Manufacturing method of organic material composite circuit board

Abstract

A variety of heat-conducting organic ceramic powder and resin are utilized, an organic material composite circuit substrate prepreg is manufactured under a certain temperature condition through a grouting technology, and then a circuit board line is formed by using a non-ferrous metal conductive adhesive through a through printing technology. And placing the organic ceramic prepreg with the circuit printed on one side or two sides on a hot press for hot pressing to obtain the organic material composite circuit board. The invention relates to the following technical contents: (1) selecting and optimizing an organic ceramic substrate material; (2) a process method for improving the heat-conducting property; (3) determining and optimizing a production route of the organic ceramic substrate; (4) the bonding performance and the conductivity of the circuit conductive paste are optimized; the process comprises the following steps: (1) grouting; and pouring the prepared ceramic slurry into the frame mold. (2) hot leveling and forming; and heating, so that the slurry is heated and automatically leveled. (3) degassing; and the residual gas in the slurry is volatilized. (4) semi-curing; raising the temperature to the curing temperature of 200 DEG C of the adhesive, and controlling the temperature to obtain the organic ceramic semi-solid sheet. And (5) forming a circuit from the composite conductive adhesive through process implementation, and printing the circuit on the organic ceramic semi-solid sheet. (6) hot pressing; and (5) placing the prepreg on a hot press for hot pressing at 180 DEG C, and completing the manufacturing of the circuit board after the hot pressing is completed.

Description

1. Technical Field

[0001] The present invention relates to a structure and a preparation method of a high thermal conductivity organic material composite circuit board.

[0002] 1. By directly compounding ceramic powder with organic resin and undergoing a simple low-temperature pressing process, high-performance organic ceramic substrates with adjustable thermal conductivity and dielectric properties can be produced efficiently and at low cost. This process does not require high-cost, high-temperature, high-pressure, or etching processing, thus solving the problem of high-performance, low-cost, and pollution-free substrate materials.

[0003] 2. Through the design of organic-inorganic interfaces and the selection and optimization of performance regulators, a three-dimensional thermally conductive and insulating structure and network with internal penetration can be obtained, realizing adjustable thermal conductivity, dielectric properties and mechanical properties of organic ceramic substrates.

[0004] 3. A large-scale, modular product line can be formed, such as the high thermal conductivity organic ceramic substrate series, with a thermal conductivity adjustable between 5-10W / m·K, which can be widely used in the field of high-power LED lighting; the low dielectric organic ceramic substrate series, with a dielectric constant that can be arbitrarily selected within the range of 3 to 10 and is very stable, with an operating temperature between -50℃ and +150℃, can be widely used in aerospace, high-end equipment manufacturing, shipbuilding, automobiles, home appliances and other fields. 2. Background Technology

[0005] The circuit board industry is a pillar industry of my country's electronic information industry, and it is also a highly polluting industry. While it brings economic development, it also brings environmental pollution.

[0006] Currently, circuit boards require two industries to complete, namely "copper clad laminate manufacturing plant" and "circuit board etching processing plant". This project integrates these two industries through new materials and new processes, as explained below:

[0007] Traditional PCB circuit board manufacturing process:

[0008] 1. Copper clad laminate production process: raw material cleaning → resin treatment → reinforcement material dipping → reinforcement material inspection → dipping material inspection → dipping material cutting → ingredients → board laying and mold installation → lamination → demoulding → edge processing

[0009] 2. Circuit board formation process:

[0010] Copper clad laminate cutting → drilling → copper plating → full board copper plating → pattern transfer ink or dry film → pattern electroplating → etching → semi-inspection → screen printing solder mask ink and character ink or solder mask dry film → hot air leveling or tin spraying → appearance → inspection → electrical testing → packaging 3. Summary of the Invention

[0011] The manufacturing process of this invention involves using organic and inorganic materials to create a thermally conductive, insulating circuit board substrate. Conductive adhesive is then printed on the substrate and heat-pressed to form the circuit. The independently developed conductive adhesive is a halogen-free, non-ferrous metal mixed conductive material with excellent solderability and conductivity. The conductive paste is then formed into copper foil circuits through a process. The production process produces no water pollution or waste gas.

