JPH0461194A - Manufacture of metal-based wiring board - Google Patents

Abstract

PURPOSE:To improve the thermal conductivity of an insulating layer by increasing bonding strength between an electroless plating layer and the insulating layer by forming the insulating layer after applying an epoxy resin material containing a high heat conduction inorganic filler on a surface of a metal base using a doctor blade, and thereafter roughening the surface to from an electroless plating layer. CONSTITUTION:An insulating layer 3 is formed by applying an insulating layer material containing epoxy resin as a chief ingredient on a surface of a metal base 2 using a doctor blade. To the epoxy resin an aluminum oxide and an aluminum nitride both being a high heat conduction inorganic filler are added by 30% by weight or more and 80% by weight or less. Then, a resist film 4 having an opening 5 of the same pattern as a circuit pattern is formed, and the surface of an exposed part of the insulating layer 3 is roughened and subjected to copper electroless plating to form an electroless plating layer 6. Then, after washing and drying the resist film 4 is removed by trichloroethane to yield a circuit pattern conductor circuit 7.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing metal-based wiring boards.

Specifically, the present invention relates to a method of manufacturing a metal-based wiring board using a truss-a-day-eve method.

[Background technology and its problems] In recent years, electronic devices have become lighter, thinner, and more dense, and the electronic components used in these devices have become more dense; The amount has increased significantly.

Therefore, wiring boards on which these electronic components are mounted are also required to have excellent heat resistance and heat dissipation. In order to meet these demands, recently printed circuit boards and wiring boards based on metal plates with high thermal conductivity such as iron, copper, and aluminum have come into use. .

The conventional method for manufacturing metal-based wiring boards selectively leaves only the necessary parts of the copper foil adhered to the surface of the metal base, and dissolves and removes the other parts by etching.
The so-called subtra-five method was common. According to the subtractive method, the copper foil is bonded to the surface of the metal base using an adhesive, so the peel strength of the copper foil is strong, or the copper foil side-etches during etching, so the height may not be high enough on a mass production basis. It took M [, - - to make the division pattern enclosure. According to the Zabuto and Latadib methods, there was a problem in wastewater treatment because a large amount of edzada liquid or ditch-purified water was used.

It has come to be used in the Azoibib method, which involves selectively depositing metal to create conductor circuits, and in the creation of high-density circuit boards. 〇) The azoibib method includes a full additive method in which a conductor circuit is formed by electroless plating on an insulating layer formed on the surface of a metal, and an insulating method formed on the surface of a metal base. There is a semi-additive method in which the thickness of the conductor circuit is obtained by applying electroless plating on top of the layer and then applying electrolytic plating on top of the layer.
Both thermosetting resins and thermoplastic resins can be used in any of the azoibib methods, but for boat fishing, Evoki 5 resin is used because it is easy to apply, versatile, and heat resistant. 1. ``Problems to be solved by the invention'' The age-dissolution method described above has difficulty in mass production, and is suitable for fine wiring, TfH-〇', metal for high-wealth practical use. It is possible to manufacture wiring boards.

1. Since the rudder and conductor circuit are fixed on the surface of the insulating layer by electroless plating, the ffl+separation strength of the metal has a stronger influence on the lamination quality of the insulating layer. In other words, the (tM state) of the electroless plating layer changes greatly depending on the surface roughening state of the insulating layer that has been roughened on the electroless plating iFi.In particular, the surface Because it is difficult to roughen, 7] - Boxy resin #I7: In the case of the edge layer, it is difficult to deposit electroless plating on the surface of the insulating layer. The disadvantage is that the peel strength of the circuit is weak.

In addition, resin materials have lower thermal conductivity than metal materials (..., so if epoxy resin is used in the insulating layer and 17, the heat dissipation of the metal base wiring board will decrease, which is an advantage of using metal). There was a problem that nothing could be done without taking advantage of the

The present invention has been made in view of the shortcomings of the ten conventional examples, and its purpose is to provide a method for manufacturing a metal-based wiring board according to the full-addition method, in which an electroless plating layer and an insulating layer are used. It is necessary to increase the bonding strength with the insulating layer and improve the thermal conductivity of the insulating layer.

[Means for Solving the Problems] Therefore, the method for manufacturing a metal-based wiring board of the present invention is as follows:
A method for manufacturing a metal-based wiring board in which an insulating layer is formed on the surface of a metal base and a conductive layer is formed on the insulating layer, the method comprising a thermally conductive inorganic filler such as aluminum oxide or aluminum nitride. An insulating layer is formed by applying an epoxy resin material containing 30% by weight or more and 80% by weight or less by a doctor blade method onto the surface of the metal base. After formation, the surface of the insulating layer is roughened 1, and then an electroless plating layer is formed on the surface of the insulating layer to provide a conductive layer.

