JPH0766953B2 - Semiconductor mounting board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor mounting substrate having conductor pins fixed as input / output pins for external connection.

(Prior Art) In a conventional semiconductor mounting substrate, a conductor pin having a supporting portion having a diameter larger than the inner diameter thereof is generally press-fitted into a through hole for external connection. According to this method
There is an advantage that the conductor pin can be fixed very easily at a short interval, but in such a method, the conductor pin is fixed by using only the difference between the inner diameter of the through hole and the diameter of the support portion of the conductor pin. Therefore, the holding force of the conductor pin is not sufficient, and furthermore, the holding force of the conductor pin varies greatly due to the variation of the inner diameter of the through hole. Therefore, when a large external force is applied in the semiconductor mounting process, there is a problem that the conductor pin may fall out or bend. Moreover, the inner wall surface of the through hole is
Since the metal plating is applied, it is inevitable that the thickness of the plating has a certain value or more, and it is difficult to suppress the variation in the inner diameter of the through hole.

Another disadvantage is that the electrical connection reliability between the conductor pins and the conductor circuit on the semiconductor mounting board cannot be said to be perfect just by mechanically fixing the conductor pins and through holes, and this type of failure is detected. In addition, there is a problem that the electrical check of each semiconductor mounting board must be performed.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and the problems to be solved are that the holding force of the conductor pin is not sufficient and that the holding force varies. Is large, and the electrical connection reliability between the conductor pin and the conductor circuit on the semiconductor mounting substrate is not perfect.

The object of the present invention is to have a high thermal conductivity, the conductor pins are firmly fixed at short intervals, and further, the electrical connection reliability between the conductor pins and the conductor circuit on the semiconductor mounting substrate can be improved. It is to provide a high semiconductor mounting substrate.

(Means for Solving Problems and Actions Thereof) Means adopted by the present invention for solving the above problems will be described with reference to FIGS. 1 to 6 corresponding to the embodiments. (1), a through hole (4) formed in the substrate (1) and having a cross-sectional corner portion of a substantially right angle, and a conductor pin (6) fixed to the through hole (4) by a supporting portion (7). A semiconductor mounting substrate (11) comprising: a flange (8) near the support (7) of the conductor pin (6).
Has a portion larger than the inner diameter of the through hole (4) and a portion smaller than the inner diameter of the through hole (4), and is formed on the outer surface of the support portion (7) on the smaller diameter side of the collar portion (8). A semiconductor mounting substrate (11) characterized in that a groove-shaped recess (10) communicating with 8) is formed, and the conductor pin (6) is fixed to the through hole (4) with solder (9). ) ”.

The semiconductor mounting substrate (11) according to the present invention will be described below in detail with reference to the drawings. In addition, as the substrate (1),
The description will be given based on an example in which the metal substrate (1) is applied, but the present invention is not limited to the metal substrate (1).

Reference numeral (1) in FIGS. 1, 2 and 3 indicates a metal substrate which is a main material portion of the semiconductor mounting substrate (11) of the present invention. When deciding the material of this metal substrate (1), it is necessary to comprehensively consider various characteristics such as dimensional stability, thermal conductivity, specific gravity, and mechanical strength. As a typical example, aluminum,
There are copper, iron or alloys of these. The thickness of this metal substrate (1) must be selected within the range of 0.5 to 3.0 mm, as long as it has sufficient mechanical strength and does not conflict with the tendency of electronic devices to be smaller and lighter. Preferably there is.

Reference numeral (2) in FIGS. 2 and 3 is a metal substrate (1)
The through hole formed in advance is shown in FIG. 1, and the through hole (4) is formed by providing the insulating layer (3) on the inner wall surface.
Are formed. As a material for the insulating layer (3),
It is suitable to use a thermosetting resin from the viewpoints of electric insulation, heat resistance, chemical resistance at the time of forming a circuit, and typical examples thereof include heat resistant epoxy resin and polyimide resin. Further, an inorganic filler or an inorganic cloth may be mixed in the thermosetting resin for the purpose of improving thermal conductivity, conductor adhesion and the like. Examples of inorganic fillers are α-alumina, fused silica, aluminum nitride, while examples of inorganic cloth are glass cloth.
Further, the mixing ratio of the inorganic filler is preferably large in order to improve the thermal conductivity, while it is preferably small in order to improve the surface smoothness and toughness of the insulating layer (3), and in order to satisfy both of them. The amount is preferably 0 to 300 parts by weight, more preferably 50 to 250 parts by weight, based on 100 parts by weight of the resin solid content. The thickness of the insulating layer (3) is preferably in the range of 50 to 500 μm in order to satisfy both the insulating property and the heat dissipation property, and the entire surface of the metal substrate (1) is covered with the insulating layer (3). In some cases, only one side or a desired part of the metal substrate (1) may be coated in order to have a heat dissipation effect.

