WO2020133965A1

WO2020133965A1 - Metal base copper foil-coated laminate and preparation method therefor

Info

Publication number: WO2020133965A1
Application number: PCT/CN2019/092321
Authority: WO
Inventors: 佘乃东; 叶晓敏; 黄增彪
Original assignee: 广东生益科技股份有限公司
Priority date: 2018-12-29
Filing date: 2019-06-21
Publication date: 2020-07-02
Also published as: CN210157469U; CN110113880A

Abstract

A laminate and a preparation method therefor. The laminate has a metal base plate formed of a copper layer and an aluminium layer in close contact, a thermally conductive insulation layer on the copper layer of the metal base plate, and a copper foil layer on the thermally conductive insulation layer. The laminate can be used as a printed circuit board.

Description

Metal-based copper-clad laminate and preparation method thereof

Cross-reference to related applications

This disclosure claims the priority of Chinese patent application numbers 201811654737.X and 201822278013.1 filed on December 29, 2018, which are incorporated by reference in their entirety.

Technical field

The present disclosure relates to the field of printed circuit substrates, in particular to a metal-based copper-clad laminate and a preparation method thereof.

Background technique

At present, high heat dissipation metal-based copper-clad laminates have been developed for printed circuit boards.

The metal-based copper-clad laminates are mainly aluminum-based copper-clad laminates and copper-based copper-clad laminates. The aluminum-based copper-clad laminate uses an aluminum plate as a substrate, and the copper-based copper-clad laminate uses a copper plate as a substrate. Due to its cost advantages, aluminum-based copper clad laminates are still the mainstream products of metal-based copper clad laminates. However, when the printed circuit board needs to transmit a larger current and at the same time generate heat more concentratedly, the thermal conductivity of the aluminum-based copper-clad plate cannot meet the requirements. In addition, the aluminum-based copper-clad laminate cannot meet the direct electroplating process of drilling, that is, the process of directly electroplating the holes drilled in the aluminum substrate. The disadvantages of copper-based copper clad laminates include high density and high cost, so their use is also limited.

Summary of the invention

In one aspect, the present disclosure provides a laminate, the laminate comprising:

A metal substrate composed of a copper layer and an aluminum layer in close contact;

A thermally conductive insulating layer on the copper layer of the metal substrate;

A copper foil layer on the thermally conductive insulating layer.

Preferably, in the metal substrate, the thickness ratio of the copper layer to the aluminum layer is 1:9 to 4:6.

Preferably, the thickness of the metal substrate is 1.0-5.0 mm.

Preferably, the bonding strength between the copper layer and the aluminum layer of the metal substrate is greater than 100 MPa.

Preferably, the surface of the copper layer in contact with the thermally conductive insulating layer is subjected to chemical surface treatment or mechanical surface treatment.

Preferably, the surface roughness Ra of the surface of the copper layer in contact with the thermally conductive insulating layer is 0.1 μm-0.6 μm.

Preferably, the thermal conductivity of the thermally conductive insulating layer is 1W/m·k-10W/m·k.

Preferably, the thermal conductivity of the thermally conductive insulating layer is 2W/m·k-4W/m·k.

Preferably, the thermally conductive insulating layer is a thermally conductive insulating layer without reinforcing material.

Preferably, the thermally conductive insulating layer is an insulating resin containing thermally conductive filler.

Preferably, the insulating resin is any one or a combination of at least two of epoxy resin, polyphenylene ether resin, and polyimide resin.

Preferably, the thickness of the heat conductive insulating layer is 0.03 mm-0.20 mm, and the thickness of the copper foil layer is 0.012 mm-0.210 mm.

Preferably, the laminate has a blind hole, the blind hole opening is on the surface of the copper foil layer, passes through the copper foil layer and the thermally conductive insulating layer, and terminates in the copper layer, wherein the The surface of the blind hole is plated with a conductive film.

