JPH0653526A - Semiconductor element and assembling method - Google Patents

Abstract

PURPOSE:To improve assembling performance of a two-sided electrode type semiconductor element in which disc electrodes are soldered to the opposite sides of a planar rectangular semiconductor chip. CONSTITUTION:In a semiconductor element wherein disc electrodes 2 are soldered oppositely to the opposite sides of a semiconductor chip 1, a rectangular diepad 2a for mounting the semiconductor chip 1 is formed while bulging in the center of the electrode. Furthermore, guide holes for passing semiconductor chip positioning pins are made on the outer peripheral side of at least two adjacent sides out of four sides of the diepad. In the assembling process, the disc electrodes having guide holes, a solder foil, and the semiconductor chip are stacked at a predetermined position with reference to a positioning pin 5 planted at a predetermined position in an assembling jig to produce a temporary assembly which is then carried into an atmospheric furnace and soldered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to products such as silicon surge absorbers and diodes, and is a semiconductor element formed by soldering discoid electrode plates on both sides of a planar semiconductor chip. The assembly method is related.

[0002]

2. Description of the Related Art As semiconductor elements such as silicon surge absorbers and diodes, those having an assembly structure in which a rectangular chip having a planar structure is sandwiched and a disk-shaped electrode plate having a diameter larger than the chip size is soldered on both surfaces thereof are known. Is. In this case, since the semiconductor chip of the planar structure has the peripheral edge of the chip covered with an insulating protective film, the central part of the electrode plate should have a size larger than the electrode surface size of the chip in advance so that the insulating protective film floats above the electrode plate. A structure is generally adopted in which a circular convex die pad having a small diameter is bulged and formed, and the electrode surface of the chip is superposed on the die pad and soldered.

[0003]

By the way, the above-described conventional semiconductor device has the following problems in terms of assembling. That is, in the process of assembling a semiconductor element, an electrode plate, a solder foil, and a semiconductor chip are sequentially stacked on an assembly jig, and then carried into an atmosphere furnace for soldering. ， The electrode plate is disk-shaped, and the chip size is smaller than the diameter of the electrode plate. Therefore, when the semiconductor chip is stacked on the electrode plate, a relative displacement occurs, and the center of the chip and the electrode plate is It often happens that they do not match. Moreover, in the conventional structure, since the convex die pad formed at the center of the electrode plate is circular, if the position where the chip overlaps with the chip is displaced as described above, not only proper soldering is not performed, but also the displacement is caused. At this point, local stress is applied to the semiconductor chip, causing defects such as chip cracks, which causes a decrease in the yield rate of products.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and its purpose is to solve the above-mentioned problems and to provide a semiconductor device having good assembling ability, for a double-sided electrode type semiconductor device described above.
And an assembling method thereof.

[0005]

In order to achieve the above object, in the semiconductor device of the present invention, a square convex die pad having the same shape as the electrode surface of the semiconductor chip is formed in the center of the electrode plate. . Further, there is the following structure as a means for assembling and aligning the semiconductor chip and the electrode plate.

(1) A guide hole for inserting a positioning pin of a semiconductor chip is drilled in the outer peripheral side of at least two adjacent sides of the four sides of the die pad formed on the electrode plate. (2) An orientation flat for positioning, which is parallel to one side of the rectangular convex die pad and corresponds to the outer dimension of the semiconductor chip, is formed in a part of the peripheral edge of the disk-shaped electrode plate.

Then, the semiconductor element is assembled as follows. That is, with respect to the electrode plate of the preceding paragraph (1), positioning pins are implanted at fixed positions in the recesses of the assembly jig, and the electrode plate, the solder foil, and the semiconductor chip having the guide holes perforated with reference to the pins are provided in predetermined positions. Then, the temporary assemblies are superposed in the same direction for temporary assembly, and then the temporary assembly is carried into an atmospheric furnace for soldering.

Further, regarding the electrode plate of the above (2), a positioning wall surface corresponding to the orientation flat of the electrode plate is formed in the recess of the assembly jig, and the electrode plate, solder foil, and The semiconductor chips are stacked in a predetermined direction and temporarily assembled, and then the temporary assembly is carried into an atmospheric furnace and soldered.