[Function] In the present invention, a thermally conductive inorganic filler is dispersed in an insulating layer made of an epoxy resin material, so if the surface of the insulating layer is roughened using a strong acid, etc. The thermally conductive inorganic filler in the layer dissolves, creating pores in the insulating layer, or the thermally conductive inorganic filler precipitates on the surface of the insulating layer, and the surface of the layer is roughened. 1. As a result, if electroless plating is not applied to the edges of the insulating layer, the electroless plating layer will not adhere to the surface of the insulating layer due to the anchoring effect of the thermally conductive inorganic filler or pores deposited on the surface. Even when an epoxy resin is used for the insulating layer, it is possible to obtain a conductive layer that is firmly attached to the conductor layer and is difficult to physically peel off, and a high peel strength can be obtained.

Furthermore, since the thermally conductive inorganic filler is dispersed in the insulating layer made of an epoxy resin material, the thermally conductive inorganic filler acts as a heat bridge, improving the thermal conductivity of the insulating layer.

If the addition amount of the thermally conductive inorganic filler is less than 30% by weight, the improvement in the thermal conductivity effect by the thermally conductive inorganic filler will be weakened, and if it exceeds 80% by weight, the thermal conductivity will be reduced. Since it becomes difficult to apply an epoxy resin material containing a conductive inorganic filler to an insulating layer, the amount added is preferably 30% by weight or more and 80% by weight or less.

Furthermore, in the present invention, since the metal base wiring board is manufactured by the Tsuruato Igaifu method, the thickness of the conductive layer can be reduced only by electroless plating. Unlike the semi-additive method, which thickens the conductor layer by electroless plating and electrolytic plating, it does not require equipment for electrolytic plating and has the advantage of simplifying manufacturing management1. Shikamo, epoxy resin material Since it is applied to the surface of the metal base using the doctor blade method, it is possible to obtain an insulating layer with a uniform thickness, and even when using a low-viscosity epoxy resin material, a large insulating layer can be formed. I can do it.

[Example] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIGS. 1(a) to 1d) show a manufacturing process for a metal base wiring board 1 using a full additive method.

In this process, first, as shown in Fig. 1(a), a five-layer compaction material using an epoxy resin is applied to the surface of the metal base 2 using a doctor brush-board method. After coating 5, an epoxy resin-based insulating layer 3 is formed.The material of the metal base 2 is not particularly limited.
Although it is possible to use iron, copper, etc., aluminum is preferable because it is easy to use. The type of epoxy resin used is not particularly limited, but for example, Bisfu J7'-R type A resin: = 5-1.
Cresol novolacs and fuconol novolacs are preferred. There are no particular limitations on the type of curing agent for the diboxy resin (i), but examples include amine-based, intoxicant-based, and latent curing agents. Epoxy resins are usually diluted with organic solvents such as gutters and aromatic hydrocarbons to facilitate coating work, and this epoxy resin contains μ) a good conductive inorganic filler to provide insulation properties. is already filled.

This insulating and thermally conductive inorganic filler includes aluminum nitride (AQ2O) and aluminum nitride (AQN).
) or preferable [, i. As a thermally conductive inorganic filler, it is desirable to use a powder with a center particle size of 200 Jn or less and a purity of 99.8% or more; if the center particle size is too thick than 2ouJ1, the epoxy resin will harden. However, if the thermally conductive inorganic filler is more likely to settle, the peel strength of the conductor circuit 7 will be reduced.
If it is less than 75% by weight, the improvement in the heat conduction effect in the insulating layer 3 will be weak, if it is more than 75% by weight, the epoxy resin will have a high viscosity and it will be difficult to coat the epoxy resin, and if it is more than 80% by weight, it will be difficult to coat. Therefore, the amount of the thermally conductive inorganic filler added is preferably 30% by weight or more and 80M% or less. Also,
As shown in FIG. 2, since the insulating layer H material 8 whose main ingredient is epoxy resin diluted with a solvent is applied onto the metal base 2 using a doctor blade 9, the insulating layer 3 has a uniform thickness. can be formed. However, even when a low-viscosity insulating layer 3 is used, a thick insulating layer 3 can be obtained and reliable insulation can be achieved.

In order to selectively deposit life and electroless plating, the first
As shown in Figure (b), the insulating layer 3 is formed by screen printing.
A resist ink is printed on the resist ink and cured by heating at 100° C. for 10 minutes to form a resist film 4 having a thickness of about 2 Qgm and having the same pattern of openings 5 as the circuit pattern. This 1/JIS) ink and [2] This is Sglen-based resin,
Silicone resin etc. Inorganic t whose main components are Cr, PB
After that, the insulating layer 3 is exposed from the cyst membrane 1. The exposed portion of the insulating layer 3 is swollen with an organic solvent or its vapor, and the surface of the exposed portion of the insulating layer 3 is roughened using a strong oxidizing agent such as oxidizing acid. Roughens the surface. This moment,
The thermally conductive inorganic filler dispersed in the epoxy resin
It precipitates or dissolves on the surface of the insulating layer 3 to generate pores, and the surface of the insulating layer is likely to be roughened.