In another aspect, the present disclosure provides a method of preparing a laminate, the method comprising:

Through high temperature lamination, a metal substrate composed of a copper layer and an aluminum layer in close contact is prepared, and

The metal substrate is pressed at high temperature with the thermally conductive insulating layer and the copper foil layer, wherein the copper layer of the metal substrate is opposite to the thermally conductive insulating layer.

Preferably, the high-temperature pressing at the time of preparing the metal substrate is performed at a temperature above 600°C.

Preferably, the high-temperature pressing of the metal substrate with the thermally conductive insulating layer and the copper foil layer includes:

Forming a thermally conductive insulating layer on the copper foil layer, and

The metal substrate and the copper foil layer on which the thermally conductive insulating layer is formed are pressed at high temperature.

Forming a thermally conductive insulating film; and

The metal substrate, the thermally conductive insulating film and the copper foil layer are pressed together at high temperature.

BRIEF DESCRIPTION

FIG. 1 is a schematic diagram of a laminate according to an embodiment of the present disclosure.

2 is a schematic diagram of a laminate with blind holes according to one embodiment of the present disclosure.

detailed description

The purpose of the present disclosure is to provide a laminate and a method of manufacturing the same to solve the above problems.

To achieve this, an embodiment of the present disclosure adopts the following technical solutions:

The laminate has a metal substrate composed of a copper layer and an aluminum layer in close contact, a thermally conductive insulating layer on the copper layer of the metal substrate, and a copper foil layer on the thermally conductive insulating layer. By high-temperature pressing, a metal substrate composed of a copper layer and an aluminum layer in close contact is prepared, and the metal substrate is pressed at high temperature with a thermally conductive insulating layer and a copper foil layer.

The present disclosure provides a laminate including:

A copper foil layer on the thermally conductive insulating layer.

As shown in FIG. 1, the laminate of the present disclosure has a structure composed of a metal substrate 1, a thermally conductive insulating layer 2 and a copper foil layer 3. Among them, when used as a printed circuit board, the copper foil layer is used to form a circuit in the printed circuit board. The thermally conductive insulating layer insulates the metal substrate and the copper foil layer from each other, and at the same time can conduct the heat on the copper foil layer to the metal substrate to prevent heat concentration in the copper foil layer. The metal substrate provides support and mechanical strength to the laminate, while at the same time acting as a heat sink.

The metal substrate 1 of the present disclosure is composed of a copper layer 12 and an aluminum layer 11 in close contact, wherein one side of the copper layer 12 is in contact with the aluminum layer 11 and the other side is in contact with the thermally conductive insulating layer 2. Compared with the pure aluminum substrate, the metal substrate of the present disclosure has better heat dissipation. Compared to pure copper substrates, the metal substrates of the present disclosure have lower density and much lower cost.

Moreover, the side of the metal substrate of the present disclosure near the copper foil layer is a copper layer, which has a similar coefficient of thermal expansion to the copper foil layer. On the contrary, if a pure aluminum substrate is used, the coefficient of thermal expansion between it and the copper foil layer is large, and damage is likely to occur.

In addition, after forming a blind hole from the copper foil layer side to the copper layer in the laminate of the present disclosure, a conductive film may be plated in the blind hole. On the contrary, if a pure aluminum substrate is used, it will be difficult to plate a conductive film.

The copper layer in the metal substrate of the present disclosure may be prepared using copper, brass, bronze, and cupronickel. Preferably, copper is used to prepare the copper layer. The thermal conductivity and electrical conductivity of red copper are more excellent, and the thermal expansion coefficient of the copper foil layer is more matched.

The copper layer and the aluminum layer are in close contact. In other words, there is no other medium such as an adhesive layer between the copper layer and the aluminum layer. The metal substrate can be made by directly pressing the copper layer and the aluminum layer. Preferably, the bonding strength between the copper layer and the aluminum layer of the metal substrate is greater than 100 MPa. The advantage is that the metal substrate will not delaminate after being subjected to cold and hot cycles, and the heat dissipation is better.

The aluminum layer in the metal substrate of the present disclosure may use 1 series, 3 series, 4 series, 5 series, and 6 series aluminum plates. Preferably, it is preferred to use 1 series aluminum plates to prepare the aluminum layer. The advantage is that the thermal conductivity of series 1 aluminum is better.

