JPH0548958B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention uses a metal as a core material, and has a conductor pin that can be used as an input/output pin for external connection, and has the effect of grounding the internal core material and dissipating heat to the outside. The present invention relates to a method of manufacturing a board for mounting electronic components on which heat dissipation pins are fixed.

(Prior technology) A board for mounting electronic components with a metal core, in which the metal surface is insulated and a conductor circuit is formed on the surface, can take advantage of the good thermal conductivity of metal, and has excellent heat dissipation characteristics. ing. Further, since it exhibits sufficient mechanical strength and has excellent dimensional stability, electronic component mounting boards using such metal core materials are widely used.

Conventionally, in the case of electronic component mounting boards using such metal core materials, the metal core has been used to take advantage of the high thermal conductivity of the internal metal core, or to provide functions such as grounding, shielding, and power supply. A method is adopted in which a conductor pin for connection with the outside is directly inserted and fixed into the through hole.

However, in the electronic component mounting board described above, since the metal core is exposed on the wall of the hole that penetrates the metal core for fixing the conductor pin, as shown in FIG. As shown in FIG. 5b, when forming a circuit pattern by etching, there was a problem that the exposed portion of the metal core would melt.
In addition, in addition to the through hole for fixing the conductor pin, the exposed part of the metal core has a reference hole for positioning or an end surface of the board, so the positioning pin is not fixed as shown in Fig. 5c. Therefore, the dimensional accuracy of external processing performed using this positioning pin as a reference may be poor, or
The positional accuracy between the external shape and each conductor pin is poor, or the fifth
As shown in Figure d, defects such as the conductor pins becoming loose or bent occurred. Furthermore, metal leaching in the plating process and etching process contaminates the respective processing solutions. In order to prevent such elution of the metal core, it is necessary to protect the metal core with a dry film resist or the like at each step, which increases enormous effort and manufacturing costs.

Therefore, these days, as shown in Fig. 4, through-holes for fixing conductor pins directly fixed to the metal core and reference holes for positioning are formed after forming the circuit pattern of Fig. 4-c, as shown in Fig. 4-d. A separate hole-drilling process was carried out.

However, according to this method, the through holes for fixing the conductor pins and the reference holes for positioning are formed in a different process from other through holes, so the positional accuracy with respect to other through holes or circuit patterns may be affected. There were problems such as the board becoming distorted, and the dimensional accuracy and positional accuracy of the external processing of the board itself being poor.

(Problems to be solved by the invention) The present invention has been made in view of the above-mentioned circumstances.
The problems to be solved are the problem of the positional accuracy of all through holes and circuit patterns that are processed in a different process from other through holes in electronic component mounting boards that use metal cores, and This is a problem with the dimensional accuracy and positional accuracy of the external shape processing itself.

It is an object of the present invention to have good positional accuracy between through-holes for conductor pins and other through-holes and conductor circuits, and accuracy in the diameter of each hole, as well as dimensional accuracy in the external processing of the board itself. Another object of the present invention is to provide a method of manufacturing a board for mounting electronic components with good positional accuracy.

(Means for Solving the Problems) In order to solve the above problems, the means taken by the present invention are explained with reference to FIGS. 1 to 3 corresponding to the embodiments. A method of manufacturing a board for mounting electronic components, the method comprising:

Step of forming a through hole 2 at a predetermined position of the metal core 1; burying an insulating material in the through hole 2 to form an insulating filling layer 3, and also forming an insulating layer 4 on the flat surface of the metal core 1. . Also, if necessary, simultaneously forming a metal foil 5 on the surface of the insulating layer 4; forming a through hole 6 for a first through hole approximately in the center of the insulating filling layer 3 at a predetermined position other than the insulating filling layer 3; a step of simultaneously forming a second through hole 7 and a reference hole 8 penetrating the metal core 1; metal replacement plating 10 on the exposed portion of the metal core 1;
After applying metal plating 11 to the entire board, a conductor circuit 12 is formed at a predetermined position on the board, and the first through hole 13 and the second through hole 1 are
4 and the step of forming the reference hole 15; the step of inserting the positioning pin 16 into the reference hole 15 and performing external processing using a mold or router; the external connection of the first through hole 13 and the second through hole 14; The step of inserting and fixing the conductor pin 17 into the through hole requires ”.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a substrate for mounting electronic components according to the present invention will be described in detail below with reference to the drawings.

