JPH08139240A - Method for mounting semiconductor element - Google Patents

Abstract

PURPOSE: To achieve a method for mounting a semiconductor element where a heat sink can be mounted while maintaining the flatness of the semiconductor element without requiring an exclusive tool or operation when soldering a plurality of semiconductor elements to a circuit substrate and mounting the heat sink. CONSTITUTION: A semiconductor element is mounted on one surface of a flat plate of thermal conductor (Step 1), the electrode lead of the semiconductor element is connected to a circuit substrate which is laid out with a specific space to the thermally conductive flat plate via solder (Step 3), and a heat sink is mounted to the other surface of the thermally conductive flat plate (Step 4).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a semiconductor element on which a heat dissipation plate is attached, and more particularly to improving the flatness of each semiconductor element when a plurality of semiconductor elements are attached to a circuit board.

[0002]

2. Description of the Related Art A heat sink is often attached to a semiconductor element (diode, transistor, FET, etc.) used in an output stage of a power supply device or an amplifier.

A procedure for mounting the semiconductor element in such a case will be described with reference to FIG. Here, L
LMT (LEAD MOUNT TECHN) is a semiconductor device equipped with electrode leads bent in a letter shape (hereinafter simply referred to as leads).
OLOGY: Lead hole insertion mounting technology). Further, here, in order to simplify the description, it is assumed that three semiconductor elements are attached to the circuit board, but the number of semiconductor elements is not limited to this.

The semiconductor elements 21, 22, 23 have leads 21a, 22a, 23a, respectively. Then, these leads are bent to form lead holes (hereinafter, simply referred to as holes) 11b, 12b, 13b of the circuit board 10.
To insert.

When the respective leads are inserted into the holes, the tip portions of the leads 21a, 22a, 23a and the patterns 11a, 12a, 13a are soldered while the semiconductor elements are pressed so as to be flat on the broken line A. To be done. Soldering of such leaded components is generally
It is performed by an automatic soldering device such as soldering.

Finally, each of the semiconductor elements 21 to 23 is attached to the heat dissipation plate 40 by using screws 31 to 33.

[0007]

In the soldering for mounting the semiconductor element as described above, it is extremely important to maintain the flatness of the broken line A in order to attach the heat sink 40. This is because maintaining the flatness improves the contact state between the semiconductor element and the heat dissipation plate 40 and makes the heat dissipation efficiency constant.

However, when mounting a plurality of semiconductor elements, it is extremely difficult to maintain the flatness of the broken line A at the soldering stage. Therefore, it is necessary to hold down a plurality of semiconductor elements by using a dedicated jig for maintaining the flatness of the broken line A during soldering.

The present invention has been made to solve the above problems, and an object thereof is to require a dedicated jig or work when mounting a heat sink by soldering a plurality of semiconductor elements to a circuit board. It is another object of the present invention to realize a mounting method of a semiconductor element, which can attach a heat sink while maintaining the flatness of the semiconductor element.

[0010]

A first means for solving the above-mentioned problems is to mount a semiconductor element on one surface of a heat-conductive flat plate, and arrange the semiconductor element so as to have a predetermined distance from the heat-conductive flat plate. An electrode lead of the semiconductor element is connected to the circuit board via solder, and a heat dissipation plate is attached to the other surface of the heat conductive flat plate.

A second means for solving the above-mentioned problems is to mount a semiconductor element on one surface of a heat conductive flat plate by using a screw and to arrange the circuit so as to have a predetermined distance from the heat conductive flat plate. The electrode lead of the semiconductor element is connected to the substrate through the solder, and the heat dissipation plate is attached to the other surface of the heat conductive flat plate by using the screw for attaching the semiconductor element to the heat conductive flat plate. Is a method of mounting a semiconductor element.

