JPH08288659A - Metal base multilayered circuit board - Google Patents

Abstract

PURPOSE: To enable mounting a power electronic element which generates heat, by making the surface roughness of a circuit surface of the lower layer of a metal base circuit board which is laminated on a metal plate be in a specified range. CONSTITUTION: On at least a part or the whole part of the main surface of a metal plate 1, a double-sided resin board 3 having metal layer 5 and a metal layer 4 which have at least circuits like a shield circuit is laminated via an insulating adhesive layer 2, and unified in a body. According to need, electronic elements as well as circuits are mounted on the double-sided resin board 3. A Cu-plating layer 7 is formed on the metal layer 5 surface. The surface roughness of the lower layer circuit surface of the double-sided resin board 3 is set as 1μm<=Rz<=10μm. In the case that the surface roughness is Rz>=0.1μm, bonding power is improved and heat dissipation can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-based multi-layered circuit board, and more particularly to a metal-based multi-layered circuit board which is capable of mounting a power electronic device having a high heat-generating property on a multi-layered portion and has excellent reliability. .

[0002]

2. Description of the Related Art In recent years, circuit boards for mounting semiconductors have been required to have high density mounting and high performance. With the miniaturization of semiconductor elements, high performance, and miniaturization of wiring density, heat generated from semiconductor elements has been increased. How to dissipate is a problem.

Under these demands, mainly in the power supply field,
A metal base circuit board in which a metal foil is laminated on a metal plate via an insulating layer has been used because it has good heat dissipation, but since it has a structure in which a thin insulating layer is applied on the metal plate, There is a problem in that noise is likely to occur and a malfunction of the module is likely to occur.

As a countermeasure against the noise, a metal-based multi-layer circuit board in which an upper layer substrate is laminated on a metal plate or a metal plate having an insulating layer provided on the surface via an adhesive layer has been widely used. In such a metal-based multilayer circuit board,
In general, a material with a low heat dissipation property such as epoxy impregnated glass cloth is used for the insulating agent layer between the metal plate and the upper substrate, and in addition, since an adhesive layer is present, high power is required. When the electronic element is mounted, there is a problem that the heat dissipation is insufficient, the temperature of the electronic element rises, and eventually a malfunction occurs.

As a countermeasure against this, a circuit board such as a resin board such as a glass epoxy multilayer board or a double-sided resin board in which two metal foils are joined via a resin filled with an inorganic material is provided with an inorganic filler for enhancing thermal conductivity. A metal-based multi-layer circuit board has been devised which is laminated on a metal plate through a filled insulating adhesive layer. (Japanese Patent Application No. 6-223692) However, such a metal-based multi-layer circuit board has a problem in that the insulating adhesive layer and the circuit board have insufficient adhesive force, and thus peel off at this interface. It was

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to mount a heat-generating high-power electronic element on a multi-layered portion, which is excellent in reliability. A metal-based multilayer circuit board is provided.

[0007]

SUMMARY OF THE INVENTION The present invention is a metal base circuit board in which a double-sided resin board having a circuit formed in at least a lower layer is laminated on a metal plate through an insulating adhesive layer. Surface roughness Rz is 0.1 μm or more 10
The metal-based multi-layer circuit board is characterized by having a thickness of not more than μm.

Further, according to the present invention, C is formed on the circuit surface of the lower layer.
The metal-based multi-layer circuit board according to claim 1, further comprising a u-plated layer, and more specifically, the Cu-plated layer includes at least Ni or Co. The substrate.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing an example of the metal-based multilayer circuit board of the present invention. The metal-based multi-layer circuit board of the present invention is a double-sided resin having a metal layer 5 having a circuit such as a shield circuit at least as a lower layer and a metal layer 4 as an upper layer on a part or the entire surface of at least one main surface of the metal plate 1. Board 3
It has a structure in which the insulating adhesive layer 2 is laminated and integrated. Although not shown, generally not only circuits but also electronic elements are mounted on the double-sided resin substrate 3 as needed, and a plurality of layers of circuit boards may be laminated on the double-sided resin substrate 3. FIG. 2 is a cross-sectional view showing another example of the metal-based multilayer circuit board of the present invention, which has a Cu plating layer 7 on the surface of the lower metal layer 5 of the double-sided resin board 3.

