JPS6252988A - Metal core printed wiring board and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a metal core printed wiring board and a method for manufacturing the same, and particularly to a metal core printed wiring board and a metal core printed wiring board equipped with through holes suitable for hybrid ICs. The present invention relates to a manufacturing method thereof.

(Prior Art) In recent years, as electronic devices have become smaller and thinner, high-density packaging has been promoted in wiring boards used in hybrid ICs. As a result, the heat dissipation of wiring boards has become an issue, and high thermal conductivity has become a problem.

Metal core printed wiring boards are used which have properties such as excellent mechanical strength and workability, and can form circuits on both sides.

The conventional technology used to manufacture such metal-core printed wiring boards is to form the necessary holes in predetermined locations on a metal substrate, and then mold them integrally with copper foil using glass epoxy or glass polyimide to fill the holes. There is a method of creating a metal core printed wiring board by filling the resin with resin and then drilling a hole approximately in the center of the hole. (For example, Industrial Research Association 198
"Printed Wiring Board Technology" published January 108, 2005, page 50)
In this method, it is first necessary to form holes at predetermined locations on the metal substrate, which is the base material of the metal core printed wiring board, for each different wiring circuit, usually using an NC multi-axis drilling machine. This is done by drilling holes in the metal substrate in accordance with the design layout. However, the workability of metal substrates is much worse than that of glass epoxy substrates, which are commonly used as printed wiring boards, so not only does it take time and time to drill holes, but expensive drills are worn out. Since the size is also large, there are problems such as poor productivity and high costs.

On the other hand, there is also a technique as seen in Japanese Unexamined Patent Publication No. 55-39673. The invention disclosed in this publication is, ``In a printed board with a metal core, a lattice-shaped metal core arranged in a fixed manner is molded and embedded in an organic insulating resin.
This is a metal cored pudding plate characterized by having holes for mounting parts, etc., an internal number in the space of the ν metal core, and a circuit pattern formed on the surface.

In this invention, a metal core is placed in the center and an organic insulating resin is molded.The relatively thin metal core is embedded in a thick mold with extremely thermally conductive resin. As a result, heat dissipation, which is the most important feature for a metal core printed wiring board, is extremely poor. There is a description that a "drilled metal core" may be used, but this metal core is "a hole for attaching parts, etc., made in the space of the metal core where the depth of the embedded metal core can be easily predicted from the side cross section." Therefore, in order for the metal core that is thickly embedded in the mold to be easily predicted from the side cross section, the pitch between each hole or this hole must be quite large.In that case, the metal core will be in a plate state. Instead, it becomes almost a net-like structure in which large holes are arranged in a regular manner, and the mechanical strength and thermal conductivity of the metal core are completely lost.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and the problems to be solved are the difficulties in manufacturing conventional metal core printed wiring boards and This is due to its high cost and poor properties such as heat dissipation.

That is, the object of the present invention is to provide a metal-core printed wiring board and a metal-core printed wiring board that are excellent in various properties such as heat dissipation, which is the most important for a metal-core printed wiring board, are capable of high-density wiring, and are easy to manufacture. The object of the present invention is to provide a manufacturing method thereof.

(Means for Solving the Problems) The means adopted by the present invention to solve the above problems is to use a metal substrate as a core having a large number of holes arranged with a regularity of predetermined pitch intervals. The printed wiring board includes an electrically insulating material filled in a hole selected from among the plurality of holes, and an electrically insulating material formed approximately at the center of the selected hole from among the holes filled with the electrically insulating material. and an electrically insulating layer covering the surface of the metal substrate, and a conductor circuit is formed on the surface of the electrically insulating layer and in selected ones of the through-holes. This is a metal core printed wiring board. And, in order to manufacture this metal core printed wiring board, the method adopted by the present invention is a manufacturing method of a metal core printed wiring board including each of the following steps (1) to (2).

■Process of arranging a large number of holes with regularity at a predetermined pitch interval on a metal substrate: (1i) Selected holes from among the large number of holes provided in the process of L.■ are filled with electrically insulating material. filling step; ■ step of coating the surface of the metal substrate with an electrically insulating material to form an electrically insulating layer; A step of forming a through hole in the center; (2) A step of forming a conductor circuit on the surface of the electrical insulating layer and in a selected one of the through holes.

Hereinafter, the means according to the present invention will be explained in more detail with reference to the following specific examples and drawings.

The metal core printed wiring board (IO) according to the present invention is as follows.