In the metal substrate of the present disclosure, the thickness ratio of the copper layer to the aluminum layer is preferably 1:9 to 4:6. Within this range, the metal substrate also has excellent heat dissipation, suitable density and suitable cost.

The thickness of the metal substrate of the present disclosure is preferably 1.0-5.0 mm. Within this thickness, sufficient heat dissipation and suitable cost can be provided.

The copper layer in the metal substrate of the present disclosure is in contact with the thermally conductive insulating layer. The thermally conductive insulating layer must have both excellent thermal conductivity and excellent insulation. Typically, the thermal conductivity thereof should not be less than 0.5W / m · k, which is not lower than the resistivity of 10 ^ohm-meters.

In order to improve the combination of the copper layer and the thermally conductive insulating layer, the surface of the copper layer in contact with the thermally conductive insulating layer may undergo surface treatment. The surface treatment may be chemical surface treatment or mechanical surface treatment. Chemical surface treatments include micro-etching, browning, blackening, etc. Mechanical surface treatment includes grinding, sand blasting, and wire drawing. The surface-treated copper layer is more firmly combined with the thermally conductive insulating layer. Preferably, the surface roughness Ra of the copper layer in contact with the thermally conductive insulating layer is 0.1 μm-0.6 μm.

The thermally conductive insulating layer in the laminate of the present disclosure may be formed of a composition containing an insulating resin, a thermally conductive filler, a curing agent, and an accelerator. Preferably, the insulating resin is any one or a combination of at least two of epoxy resin, polyphenylene ether resin, and polyimide resin. The thermally conductive insulating layer may also contain reinforcement materials. However, it is preferable to use an insulating layer without reinforcing materials because the insulating layer without reinforcing materials can achieve better thermal conductivity. The reinforcing material in the present disclosure refers to fibrous reinforcing materials, such as glass fiber cloth and non-woven cloth. The thermally conductive insulating layer of the present disclosure is preferably not a material obtained by dip coating resin on fabrics such as glass fiber cloth, non-woven fabric, etc., but a glue film, resin coating, etc. that does not contain a reinforcing material.

The thickness of the thermally conductive insulating layer of the present disclosure is preferably 0.03-0.20 mm. Within this thickness range, the thermally conductive insulating layer has both excellent insulation and excellent thermal conductivity.

The thermal conductivity of the thermally conductive insulating layer of the present disclosure is preferably 1-10 W/m·k, and more preferably 2-4 W/m·k. When the thermal conductivity is too low, the heat cannot be transferred from the copper foil side to the metal substrate side in time. However, the higher the thermal conductivity, the better, because in order to achieve a higher thermal conductivity, a higher proportion of thermally conductive filler must be added, which will lead to a decrease in the density and mechanical properties of the thermally conductive insulating layer. The inventor found that within the above range, the thermal conductivity and mechanical properties of the thermally conductive insulating layer reached an optimal balance. Moreover, the thermal expansion coefficient of the thermally conductive insulating layer within this range is similar to the copper foil layer and the metal substrate, and the matching between thermal conduction and heat dissipation is the best. The heat on the copper foil layer can be quickly conducted to the metal substrate when subjected to cold and heat cycles, which avoids the breakage of the circuit or circuit pad of the copper foil layer and improves the reliability of the circuit.

The copper foil layer of the present disclosure may use a copper foil layer material conventional in the field of printed circuit boards, and preferably electrolytic copper or rolled copper is used. The thickness of the copper foil layer may be a conventional thickness, preferably 0.012-0.210 mm.

The laminate of the present disclosure may have blind holes. As shown in FIG. 2, the blind hole 5 opens on the surface of the copper foil layer 3, passes through the copper foil layer 3 and the thermally conductive insulating layer 2, and terminates in the copper layer 12, wherein the A conductive film 4 is plated on the surface of the blind hole 5. After plating the blind hole 5, the metal substrate 1 can be used as a conductive layer.