Reference numeral 1 in FIGS. 1, 2 and 3 is
The metal core which forms the main material part of the semiconductor mounting board of this invention is shown. When determining this metal core 1', it is necessary to comprehensively consider various properties such as thermal conductivity, mechanical strength, specific gravity, and dimensional stability. As an example,
It can be aluminum, copper, iron, or an alloy of these. In addition, the thickness of the metal core 1 must be selected within a range that has sufficient mechanical strength and does not conflict with the trend of miniaturization and weight reduction of electronic devices.
It is desirable to be in the range of 0.5 to 3.0 mm.

Reference numeral 2 indicates a through hole formed in advance in the metal core 1, and an insulating filling layer 3 is provided on the inner wall surface of the through hole to insulate the first through hole from the metal core. The material for this insulating filling layer 3 is as follows:
From the viewpoints of electrical insulation, heat resistance, chemical resistance during conductor circuit formation, etc., it is appropriate to use thermosetting resins, and typical examples include heat-resistant epoxy resins and polyimide resins. Furthermore, inorganic fillers or inorganic fibers may be mixed into these thermosetting resins for the purpose of improving thermal conductivity or conductor adhesion strength. Examples of inorganic fillers include α-alumina, fused silica, and aluminum nitride, and examples of inorganic fibers include glass fibers and glass cloth.

The purpose of the first through hole 13 is not only to conduct the conductor circuits 12 on the front and back sides of the board, but also to securely fix a conductor pin 17, which will be described later, to a through hole that requires external connection among the first through holes 13. It's a purpose. The hole diameter of this through hole is 50% of the board thickness considering high density and workability.
It is preferably in the range of ~300%.

Reference numeral 14 denotes a second through hole that penetrates the metal core 1 and is formed simultaneously with the formation of the first through hole. The cross section of the metal core 1 inside this second through hole 14 has a thickness of 0.2 to
A metal replacement plating 10 of 0.6 μm is formed. The types of metals used in this metal substitution plating method include zinc,
Zinc-tin alloy, etc. This metal substitution plating 10 serves as a protective film that prevents the metal core 1 from being eluted due to contact with chemicals during plating and etching in subsequent processes, and maintains the hole diameter accuracy during drilling of the second through hole 14. There is. Further, similarly to the first through hole 13, a conductor pin 17 (described later) is inserted and fixed in the second through hole that requires external connection, and this conductor pin 17 absorbs the heat accumulated in the internal metal core 1. In addition to discharging energy to the outside, it can also be used as a ground, shield, and power source.

Reference numeral 17 indicates a conductor pin. As described above, when this conductor pin is inserted and fixed in the first through hole 13, it provides an electrical connection between the conductor circuit 12 on the electronic component mounting board and the outside, and is inserted into the second through hole 14. When inserted and fixed, it is connected to the conductor circuit 12 on the electronic component mounting board and the metal core 1 inside, and also functions as a conductor for heat radiation to the outside, earth, shield, and power source. The material of the conductor pin 17 must have low electrical resistance, sufficient mechanical strength, good thermal conductivity, and good solderability. As a material satisfying this requirement, it is preferable that the main material is Ni, Fe, Co, Cu, or an alloy thereof, and the surface thereof is subjected to solder plating or nickel-gold plating. The external dimensions of the conductor pin are preferably thin and short when considering high-density mounting, but considering workability and the technical level of mounting, the length should be 3 to 10 mm, and the thickness should be 0.3 to 1.0 mm in diameter. It is preferable to use one in the range of .

Reference numeral 12 indicates a conductor circuit. As the material of the conductor circuit 12, it is necessary to select a metal that has low conduction resistance and is easy to form a circuit, and copper is a typical example. The conductor circuit 12 formed of copper may be plated with solder, nickel, gold, etc. to prevent corrosion, improve solderability, and further improve bonding performance. This conductor circuit 1
The thickness of 2 is preferably in the range of 5 to 70 μm in order to satisfy the other requirements, because on the one hand, it is preferable to be thick in order to reduce the conductor resistance, but in order to form high-density wiring, it is preferable to make it thin. Also, the width of the conductor circuit is 30 to 500 μm for the same reason as above.
is preferred.