[0012] The purpose of this invention is to utilize a rational material molding structure and preparation method to produce a circuit board with high thermal conductivity, high insulation, breakdown resistance, and stable performance. This circuit board can meet the needs of most circuit board application markets and is widely used in lighting, digital home appliances, communications, and other fields. To achieve this goal, two approaches were identified: an innovative formulation and an innovative process. The product of this invention has passed ROHS certification testing and obtained a ROHS certification report issued by SGS.

[0013] 1. Technical content of the invention

[0014] 1) Selection and optimization of organic ceramic substrate materials;

[0015] 2) Process methods for improving thermal conductivity;

[0016] 3) Determination and optimization of production routes for organic ceramic substrates;

[0017] 4) Optimization of the bonding performance and conductivity of the circuit conductive paste;

[0018] 2. Technical route

[0019] In the present invention, Al2O3 is used as the main ceramic and epoxy resin is used as the basic organic phase, and the formulation and process are optimized according to different needs. Figure 4 shown

[0020] First, considering the polarity and performance differences between organic and inorganic phases, ceramic powder that has not been surface treated cannot form a homogeneous system with the resin, and macroscopic phase separation such as agglomeration is easily caused, resulting in severe anisotropy of the performance of the obtained organic ceramic system, which cannot meet normal use needs. To this end, we need to perform interface treatment on the ceramic powder. However, different treatment methods have a great influence on the performance of the composite system. The usual method is to use organic silane coupling agents such as KH550 and KH560, but due to the limited addition amount and the very small total content of resin in the organic ceramic system, the effect of these coupling agents is also limited.

[0021] In order to effectively achieve uniform dispersion of the two, we perform surface activation treatment on the ceramic powder and modify the surface of the multi-branched resin ceramic powder to obtain a three-dimensional thermal conductive and insulating structure and network that penetrates the interior, effectively bringing into play the respective advantages of the organic and inorganic phases.

[0022] In terms of improving thermal conductivity, ceramics have a very high thermal conductivity, with Al2O3 generally exceeding 20W / m·K. However, due to the presence of numerous voids in low-temperature cold-pressed ceramic plates, which are poor conductors of heat, their thermal conductivity is very low. Consequently, simple low-temperature cold-pressed ceramic plates have very low thermal conductivity and no mechanical strength at all. Adding organic resins can bond ceramic powders to form a flat substrate, but organic resins such as epoxy resins have very low thermal conductivity. By adding a small amount of highly thermally conductive AlN or metal powder and controlling the particle size, and by manipulating the powder's micro- and nanostructures as well as the pressing process, the void content in the substrate is reduced, reducing both spatial and interfacial thermal resistance, thereby achieving a highly thermally conductive organic ceramic substrate.

[0023] The conductive paste for circuit boards must optimize its adhesion and conductivity. The paste must be printable and, after processing, exhibit pull-off strength, solderability, and conductivity that meet PCB requirements. It uses a 1000-mesh irregular copper powder in a 10:1 ratio of epoxy C976-3, C692-501, and benzyl alcohol. Under suitable processing conditions, it can achieve a pull-off strength of 10kg, good solderability, and an on-resistance below 20kΩ.

[0024] Process steps:

[0025] (a) Frame grouting: The frame is placed flat on a non-stick film and the prepared ceramic slurry is poured into the frame made of hard material. The deformation of the frame does not exceed 2% under a pressure below 2MPa / cm2.

[0026] (b) Heating and leveling: Heat the bottom to make the slurry level itself. The heating temperature is 50℃.

[0027] (c) Degassing: gradually increase the bottom heating temperature to 150°C to evaporate the residual gas in the slurry.

[0028] (d) semi-curing; heating to the curing temperature of the organic binder, 200° C., and controlling the time for 10 minutes to obtain an organic ceramic semi-cured sheet.

[0029] (e) peeling off the non-stick film on the back of the organic ceramic semi-solid sheet, and printing the circuit on the organic ceramic semi-solid sheet using the composite conductive adhesive through a screen printing process.

[0030] (f) hot pressing; placing the prepreg sheet with the printed circuit (5) on a hot press at 180°C, and completing the circuit board production after the hot pressing is completed.