It should be understood that each layer in the laminate of the present disclosure may be patterned. Therefore, for example, a laminate in which a patterned copper foil layer can be used as a printed circuit substrate, and such a printed circuit substrate also belongs to the laminate of the present disclosure. Moreover, the laminate of the present disclosure may also have a conventional configuration in printed circuit boards such as through holes, blind holes, and the like.

Various methods can be used to prepare the laminate of the present disclosure.

A method of preparing a laminate includes:

The metal substrate is pressed together with the thermally conductive insulating layer and the copper foil layer at high temperature.

Generally, a metal substrate is made by directly laminating a copper layer and an aluminum layer at high temperature.

Subsequently, the metal substrate, the thermally conductive insulating layer and the copper foil layer are pressed at high temperature to form a laminate. Pressing pressure and temperature range can be 20-100kgf/cm ² and 150-250℃

Preferably, the pressing temperature of the copper layer and the aluminum layer when preparing the metal substrate is higher than 600°C.

In one embodiment, the high-temperature pressing of the metal substrate with the thermally conductive insulating layer and the copper foil layer includes:

Forming a thermally conductive insulating layer on the copper foil layer, and

In another embodiment, the high temperature lamination of the metal substrate with the thermally conductive insulating layer and the copper foil layer includes:

Forming a separate thermally conductive insulating film; and

Specifically, an insulating and thermally conductive composition containing an insulating resin, a thermally conductive filler, a curing agent, and an accelerator may be coated on the copper foil layer, and then pressed with a metal substrate at high temperature. It is also possible to first form a separate insulating and thermally conductive composition film, and then press-bond it with the copper foil layer and the metal substrate at high temperature.

It should be understood that the method of preparing the laminate of the present disclosure is not limited to these.

The laminate of the present disclosure has excellent heat dissipation, cost and reliability, can be processed to form plated blind holes, and is suitable for use as a printed circuit board for electronic components requiring high current and high heat dissipation.

The present disclosure is illustrated below by examples and comparative examples. It should be noted that the embodiments are for illustrative purposes only, and are not intended to limit the present disclosure.

Unless otherwise specified, the materials used in the examples and comparative examples are as follows.

The copper foil layer is electrolytic copper with a thickness of 0.035mm.

The reinforced material of the insulating layer is fiberglass cloth.

The copper layer is red copper.

The surface roughness Ra of the copper layer and the thermally conductive insulating layer was 0.4 μm.

The aluminum layer is 1 series aluminum.

The thermal paste is Dow Corning SC102.

Among them, the size of the laminate, that is, the length and width of the copper foil layer, the copper layer, and the aluminum layer are 500 mm × 600 mm, respectively.

In this disclosure, the manner of performing performance evaluation is as follows.

Thermal conductivity of the whole board: the metal substrate is prepared into a sample of 25.4mm×25.4mm, using ASTM D5470 test method.

Surface roughness Ra: The metal substrate is prepared as a sample of 100 mm × 100 mm, and the method is tested according to the surface roughness of the metal foil in IPC-TM-6502.2.17A.

Cost factor: comprehensively consider the price and processing cost of copper and aluminum plates, and use pure aluminum plates as the coefficient 1 and pure copper plates as the coefficient 10 for calculation.

Drilling and electroplating: blind holes are drilled first, and then electrochemical copper plating. Evaluate the efficiency and process feasibility of electroplating, and evaluate the combination of hole wall plating after electroplating.

Withstand the number of cold and hot cycles: After several cold and hot cycles between -45℃ and 125℃, slice and analyze the combination of each layer to see if there is delamination. If there is delamination, it is invalid.