The double-sided resin substrate 3 of the present invention is one in which two or more metal layers 4 and 5 are laminated via an insulating adhesive layer 6 obtained by curing a resin containing an inorganic filler. There, boron nitride, aluminum oxide, as an inorganic filler,
It is a resin containing 45% by volume to 80% by volume of any one of silicon oxide or a mixture containing two or more of these.

Examples of the above-mentioned resin include epoxy resin, polyimide resin, phenol resin and the like, and epoxy resin is preferable because of its strong adhesive force. Regarding the thickness of the insulating adhesive layer 6 of the double-sided resin substrate 3, in terms of heat dissipation and withstand voltage characteristics of the obtained metal-based multilayer circuit board.
It is preferably 20 μm to 200 μm. Depending on the characteristics required for the metal-based multilayer circuit board, the double-sided resin board 3 may be used instead of the conventionally known glass epoxy resin board, polyimide resin board, phenol resin board, or other resin board or surface. It is also possible to use an electrically insulating metal substrate or ceramic substrate.

In the present invention, the surface of the circuit underlying the double-sided resin substrate 3 has a surface roughness Rz of 0.1 μm or more and 10 μm or less. The double-sided resin substrate 3 is laminated on the metal plate 1 with the insulating adhesive layer 2 interposed therebetween. The bonding force of the double-sided resin substrate 3 is not only unevenness of the circuit itself, but also the circuit and double-sided resin substrate 3 in contact with the insulating adhesive layer 2. It is affected by the material and surface properties of the insulating adhesive layer 6. The inventors repeatedly conducted experiments on this point and found that the surface roughness of the circuit surface governs the bonding force, especially when the circuit surface is Cu or a Cu-plated layer containing at least Ni or Co. It was found that the bonding force can be improved when the surface roughness Rz is 0.1 μm or more, and the present invention has been achieved.

When the surface roughness of the circuit surface of the lower layer of the double-sided resin substrate 3 is less than 0.1 μm in Rz, sufficient bonding force cannot be obtained, and the lower layer circuit of the double-sided resin substrate is not used during or before use. A gap is generated between the insulating adhesive layer 2 and the heat dissipation property is significantly deteriorated. On the other hand, the surface roughness is R
When z exceeds 10 μm, electric field concentration occurs in the uneven portion of the surface, resulting in poor withstand voltage. Although the reason for the surface material of the lower layer of the double-sided resin substrate 3 is unknown, it is preferable that it is copper because a strong bonding force can be obtained, and particularly, the Cu plating layer 7 containing at least Ni or Co. The above-mentioned effects are remarkable when the are laminated, which is preferable.

The material of the lower layer circuit of the double-sided resin substrate 3 is not particularly specified, and copper, aluminum, nickel, iron, tin, silver, titanium, alloys of these metals, or several metals or alloys thereof. A laminated clad foil or metal plating such as Ni plating or (Ni + gold) plating may be applied. These metals or alloys are generally supplied in the form of a thin layered foil having a thickness of about 9 to 500 μm, and the surface roughness is Rz of 0.
It is less than 1 μm.

In the present invention, the surface of the metal layer 5 which is the surface of the circuit below the double-sided resin substrate 3 is roughened to the above-mentioned 0.1 μm.
Adjust so that it is 10 μm or less. Machining may also be used as a method of adjusting the surface roughness. In addition, when the lower layer circuit of the double-sided resin substrate is made of Cu, a method of performing corrosion treatment with various liquids (etching treatment) or a method of treating with an oxidizing liquid (blackening treatment or browning treatment) is known. The surface treatment method can be used.