As shown in FIGS. 1 and 2, a metal substrate (11) having a large number of holes (12) arranged with a regularity of predetermined pitch intervals and a large number of holes (12) are selected. an electrically insulating material (13) filled in the hole (12) filled with the electrically insulating material (13); and a through hole (15) formed approximately at the center of a selected one of the holes filled with the electrically insulating material (13). ,
Electrical insulation layer (14) covering the surface of the metal substrate (11)
The surface of this electrically insulating layer (10) and the through hole (1
The conductor circuit (1) is inserted into the selected through hole (15) of the
8) must be formed.

In the present invention, it is not necessary to fill all of the holes (12) provided in the metal substrate (11) with the electrically insulating material (13). It can be used for fixing to the processing machine or the equipment itself, or to fixing other parts to the metal core printed wiring board (10), in particular through holes ( 1
5) can be advantageously used as a reference hole to be aligned with a bottle to form.

Recently, in this type of printed wiring board, wiring circuits are often designed using computers, and as a result, the positions of through holes and wiring patterns tend to be designed with a certain regularity. is getting stronger. Moreover, this regularity is limited to a reference grid with a certain pitch interval (generally, the IC packages currently in use, that is, electronic components, are mainly 100ml-DIP, so the unit size is 100si1).
In other words, approximately 2.54m+* is the mainstream. ), even if a large number of holes (12) are arranged in advance on the metal substrate (11) with this predetermined pitch regularity, there will be no problem in the design of the conductor circuit (16). This is rarely a problem.

In addition, when designing the conductor circuit (1B), among the large number of holes (12) arranged according to the regularity of predetermined pitch intervals, the holes (12) that are not used as through holes are made of electrically insulating material (13). All you have to do is fill it up. Depending on the presence of unused holes (12),
The strength of the metal core (11) is not impaired;
This is because the hole (12) itself is not so large and above all, the metal core (11) has sufficient strength. Therefore, when forming the hole (12), there is no need to create a special mold for each board with a different wiring circuit, or use an NC multi-axis drilling machine to drill the hole each time. By punching using a general-purpose mold, it can be mass-produced at an extremely low cost.

The material of the metal substrate (11) in the present invention is preferably an aluminum plate, a copper plate, or a steel plate. The reason for this is that the metal core printed wiring board (10) according to the present invention has excellent thermal conductivity, workability, mechanical strength, cost, etc. Among them, aluminum plate is the most suitable material. can be used to advantage.

The large number of holes (12) arranged in the metal substrate (11) in the present invention need to have a regularity of a predetermined pitch interval in order to form through holes. It is preferable that the lines be arranged parallel to at least one direction and having a predetermined pitch interval. For example, the arrangement as shown in (A) to (F) in FIG. It can be distributed. Further, the size of the hole (12) itself can be changed as appropriate. In particular, if most of the holes (12) are arranged in a grid pattern as shown in FIG. 2(A), wiring design can be facilitated and the wiring design can be excellent in versatility. @Metal substrate (l
The pitch interval of the large number of holes (12) provided in l) is as follows:
2,54 ■ wet (
100111) or less, and it is advantageous to make the hole diameter 1.6Iφ or less in order to take advantage of the thermal conductivity and mechanical strength of the metal substrate (11).

In forming the conductive circuit (16) on the metal substrate (11), it is naturally necessary to form an electrically insulating layer (14). The thickness of this electrical insulating layer (14) is preferably 1100p or less, especially 50p or less.
It is preferable that the thickness is less than μm. The reason is that if the thickness of the electrical insulating layer (14) is less than 100 gm, the thermal characteristics of the metal substrate (11) cannot be utilized.
It is best to make it as thin as possible while ensuring electrical insulation.

an electrically insulating material (13) filled in the hole (12);
and an electrically insulating layer (
As the material for 14), any material that has excellent electrical insulation, thermal properties, ability to fill through holes, and adhesion to the metal substrate (11) can be suitably used. In particular, heat-resistant resins are suitable. As the heat-resistant resin mentioned here, which is preferably used as the main body, for example, epoxy resin, heat-resistant epoxy resin, epoxy-modified polyimide resin, polyimide resin, phenol resin, triazine resin, etc. can be advantageously used, and silica , alumina, poron nitride,
Inorganic fillers made of powders such as silicon nitride, beryllia, and glass, or glass fibers can be contained in the heat-resistant resin.

