 12ml / L N-methylthiourea, and water as the solvent.

[0056] Example 3

[0057] The difference between this embodiment and Embodiment 1 is that the via-filling electroplating technology steps are as follows: Step 3: Use an electroplating solution to perform via-filling electroplating on the multilayer circuit board to fill the holes. The electroplating solution includes: 180g / L copper sulfate pentahydrate, 55g / L sulfuric acid, 60mg / L chloride ions, 60ml / L sodium N,N-dimethylthiocarbamoylpropanesulfonate, 40ml / L sodium dodecyl sulfate, 12ml / L N-methylthiourea, and water as the solvent.

[0058] Example 4

[0059] The difference between this embodiment and Embodiment 1 is that the pre-impregnation solution includes: 270 g / L copper sulfate pentahydrate, 60 g / L sulfuric acid, 50 mg / L chloride ions, 15 ml / L sodium N,N-dimethylthiocarbamoylpropanesulfonate, 10 ml / L sodium dodecyl sulfate, and 12 ml / L N-methylthiourea, with water as the solvent.

[0060] Performance testing

[0061] 1. Conductivity test: According to IPC 9252A: Electrical test requirements for unassembled printed circuit boards, the circuit boards in Examples 1-4 were tested. If the resistance at the continuity point is ≤1Ω, it is considered qualified; otherwise, it is considered unqualified. The test results are shown in Table 1.

[0062] 2. Thermal conductivity test: 2W components were mounted on the copper block area on the front side of the heat dissipation circuit board in Examples 1-4. After the components worked for 2 hours, the temperature difference between the front and back sides of the copper block area was tested. A temperature difference greater than 1.5℃ was considered unqualified, a temperature difference of 1-1.5℃ was considered fair, and a temperature difference less than 1℃ was considered qualified. The test results are shown in Table 1.

[0063] Conductive thermal conductivity Example 1 qualified qualified Example 2 Unqualified Unqualified Example 3 Unqualified Unqualified Example 4 Unqualified Unqualified

Claims

1. A manufacturing process for a heat dissipation circuit board with embedded copper pillars, characterized in that, Includes the following steps: (1) Drilling: Drilling holes on a circuit board; The circuit board is a Teflon multilayer circuit board with 10 layers. The hole is a round hole; The diameter D of the hole is 0.12 mm; (2) Copper plating: In order to ensure the continuity of the circuit in the circuit board, copper plating is required on the hole wall to achieve conductivity through the contact between the copper layer and the copper pillar; The thickness d of the copper layer on the hole wall is 0.02 mm; (3) Insert copper pillars and plate copper again: Insert suitable copper pillars into the holes, and then use the hole-filling electroplating technology. The copper pillars and the copper holes of the substrate are connected into a whole by electroplating copper, and the gaps in the middle are completely filled by the copper plating layer. The copper pillar is circular in shape, and its diameter is 0.09 mm. The hole-filling electroplating technology involves the following steps: Step 1: Prepare the pre-impregnation solution: The pre-impregnation solution includes: 55 g / L sulfuric acid, 180 g / L copper sulfate pentahydrate, 60 ml / L chloride ions, 60 mg / L sodium N,N-dimethylthiocarbamoyl propane sulfonate, and 40 mg / L sodium dodecyl sulfate, with water as the solvent; Step 2: Immerse the multilayer circuit board in the prepreg solution, ensuring that the holes are fully wetted: Apply ultrasonic vibration to the prepreg solution to remove air bubbles in the holes through vibration, thus ensuring that the holes are fully wetted by the prepreg solution. The ultrasonic vibration time is controlled between 10-40 seconds. Step 3: Use an electroplating solution to fill the holes in the multilayer circuit board. The electroplating solution includes: 270 g / L copper sulfate pentahydrate, 60 g / L sulfuric acid, 50 mg / L chloride ions, 15 ml / L sodium N,N-dimethylthiocarbamoyl propane sulfonate, 10 ml / L sodium dodecyl sulfate, and 12 ml / L N-methylthiourea, with water as the solvent. The current density during the hole-filling electroplating was 1.8 ASD, and the electroplating time was 1 hour.

2. A heat dissipation circuit board with embedded copper pillars prepared by the preparation process according to claim 1.