CN221979168U - High thermal conductivity PCB circuit board - Google Patents

Abstract

The utility model discloses a high-heat-conductivity PCB (printed circuit board), which comprises a red copper substrate, an ultrathin Kang Tongbo layer and a copper foil layer, wherein the ultrathin Kang Tongbo layer and the copper foil layer are respectively coated on the upper surface and the lower surface of the red copper substrate; the bonding layer comprises a high heat conduction insulating adhesive layer and a rough surface structure arranged on the upper surface and the lower surface of the red copper substrate; the high heat conduction PCB circuit board also comprises a plurality of conductive through holes, and the conductive through holes are electrically connected with the ultrathin Kang Tongbo layers and the copper foil layers. The constantan is used as the carrier of the heating wire, so that the property of the circuit board is not easy to change along with the temperature change, and the red copper is used as the substrate, so that the redundant heat energy can be absorbed and stored by the red copper substrate, and the circuit and the components can be kept in a constant temperature state; through setting up the frosted structure at the both sides of red copper base plate, improve the roughness of red copper base plate surface, strengthen its and the high heat conduction insulating glue layer between the adhesion nature, avoid appearing the layering problem simultaneously.

Description

High thermal conductivity PCB circuit board

Technical Field

The utility model relates to the technical field of circuit boards, in particular to a high thermal conductivity PCB circuit board.

Background Art

In aerospace activities, due to the uncertainty of the environment, the operating range of the equipment sometimes reaches minus 130℃ (such as the moon). Therefore, to ensure the long-term normal operation of the equipment, the circuit part of the equipment needs to maintain a constant temperature to prevent the components from freezing. Therefore, when designing the circuit, it is necessary to layout the heating circuit around the important components to ensure that they will not overheat. Therefore, this circuit is invented according to the design requirements.

Summary of the invention

In order to overcome the above-mentioned defects, the utility model provides a high thermal conductivity PCB circuit board.

The utility model adopts a technical solution to solve the technical problem: provide a high thermal conductivity PCB circuit board, which includes a copper substrate, and an ultra-thin copper foil layer and a copper foil layer respectively covered on the upper and lower surfaces of the copper substrate, and a bonding layer is provided between the copper substrate and the ultra-thin copper foil layer and between the copper substrate and the copper foil layer;

The bonding layer includes a high thermal conductivity insulating adhesive layer and a rough surface structure provided on the upper and lower surfaces of the copper substrate;

The high thermal conductivity PCB circuit board also includes a plurality of conductive through holes, and the conductive through holes electrically connect the ultra-thin Constantan copper foil layer and the copper foil layer.

As a further improvement of the utility model, the thickness of the copper substrate is 0.1-3.0 mm, and the copper substrate is processed by a browning process to form the rough surface structure on its upper and lower surfaces.

As a further improvement of the present invention, the roughness of the upper and lower surfaces of the copper substrate is 0.5-5.0 μm.

As a further improvement of the present invention, the ultra-thin copper foil layer has a thickness of 1.5-3.0 μm, and a heating wire circuit is arranged thereon, and the heating wire width of the heating wire circuit is 10-100 μm.

As a further improvement of the present invention, the copper foil layer is oxygen-free copper, and the purity of the oxygen-free copper is above 99.99%, and the thickness of the copper foil layer is 12-50 μm.

As a further improvement of the utility model, the high thermal conductivity insulating adhesive layer is polyimide adhesive or polymerized imide adhesive.

As a further improvement of the present invention, the melting temperature of the high thermal conductivity insulating adhesive layer is greater than 350°C.

The beneficial effects of the utility model are:

1. By using constantan as the carrier of the heating wire, the circuit board is not easy to change its properties with temperature changes, ensuring the stability of the heating circuit. At the same time, by using copper as the substrate, excess heat energy can be absorbed and stored by the copper substrate, so that the circuit and components can be kept in a constant temperature state;

2. By setting a rough surface structure on both sides of the copper plate substrate, the roughness of the surface of the copper plate substrate is improved, the adhesion between it and the high thermal conductivity insulation adhesive layer is enhanced, and the problem of delamination is avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of the utility model.