After roughening the surface of the insulating layer 3 with Koji, Pc1-3 [
Activate the exposed part of the insulating layer 3 with 1-series AKZA-tar, then dissolve 30 g of citric acid and 280 mQ of concentrated salt to make an IQ solution (Pd desorption solution at 20°C for 5 minutes). The Pd on the resist film 4 is removed by immersion and washing with water.After this, as shown in FIG.
) is obtained, and an electroless metal layer (3
"form".

After washing with water and drying, as shown in FIG. 1(d), the Tri-Click R-7 (: 11-piece trowel resist) film 4 is removed to obtain a conductor circuit 7 having a circuit pattern.

In this way, if a metal-based wiring board is manufactured using the full-above-eve method, the thickness of the conductor circuit can be obtained only by electroless plating. In addition, as mentioned above, insulating layer such as AΩ203 or AQN can be easily manufactured using electrolytic plating equipment. If a thermally conductive inorganic filler is dispersed, the surface of the insulating layer will be easily roughened, so when forming an electroless plating layer on the surface of the insulating layer, 3.Thermal conductivity of the insulating layer is improved by these thermally conductive inorganic fillers without impairing the insulation properties of the insulating layer. As a result, the heat dissipation properties of the metal-based wiring board are improved by increasing the heat dissipation rate.For example, 1.
The thermal conductivity of wafer is 20 W/m', the thermal conductivity of 5102 is 3,3 W7Im', and the thermal conductivity of aluminum nitride (AQN) is 100 W/m-γ. By filling the insulating layer with powder such as alumina, aluminum nitride, or aluminum, the thermal conductivity of the insulating layer can be greatly improved.

In particular, by using aluminum, it is possible to obtain an insulating layer that is inexpensive and has high thermal conductivity.Furthermore, the heat-resistant layer 1 and Improves thermal shock resistance.

In the above embodiment, the conductor circuit was formed only on one side of the metal base wiring board, but it goes without saying that the conductor circuit may be provided on the screen of the metal base wiring board.

Hereinafter, more specific embodiments of the present invention will be described in comparison with two conventional examples.

(Example) After degreasing an aluminum substrate with a thickness of 1[l'1I11] with trichloroethane, an epoxy resin composition having the composition shown in Table 1 was applied to the surface of the aluminum substrate by a doctor blade method12, and cured at room temperature. After that, it was further heat-cured at 160'C for 5 hours to form an insulating layer.

Table 1 Next, Cyst Ink (Asahi Chemical Research Disruption, MTA~
509) onto the insulating layer by screen printing [
7,100°C] for 0 minutes to obtain a cyst film with a predetermined pattern (20 mm thick). .

After this, the aluminum substrate on which the resist film was formed was
After roughening the surface by immersing it in a chromium-sulfuric acid solution heated to 5°C for 5 minutes, it was washed with water, and then immersed in dilute hydrochloric acid. Then, activation treatment (2) and activation treatment (2) were performed under the conditions shown in Table 2.

Table 2 (blank below) Furthermore, under the conditions shown in Table 3, the Pd on the film was removed.

Electroless copper plating was carried out under the conditions shown in Table 3 and Table 4. Obtained.

Table 4 (margins below) [7] After obtaining the required film thickness using only electroless polishing, the resist film was washed with water and dried, and the resist film was removed using l-lichloro and ryo-tan. , created a conductive circuit 6
(Conventional Example 1) The composition shown in Table 5 was coated on an aluminum substrate with a thickness of 1 mm using the H method, such as electrostatic coating with adhesive, and after the solvent was evaporated and dried, it was heated at 180'C. The film was heated for 2 hours to cure and form an insulating layer. Then, a conductor circuit with a desired pattern was obtained by the same full additive method as in the example.

Table 5 was obtained. Thereafter, the copper foil was etched using iron chloride, and a conductive circuit with a desired pattern was obtained using the subtractive method.

(Comparison of Example, Conventional Example] and Conventional Example 2) After obtaining the metal base wiring boards of the Example, Conventional Example 1 and Conventional Example 2 as in E-Me, For wiring boards, seven rules were determined and compared: peel strength of conductor circuits, solder heat resistance, thermal conductivity in the thickness direction of wiring boards, and minimum wiring width of conductor circuits.

The results are shown in Table 6 below.