The present invention is also based on the finding that a Cu plated layer having a surface roughness Rz of 0.1 μm or more and 10 μm or less can be obtained by selecting the Cu plating conditions. The Cu alloy layer 7 provided on the surface of the circuit-formed metal layer 5 under the double-sided resin substrate 3 of the present invention has a surface roughness Rz of 0.1 μm or more and 10 μm or less, Furthermore, at least Ni
Alternatively, it contains Co.

There are electric Cu plating and electroless Cu plating as a method of performing Cu plating. In the present invention, any method is available as long as the obtained Cu plating has a surface roughness Rz of 0.1 μm to 10 μm. However, electroless Cu
Plating is a preferred method because it is possible to obtain plated layers of various alloys and surface structures. The electroless Cu plating can be easily performed, for example, by immersing the object to be plated in a copper sulfate aqueous solution containing formalin, glyoxylate or sodium hypophosphite in a reducing agent for several tens of seconds. At this time, in order to ensure the stability of the electrolytic solution, for example, a buffering agent such as boric acid or a complexing agent such as sodium citrate is used. As an example of Cu plating that can be used in the present invention,
Bath composition as copper sulfate 0.032M, sodium hypophosphite 0.2
7M, 0.052M sodium citrate, 0.5M boric acid as the base, cobalt sulfate, nickel sulfate 0.00
It is possible to immerse the object to be plated for several tens of seconds to several hours under the condition of a bath temperature of 50 to 70 ° C. using 1 to 0.01 M added, and the surface roughness of the Cu plating layer obtained under these plating conditions. It can also be adjusted.

The content of Ni and / or Co is not particularly limited, but is preferably 0.1% by weight or more and 15% by weight or less in the Cu plating layer 7. The content of Ni and / or Co is
It is considered that a desired amount of 0.001 M or more is added to the electrolytic solution during Cu plating, plays a role of a nucleating agent when Cu is deposited, and is co-deposited with Cu.
When Ni and / or Co exceeds 15% by weight in the Cu plating layer, the surface roughness of the obtained Cu plating layer is 10 μm.
May exceed. Thus, Ni and / or Co
By adjusting the amount added, Rz is 0.1μm or more and 10μ
A Cu plated layer having a surface roughness of m or less can be easily obtained without post-treatment.

Similarly, for example, by keeping the temperature of the electrolytic solution low at the time of Cu plating, a Cu plating layer containing neither Ni nor Co and having a surface roughness Rz of 0.
It is possible to obtain one having a size of 1 μm or more and 10 μm or less. still,
Regarding the thickness of the Cu plating layer 7, Ni and / or Co
Regardless of whether or not it is included, it is preferably 0.01 to 10 μm. If the thickness of the Cu plating layer is less than 0.01 μm, the adhesive force is not exerted, and if the thickness exceeds 10 μm, the plating layer undergoes cohesive failure and the expected adhesive strength cannot be obtained.

As the insulating adhesive layer 2 used in the present invention,
A resin containing a powder of one or more kinds of metal oxides and / or metal nitrides. The metal oxides and metal nitrides contained are aluminum oxides from the viewpoint of heat dissipation,
Silicon oxide and boron nitride are preferable. The resin is not particularly specified, but an epoxy resin, a polyimide resin,
BT resin, phenol resin, fluororesin, butyral resin, and a mixture thereof are used. Among the above-mentioned resins, epoxy resin is particularly preferable because the bonding strength can be improved when the surface of the metal layer 5 on which the circuit is formed, which is the lower layer of the double-sided resin substrate 3, is plated with Cu. The thickness of the insulating adhesive layer 2 is not particularly limited, but is preferably 200 μm or less in consideration of thermal conductivity.

As the metal plate 1 used in the metal-based multilayer circuit board of the present invention, aluminum and aluminum alloys having good thermal conductivity, copper and copper alloys, iron and iron alloys, etc. or copper / iron-nickel alloy / copper. A composite material such as aluminum / iron-nickel alloy / aluminum can be used. The thickness of the metal plate 1 is not particularly limited, but 0.5 mm to 3.0 mm is generally used.

The present invention will be described in more detail based on the following examples.