Combined with the attached drawings, the following description is given:

1. Copper substrate; 2. Ultra-thin copper foil layer; 3. Copper foil layer; 4. High thermal conductivity insulating adhesive layer; 5. Conductive through-hole.

DETAILED DESCRIPTION

A preferred embodiment of the present utility model is described in detail below in conjunction with the accompanying drawings.

The high thermal conductivity PCB circuit board provided by the utility model comprises a copper substrate 1, and an ultra-thin constantan foil layer 2 and a copper foil layer 3 respectively covered on the upper and lower surfaces of the copper substrate 1, and a bonding layer is arranged between the copper substrate 1 and the ultra-thin constantan foil layer 2 and between the copper substrate 1 and the copper foil layer 3; the bonding layer comprises a high thermal conductivity insulating adhesive layer 4 and a rough surface structure arranged on the upper and lower surfaces of the copper substrate 1; the high thermal conductivity PCB circuit board also comprises at least one conductive through hole 5, and the conductive through hole 5 electrically connects the ultra-thin constantan foil layer 2 and the copper foil layer 3.

The thickness of the copper substrate 1 is 0.1-3.0 mm, and the rough surface structure of the upper and lower surfaces of the copper substrate 1 makes its surface roughness 0.5-5.0 μm. The thickness of the ultra-thin copper foil layer 2 is 1.5-3.0 μm, and a heating wire circuit is arranged thereon, and the heating wire width of the heating wire circuit is 10-100 μm. The copper foil layer 3 is oxygen-free copper, and the purity of the oxygen-free copper is more than 99.99%, and the thickness of the copper foil layer 3 is 12-50 μm. Within the normal range, excess heat can be absorbed and stored by the copper substrate, so that the circuit and components can be kept in a constant temperature state.

The high thermal conductivity insulating adhesive layer 4 is a polyimide adhesive or a polymerized imide adhesive that can quickly transfer heat to the bonding part, reduce thermal resistance, and improve heat dissipation efficiency. In addition, it has high bonding strength and light weight, which can reduce the weight of the circuit board. In addition, it also has good bonding strength and weather resistance, and can work in extreme temperatures and environments to ensure the normal operation of the equipment. The high thermal conductivity insulating adhesive layer 4 forms an insulating layer between the copper substrate 1 and the ultra-thin copper foil layer 2 and between the copper substrate 1 and the copper foil layer 3 to prevent interlayer series short circuits.

The method for manufacturing the above-mentioned high thermal conductivity PCB circuit board specifically includes:

Step 1, prepare the required copper substrate 1, ultra-thin copper foil layer 2 and copper foil layer 3. The sheet material is processed into the size that meets the engineering design through cutting, baking, planing and grinding. Baking can remove moisture and eliminate the internal stress of the material to prevent the board from warping. According to the power requirement, the copper substrate 1 of the embodiment of the present application has a thickness of 2.0mm; the thickness of the ultra-thin copper foil layer 2 is 1.8μm, and the thickness of the copper foil layer 3 is 25μm.

Step 2, after drilling a positioning hole on the copper substrate 1 by mechanical drilling according to the circuit layout design, using the positioning hole as a positioning reference, drilling a through hole on the copper substrate 1, and filling the through hole with resin; wherein the through hole serves as a basic hole for subsequent processing of the conductive through hole 5, and therefore, the aperture of the through hole at this time is larger than the aperture of the wire through hole 5, so that after drilling the through hole filled with resin, a resin layer is reserved on the hole wall of the through hole to prevent the copper substrate 1 from being short-circuited with the upper and lower ultra-thin copper foil layers 2 and the copper foil layer 3.

