CN110113880A - Metal-based copper-clad laminate and preparation method thereof - Google Patents

Abstract

The invention provides a laminated board and a preparation method thereof. The laminate has a metal substrate composed of a copper layer and an aluminum layer in close contact, a heat conductive insulating layer on the copper layer of the metal substrate, and a copper foil layer on the heat conductive insulating layer. The laminated board has lower density and cost, high heat dissipation performance and capability of enduring cold and hot cycles. The laminate of the present invention is also suitable for forming blind holes therein and plating conductive films.

Description

Metal base copper clad laminate and its preparation method

technical field

The invention 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, metal-based copper clad laminates with high heat dissipation have been developed for printed circuit substrates.

Metal-based copper-clad laminates are mainly aluminum-based copper-clad laminates and copper-based copper-clad laminates. Aluminum-based copper-clad laminates use aluminum plates as substrates, while copper-based copper-clad laminates use copper plates as substrates. Due to the cost advantage, aluminum-based copper-clad laminates are still the mainstream product of metal-based copper-clad laminates. However, when the printed circuit board needs to transmit a larger current and generate heat more intensively at the same time, the thermal conductivity of the aluminum-based copper clad laminate 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 cannot be performed. The disadvantages of copper-based CCL include high density and high cost, so its use is also limited.

Contents of the invention

The purpose of the present invention is to provide a laminated board and its preparation method to solve the above problems.

For reaching this purpose, the present invention adopts following technical scheme:

The laminate has a metal substrate consisting 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 with a heat-conducting insulating layer and a copper foil layer at high temperature.

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

a metal substrate consisting 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 metal substrate has a thickness of 1.0-5.0mm.

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 fillers.

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

Preferably, 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 The surface of the blind hole is plated with a conductive film.

In another aspect, the present invention provides a method of making a laminate, the method comprising:

A metal substrate consisting of a copper layer and an aluminum layer in close contact is prepared by high temperature pressing, and

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

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

Preferably, the high-temperature lamination 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 formed with the thermally conductive insulating layer are pressed together at high temperature.

Preferably, the high-temperature lamination 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 heat-conducting insulating film and the copper foil layer are pressed together at high temperature.

The laminates of the present invention have low density and cost while having high heat dissipation and can withstand thermal and cooling cycles. The laminates of the present invention are also suitable for forming blind vias therein and for electroplating.

Description of drawings

Figure 1 is a schematic diagram of a laminate according to one embodiment of the present invention.

Figure 2 is a schematic illustration of a laminate with blind vias according to one embodiment of the present invention.

Detailed ways

The invention provides a kind of laminated board, described laminated board comprises:

a metal substrate consisting 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.

As shown in FIG. 1 , the laminated board of the present invention has a structure consisting 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 substrate, the copper foil layer is used to form circuits in the printed circuit substrate. The thermally conductive insulating layer insulates the metal substrate and the copper foil layer from each other, and at the same time conducts 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 acting as a heat sink.

The metal substrate 1 of the present invention 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 invention has better heat dissipation. Compared with pure copper substrates, the metal substrates of the present invention have lower density and much lower cost.

Moreover, the side of the metal substrate of the present invention close to 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 thermal expansion coefficient difference between it and the copper foil layer is large, and it is easy to be damaged.

Furthermore, after forming a blind hole from the copper foil layer side to the copper layer in the laminate of the present invention, 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 invention can be prepared using red copper, brass, bronze, and white copper. Preferably, red copper is used to prepare the copper layer. Copper conducts heat and electricity better, and matches the coefficient of thermal expansion of the copper foil layer better.

The copper layer is in close contact with the aluminum layer. In other words, there is no other medium such as an adhesive layer between the copper layer and the aluminum layer. Metal substrates can be made by direct lamination of copper and aluminum layers. 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 be delaminated after being subjected to cold and heat cycles, and the heat dissipation is better.

The aluminum layer in the metal substrate of the present invention can use 1-series, 3-series, 4-series, 5-series and 6-series aluminum plates. Preferably, the aluminum layer is prepared by preferentially using series 1 aluminum plates. The advantage is that the 1-series aluminum conducts heat better.

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

The thickness of the metal substrate of the present invention 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 invention is in contact with the thermally conductive insulating layer. The thermally conductive insulating layer needs to have both excellent thermal conductivity and excellent insulation. Typically, its thermal conductivity should not be lower than 0.5 W/m·k, and its resistivity should not be lower than 10 ⁸ ohm·m.