Reference numeral 18 indicates solder. This solder 18
is filled in this portion after the conductor pin 17 is inserted into the first through hole 13 and the second through hole 14. The conductor pin 17 is inserted into the first through hole 13 and the second through hole 14.
It is formed in order to firmly fix it inside and to improve the reliability of electrical connection.

In fixing the conductor pins using the solder 18, it is possible to achieve more solid soldering if the entire inner wall of the second through hole 14 is plated with metal.

(Actions of the Invention) By adopting the above measures, the present invention has the following effects.

That is, in the method of manufacturing a board for mounting electronic components according to the present invention, the first through hole 6, the second through hole 7, and the reference hole 8 are formed at the same time. 2. The exposed parts of the metal core 1 of the through-hole 7 for the through-hole and the through-hole 8 for the reference hole are covered with a protective film 1 made of metal substitution plating that does not dissolve in chemical solutions such as plating or etching.
0 is formed, the first through hole 13, the second through hole 14, and the reference hole 15 have good positional accuracy and maintain accuracy in hole diameter.

Therefore, when the positioning pin 16 is inserted into the reference hole 15 and the external shape is processed using a mold, a router, etc., the dimensional accuracy and positional accuracy are also good.

(Example) Example 1 The electronic component mounting board shown in FIG. 1 was manufactured as follows.

For the metal core 1 shown in Figure 1a, an aluminum plate 1 with a thickness of 1.0 mm and a size of 50 x 50 mm is used.
As shown in Figure b, multiple through holes 1 with a diameter of 1.5 mm are
It was formed by etching. After embedding an insulating material in the plurality of through-holes 1 to form an insulating filling layer 3 (FIG. 1c), a prepreg 4 having a thickness of 30 μm and a thickness of 18μm copper foil 5 at 170℃, 1.5hr, 40Kgf/cm ²
It was integrally molded under the following conditions (Fig. 1d). The insulating filling layer 3 is mainly composed of a heat-resistant epoxy resin, and 150 parts by weight of α-alumina powder with an average particle size of 5 μm is mixed into this main material based on 100 parts by weight of the resin solid content. . At the same time, a through hole 6 for a first through hole with a diameter of 0.5 mm is made approximately in the center of the insulating filling layer 3 formed as shown in FIG. 0.5mm
A through hole 7 for a second through hole and a through hole 8 for a reference hole with a diameter of 2.0 mm to be used in subsequent steps were formed by drilling (Fig. 1e). After the portions of the reference hole through hole 8 and the second through hole 7 where the metal cores are exposed and the portions where the metal cores are exposed on the end surface 9 are replaced with zinc (FIG. 1 f ), electroless copper plating is applied to the entire board,
Furthermore, electrolytic copper plating was applied (Fig. 1g). The thickness of copper by electroless copper plating and electrolytic copper plating is
They are 0.5 μm and 20 μm, respectively. After forming resists on the front and back surfaces of the substrate, a conductor circuit 12 was formed on the substrate by exposure, development, and etching using a circuit pattern film (FIG. 1h). Reference hole 1
Insert a positioning pin into 5, process the external shape using a mold or router (Fig. 1i), and then insert a conductor pin 17 into the through hole that requires external connection among the first and second through holes. Insert
It was fixed with solder (Fig. 1j).

Example 2 The electronic component mounting board shown in FIG. 1j was manufactured by the method shown in FIG. FIG. 1c in Example 1
An insulating material was applied to the front and back surfaces of the substrate shown by using a roller coater to form an insulating layer 4 (FIG. 2k). This insulating material is the same as that used for filling holes in Example 1, and has a thickness of 30 to 30 mm.
Formed to 50μm. Similar to the steps e and f in FIG. 1, after the steps l and m in FIG. An electronic component mounting board was formed in the same manner as in Example 1, except that the conductor circuit 12 was formed by applying electroless plating and electrolytic plating to the portion exposed from the resist 19 and peeling off the resist 19.