The conductor circuit (16) can be formed using a printed wiring board or a hybrid ICf1. Various methods commonly used for wire plates can be used, such as plating, metal foil adhesion, resin conductor paste, vapor deposition, thick film conductor paste, and combinations thereof. . In particular, with regard to plating methods, the conventionally used thick film conductors have high sheet resistance, high Takaoka wave transmission loss, low fine line properties and difficulty in increasing density, and cautions regarding migration. This plating method can be advantageously used because it can solve various problems such as the need for Note that, as this plating method, a tenting method, a panel pattern mixing method, a full additive method, a semi-additive plating method, etc. can be used, and a multi-wire method, etc. can be used as a method for forming a conductor circuit.

Next, a method for manufacturing a metal core printed wiring board (10) according to the present invention will be explained based on FIG.

■ to ■ in Fig. 3 represent the process (process dispute) of arranging a large number of holes (12) in the metal substrate (11) shown in Fig. 1 with regularity at a predetermined spacing of 2,000 peas. a step (step ■) of filling a hole (12) selected from among a large number of holes (12) arranged in the hole (12) with an electrically insulating material (13);
Step (2) of coating the surface of the metal substrate (11) with an electrically insulating material (14) to form an electrically insulating layer! Step (Step ■) of forming a through hole (15) approximately in the center of a selected hole among the holes (12) filled with the gas insulating material (13);
, and the surface of the electrically insulating layer (14) and the through hole (15)
Conductor circuit (16) in selected through hole (15) of
FIG. 3 is a process explanatory diagram of the manufacturing method according to the present invention, including a step of forming (step ①).

■ in Fig. 3 is the part of the metal base &(II) in which a large number of holes (12) are arranged with a regularity of 1-interval.
The manufacturing method of (10) will be explained based on FIG.

■ to ■ in FIG. 3 are steps (step ■) of arranging a large number of holes (12) in the metal substrate (11) shown in FIG. A step (step @) of filling a hole (12) selected from a large number of holes (12) with an electrically insulating material (13), filling the surface of the metal substrate (11) with an electrically insulating material (14) Step (step (S)) of forming an electrically insulating layer by coating the electrically insulating material (13), forming a through hole (15) approximately in the center of a selected hole (12) filled with the electrically insulating material (13). Process (process ■),
and a step of the manufacturing method according to the present invention, which includes a step (step ①) of forming a conductor circuit (16) on the surface of the electrically insulating layer (14) and in a selected one of the through holes (15). It is an explanatory diagram.

FIG. To manufacture this metal substrate (11),
A mold having a large number of perforated bottles and holes arranged at regular intervals of a predetermined pitch is used, and the metal substrate (11) is formed by punching a metal plate using this mold. Of course, the arrangement of the above-mentioned perforated bottles may be as shown in FIG.
Preferably, the arrangement is based on regularity using 54 ugliness 5 (lol] eil) as a reference unit.

■ in Figure 3 shows that selected holes among the many drilled holes (12) are filled and solidified with an electrically insulating material (13), and then the surface of the metal substrate (11) is polished to make it smooth. FIG. As a method of filling only selected holes (12) with this electrically insulating material (13), for example, a mask such as a screen, a metal mask, or a photosensitive dry film is used to provide electrical insulation only in predetermined holes (12). Examples of methods include press-filling the material (13) with a squeegee or the like, or using an automatic hole-filling machine using a bottle or a direct drawing device for thick films.

Note that the holes (12) that are not filled with the electrically insulating material (13) are as follows:
For example, it can be used particularly advantageously as a hole for inserting a guide pin for positioning, so that the position of the metal core can be easily determined from the side cross section, as shown in Japanese Unexamined Patent Publication No. 55-39673 mentioned above. There is no need to be able to predict it, and the hole into which the guide bottle is inserted must be a guard hole (
This is because the diameters of the hole (12) and the hole for the guide bin may be different, which may be performed by separately forming the hole (12) after forming the hole (12).

In addition, when filling all the holes (12) with the filling insulating material (13), in addition to the above-mentioned method, for example, directly press-fitting with a squeegee without using a mask, or using a roller-type hole-filling machine. You can also use In addition, electrical insulating materials (
In order to improve the adhesion of 13) to the metal substrate (11), it is preferable to chemically or physically roughen the inner surface of the hole, for example, anodizing or chemical oxidation treatment for an aluminum plate, and blackening for a copper plate. For steel plate treatment, it is advantageous to perform a par force rising treatment or the like.