In order to improve the bonding between the copper layer and the thermally conductive insulating layer, the surface of the copper layer in contact with the thermally conductive insulating layer may be subjected to surface treatment. Surface treatment can be chemical surface treatment or mechanical surface treatment. Chemical surface treatment includes microetching, browning, blackening, etc. Mechanical surface treatment includes grinding, sandblasting, wire drawing, etc. The surface-treated copper layer is more firmly bonded to 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 invention may be formed of a composition comprising 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 reinforcing materials. However, it is preferable to use the insulating layer without reinforcement material, because the insulation layer without reinforcement material can achieve better thermal conductivity. The reinforcing material in the present invention refers to a fibrous reinforcing material, such as glass fiber cloth and non-woven fabric. The thermally conductive insulating layer of the present invention is preferably not a material obtained by dipping resin on fabrics such as glass fiber cloth and non-woven fabric, but an adhesive film, resin coating, etc. that do not contain reinforcing materials.

The thickness of the thermally conductive insulating layer of the present invention is preferably 0.03-0.20mm. In this thickness range, the thermally conductive insulating layer combines excellent insulation with excellent thermal conductivity.

The thermal conductivity of the thermally conductive insulating layer of the present invention is preferably 1-10 W/m·k, more preferably 2-4 W/m·k. When the thermal conductivity is too low, heat cannot be conducted 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 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 inventors have found that within the above range, the thermal conductivity and mechanical properties of the thermally conductive insulating layer are optimally balanced. Moreover, within this range, the thermal expansion coefficient between the thermally conductive insulating layer and the copper foil layer and the metal substrate is similar, and the matching of heat conduction and heat dissipation is the best. When subjected to cold and heat cycles, the heat on the copper foil layer can be quickly conducted to the metal substrate, avoiding the breakage of the copper foil layer circuit or the circuit pad, and improving the reliability of the circuit.

The copper foil layer of the present invention can use conventional copper foil layer materials in the field of printed circuit boards, preferably electrolytic copper or rolled copper. The thickness of the copper foil layer can be a conventional thickness, preferably 0.012-0.210mm.

The laminates of the invention 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 heat-conducting insulating layer 2, and terminates in the copper layer 12, wherein the The surface of the blind hole 5 is plated with a conductive film 4 . After electroplating the blind hole 5, the metal substrate 1 can be used as a conductive layer.

It should be understood that each layer in the laminates of the present invention may be patterned. Therefore, for example, a laminate having a patterned copper foil layer therein can be used as a printed circuit substrate, and such a printed circuit substrate also belongs to the laminate of the present invention. Moreover, the laminated board of the present invention may also have a conventional structure in printed circuit boards such as through holes and blind holes.

Laminates of the present invention can be prepared using a variety of methods.

A method of making a laminate comprising:

A metal substrate consisting of a copper layer and an aluminum layer in close contact is prepared by high temperature pressing, and

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

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

Subsequently, the metal substrate, the thermally conductive insulating layer and the copper foil layer are pressed together at high temperature to form a laminate. Pressing pressure and temperature range can be 20-100kgf/ ^cm2 and 150-250℃

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

In one embodiment, the high-temperature lamination 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 formed with the thermally conductive insulating layer are pressed together at high temperature.

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

The metal substrate, the heat-conducting insulating film and the copper foil layer are pressed together at high temperature.

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

It should be understood that the methods of making the laminates of the present invention are not limited to these.

The laminated board of the invention has excellent heat dissipation, cost and reliability, can be processed to form blind holes that can be plated, and is suitable for use as a printed circuit substrate of electronic components with high current and high heat dissipation requirements.

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

Unless otherwise specified, the materials used in Examples and Comparative Examples are as follows.

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

The reinforcing material of the insulating layer is glass fiber cloth.

The copper layer is copper.

The surface roughness Ra of the copper layer in contact with the thermally conductive insulating layer is 0.4 μm.

The aluminum layer is 1 series aluminum.

The thermal paste is Dow Corning SC102.

Wherein, the dimensions of the laminated board, 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 the present invention, 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, and the test method of ASTM D5470 is adopted.

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

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

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

The number of cold and heat cycles: after several cold and heat cycles between -45°C and 125°C, slice to analyze the combination of each layer and whether there is delamination. If delamination occurs, it is invalid.

Example 1

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After baking and semi-curing at a temperature of 160°C, the copper foil layer coated with a thermally conductive insulating layer is laminated to the 1.0mm copper-aluminum plate (copper layer thickness 0.3mm, aluminum layer thickness 0.7mm) that has been treated by browning surface copper surface. After high-temperature lamination at a temperature of 200°C and a pressure of 40kgf/cm ² , copper-aluminum-based copper-clad laminates can be produced. The thermally conductive insulating layer is an insulating resin containing thermally conductive fillers, with a thermal conductivity of 3W/m·k and a thickness of 0.050mm.

Example 2

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

Example 3

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

Example 4

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil layer coated with a thermally conductive insulating layer is laminated to the copper surface of a 1.0mm copper-aluminum plate (the thickness of the copper layer is 0.4mm, and the thickness of the aluminum layer is 0.6mm). Finally, copper-aluminum-based copper-clad laminates can be produced. The thermally conductive insulating layer is an insulating resin containing thermally conductive fillers, with a thermal conductivity of 3W/m·k and a thickness of 0.050mm.