【Example】

Example 1 An epoxy resin containing 78% by weight of crushed aluminum oxide was applied as an insulating adhesive layer on an aluminum plate having a thickness of 1.5 mm to a thickness of 200 μm. On the other hand, a glass epoxy resin substrate having a substrate thickness of 60 μm and metal layers of 35 μm thickness on both sides is formed with a desired circuit and through holes, and then the surface of one side of the circuit is roughened by etching and further Cu-plated. Was applied.
At this time, the surface roughness of the Cu plating layer was 0.1 μm in Rz. Next, on the insulating adhesive layer on the aluminum plate, a circuit plated with Cu was faced to the insulating adhesive layer and directly laminated by a laminating method to produce a metal-based multilayer circuit board. Regarding this metal-based multi-layer circuit board, the adhesion strength between the insulating adhesive layer and the circuit board
It was examined by a 90 ° peeling method according to S C6481. Also, float the same metal-based multilayer circuit board on a solder bath at 260 ℃,
The adhesive strength after the minute treatment and the presence or absence of swelling were observed. The 90 degree peel strength before and after the solder bath treatment is 1.
It was good at 9 and 1.8 kgf / cm. In addition, no swelling occurred.

Examples 2 to 7 and Comparative Example 1 Example 1 was repeated except that the conditions for producing the Cu plating layer were changed variously.
Various metal-based multilayer circuit boards obtained through the same operation as above were evaluated in the same manner as in Example 1 to be Examples 2 to 7. In addition, as a comparative example, the same operation and evaluation were performed for a surface not roughened by etching and having no Cu plating layer. The results are shown in Table 1 together with the results of Example 1.

Example 8 On a 1.5 mm thick aluminum plate, crushed aluminum oxide was used as an insulating adhesive layer.
An epoxy resin containing 78% by weight was applied to a thickness of 200 μm. On the other hand, a glass epoxy resin substrate with a base material thickness of 60 μm and metal layers of 35 μm thickness on both sides is formed with a desired circuit and through holes, and then the one side circuit is blackened with an alkaline aqueous solution containing chlorite as a main component. The chemical treatment was performed. At this time, the surface roughness of the blackened circuit is 0.2 in Rz.
μm. Next, on the insulating adhesive layer on the aluminum plate, the circuit subjected to the blackening treatment was faced to the insulating adhesive layer and directly laminated by a laminating method to prepare a metal-based multilayer circuit board. The same evaluation as in Example 1 was performed on this metal-based multilayer circuit board. Table 1 shows the results.

Example 9 A metal-based multilayer circuit board obtained by the same operation as in Example 8 except that etching treatment was performed with a sulfuric acid-hydrogen peroxide aqueous solution instead of the blackening treatment, The same evaluation was performed. The results are shown in Table 1.
Shown in

[0026]

[Table 1]

[0027]

According to the present invention, the double-sided resin substrate and the metal plate are firmly bonded via the insulating adhesive layer, and as a result, a metal-based multi-layer circuit substrate having excellent heat dissipation can be easily obtained. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a metal-based multilayer circuit board of the present invention.

FIG. 2 is a cross-sectional view showing another example of the metal-based multilayer circuit board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal plate 2 Insulating adhesive layer 3 Double-sided resin substrate 4 Metal layer as upper layer of double-sided resin substrate 5 Metal layer on which lower layer of double-sided resin substrate is formed circuit 6 Insulating adhesive layer of double-sided resin substrate 7 Cu plating layer

Claims (3)

[Claims] 1. A metal base circuit board in which a double-sided resin substrate having a circuit formed in at least a lower layer is laminated on a metal plate via an insulating adhesive layer, and the surface roughness of the circuit surface of the lower layer is 0.1 μm in Rz. A metal-based multilayer circuit board having a thickness of 10 μm or more. 2. The metal-based multi-layer circuit board according to claim 1, wherein a copper (Cu) plating layer is provided on a surface of the lower circuit. 3. The metal-based multilayer circuit board according to claim 2, wherein the Cu plating layer contains at least either nickel (Ni) or cobalt (Co).