[0031] Compared with traditional circuit board preparation methods, the present invention has the advantages of low equipment requirements, easy process control, and low energy consumption. The finished product has high thermal conductivity and high electrical insulation performance, good breakdown resistance, and is fully suitable for most circuit board usage requirements. It can also greatly reduce the technical cost of high heat dissipation. IV. Description of the Figures

[0032] The above-mentioned features, differences and advantages of the present invention will be more clearly understood through detailed description with reference to the accompanying drawings.

[0033] Figure 1 It is a schematic diagram of the hard material frame mold structure;

[0034] Figure 2 It is a schematic diagram of the printed circuit of the present invention;

[0035] Figure 3 It is a technical route;

[0036] Figure 4 This is a schematic diagram of the preparation process of the thermally conductive organic ceramic plate of the present invention; V. Specific Implementation Methods

[0037] The present invention is described in detail below with reference to the accompanying drawings.

[0038] First, a frame mold is made of hard material. Its purpose is to limit the thickness and external dimensions of the organic ceramic plate. When selecting the frame mold, a material with low pressure resistance and poor adhesion to the slurry should be selected. Metal materials such as stainless steel can be used. Figure 1 shown.

[0039] Before grouting, the formwork should be placed flat on a non-stick film to prevent grout from leaking. The grouting volume should be pre-weighed according to the size of the formwork. Once grouting is complete, the formwork can be placed on a heated plate for leveling. This leveling process primarily involves the organic binder in the slurry. To ensure consistent sheet thickness, the heated plate should be adjusted horizontally beforehand. Once the slurry has completely filled the formwork, the degassing process can begin.

[0040] The purpose of degassing is to volatilize the solvent in the slurry system to avoid the formation of pores or pinholes after curing, thereby reducing the voltage resistance of the substrate. The degassing process should be carried out in stages, gradually increasing from 60°C to 150°C.

[0041] The semi-curing process is carried out after degassing, raising the temperature to about 180°C and leaving it for about 30 minutes. At this time, the organic ceramic substrate is in a semi-cured state, that is, the surface is hard when cooled.

[0042] During the process of printing circuits, the circuit paste is printed on the organic ceramic substrate in a semi-cured state. Printing can be done on one or both sides of the substrate, and then the hot pressing process can begin. Figure 2 shown.

[0043] The equipment used for hot pressing is a customized hot press. The organic ceramic prepreg with circuits printed on one or both sides is placed on the hot press together with the frame mold using stainless steel plate layers for hot pressing. In order to improve efficiency, the hot press uses a multi-layer press to form an organic material composite circuit board.

[0044] The specific process diagram is as follows: Figure 3 shown.

[0045] The present invention has the functions of a circuit board and basically has the use value of a ceramic circuit board. The following table can illustrate the advantages of the present invention over high thermal conductivity aluminum substrates and ceramic boards:

[0046] Table 1 is a performance comparison of the present invention, aluminum-based copper-clad laminates, and ceramic plates.

[0047] Table 1

[0048]

Claims

1. A method for manufacturing an organic material circuit board, the method comprising: (a) preparing a plate frame mold using a hard material, wherein the deformation of the hard material does not exceed 2% under a pressure lower than 2 MPa / cm2; (b) pouring the composite ceramic slurry into the plate frame mold described in step (a) and heating it to level it; (c) baking the heated and leveled organic ceramic slurry in step (b) together with the plate frame mold at a low temperature to form an organic ceramic semi-solid sheet, wherein the low temperature is 80 to 250° C.; (d) bonding the copper-silver paste printed circuit and the organic ceramic semi-solid sheet under hot pressing conditions, and fully curing the organic ceramic semi-solid sheet, wherein the hot pressing conditions are: a temperature below 200° C. and a pressure not exceeding 1.8 MPa / cm2.

2. The method according to claim 1, wherein the hard material is selected from stainless steel and hard iron.

3. The method according to claim 1, wherein the composite ceramic slurry comprises, by weight, 25-35 parts of aluminum oxide powder, 10-15 parts of silicon dioxide powder, 5-10 parts of aluminum nitride powder, 50-70 parts of an organic binder, and 5-10 parts of a solvent.

4. The method according to claim 2, wherein the copper-silver paste is used to print the circuit under hot pressing conditions, wherein the copper-silver paste contains nano-scale irregular copper powder.

Images