Example 1

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After baking and curing at a temperature of 160℃, the copper foil coated with a thermally conductive insulating layer is laminated on a 1.0mm copper-aluminum plate (copper layer thickness 0.3mm, aluminum layer thickness 0.7mm) treated by browning the surface Copper surface. After being pressed at a high temperature of 200°C and a pressure of 40kgf/cm ² , a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Example 2

Coat the resin of the thermally conductive insulating layer on the release film, and after baking and semi-curing, peel off the thermally conductive insulating layer from the release film, and then sandwich it between the rough surface of the copper foil layer and the browned surface Between 1.0mm copper and aluminum plates (copper layer thickness 0.3mm, aluminum layer thickness 0.7mm). After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Example 3

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil coated with a thermally conductive insulating layer is laminated on the copper surface of a 1.0 mm copper-aluminum plate (copper layer thickness 0.1 mm, aluminum layer thickness 0.9 mm) that has been surface-treated by browning. After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Example 4

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil coated with a thermally conductive insulating layer is laminated on the copper surface of a surface-treated 1.0mm copper-aluminum plate (copper layer thickness 0.4mm, aluminum layer thickness 0.6mm), and pressed at high temperature After that, a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Example 5

The thermally conductive insulating layer containing the reinforcing material is sandwiched between the matte surface of the copper foil layer and the 1.0mm copper-aluminum plate (copper layer thickness 0.3mm, aluminum layer thickness 0.7mm) treated by browning the surface. After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a reinforcing material, the thermal conductivity is 2 W/m·k, and the thickness is 0.100 mm.

Example 6

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After being baked and semi-cured, the copper foil coated with a thermally conductive insulating layer is laminated on the copper surface of a 1.0mm copper-aluminum plate (copper layer thickness 0.05mm, aluminum layer thickness 0.95mm) treated by browning surface treatment. After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Example 7

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil coated with a thermally conductive insulating layer is laminated on the copper surface of a 1.0mm copper-aluminum plate (copper layer thickness 0.6mm, aluminum layer thickness 0.4mm) that has been treated with a browning surface. After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Example 8

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil coated with a thermally conductive insulating layer is laminated on the copper surface of a 1.0 mm copper-aluminum plate (copper layer thickness 0.3 mm, aluminum layer thickness 0.7 mm) that has been surface-treated by browning. After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced. The thermal conductivity of the thermally conductive insulating layer is 0.5 W/m·k.

Example 9

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. The thermal conductivity of the thermally conductive insulating layer is 12W/m·k. After baking and semi-curing, the copper foil coated with a thermally conductive insulating layer is laminated on the copper surface of a 1.0 mm copper-aluminum plate (copper layer thickness 0.3 mm, aluminum layer thickness 0.7 mm) that has been surface-treated by browning. After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced.

Comparative example 1

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil coated with a thermally conductive insulating layer is laminated on a 1.0 mm aluminum plate treated with anodizing surface. After high-temperature pressing, an aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Comparative example 2

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil coated with a thermally conductive insulating layer is laminated on a 1.0 mm copper plate treated with a browned surface. After high temperature lamination, a copper-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Comparative Example 3

The resin of the thermally conductive insulating layer is coated on the rough surface of the copper foil layer. After being baked and semi-cured, the copper foil coated with a thermally conductive insulating layer is laminated on a 0.3 mm copper plate treated with a browning surface, and pressed at high temperature. Then, using Dow Corning SC102 thermal paste to adhere the copper plate to the 0.7mm aluminum plate, a copper-aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler, and has a thermal conductivity of 3 W/m·k and a thickness of 0.050 mm.

Comparative Example 4

The thermally conductive insulating layer containing the reinforcing material is sandwiched between the matte surface of the copper foil layer and the 1.0 mm aluminum plate surface-treated by anodization. After high-temperature pressing, an aluminum-based copper-clad laminate can be produced. The thermally conductive insulating layer is an insulating resin containing a reinforcing material, the thermal conductivity is 2 W/m·k, and the thickness is 0.100 mm.

Comparative example 5

Apply the resin of the thermally conductive insulating layer to the release film, and after baking and semi-curing, peel off the thermally conductive insulating layer from the release film, and then press and clamp it to 2 sheets with a browning surface treatment of 1.0 mm of copper and aluminum plates (copper layer thickness 0.3mm, aluminum layer thickness 0.7mm). After high temperature lamination, a copper-aluminum-based copper-clad laminate can be produced.