Table 6 (Conventional Example 2) An insulating layer was formed by applying an adhesive having the composition shown in Table 5 as in Conventional Example 1 to an aluminum substrate with a thickness of 35 m, and then drying it to form an insulating layer. Copper foil was layered on the insulating layer and heated and pressed at 180°C for 12 hours at a pressure of 5 kg f/cm2 to form a copper-clad metal base wiring board.The method for measuring the peel strength of conductor circuits is 1. J I SC64815
, in accordance with Section 7. That is, after forming a conductor layer on the surface of the aluminum substrate via an insulating layer, the conductor is removed from both sides of the aluminum substrate by photolithographic cutting or etching L2.As shown in FIG. (Length I, = J, 00m111, Width W≧25m
A sample 23 is prepared by leaving the conductor 22 with a width W1 and Omm at the center of the n+), and the minimum load per unit width F when the conductor 22 is peeled off in a direction perpendicular to the aluminum substrate 21 using a tensile tester. 17 were measured. In addition, the solder heat resistance is determined by the melting temperature in the Hirata tank (in this case, 260"C).
A metal-based wiring board was immersed in a solder solution, and the time until the aluminum board and the insulating layer peeled off or cracks appeared in the epoxy resin of the insulating layer was measured. Furthermore, itl of the thermal conductivity in the thickness direction of the wiring board,
The lI constant is determined as shown in Figure 4 (as shown in Figure 4). The heat dissipating flock 32 and the heat source 3 are connected by a thermocouple;
! ’) is performed by measuring the temperature difference between the temperature and the heat generated! 3
Thermal conductivity was determined from the ratio of the 1-rise temperature (m'K) of the heat dissipation block I-7 block 32 and the power consumption (W) based on the temperature of 5.

As can be seen from Table 6 above, the solder heat resistance of the examples is as follows:
Similarly to Conventional Example 1, which is also made by the full additive method, it has a heat resistance time that is twice or more than twice that of Conventional Example 2 which is made by the subtractive method. Furthermore, the minimum wiring width is also the same as that of the embodiment using the full additive method and the conventional example 1.
When compared with conventional example 2 using the subtractive method,
An extremely fine minimum wiring width has been achieved.

Moreover, the conductor peel strength is the highest in Conventional Example 2 obtained by the subtractive method. However, when comparing Example and Conventional Example 1, which were also made using the full additive method, in Example, a peel strength four times that of Conventional Example I was obtained, and the effect of mixing alumina powder into the insulating layer was It is noticeable. Furthermore, the thermal conductivity of the metal-based wiring board of the example is four times the thermal conductivity of each of conventional examples 1 and 2, and by dispersing the thermally conductive inorganic filler, A high thermal conductivity was obtained.

Therefore, by dispersing the thermally conductive inorganic filler in the insulating layer, it was possible to obtain a metal-based wiring board with excellent characteristics.

"Effects of the Invention" According to the present invention, the bonding between the electroless plating layer and the insulating layer during electroless plating is difficult due to the thermally conductive inorganic filler precipitated or dissolved on the surface of the insulating layer by the surface roughening treatment. This can be achieved by increasing the peel strength of the conductor circuit. In addition, since a thermally conductive inorganic filler is dispersed in the insulating layer, the thermal conductivity of the insulating layer is improved, the thermal conductivity of the entire metal-based wiring board is improved, and the heat dissipation of the metal-based wiring board is improved. further improves. Moreover, since the conductor layer is formed on the surface of the metal-based wiring board using a full semi-additive method, a high-density multilayer board with no side etching concerns can be obtained, and electrolytic plating equipment is not required. This reduces equipment costs and facilitates process control.

Furthermore, since the insulating layer is formed by applying l-boxy resin material using the doctor blade method, it is possible to form an insulating layer with a uniform thickness, and it is also easy to form a thick insulating layer. Nidetori.

[Brief explanation of drawings]

Figures 1 (a), (b), (c) and (d) are schematic sectional views showing the manufacturing process of one embodiment of the present invention, Figure 2 is a schematic view showing the method of applying the insulating layer in the above, and Figure 3 The figure is a perspective view for explaining a method for measuring the peel strength of a conductor circuit, and FIG. 4 is a front view showing an apparatus for measuring the thermal conductivity of a metal base wiring board. 2...Metal base 3...Insulating layer 6...Electroless plating layer 7...Conductor circuit (b no (C) Continuation of figure 1 page ' 0 Invention Akira Daiobayashi

Claims (1)

[Claims] (1) A method for manufacturing a metal-based wiring board in which an insulating layer is formed on the surface of a metal base and a conductive layer is formed on the insulating layer, the method comprising using a material with good thermal conductivity such as aluminum oxide or aluminum nitride. After forming an insulating layer by applying an epoxy resin material containing an inorganic filler at a ratio of 30% to 80% by weight to the surface of the metal base using a doctor blade method, the surface of the insulating layer is roughened. 1. A method for manufacturing a metal-based wiring board, characterized in that a conductive layer is provided by forming an electroless plating layer on the surface of the insulating layer.