The through hole (4) is, of course, intended to electrically connect the conductor circuits (5) on the front and back sides of the board, like the ordinary electric circuit board of this type. It is also intended to securely fix a conductor pin (6) described later to 4), and at that time, the conductor pin (6) and the conductor circuit (5) are electrically connected. Of course. The smaller the hole diameter of the through hole (4), the higher the wiring density. However, if it is extremely small, the processing becomes difficult.
It is preferably in the range of 300%.

Furthermore, since it is necessary to fix the conductor pin (6) to the through hole (4), the finished diameter of the through hole (4), that is, the inner diameter, is a support portion (which constitutes a part of the conductor pin (6) ( It is necessary to be within 50 to 99% of the maximum outer diameter of 7). The reason is that when the inner diameter of the through hole (4) is less than 50% of the outer diameter of the support portion (7) of the conductor pin (6), the support portion (7) is fitted and fixed to the through hole (4). Not only is it difficult to perform, but even if fitting and fixing are possible, the through hole (4) will crack and become useless as a substrate, while the through hole (4) has an inner diameter of more than 99%. The support portion (7) of the conductor pin (6) with respect to the through hole (4)
It is difficult to fit and fix the conductor pin (6), and the conductor pin (6) easily falls off.

And this through hole (4) is the above-mentioned insulating layer (3).
Is formed substantially at the center, and the corners of the cross section are formed at a substantially right angle. The section corner of the through hole (4) is
As shown in FIGS. 2 and 3, the through hole (4)
In the cross-section that appears when the portion corresponding to (3) is cut vertically, it means the corners formed at the upper and lower ends of the insulating layer (3) or the conductor layer (5). In order to make the cross-sectional corners of the through hole (4) substantially right angles, the following method is usually used.

That is, first, a through hole (2) is formed in a metal substrate (1), an insulating material is embedded in the through hole (2), and an adhesive insulating layer (3a) is provided on a necessary surface of the metal substrate (1). A copper foil (not shown) is laminated and integrated via the above. After the insulating material is completely cured, a hole in a direction substantially perpendicular to the metal substrate (1) is formed in the through hole (2) at substantially the center of the insulating material. According to this method, the corners of the cross section of the insulating layer (3) are already substantially right angles, and therefore the corners of the cross section of the conductor layer (5) formed by plating and etching are also substantially right angles. The reason why the insulating layer (3a) is formed so that the cross-sectional corners thereof are substantially right angles is that when the conductor pin (6) is fitted and fixed in the through hole (4), the conductor pin (6) is This is to make it substantially perpendicular to the metal substrate (1). This is because high-density mounting becomes impossible unless the conductor pins (6) are substantially perpendicular to the metal substrate (1).

Reference numeral (6) in FIG. 1, FIG. 2, FIG. 3, FIG. 5, and FIG. 6 indicates a conductor pin. This conductor pin (6)
Is a conductor circuit (5 on the semiconductor mounting substrate (11) of the present invention.
a) is used to provide electrical connection with the outside, and also serves as a mechanical reinforcement when fixing the semiconductor mounting board (11) to a printed wiring board (not shown) by soldering. It will be achieved. In order to achieve each of the above purposes of use, the material of the conductor pin (6) must have low electrical resistance, sufficient mechanical strength, and good solderability. For this reason, it is preferable to use an Fe-Ni-based alloy, an Fe-Ni-Co-based alloy, a copper-based alloy, or the like as a main material, the surface of which is appropriately plated with solder or nickel-gold. The outer dimensions of the conductor pins (6) are preferably thin and short in order to increase the mounting density, while workability when fitting and fixing the conductor pins to the semiconductor mounting board (11) and the semiconductor mounting board. Considering the state of the art when mounting (11) on a printed wiring board, extremely thin and short ones are not practical. Therefore, it is preferable to use the conductor pin (6) having a length of 3 to 10 mm and a thickness of 0.3 to 1.0 mm.

Reference numeral (7) in FIGS. 2, 3, 5, and 6
Indicates a support portion forming a part of the conductor pin (6). As described above, the support portion (7) is a portion necessary for fixing the conductor pin (6) to the through hole (4) and, at the same time, has a shape in which the through hole (4) is easily filled with solder. Something is also needed. Therefore, as in the case of the collar portion (8) described later, the diameter of the support portion (7) needs to have a larger portion and a smaller portion than the inner diameter of the through hole (4). As a typical example, there is a flat shape as shown in FIG. 2, FIG. 3, FIG. 5 and FIG. A groove-shaped recess (10) communicating with the flange (8) is formed on the outer surface of the support (7) on the smaller diameter side of the flange (8). In the conductor pin (6) of this shape, the recess (10) and the through hole (4)
Since the solder (9) is more smoothly filled in the through hole (4) through the gap between and, the conductor pin (6) is firmly fixed to the through hole (4), and further, the support portion (7). ) And the solder (9) have a large contact area, there is an advantage that the connection reliability between the conductor pin (6) and the through hole (4) is improved.