Comparative Example 6

The resin of the thermally conductive insulating layer is coated on a 0.05mm aluminum foil, and after baking and semi-curing, then it is pressed and clamped on a 1.0mm copper-aluminum plate (copper layer thickness 0.95mm, aluminum layer) On the copper surface with a thickness of 0.05mm), after high temperature pressing, a copper-aluminum-based aluminum foil-clad laminate can be prepared.

The laminates of Examples 1-9 and Comparative Examples 1-6 were characterized for performance, and the results are shown in the following table.

Examples 1-9 are all laminates of the embodiments of the present disclosure. In Comparative Example 1, a pure aluminum substrate was used. In Comparative Example 2, a pure copper substrate was used. In Comparative Example 3, a copper plate and an aluminum plate were bonded using a thermal paste. In Comparative Example 4, a pure aluminum substrate is used and the insulating and thermally conductive layer contains a reinforcing material. In Comparative Example 5, a copper-aluminum composite board was used instead of copper foil. In Comparative Example 6, aluminum foil was used instead of copper foil, and the aluminum layer in the metal substrate was very thin.

In Comparative Example 1, a pure aluminum substrate was used, and there was no copper layer in the metal substrate. The thermal conductivity of the obtained laminate is 40W/m·K, and the number of cold and heat cycles is less than 100, and the drilling and plating are difficult and the reliability is low.

In Comparative Example 2, a pure copper substrate was used, and there was no aluminum layer in the metal substrate. The metal base density of the resulting laminate is as high as 8.9 g/cm ³ and the cost factor is as high as 10.

In Comparative Example 3, a copper-aluminum composite substrate was used, but the copper layer and the aluminum layer were bonded by a thermal paste. The production process of the laminate is very complicated, withstands less than 100 heat and cold cycles, and can not be drilled and plated.

In Comparative Example 4, a pure aluminum substrate was used, and an insulating layer with a reinforcing material was used. Such a laminate obtains excellent strength by sacrificing a certain thermal conductivity. However, as in Comparative Example 1, the number of cold and heat cycles is less than 100, and drilling and plating are difficult and the reliability is low.

In Comparative Example 5, a metal substrate composed of a copper layer and an aluminum layer is used on both sides of the insulating layer, but the laminate cannot be used to design circuits on the aluminum layer.

In Comparative Example 6, the thickness ratio of the aluminum layer is low, and aluminum foil is used instead of copper foil. Therefore, compared with Examples 1-4, the aluminum foil has a larger resistance, poor conductive layer effect, and difficult drilling and electroplating. 100 times.

In Examples 1 to 9, a metal substrate composed of a copper layer and an aluminum layer in close contact was used. Compared with laminates using pure aluminum substrates under the same conditions, their thermal conductivity is increased, and the number of cycles of cooling and heating is also increased. Compared with laminates using pure copper substrates under the same conditions, their density and cost coefficient are reduced. In addition, the metal substrate composed of the copper layer and the aluminum layer in close contact is also conducive to drilling and plating.

In Examples 1-9, Example 5 uses a thermally conductive insulating layer with a reinforcing material, the strength of which is greatly increased. Although the thermal conductivity of the whole board is relatively low, it is still higher than that of Comparative Example 4 which also uses a thermally conductive insulating layer with a reinforcing material. The thickness ratio of the copper layer in Example 6 is low, so compared with Examples 1-4, the number of cycles of cooling and heating is lower, the thermal conductivity is reduced, and the drilling plating is relatively difficult, but compared with Comparative Example 1 It still has a high thermal conductivity and a high number of cooling and heating cycles, and the reliability of the drilled hole plating structure is still high. The thickness ratio of the copper layer in Example 7 is high, so compared with Examples 1-4, the cost coefficient is higher and the density is higher, but compared with Comparative Example 2, it still has low cost and low density. The thermally conductive insulating layer with a thermal conductivity of 0.5 W/m·k used in Example 8 has a low thermal conductivity, a large thermal expansion coefficient, and less than 300 heat and cold cycles. The thermally conductive insulating layer with a thermal conductivity of 12 W/m·k used in Example 9 has more filler content in the thermally conductive insulating layer, the density of the adhesive layer is poor, the reliability of the drilling electroplating is poor, and the resistance to cold and heat cycles is reduced frequency. However, the performance of the solutions of Examples 8 and 9 withstanding the number of cycles of heating and cooling is still better than that of Comparative Example 1, and the cost is much lower than that of Comparative Example 2.