[0009]

As described above, when the convex die pad bulged in the center of the electrode plate is formed into a rectangular shape having the same shape as the electrode surface of the rectangular semiconductor chip, the semiconductor chip is superposed on the electrode plate in the assembly process. Is easier to align, and the area of the die pad to be soldered to the chip's electrode surface is larger than that of a circular die pad, which increases the bonding strength between the semiconductor chip and the electrode plate, and also improves the operating characteristics of the semiconductor device. improves.

Further, at the time of assembling a semiconductor element, a guide hole, an electrode plate having an orientation flat, a solder foil, and a semiconductor chip are used as a positioning reference by using a positioning pin or a positioning wall implanted in a recess of an assembly jig. The rectangular semiconductor chip and the rectangular die pad of the electrode plate are positioned in the correct direction by inserting them in a predetermined direction and stacking them. Then, while the temporary assembly state is maintained and the solder is put in the atmosphere furnace to perform soldering, the relative movement of the semiconductor chip and the electrode plate due to melting of the solder is regulated by the positioning pin or the orientation flat. , The semiconductor chip is correctly soldered and joined to the central portion of the electrode plate without causing displacement.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIGS. 1 and 2 show an embodiment corresponding to claims 1, 2 and 3 of the present invention. In the drawings, 1 is a rectangular semiconductor chip having a planar structure, and 2 is a semiconductor chip 1 sandwiched therebetween. A disk-shaped electrode plate soldered on both sides thereof, 2a is a convex die pad bulged in the center of the electrode plate 2, 3 is a solder layer, and 4 is an assembly jig.

Here, the convex die pad 2a has an outer shape (length A of one side) of the same size as the electrode surface of the rectangular semiconductor chip 1 or a square shape of a size smaller than the electrode surface. There is. Further, among the four sides around the rectangular die pad 2a, at least the outer peripheral side of two adjacent sides is provided with a positioning pin described later according to the outer size of the semiconductor chip 1 (length B of one side) at the center of each side. Through guide hole 2b
Are perforated in the electrode plate 2. The guide hole 2a may be a round hole having a hole diameter of about 0.2 to 0.5, or may be formed as an elongated hole having the same diameter.

Next, a method of assembling a semiconductor device using the electrode plate having the above structure will be described. First, a recess corresponding to the outer diameter of the electrode plate 2 is formed in the assembly jig 4, and two positioning pins 5 are set up in advance at fixed positions in this recess. Next, the first electrode plate 2 is set in the assembly jig through the guide hole 2a through the pin 5 with the convex die pad 2a facing upward with the positioning pin 5 as a reference. Subsequently, a solder foil is placed on the die pad 2a, and the rectangular semiconductor chip 1 is positioned and overlapped so that the two sides of the peripheral edge of the rectangular semiconductor chip 1 abut the positioning pin 5. Then, the solder foil is placed on the electrode surface of the semiconductor chip 1, and finally, the convex die pad 2a is faced down to position the second electrode plate 2 on the positioning pin 5
Pass through and stack. This completes the temporary assembly of the semiconductor element, and the electrode surface of the rectangular semiconductor chip 1 is aligned with the rectangular convex die pad 2a formed on the electrode plate 2 and overlaps with the correct position.

After the above-mentioned temporary assembly work is completed, the temporary assembly of the semiconductor element is carried into the atmospheric furnace together with the assembly jig 4 and soldered. In this soldering process, the movement of the semiconductor chip 1 is restricted by the two positioning pins 5, so that the semiconductor chip 1 is not accidentally deviated from a predetermined position and is soldered at a position where it is correctly overlapped with the die pad 2a.
Then, after the solder is solidified, the semiconductor element is taken out from the assembly jig 4, and the pin 5 that has passed through the guide hole 2a of the electrode plate 2 is pulled out. The positioning pin 5 can be repeatedly planted in the assembly jig 4 for repeated use.

Embodiment 2 FIGS. 3 and 4 show an embodiment corresponding to claims 1, 4 and 5 of the present invention. The difference from Embodiment 1 is that the electrode plate 2 is different. An orientation flat 2c for alignment that is parallel to one side of the rectangular die pad 2a is formed in a part of the peripheral edge thereof, and a flat positioning wall surface 4a corresponding to the orientation flat 2c is formed in the recess of the assembly jig 4. Are formed. In addition, the orientation flat 2c is a state in which the semiconductor chip 1 does not protrude from the electrode plate 2 in the state where the square semiconductor chip 1 is aligned with the square die pad 2a as shown in FIG. It is formed at a position that is almost aligned with the edge.