Example 5

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

Example 6

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil layer 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) that has been treated by browning surface, After high-temperature lamination, copper-aluminum-based copper-clad laminates can be produced. The thermally conductive insulating layer is an insulating resin containing thermally conductive fillers, with a thermal conductivity of 3W/m·k and a thickness of 0.050mm.

Example 7

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After baking and semi-curing, the copper foil layer 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 by browning surface, After high-temperature lamination, copper-aluminum-based copper-clad laminates can be produced. The thermally conductive insulating layer is an insulating resin containing thermally conductive fillers, with a thermal conductivity of 3W/m·k and a thickness of 0.050mm.

Example 8

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After being baked and semi-cured, the copper foil layer coated with a heat-conducting 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 treated by browning. After high-temperature lamination, copper-aluminum-based copper-clad laminates can be produced. The thermal conductivity of the thermally conductive insulating layer is 0.5W/m·k.

Example 9

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. The thermal conductivity of the thermally conductive insulating layer is 12W/m·k. After being baked and semi-cured, the copper foil layer coated with a heat-conducting 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 treated by browning. After high-temperature lamination, copper-aluminum-based copper-clad laminates can be produced.

Comparative example 1

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After being baked and semi-cured, the copper foil layer coated with a thermally conductive insulating layer is laminated on a 1.0mm aluminum plate that has been treated by anodic oxidation. After high-temperature lamination, aluminum-based copper-clad laminates can be produced. The thermally conductive insulating layer is an insulating resin containing thermally conductive fillers, with a thermal conductivity of 3W/m·k and a thickness of 0.050mm.

Comparative example 2

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After being baked and semi-cured, the copper foil layer coated with a heat-conducting insulating layer was laminated on a 1.0mm copper plate treated by browning surface. After high-temperature lamination, copper-based copper-clad laminates can be produced. The thermally conductive insulating layer is an insulating resin containing thermally conductive fillers, with a thermal conductivity of 3W/m·k and a thickness of 0.050mm.

Comparative example 3

Coat the resin of the heat conducting insulation layer on the rough surface of the copper foil layer. After being baked and semi-cured, the copper foil layer coated with a thermally conductive insulating layer is laminated to a 0.3mm copper plate that has been surface-treated by browning, and then laminated at high temperature. Subsequently, use Dow Corning SC102 thermal paste to adhere the copper plate to the 0.7mm aluminum plate to obtain a copper-aluminum base copper-clad laminate. The thermally conductive insulating layer is an insulating resin containing thermally conductive fillers, with a thermal conductivity of 3W/m·k and a thickness of 0.050mm.

Comparative example 4

A thermally conductive insulating layer containing reinforcing material is sandwiched between the rough side of the copper foil layer and a 1.0mm aluminum plate that has been surface-treated by anodizing. After high-temperature lamination, aluminum-based copper-clad laminates can be produced. The thermally conductive insulating layer is insulating resin containing reinforcing materials, with a thermal conductivity of 2W/m·k and a thickness of 0.100mm.

Comparative Example 5

Coat the resin of the heat-conducting insulating layer on the release film, after baking and semi-curing, peel off the heat-conducting insulating layer from the release film, and then clamp it between two 1.0 mm between copper and aluminum plates (copper layer thickness 0.3mm, aluminum layer thickness 0.7mm). After high-temperature lamination, copper-aluminum-based copper-clad laminates can be produced.

Comparative example 6

Coat the resin of the heat-conducting insulating layer on a 0.05mm aluminum foil, bake and semi-cure it, and then press and clamp it on a 1.0mm copper-aluminum plate (thickness of the copper layer is 0.95mm, aluminum layer The copper surface with a thickness of 0.05mm) can be made into a copper-aluminum base aluminum foil-clad laminate after high-temperature lamination.

The laminates of Examples 1-9 and Comparative Examples 1-6 were characterized and the results are shown in the table below.

Examples 1-9 are all laminates of embodiments of the present invention. Comparative Example 1 used a pure aluminum substrate. In Comparative Example 2, a pure copper substrate was used. Comparative Example 3 uses thermal paste to bond copper and aluminum plates. In Comparative Example 4, a pure aluminum substrate is used and the insulating and heat-conducting layer contains reinforcing materials. In Comparative Example 5, a copper-aluminum composite board was used instead of copper foil. In Comparative Example 6, aluminum foil is used instead of copper foil, and the aluminum layer in the metal substrate is 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 laminated board is 40W/m·K, and the number of cold and heat cycles is less than 100, and it is difficult to drill holes for electroplating, 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 resulting laminates have metal matrix densities as high as 8.9 g/cm ³ and cost factors 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 thermally conductive paste. The production process of the laminate is very complicated, and the number of cold and heat cycles is less than 100, and it cannot 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 laminates gain superior strength by sacrificing some thermal conductivity. However, like Comparative Example 1, the number of cold and heat cycles it withstands is less than 100, and the drilling and plating are difficult, and the reliability is low.