The laminates in Examples 1-4 have both high thermal conductivity sufficient for use as a printed circuit board, suitable density and cost, good resistance to cold and heat cycles, and can be used for drilling and plating. In Example 2, a laminate is prepared by first forming a separate insulating and thermally conductive film, and the results show that it also has good performance.

The laminate of the present disclosure has lower density and cost, and at the same time has high heat dissipation and can withstand cold and hot cycles. The laminate of the present disclosure is also suitable for forming blind holes therein and performing electroplating.

Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. In this way, if these modifications and variations of the present disclosure fall within the scope of the claims of the present disclosure and equivalent technologies thereof, the present disclosure is also intended to include these modifications and variations.

Claims

A laminate comprising:

A metal substrate composed of a copper layer and an aluminum layer in close contact;

A thermally conductive insulating layer on the copper layer of the metal substrate;

A copper foil layer on the thermally conductive insulating layer.
The laminate according to claim 1, wherein

In the metal substrate, the thickness ratio of the copper layer to the aluminum layer is 1:9 to 4:6.
The laminate according to claim 1, wherein

The thickness of the metal substrate is 1.0-5.0 mm.
The laminate according to claim 1, wherein the bonding strength between the copper layer and the aluminum layer of the metal substrate is greater than 100 MPa.
The laminate according to claim 1, wherein

The surface of the copper layer in contact with the thermally conductive insulating layer undergoes chemical surface treatment or mechanical surface treatment.
The laminate according to claim 1, wherein

The surface roughness Ra of the surface of the copper layer in contact with the thermally conductive insulating layer is 0.1 μm-0.6 μm.
The laminate according to claim 1, wherein the thermal conductivity of the thermally conductive insulating layer is 1W/m·k-10W/m·k.
The laminate according to claim 7, wherein the thermal conductivity of the thermally conductive insulating layer is 2W/m·k-4W/m·k.
The laminate according to claim 1, wherein

The thermally conductive insulating layer is a thermally conductive insulating layer without reinforcing materials.
The laminate according to claim 1, wherein

The thermally conductive insulating layer is an insulating resin containing a thermally conductive filler.
The laminate according to claim 10, wherein the insulating resin is any one or a combination of at least two of epoxy resin, polyphenylene ether resin, and polyimide resin.
The laminate according to claim 1, wherein

The thickness of the thermally conductive insulating layer is 0.03mm-0.20mm, and the thickness of the copper foil layer is 0.012mm-0.210mm.
The laminate according to claim 1, wherein

The laminate has a blind hole, the blind hole opens on the surface of the copper foil layer, passes through the copper foil layer and the thermally conductive insulating layer, and terminates in the copper layer, wherein the blind hole The surface is plated with conductive film.
A method for preparing the laminate according to claim 1, the method comprising:

Through high temperature lamination, a metal substrate composed of a copper layer and an aluminum layer in close contact is prepared, and

The metal substrate is pressed together with the thermally conductive insulating layer and the copper foil layer at high temperature.
The method according to claim 14, wherein

The high-temperature pressing during the preparation of the metal substrate is performed at a temperature of 600° C. or higher.
The method according to claim 14, wherein

The high-temperature pressing of the metal substrate with the thermally conductive insulating layer and the copper foil layer includes:

Forming a thermally conductive insulating layer on the copper foil layer, and

The metal substrate and the copper foil layer on which the thermally conductive insulating layer is formed are pressed at high temperature.
The method according to claim 14, wherein

The high-temperature pressing of the metal substrate with the thermally conductive insulating layer and the copper foil layer includes:

Forming a thermally conductive insulating film; and

The metal substrate, the thermally conductive insulating film and the copper foil layer are pressed together at high temperature.