■ in Figure 3 is a cross section of a metal substrate (11) in which one selected hole (12) is filled with an electrically insulating material, and the surface of the metal substrate (11) is coated with an electrically insulating material to form an electrically insulating layer (14). It is a diagram. Examples of methods for coating the surface of the metal substrate (11) with an electrically insulating material to form the electrically insulating layer (14) include roller coating, dip coating, spray coating, spinner coating, and screen printing. The electrical insulating layer (14) is formed by coating and drying. In addition, in the coating process of this electrically insulating layer (14), the surface of the metal substrate (11) has already been roughened when filling with the electrically insulating material (13), or the surface of the metal substrate (11) has not been roughened. By carrying out the treatment, the coated electrically insulating material (14) is reliably held in close contact with the metal core (11) and will not easily peel off later.

・■ in Figure 3 is a through hole (+5) formed in the center of the mulberry tree of the selected one of the electrical insulating materials 4 (+3) filled in the 5 holes (12) (-7). The through hole (15) can be formed, for example, by drilling with a drill, or by exposure and development using a photosensitive heat-resistant resin as an electrically insulating material. etc., and the most practical method is to use a knife pin to align the hole and then use an NC multi-axis drilling machine to drill the hole.In this way, However, since the electrically insulating material (13) is mainly made of, for example, a #thermal resin and has superior drilling properties compared to the metal substrate (11), there is no problem.

(+2) to ■ in FIG. 3 are cross-sectional views showing the process of forming the conductive circuit (16) on the surface of the electrically insulating layer (14) and the selected through hole (15). In this case, an electrically insulating layer (14) formed on the surface of a metal substrate (11) is used.
) is roughened, and then a conductor circuit (16) is formed. When forming this conductor circuit (16), for example, panel plating is applied to the surface of the electrical insulating layer (14) using a non-reducible steel plate, and then one-touching is performed using a tenty-knob method using a photosensitive dry film. It will be done. This method has a low sheet resistance and is easy to obtain high conductor adhesion strength, so metal core printed wiring boards (10
) is particularly advantageous as a method for forming the conductor circuit (16). In addition, when forming the conductor circuit (16) by electroless plating or by electrolytic plating after electroless plating, for example, in order to improve the i antecedent between electroless plating and 15 insulating layer (14), Either the surface of the electrical insulating layer (14) is roughened directly by a physical or chemical method, or the surface of the electrical insulating layer (14) is coated with various conventionally known adhesives for electroless plating and then chemically roughened. It is preferable to roughen the surface by mechanically kneeling and etching it. Of course, it is also possible to simply apply a copper foil to the surface of the electrical insulating layer (14) and then perform an etching process.
This process can be performed.

In particular, when applying the present invention, a mixture of heat-resistant resin and silica fine powder is used as the adhesive for electroless plating, and the metal substrate (11), the electrically insulating layer (14), or each through hole (15) is used as the adhesive for electroless plating. ) after applying it to the inner surface of
Roughening the surface of the adhesive for electroless plating by exposing fine silica powder and removing it by dissolving it with hydrofluoric acid can particularly improve the adhesion with electroless plating. It is suitable because it has excellent heat resistance and electrical reliability.

In the present invention, instead of the full additive method using electroless plating or the semi-additive method for forming the conductor circuit [16], the conductor circuit is formed by a method of bonding copper foil and then performing a normal printing process. (
16) can also be formed. As the adhesive in this case, an adhesive sheet made of semi-cured #thermal resin, a prepreg made of glass cloth impregnated with heat-resistant resin, etc. can be used, or a liquid adhesive can also be used.

In explaining the manufacturing method above, the steps (17) to (17) do not necessarily have to be performed in this numerical order. In addition, after performing steps ① and ① at the same time, a conductor circuit (1G) is immediately formed on the surface, and after forming the necessary through hole (+5), a conductor circuit (18) is formed only therein. Furthermore, step (■) may be performed after -I-step (■),
Steps (1) and (2) may be performed at the same time. In short, all that is required is to finally form the metal core printed circuit board (10) as shown in FIG. It can be changed as necessary.

・Incidentally, for example, an overcoat material may be printed on the metal core printed wiring board (10) formed in this way,
It can be used to form printed resistors or plated resistors, or to perform cutting processes. Further, the metal core printed wiring board (10) according to the present invention can be multilayered by printing a thick film paste or resin paste, or multilayered by, for example, a polyimide insulating film and plated wiring.

Next, the present invention will be explained by examples.