Next, a method of assembling a semiconductor device using the electrode plate having the above structure will be described. First, the orientation flat 2c of the electrode plate 2 is aligned with the above-mentioned positioning wall surface 4a formed in the recess of the assembly jig 4 so that the convex die pad 2a faces upward.
Is set in the assembly jig. Subsequently, a solder foil is placed on the die pad 2a, and the square semiconductor chips 1 are stacked with their sides aligned so that one side of the square semiconductor chip 1 is along the positioning wall surface 4a of the assembly jig 4. Next, after the solder foil is placed on the electrode surface of the semiconductor chip 1, the convex die pad 2a is finally faced downward to assemble the second electrode plate 2 into the orientation flat 2c in the same manner as the first electrode plate. The jig 4 is inserted so as to face the positioning wall surface 4a. This completes the temporary assembly of the semiconductor element, and the electrode surface of the rectangular semiconductor chip 1 is aligned with the rectangular convex die pad 2a formed on the electrode plate 2 and overlaps at the correct position.

After the above-mentioned temporary assembly work is completed, the temporary assembly of semiconductor elements is carried into the atmospheric furnace together with the assembly jig 4 and the semiconductor chip 1 and the electrode plate 2 are soldered. In this case, the positioning wall surface 4a of the assembly jig 4 acts so as to restrain the movement of the semiconductor chip 1 and the electrode plate 2 to change their directions in the assembly jig. Therefore, the semiconductor chip 1 is soldered at a position where it is correctly overlapped with the die pad 2a of the electrode plate 2 while being held in a fixed orientation.

[0018]

As described above, according to the present invention, the semiconductor chip can be correctly aligned and soldered to the electrode plate when assembling the semiconductor element, which causes a problem in the conventional structure. The misalignment of the chips is eliminated, and the rate of non-defective products can be significantly improved.

[Brief description of drawings]

1A and 1B are views showing an assembled state of a semiconductor device according to a first embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a sectional view.

FIG. 2 is a diagram showing a structure of an electrode plate in FIG.
(A) is a plan view, (b) is a sectional view,

3A and 3B are diagrams showing a structure of an electrode plate corresponding to Example 2 of the invention, in which FIG. 3A is a plan view and FIG. 3B is a side view.

4A and 4B are diagrams showing an assembled state of a semiconductor device adopting the electrode plate of FIG. 3, in which FIG. 4A is a plan view and FIG.

[Explanation of symbols]

 1 semiconductor chip 2 electrode plate 2a convex die pad 2b guide hole 2c orientation flat 4 assembly jig 4a positioning wall surface 5 positioning pin

Claims (5)

[Claims] 1. A semiconductor element in which a rectangular semiconductor chip having a planar structure is sandwiched and disc-shaped electrode plates are superposed on both electrode faces and soldered to each other, and the same shape as the electrode face of the semiconductor chip is formed in the center of the electrode plate. A semiconductor device having a rectangular convex die pad bulgingly formed. 2. The semiconductor element according to claim 1, wherein a guide hole through which a positioning pin of the semiconductor chip is inserted is formed on the outer peripheral side of at least two adjacent sides of the four sides of the die pad bulged on the electrode plate. A semiconductor device characterized by the above. 3. An electrode plate in which a positioning pin is planted at a fixed position in a recess of an assembly jig, and a guide hole is formed on the basis of the pin.
3. The method for assembling a semiconductor device according to claim 2, wherein the solder foil and the semiconductor chip are superposed in a predetermined direction for temporary assembly, and then the temporary assembly is carried into an atmospheric furnace for soldering. 4. A semiconductor element according to claim 1, wherein an orientation flat for positioning, which is parallel to one side of the rectangular convex die pad and corresponds to the outer dimension of the semiconductor chip, is formed on a part of the peripheral edge of the disk-shaped electrode plate. A semiconductor element having a notch formed therein. 5. A positioning wall surface corresponding to the orientation flat of the electrode plate is formed in the recess of the assembly jig, and the electrode plate, the solder foil, and the semiconductor chip are superposed in a predetermined direction on the basis of the positioning wall surface. 6. The method for assembling a semiconductor device according to claim 4, wherein the temporary assembly is carried out, and then the temporary assembly is carried into an atmosphere furnace and soldered.