[0012]

In the method for mounting a semiconductor element, which is the first means for solving the problems, the semiconductor element is first attached to one surface of the heat conductive flat plate, and then has a predetermined distance from the heat conductive flat plate. The electrode lead of the semiconductor element is connected to the circuit board arranged on the substrate via solder, and a heat radiating plate is attached to the other surface of the heat conductive flat plate. This makes it possible to attach the heat sink while maintaining the flatness of the semiconductor elements without the need for a special jig or work when soldering multiple semiconductor elements to the circuit board and attaching the heat sink. Become.

In a semiconductor element mounting method which is a second means for solving the problem, the semiconductor element is first attached to one surface of the heat conductive flat plate by using a screw, and then the heat conductive flat plate and a predetermined surface are mounted. The electrode leads of the semiconductor element are connected to the circuit board arranged so as to have a gap via solder, and the semiconductor element is attached to the heat conductive plate on the other surface of the heat conductive plate. It is attached to the heat sink using the screws. This makes it possible to attach the heat sink while maintaining the flatness of the semiconductor elements without the need for a special jig or work when soldering multiple semiconductor elements to the circuit board and attaching the heat sink. Become.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a flowchart showing a method of mounting a semiconductor device according to an embodiment of the present invention. FIG. 2 is a cross-sectional configuration diagram showing a state in which the semiconductor element is mounted by the mounting method according to this embodiment.

Here, in order to simplify the explanation, the number of semiconductor elements (diodes, transistors, FETs) is three.
Will be described as an example. However, in reality, the number of semiconductor elements is not limited to this. Further, the semiconductor elements 21 to 23 are assumed to be leaded parts, and L
Each lead and the pattern of the circuit board 10 are connected by soldering by MT (lead hole insertion mounting technique). Also,
Each of the semiconductor elements 21 to 23 has holes 21b to 23b for screwing to the heat dissipation plate.

Here, with reference to FIGS. 1 and 2, a method of mounting the semiconductor device of this embodiment will be described in accordance with procedures. First, the semiconductor element 21-23 is a copper plate 5 as a heat conductive flat plate.
0 (FIG. 2 (a)). The copper plate 50 is
It is assumed that the semiconductor elements 21 to 23 have screw holes 51a to 53a at positions corresponding to the holes 21b to 23b. Then, with the positions of the holes aligned, screws 31 to 31
The semiconductor elements 21 to 23 are attached to the copper plate 50 by 33 (step in FIG. 1). If necessary, silicon grease or the like is applied.

The heat conductive flat plate formed by the copper plate 50 used in this embodiment radiates heat while maintaining flatness between each semiconductor element and a heat radiating plate which will be described later. Therefore, it has a role as a jig for maintaining the flatness in the mounting stage, and a role as a heat dissipation plate after the mounting is completed. Therefore, a material with high thermal conductivity is preferable,
Generally, it is preferable to use copper or aluminum. However, other than this, as long as it has high thermal conductivity, it is possible to use not only metal but also metal.

Next, the copper plate 5 is formed by using the spacers 61 and 62.
0 and a predetermined distance are maintained, and the hole 11b
The circuit board 10 is attached and fixed so that the leads 21a to 23a are inserted into the electrodes 13a to 13b (FIG. 1 step, FIG. 2B).

Then, each pattern 11a of the circuit board 10
13a and the leads 21a to 23a are connected by soldering (FIG. 1 step, FIG. 2C). Since each of the semiconductor elements 21 to 23 is already attached to the copper plate 50 fixed by the spacers 61 and 62, no dedicated jig or pressing work is required to maintain the flatness between the plurality of semiconductor elements. become. Therefore, soldering can be easily performed. Various types of soldering such as flow soldering are possible here.

After the soldering is completed, the heat sink 40 is attached. The heat sink 40 is attached to the surface of the copper plate 50 opposite to the surface on which the semiconductor elements 21 to 23 are attached, with the insulating sheet 70 sandwiched as necessary (FIG. 1 step, FIG. 2D). At this stage, the copper plate 50 and the heat sink 4
Since it is mounted between 0 and 0, there is no problem in terms of flatness. Therefore, there is no partial unevenness or variation in heat conduction. Further, since the flat surfaces are attached to each other, work efficiency is significantly improved. The copper plate 50 and the heat sink 40 are attached to each other by screwing or the like at an end (not shown).