Example (Example) A metal core printed wiring board was manufactured by the following steps (1) to (5).

(1) External dimensions 250 x 25hm, thickness 1.0
am(7) 7)L/ By punching out the miniram board using a standardized general-purpose die, it is cut into a 1.2m grid pattern with a pitch interval of 2.54cm layers as shown in Figure 2 (A).
An aluminum plate with holes of s+φ was prepared.

(2) Heat-resistant epoxy resin (manufactured by Mitsui Petrochemical Industries, TA-
1850) An electrical insulating material in which 300 parts by weight of silane-coupled α-alumina fine powder (manufactured by Sumitomo Aluminum Refining Co., Ltd.) with a particle size of 1 to 5 μm is uniformly dispersed in 100 parts by weight of solid content is screen printed using a metal mask. Fill all the holes except for the reference holes for the guide pins provided around the aluminum base with a machine, and dry at 180℃ for 20 minutes in a hot air dryer.
After heat curing for a minute, excess electrical insulating material protruding from the holes of the aluminum substrate was polished off to smooth the surface of the aluminum substrate.

(3) After roughening the surface of this aluminum substrate by anodic oxidation using phosphoric acid, the electrical insulating material is
After immersing it in a solution containing a solvent containing
Dry at 20° C. for 20 minutes to apply a dip coat, and furthermore, 80 parts by weight of silane-coupled fine silica powder having a particle size of 1 to 3 g to 3 m is uniformly mixed on the surface of 100 parts by weight of the solid content of the heat-resistant epoxy resin. The adhesive for electroless plating prepared above was applied using a roller coater and cured by heating at 180° C. for 2 hours to form an electrically insulating layer with a thickness of about 25 μLm.

(4) After lightly polishing the surface of the adhesive layer for electroless plating covering the aluminum substrate, 11 ships 25%
The surface of the adhesive layer was roughened by immersion in an aqueous solution of hydrofluoric acid for 2 minutes, and then an NG multi-axis drilling machine (!'I
Manufactured by XCELLON AUTOMATION, MARK
After aligning the holes with the reference hole for the guide pin using a VDRILLER, a through hole with a diameter of 0.8 dia. was formed approximately at the center of a predetermined hole among the holes filled with electrically insulating material. .

(5) Palladium catalyst (S) on the surface of the aluminum substrate with through holes formed Cataposit 44 made by IIPLEY
), and plated the panel with a plating thickness of 18Bm using an electroless steel plating solution with the composition shown below.
1 Formalin (37%) 0.3 mol/NaOH 0.35 mol/liter EDT A O, 12 mol/1 Additive Small value Plating temperature near 0-72°C PH: 12. 4 Then a photosensitive dry film (E, 1.Dup.

nt, l, Liston 1015) as an etching resist, the pattern is etched with a cupric chloride etching solution, and the resist is removed with methylene chloride by a tending method to remove the surface of the electrical insulating layer and the through holes. A conductor circuit was formed in a predetermined through hole.

The double-sided through-hole metal core printed wiring board manufactured as described above has a high-density fine pattern with a minimum conductor line width of 11001 L, and a temperature rise of 2.8 in a heat dissipation test with a power transistor mounted. ℃/W, indicating excellent heat dissipation.

(Effects of the Invention) As detailed above, in the present invention, as exemplified in the above embodiment, a metal substrate having a large number of holes (12) arranged with a regularity of predetermined pitch intervals is provided. (11), an electrically insulating material (13) filled in the selected hole (12) of the reply (12), and this electrically insulating material (13);
3) a through hole (15) formed in a selected part of the filled hole, an electrically insulating layer (14) covering the metal substrate (11), and a surface of this electrically insulating layer (14). The feature lies in that a conductor circuit (16) is formed in the selected through hole (15).

As a result, this metal core printed wiring board (10) has excellent versatility, and its manufacturing cost can be relatively reduced. In other words, in this type of printed wiring board, a computer is used to create a regular circuit design. A desired metal core printed wiring board can be easily manufactured by appropriately selecting and using the provided holes (12).Furthermore, whether or not the holes (12) are filled with the filling insulating material (13) is determined by the following: The conductor circuit (16
) It is no longer necessary to use an NC drilling machine to drill holes in a metal plate or to create a special mold for each different board.
Since the holes can be easily punched using a standardized general-purpose mold, manufacturing costs can be reduced. In addition, the metal core printed wiring board (10) according to the present invention can be used in the conductor circuit (1B) required by the orderer by keeping the metal core (11) with the hole (12) formed in stock. Since we can respond immediately, we can deliver the required metal core printed wiring board (10) to the customer in an extremely short delivery time.