In Comparative Example 5, a metal substrate consisting of copper and aluminum layers is used on both sides of the insulating layer, but the resulting laminate cannot be designed with a circuit on the aluminum layer.

In Comparative Example 6, the thickness ratio of the aluminum layer is relatively low, and aluminum foil is used instead of copper foil. Therefore, compared with Examples 1-4, the aluminum foil has a large resistance, poor effect as a conductive layer, difficult drilling and electroplating, and the number of cold and heat cycles is less than 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, its thermal conductivity is increased, and the number of cold and heat cycles is also increased, while compared with laminates using pure copper substrates under the same conditions, its density is reduced and the cost factor is reduced. In addition, metal substrates composed of copper and aluminum layers in close contact are also conducive to drilling plating.

Among the examples 1-9, the example 5 adopts the heat-conducting insulating layer with reinforcing material, and its strength is greatly increased. Although its overall thermal conductivity is relatively low, it is still higher than that of Comparative Example 4, which also uses a thermally conductive insulating layer with reinforcing materials. In Example 6, the copper layer thickness ratio is relatively low, so compared with Examples 1-4, the number of cold and heat cycles is lower, the thermal conductivity is reduced, and the drilling and plating is relatively difficult, but compared with Comparative Example 1 , still has high thermal conductivity, high cooling and heating cycle times, and the reliability of the drilled electroplating structure is still high. In Example 7, the proportion of copper layer thickness 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 heat-conducting insulating layer with a thermal conductivity of 0.5 W/m·k used in Example 8 has a low thermal conductivity and a large coefficient of thermal expansion, and the number of cold and heat cycles it withstands is less than 300. The heat-conducting insulating layer with a thermal conductivity of 12W/m k used in Example 9 has more filler content in the heat-conducting insulating layer, the compactness of the adhesive layer is poor, the reliability of drilling and plating is poor, and it reduces the ability to withstand cold and heat cycles. frequency. However, the performance of the solutions of Examples 8 and 9 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 high thermal conductivity sufficient to be used as printed circuit boards, suitable density and cost, good resistance to cold and heat cycles, and can be used for drilling and electroplating. In Example 2, a laminate is prepared by first forming a separate insulating and heat-conducting film, and the results show that it also has good performance.

Apparently, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (17)

1. A laminate comprising: a metal substrate consisting 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. 2. The laminate according to claim 1, wherein, In the metal substrate, a thickness ratio of the copper layer to the aluminum layer is 1:9 to 4:6. 3. The laminated panel of claim 1, wherein, The thickness of the metal substrate is 1.0-5.0mm. 4. The laminated board 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. 5. The laminate of claim 1, wherein: The surface of the copper layer in contact with the thermally conductive insulating layer is subjected to chemical surface treatment or mechanical surface treatment. 6. The laminate of 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. 7. The laminated board according to claim 1, wherein the thermal conductivity of the thermally conductive insulating layer is 1 W/m·k-10 W/m·k. 8. The laminated board according to claim 7, wherein the thermal conductivity of the thermally conductive insulating layer is 2W/m·k-4W/m·k. 9. The laminate of claim 1, wherein: The thermally conductive insulating layer is a thermally conductive insulating layer without reinforcing material. 10. The laminate of claim 1, wherein: The thermally conductive insulating layer is insulating resin containing thermally conductive fillers. 11. The laminated board 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. 12. The laminated panel of claim 1, wherein: The thickness of the heat conducting insulating layer is 0.03mm-0.20mm, and the thickness of the copper foil layer is 0.012mm-0.210mm. 13. The laminate of 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 heat-conducting insulating layer, and terminates in the copper layer, wherein the blind hole The surface is coated with a conductive film. 14. A method of making the laminate of claim 1, said method comprising: A metal substrate consisting of a copper layer and an aluminum layer in close contact is prepared by high temperature pressing, and The metal substrate is pressed together with the thermally conductive insulating layer and the copper foil layer at high temperature. 15. The method of claim 14, wherein, The high-temperature press-bonding during the preparation of the metal substrate is performed at a temperature above 600°C. 16. The method of claim 14, wherein, The high-temperature lamination of the metal substrate with the heat-conducting 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 formed with the thermally conductive insulating layer are pressed together at high temperature. 17. The method of claim 14, wherein, The high-temperature lamination of the metal substrate with the heat-conducting insulating layer and the copper foil layer includes: forming a thermally conductive insulating film; and The metal substrate, the heat-conducting insulating film and the copper foil layer are pressed together at high temperature.