FIG. 3 is a sectional view showing another example of how the copper plate 50 and the heat sink 40 are attached. Although the mounting screws are used in the above-described example, the screws that are longer than the thickness of the copper plate and the semiconductor device are used as the screws for fixing each semiconductor element to the copper plate 50 (or a thin copper plate is used). It is also possible to provide holes and screw them together. By integrally screwing in this manner, there is an advantage that the degree of adhesion between the semiconductor element, the copper plate, and the heat dissipation plate is further increased. However, it is necessary to fix the semiconductor element and the copper plate with screws once, and loosen the screws and re-tighten at the stage of mounting the heat sink. In this case, it is possible to temporarily fix the semiconductor element and the copper plate with a nut or the like at the time of soldering.

As described in detail above, the semiconductor element is attached to one surface of the heat conductive flat plate, and the electrode lead of the semiconductor element is mounted on the circuit board arranged so as to have a predetermined distance from the heat conductive flat plate. According to the mounting method of the semiconductor element in which the heat radiating plate is attached to the other surface of the heat conductive flat plate by connecting via the solder, when the heat radiating plate is already attached when the plurality of semiconductor elements are soldered to the circuit board, Since the flatness is ensured, the heat dissipation plate can be attached while maintaining the flatness of the semiconductor element without requiring a dedicated jig or work.

Further, the semiconductor element is attached to one surface of the heat conductive flat plate by using screws, and the electrode leads of the semiconductor element are soldered to the circuit board arranged so as to have a predetermined distance from the heat conductive flat plate. According to the mounting method of the semiconductor element, the heat radiating plate is attached to the other surface of the heat conductive flat plate by using a screw that attaches the semiconductor element to the heat conductive flat plate. Since the flatness is already secured when mounting the heat sink after soldering the semiconductor element to the circuit board, the heat sink is mounted while maintaining the flatness of the semiconductor element without the need for a dedicated jig or work. Since the heat conductive flat plate and the heat radiating plate are attached with a common screw, the heat radiating efficiency is improved.

[0024]

As described in detail above, in the method of mounting a semiconductor element of the present invention, the semiconductor element is first attached to one surface of the heat conductive flat plate, and then the heat conductive flat plate and the predetermined distance from each other. The electrode leads of the semiconductor element are connected to the circuit board arranged so as to have solder via solder, and a heat radiating plate is attached to the other surface of the heat conductive flat plate. This makes it possible to attach the heat sink while maintaining the flatness of the semiconductor elements without the need for a special jig or work when soldering multiple semiconductor elements to the circuit board and attaching the heat sink. Become.

[Brief description of drawings]

FIG. 1 is a flowchart showing a mounting procedure of a semiconductor element in an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a semiconductor device used in an embodiment of the present invention.

FIG. 3 is a configuration diagram showing a configuration of a semiconductor device used in an embodiment of the present invention.

FIG. 4 is a configuration diagram showing a configuration example of a conventional semiconductor element mounting method.

[Explanation of symbols]

 10 circuit board 11a-13a pattern 11b-13b hole 21-23 semiconductor element 21a-23a lead 31-33 screw 40 heat sink 50 copper plate 61,62 spacer 70 insulating sheet

Claims (2)

[Claims] 1. A semiconductor element is attached to one surface of a heat conductive flat plate, and an electrode lead of the semiconductor element is connected via solder to a circuit board arranged so as to have a predetermined distance from the heat conductive flat plate. Then, a heat dissipation plate is attached to the other surface of the heat conductive flat plate. 2. A semiconductor element is attached to one surface of a heat conductive flat plate with a screw, and electrode leads of the semiconductor element are soldered to a circuit board arranged so as to have a predetermined distance from the heat conductive flat plate. A mounting method of a semiconductor element, characterized in that a heat dissipation plate is attached to the other surface of the heat conductive flat plate by using a screw that attaches the semiconductor element to the heat conductive flat plate.