Reference numeral (8) in FIGS. 2 to 6 indicates a flange portion of the conductor pin (8). It is necessary that the diameter of the collar portion (8) has a portion that is larger than the inner diameter of the through hole (4) into which the conductor pin (6) is fitted and fixed, and a portion that is smaller than that. The reason is that, when the conductor pin (6) is fitted and fixed in the through hole (4), a portion larger than the inner diameter of the through hole (4) serves as a stopper, and the conductor pin (6) becomes a through hole (4). 4) It is prevented from being inserted more than necessary depth into the inside, and at the same time, when the conductor pin (6) and the through hole (4) are fixed by the solder (9) described later, the through hole (4) Since the portion smaller than the inner diameter of the solder plays the role of a through hole to facilitate the penetration of the solder (9) into the through hole (4), the conductor pin (6) is securely fixed to the through hole (4). This is because that. In order to achieve the above object, it is preferable that the diameter of the flange portion (8) is larger than the inner diameter of the through hole (4) by 50 to 300% larger than the inner diameter of the through hole (4). The reason is that if it is less than 50%, the flange portion (8) is not able to withstand the pressure when inserting the conductor pin (6) into the through hole (4) and is easily damaged. This is because it is impossible to arrange the pins (6) in high density. If the diameter is smaller than the inner diameter of the through hole (4), it is 5 to the inner diameter of the through hole (4).
It is preferably 50% smaller. The reason is that if it is less than 5%, it becomes difficult for the solder (9) to penetrate into the through hole (4), and if it exceeds 50%, the mechanical strength of the conductor pin (6) itself becomes insufficient. Is. Further, the thickness of the collar portion (8) needs to be determined within a range where sufficient mechanical strength is obtained and does not impair the miniaturization of the semiconductor mounting substrate, and a range of 0.2 to 2 mm is preferable.

Reference numeral (9) in FIGS. 2 and 3 indicates solder. After the conductor pin (6) is fitted and fixed to the through hole (4), the solder (9) passes through the gap between the support portion (7) of the conductor pin (6) and the through hole (4) and the through hole (4). Filled inside, the conductor pin (6)
The purpose is to strengthen the fixation to the through hole (4). If the solder is completely filled in the through hole (4), the adhesive force of the conductor pin can be used only by utilizing the difference between the inner diameter of the through hole (4) and the diameter of the support portion (7) of the conductor pin (6). As compared with the case where the fixing of (6) is performed, not only the fixing is stronger, but also the variation of the diameter of the supporting portion (7) and the variation of the plating thickness of the inner surface of the through hole (4) cause the through hole ( Since it is hardly affected by the variation in the inner diameter of 4), a uniform holding force can be obtained. Therefore, in the step of mounting the semiconductor on the semiconductor mounting board (10) of the present invention, some external force (for example, a jig for mounting the semiconductor and the conductor pin (6) is contacted, or the semiconductor mounting board is erroneously mounted. Even when an external force of a kind such as dropping onto the floor is applied, the problem that the conductor pin (6) falls off or bends does not occur. The filling of the solder (9) into the through hole (4) is performed by dipping the substrate in a molten solder bath, jetting through the jet solder bath, and melting the printed solder paste or solder ring. It is performed using a method such as the reflow method.

As the material of the conductor circuit (5a) formed on the surface of the semiconductor mounting substrate (11) shown in FIG. 1, it is necessary to select a metal that has low conduction resistance and is easy to form a circuit. Copper is a typical example. The conductor circuit (5a) made of copper may be plated with solder, nickel, gold or the like on its surface in order to prevent corrosion, improve solderability, or improve bondability.
The thickness of the conductor circuit (5a) is preferably thick in order to reduce the conduction resistance, while it is preferably thin in order to increase the wiring density of the circuit, and preferably in the range of 5 to 70 μm to satisfy both. . The width of the conductor circuit (5a) is preferably in the range of 30 to 500 μm for the same reason.

Next, examples of the semiconductor mounting substrate (11) according to the present invention will be described.

(Example) -Example A semiconductor mounting substrate (1 shown in FIG. 1, FIG. 2 and FIG. 3
1) was manufactured as follows.

As shown in FIGS. 5 and 6 as the conductor pin (6), the outer surface of the support portion (7), which is on the smaller diameter side of the collar portion (8), communicates with the collar portion (8). The one having a groove-shaped recess (10) was used.