Step 3, after the upper and lower surfaces of the copper substrate 1 obtained in step 2 are coated with a browning solution and dried (i.e., a browning process), a rough surface structure is formed on the upper and lower surfaces of the copper substrate 1; a thin browning film is formed on the surface of the copper substrate 1 treated with the browning solution, and this film can enhance the roughness of the copper surface. In this embodiment, the surface roughness of the copper substrate 1 is 2.0 μm; the adhesion between it and the high thermal conductive insulating adhesive layer 4 is improved, and the problem of stratification is avoided.

Step 4: coating a high thermal conductivity insulating colloid on the upper and lower surfaces of the copper substrate 1 with a rough surface structure, so as to form a high thermal conductivity insulating adhesive layer 4 on the upper and lower surfaces of the copper substrate 1 .

Step 5, stacking the copper foil layer 3, the copper substrate 1 obtained in step 4, and the ultra-thin copper foil layer 2 from bottom to top in sequence to form a laminated board, and pressing the laminated board using a high-temperature pressing process with a hot press to form a PCB primary board; wherein, since the high thermal conductive insulating colloid uses polyimide glue or polymerized imide glue, its melting point reaches 350°C, the hot pressing temperature output by the hot press is greater than 350°C, and the high thermal conductive insulating glue layer 4 can be melted during hot pressing, so that the ultra-thin copper foil layer 2 and the copper foil layer 3 are effectively bonded to the upper and lower surfaces of the copper substrate 1.

Step 6: Use an X-Ray drilling machine to mill holes on the primary PCB board corresponding to the positioning holes of the copper substrate 1.

Step 7, taking the punching in step 6 as the reference PIN hole, on the resin-filled through hole corresponding to the copper substrate 1 of the PCB primary board, a pre-conductive channel concentric with the through hole is drilled, and then an electroplated copper layer is formed in the pre-conductive channel and on the surface of the ultra-thin copper foil layer 2 and the copper foil layer 3 through desmearing, PTH copper deposition, and VCP copper plating processes, so that the hole is metallized to form a conductive through hole 5, thereby achieving interlayer conduction.

Step 8, according to the circuit design drawing, using the perforation as the reference PIN hole, the heating wire circuit is processed on the ultra-thin copper foil layer 2 by pattern transfer.

In addition, the width of the heating wire is set between 10-20 μm to meet customers' different heating power requirements for finished boards. In this embodiment, the width of the heating wire is 50 μm.

Graphic transfer specifically includes:

S1, Graphics pre-treatment: Clean the surface of the ultra-thin copper foil layer 2 to ensure that the board surface is dry, clean, free of oxidation, glue stains, etc. before sticking the dry film.

S2, dry film pasting: photosensitive material, i.e. dry film, is pasted on the copper surface through a laminator.

S3, exposure: using the principle of photosensitive photography, the dry film is exposed to ultraviolet light, a polymerization reaction occurs, and the pattern transfer is completed. To ensure the accuracy of the pattern transfer, this embodiment uses an LDI exposure machine to transfer the pattern.

S4, DES means developing, etching and stripping: after developing, etching, stripping and removing the dry film and excess copper foil outside the pattern, the required heating wire circuit is produced.

Step 9, according to the circuit design drawing, with the perforation as the reference PIN hole, the bottom graphic circuit is formed on the copper foil layer 3 through film lamination, exposure, development, pattern electroplating, and etching (the specific production process is the same as the heating wire circuit production process), completing the preliminary production of the circuit board.

Step 10, cover the copper surface of the circuit board that does not need to be soldered with a layer of solder mask ink; during the DIP and SMT process, the tin liquid or solder paste will not react with the solder mask oil film, thereby avoiding problems such as tin short circuit. The color of the solder mask is generally green, but there are also blue, black, white and red, etc., which can be selected according to the purpose of the product and the needs of the customer.

Step 11, a surface treatment layer is formed on the copper surface not covered by the solder resist ink by a chemical nickel-palladium-gold process; the copper surface not covered by the solder resist ink (such as pads, hole rings, cursor points, etc.) is easily oxidized, so a surface treatment layer is formed on the copper surface not covered by the solder resist ink by a chemical nickel-palladium-gold process, which not only covers the copper surface with a nickel-palladium-gold layer to delay the oxidation of the copper surface, but also can easily react with the tin solution or solder paste of the subsequent DIP or SMT process, which is beneficial to welding.