Furthermore, according to the metal core printed wiring board according to the present invention, the surface of the metal substrate is simply coated without embedding the metal substrate in a resin. It has excellent dissipation properties, and the holes arranged in the metal substrate and the spacing between them can be made small.Not only is it suitable for high-density wiring, but it is also suitable for the thermal conductivity and mechanical strength of the metal substrate. It is possible to effectively utilize the characteristics of

[Brief explanation of drawings]

Fig. 1 is a partial longitudinal sectional view of the metal core printed wiring board according to 1 of the present invention, Fig. 2 is a t-side view illustrating the arrangement of holes T) drilled in the metal core, and Fig. 3 is a partial longitudinal sectional view of the metal core printed wiring board according to 1 of the present invention. FIG. 3 is a partial cross-sectional view for explaining the steps according to the method of the invention. Wait 1 explanation! 0...Metal! 'P・l, 1. Wiring board, 11.
...metal core, 1J hole, l: (...'π faint W, t
lL 1<...electrical insulating layer, i5-.Yl'J41.
1t3-jS body i'il'18-Fig.
No. o00o00000 1] 14 Figure 3

Claims (1)

[Scope of Claims] 1) A printed wiring board having a core made of a metal substrate having a large number of holes arranged with regularity at predetermined pitch intervals, the hole being selected from the large number of holes. an electrically insulating material filled in the metal substrate, a through hole formed approximately at the center of a selected hole filled with the electrically insulating material, and an electrically insulating layer covering the surface of the metal substrate. A metal core printed wiring board comprising: a conductor circuit formed on the surface of the electrically insulating layer and in selected through holes of the through holes. 2) The metal core printed wiring board according to claim 1, wherein the plurality of holes are provided by punching the metal substrate using a mold. 3) Most of the holes among the large number of holes are arranged in a grid pattern.
The metal core printed wiring board according to any of paragraphs. 4) The metal core printed wiring according to any one of claims 1 to 3, wherein the plurality of holes provided in the metal substrate have a pitch interval of 2.54 mm or less. Board. 5) The material of the metal substrate is an aluminum plate, a copper plate,
The metal core printed wiring board according to claims 1 to 4, which is either a steel plate or a steel plate. 6) The metal core printed wiring board according to any one of claims 1 to 5, wherein the electrically insulating material and the material of the electrically insulating layer are mainly made of a heat-resistant resin. 7) The metal core printed wiring board according to any one of claims 1 to 6, wherein the electrical insulating layer has a thickness of 100 μm or less. 8) The metal core printed wiring board according to any one of claims 1 to 7, wherein the conductor circuit is formed by a plating method. 9) A method for manufacturing a metal core printed wiring board, including each of the following steps (a) to (e). (a) Step of arranging a large number of holes with regularity at a predetermined pitch interval on a metal substrate: (b) Electrical conduction inside selected holes among the large number of holes arranged in step (a) above. Step of filling with an insulating material: (c) Step of coating the surface of the metal substrate with an electrically insulating material to form an electrically insulating layer; (d) Hole filled with the electrically insulating material in the step of (b) above. (e) forming a conductor circuit on the surface of the electrical insulating layer and in the selected one of the through holes; 10) The method of manufacturing a metal core printed wiring board according to claim 9, wherein the large number of holes are provided by punching the metal substrate using a mold. 11) Most of the holes among the large number of holes are arranged in a grid pattern.
A method for manufacturing a metal core printed wiring board according to item 0. 12) When forming a large number of holes in the metal substrate,
The method for manufacturing a metal core printed wiring board according to any one of claims 9 to 11, characterized in that the pitch interval is set to 2.54 mm or less. 13) The metal core printed wiring according to any one of claims 9 to 12, wherein the material of the metal substrate is an aluminum plate, a copper plate, or a steel plate. Method of manufacturing the board. 14), the electrically insulating material and the material of the electrically insulating layer are:
14. The method for manufacturing a metal core printed wiring board according to any one of claims 9 to 13, characterized in that a heat-resistant resin is mainly used. 15) The thickness of the electrical insulating layer is 100 μm or less.
15. The method for manufacturing a metal core printed wiring board according to any one of Item 14. 16) The method for manufacturing a metal core printed wiring board according to any one of claims 9 to 15, wherein the conductor circuit is formed by a plating method.