For the metal substrate (1), aluminum having a thickness of 1.0 mm and a size of 25 × 25 mm is used, and a plurality of through holes (2) formed therein has a diameter of 1.5 mm. The thickness of the adhesive insulating layer (3a) formed on the front and back surfaces of the metal substrate (1) of the semiconductor mounting substrate (11) is 50 μm, and the insulating layer (3) formed on the inner wall surface of the through hole (2). The thickness of) is 450 μm. This insulating layer (3) is mainly composed of a heat-resistant epoxy resin, in which 150 parts by weight of α-alumina powder having an average particle diameter of 5 μm is mixed with 100 parts by weight of the resin solid content. . Then, a conductor layer (5) having a thickness of 30 μm is formed on the surface of the insulating layer (3) in the through hole (2).

Furthermore, the conductor pin (6) is a copper-based alloy plated with solder, and its length is 5 mm below the collar (8).
It is 0.46 mm and the maximum outer diameter of its support (7) is 0.57 mm. Then, solder is filled in the gap between the through hole (4) and the support portion (7) and the vicinity of the collar portion (8) by the dipping method. On the other hand, the conductor circuit (5a) formed on the surface of the semiconductor mounting substrate (11) has a copper conductor surface having a thickness of 40 μm plated with nickel having a thickness of 8 μm, and further has a gold plating layer having a thickness of 0.5 μm. It has been given.

Comparative Example 1 A semiconductor mounting substrate was manufactured in the same manner as in the example except that the flange portion (28) had a circular flat plate shape as shown in FIGS. 7 and 8 as the conductor pin (26). did.

Comparative Example 2 As shown in FIG. 7 and FIG. 8 as the conductor pin (26), the flange portion (28) has a circular flat plate shape, and the inside of the through hole (24) and the flange portion (28) are used at the same time. ) A semiconductor mounting substrate was manufactured in the same manner as in Example 1 except that solder was not provided in the vicinity.

Comparative Example 3 A semiconductor mounting substrate was manufactured in the same manner as in the example except that a conductor pin having no groove was used as the conductor pin.

The tensile strength (holding force) in the vertical direction of the conductor pins (6) and (26) of the semiconductor mounting boards (11) and (21) and the conductor pins (6), () obtained in the above Examples and Comparative Examples. The following table shows the results of measuring the electrical connection reliability between the (26) and the conductor circuits (5a) and (25a).

(Effects of the Invention) As described in detail above, in the present invention, the diameter of the collar portion (8) near the support portion (7) of the conductor pin (6) in the present invention is The through hole (4) has a portion larger than the inner diameter and a portion smaller than the inner diameter, and the conductor pin (6) is fixed to the through hole (4) with solder (9); and a supporting portion (7). Is characterized in that a groove-shaped recess (10) communicating with the flange (8) is formed on the outer surface of the flange (8) on the smaller diameter side.
As a result, a semiconductor mounting substrate (1
The conductor pin (6) is firmly fixed to the through hole (4) without impairing the high thermal conductivity of 1), and even if the thickness of the through hole plating varies, the conductor pin (6) A semiconductor mounting board (11) having a small variation in holding force and a highly reliable electrical connection between the conductor pin (6) and the conductor circuit (5a) on the semiconductor mounting board (11) is formed by a simple structure. Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a semiconductor mounting substrate according to the present invention, FIGS. 2 and 3 are vertical sectional views of a conductor pin fixing portion, and FIG. 4 is a bottom view of the same. 5 and 6 are a front view and a side view of the conductor pin according to the embodiment, and FIGS. 7 and 8 are a front view and a side view of the conductor pin according to Comparative Examples 1 and 2. DESCRIPTION OF SYMBOLS 1 ... Metal substrate, 2 ... Through hole, 3 ... Insulating layer, 3a ... Adhesive insulating layer, 4 ... Through hole, 5 ... Conductor layer, 5a ... Conductor circuit, 6
... conductor pins, 7 ... support portion, 8 ... collar portion, 9 ... solder, 10 ... recessed portion, 11 ... semiconductor mounting substrate.

Claims (1)

[Claims] 1. A semiconductor mounting substrate comprising a substrate, a through hole formed in the substrate and having a cross-sectional corner portion of a substantially right angle, and a conductor pin fixed to the through hole by a supporting portion. The diameter of the collar portion near the support portion of the pin has a portion that is larger than the inner diameter of the through hole and a portion that is smaller than the inner diameter of the through hole, and the outer surface of the support portion on the smaller diameter side of the collar portion A semiconductor mounting substrate, characterized in that a groove-shaped recess communicating with the through hole is formed, and the conductor pin is fixed to the through hole with solder.