Example 3 As shown in FIG. 3, a resin-rich prepreg 4 and a copper foil 5 are integrally formed on the front and back surfaces of an aluminum plate 1 (FIG. 1b) having a through hole 2 formed by etching by heating and pressing. By doing so,
An electronic component mounting board was formed by the steps of Example 1 except for the step of extruding and embedding resin into the through hole 2.

(Effects of the Invention) As described above in detail, the method for manufacturing a board for mounting electronic components according to the present invention is characterized by including the following steps, as illustrated in detail in the above embodiments. A method for manufacturing a board for mounting electronic components.

Step of forming a through hole at a predetermined position of the metal core: An insulating material is buried in the through hole to form an insulating filling layer, and an insulating layer is also formed on the flat surface of the metal core. Also, if necessary, simultaneously forming a metal foil on the surface of the insulating layer; forming a through hole for a first through hole approximately in the center of the insulating filling layer, and placing the metal core in a predetermined position other than the insulating filling layer. A step of simultaneously forming a penetrating through hole for a second through hole and a through hole for a reference hole; A step of covering the exposed portion of the metal core with metal replacement plating; After applying metal plating to the entire substrate, A step of forming a conductor circuit at a predetermined position on the top, and also forming a first through hole, a second through hole, and a reference hole; A step of inserting a positioning pin into the reference hole and performing external processing using a mold, a router, etc.; The method is characterized by the step of inserting and fixing a conductor pin into a through hole that requires an external connection among the first through hole and the second through hole.

Therefore, in the method of manufacturing a board for mounting electronic components according to the present invention, the through holes for the first through hole, the through hole for the second through hole, and the through hole for the reference hole are formed at the same time, and the through hole for the second through hole is formed simultaneously. On the exposed parts of the metal cores of the through-holes for holes and the through-holes for reference holes, a protective film is formed by metal substitution plating that does not dissolve in chemical solutions such as plating and etching. In addition, the positional accuracy and hole diameter accuracy of the reference hole, which is important for positioning during board manufacturing and component mounting, are maintained, and when the positioning pin is inserted into the reference hole and the external shape is processed using a mold or router, etc. , its dimensional accuracy and positional accuracy are also improved.

In other words, according to the present invention, the positional accuracy of the through holes for conductor pins and other through holes and conductor circuits and the accuracy of each hole diameter are good, and the dimensional accuracy and positional accuracy of the external processing of the board itself are good. It is possible to provide a method for manufacturing a board for mounting electronic components with good performance.

[Brief explanation of drawings]

FIGS. 1 to 3 are partial cross-sectional views showing a method for manufacturing a board for mounting electronic components according to the present invention, and FIGS. 4 and 5 show a conventional method for manufacturing a board for mounting electronic components in order. FIG. Explanation of symbols, 1...Metal core, 2...Through hole, 3
...Insulating filling layer, 4...Insulating layer such as prepreg,
5... Copper foil, 6... Through hole for first through hole,
7... Through hole for second through hole, 8... Through hole for reference hole, 9... Metal core end surface, 10... Metal coating by metal replacement plating, 11... Metal plating, 1
2... Conductor circuit, 13... First through hole, 1
4...Second through hole, 15...Reference hole, 16
...Positioning pin, 17...Conductor pin, 18...
Handa, 19...Resist.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a board for mounting electronic components, characterized by including the following steps. Step of forming a through hole at a predetermined position of the metal core: An insulating material is buried in the through hole to form an insulating filling layer, and an insulating layer is also formed on the flat surface of the metal core. Also, if necessary, at the same time, forming a metal foil on the surface of the insulating layer; forming a through hole for a first through hole approximately in the center of the insulating filling layer, and forming a metal core in a predetermined position other than the insulating filling layer; a step of simultaneously forming a through hole for a second through hole and a through hole for a reference hole that penetrate through the substrate; a step of covering the exposed portion of the metal core with metal substitution plating; after applying metal plating to the entire substrate, A step of forming a conductor circuit at a predetermined position on the board, as well as forming a first through hole, a second through hole, and a reference hole; A step of inserting a positioning pin into the reference hole and performing external processing using a mold, router, etc. a step of inserting and fixing a conductor pin into a through hole that requires an external connection among the first through hole and the second through hole;