The specific processing process of the nickel-palladium-gold process is: degreasing - micro-etching - pre-impregnation - activation - nickel precipitation - palladium precipitation - gold precipitation - drying, and each link will undergo multi-stage water washing treatment.

Step 12, using the perforation as the reference PIN hole, the circuit board is cut by a milling machine, and then inspected and put into storage. That is, using the perforation as the reference PIN hole, a high-precision milling machine is used to mill out the large board into the shape of the unit board according to the customer's requirements for the finished board to obtain the finished board required by the customer.

The inspection includes electrical performance test and appearance inspection.

Specifically, the electrical performance test mainly involves open and short circuit detection of the network of the finished board through the test points where the test needle contacts the network. Automatic testing machines are often used to pick out bad boards, which is highly efficient and saves testing time.

Appearance inspection mainly involves inspecting the surface, through holes, and seesaw of finished boards. Those that pass the inspection will be put into storage, while those that fail the inspection will be scrapped.

In summary, the high thermal conductivity PCB circuit board provided by the utility model adopts constantan as the carrier of the heating wire, so that the circuit board is not easy to change its properties with temperature changes, thereby ensuring the stability of the heating circuit. At the same time, by using copper as the substrate, excess heat energy can be absorbed and stored by the copper substrate, so that the circuit and components can be kept in a constant temperature state; by arranging a rough surface structure on both sides of the copper plate substrate, the roughness of the surface of the copper plate substrate is improved, and the adhesion between it and the high thermal conductivity insulating adhesive layer is enhanced, while avoiding the problem of stratification.

In the above description, many specific details are described to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited by the specific implementation disclosed above. At the same time, any person familiar with the technical field can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims (7)

1. The utility model provides a high heat conduction PCB circuit board which characterized in that: the copper foil comprises a red copper substrate (1), and an ultrathin Kang Tongbo layer (2) and a copper foil layer (3) which are respectively connected to the upper surface and the lower surface of the red copper substrate (1), wherein bonding layers are respectively arranged between the red copper substrate (1) and the ultrathin Kang Tongbo layer (2) and between the red copper substrate (1) and the copper foil layer (3);

the bonding layer comprises a high heat conduction insulating adhesive layer (4) and a rough surface structure arranged on the upper surface and the lower surface of the red copper substrate (1);

The high-heat-conductivity PCB circuit board further comprises a plurality of conductive through holes (5), and the conductive through holes (5) are electrically connected with the ultrathin Kang Tongbo layers (2) and the copper foil layers (3).

2. The high thermal conductivity PCB wiring board of claim 1, wherein: the thickness of the red copper substrate (1) is 0.1-3.0mm, and the upper surface and the lower surface of the red copper substrate (1) form the frosted surface structure after being processed by a palm chemical process.

3. The high thermal conductivity PCB wiring board of claim 2, wherein: the roughness of the upper and lower surfaces of the red copper substrate (1) is 0.5-5.0 mu m.

4. The high thermal conductivity PCB wiring board of claim 1, wherein: the thickness of the ultrathin Kang Tongbo layer (2) is 1.5-3.0 mu m, heating wire lines are arranged on the ultrathin Kang Tongbo layer, and the heating wire width of the heating wire lines is 10-100 mu m.

5. The high thermal conductivity PCB wiring board of claim 1, wherein: the copper foil layer (3) is oxygen-free copper, the purity of the oxygen-free copper is more than 99.99%, and the thickness of the copper foil layer (3) is 12-50 mu m.

6. The high thermal conductivity PCB wiring board of claim 1, wherein: the high-heat-conductivity insulating adhesive layer (4) is polyimide adhesive or polyimide adhesive.

7. The high thermal conductivity PCB of claim 6, wherein: the melting temperature of the high-heat-conductivity insulating adhesive layer (4) is higher than 350 ℃.