JP3262245B2 - High voltage semiconductor rectifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage semiconductor rectifier, and more particularly, to a method for applying a joint coating resin.

[0002]

2. Description of the Related Art Referring to FIG. FIG. 4 is a sectional view of a conventional high-voltage semiconductor rectifier. High-voltage semiconductor rectifiers (hereinafter referred to as rectifiers) used in control circuits of video equipment require a high reverse withstand voltage of 6 to 24 kV, but such a high withstand voltage cannot be obtained with one PN junction. , A plurality of PN junctions are connected in series. That is, a plurality of semiconductor substrates on which a PN junction has been formed are stacked and fixed via solder, to produce a laminate, and cut into a dice pattern using a blade saw or a wire saw or the like.
A 1 mm square columnar laminate is produced.

As shown in FIG. 4, a columnar laminated body 10 is formed by laminating a plurality of diode chips 1 via solder 2 and fixing them. The flat surface 31 a of the formed header 31 is fixed via the solder 4. After washing the ones of the state in the etching solution or the like, both the flat surface 31a of the F Dda 31
The joint coating resin 5 is applied to the side surface of the columnar laminated body 10 between them, and is further sealed with the mold resin 6 to produce a rectifying body.

[0004]

According to the method described above,
High temperature, high pressure and high humidity (temperature 120 ° C, pressure 2at)
m, humidity 100%) After leaving in a pressure kiln for 50 hours,
In a pressure cooker test (hereinafter referred to as PCT) in which the high-temperature leakage current in the opposite direction is measured to evaluate the moisture resistance, moisture enters the columnar laminate through a gap between the connection conductor and the mold resin. However, there is a problem that the high-temperature leakage current does not fall below the specified value of 1.0 μA.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a structure in which moisture does not enter the columnar laminate from a gap between a connection conductor and a molding resin, and has a high humidity resistance. It is to provide a device.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a columnar laminate in which diode chips each having a PN junction are laminated via solder, and an end face pair of the columnar laminate .
The connection conductor having a header having a diameter larger than the square
Are fixed to both ends of the columnar laminated body, a joining coating resin is applied to the peripheral area of the columnar laminated body, and furthermore, an epoxy resin is used.
In a high-voltage semiconductor rectifier that is sealed with a molding resin, the bonding coating resin is a polyimide resin.
Resin covering from columnar laminate to connection conductor beyond header
Rukoto be coated or edge surface distance between the columnar laminate secured end and the connecting wire fixing end of the header, it can be achieved by at least 1 mm.

[0007] Connection lead to further, it is effective that it is a conductor in which the silver plating.

[0008]

According to the structure of the present invention, in the rectifier in which the joining coating resin is applied to the peripheral region of the columnar laminate and further sealed with the mold resin, the joining coating resin is made of polyimide resin.
And the bonding coating resin passes over the header from the columnar laminate.
Since was Rukoto be coated up to connecting wires, forming the structural moisture does not enter the columnar laminate portion than the gap between the connecting wire and the molding resin may have a high moisture resistance. In addition, since the edge distance between the columnar laminate fixing end of the header and the connection conductor fixing end is at least 1 mm, the bonding coating resin does not protrude from the end surface of the mold resin, and the customer can print on the printed circuit board. When implementing,
Since there is no impurity on the surface of the connection conductor, the solderability is not reduced. Further, it is generally known that the adhesion between the polyimide resin and silver or between the polyimide resin and the epoxy resin is good.

In the present invention, the joining and coating resin is a polyimide resin, the connecting conductor is a silver-plated conductor, and the molding resin is an epoxy resin. Adhesion between the resin and the epoxy resin is improved, and it is possible to prevent moisture and the like from entering the rectifier.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An explanation will be given based on FIGS. 1, 2 and 3. FIG. FIG. 1 is a sectional view of a rectifier body showing this embodiment, FIG. 2 is an explanatory view showing a change in high-temperature leakage current when a joint coating resin is coated on each position of a connection conductor, and FIG. FIG. 9 is an explanatory diagram showing a change in leakage current. Elements having the same functional elements as in the conventional example are denoted by the same reference numerals.

The thickness of the diode chip 1 in which the PN junction is formed is 280 μm, and the thickness of the solder 2 is 45 μm. The dimensions of the columnar laminate cut in a dice pattern are 0.1 mm.
It is 7 to 1 mm square. The manufacturing method before coating with the bonding coating resin is the same as the conventional example. [Example 1] A polyimide resin was used as the bonding coating resin 5, and as shown in FIG.
A plurality of rectifiers each covering up to point E and point E were manufactured. C. Each high temperature leakage current after T50 hours was measured. Those up to the point A are the same as those of the conventional example.
Point B is covered with the joining coating resin 5 to about half the width of the flat surface 31a of the header 31. At point C, the entire surface of the header 31 and a very small portion of the connection conductor 3 are covered with the joining coating resin 5. At point D, the entire surface is covered with the joining coating resin 5 up to the end surface 6a of the mold resin, which indicates that the tip 5a of the joining coating resin 5 is inside the end surface 6a. At the point E, the joining coating resin completely protrudes from the end face 6a. The result is shown in FIG. According to this, it can be seen that those coated with polyimide resin from point C to point E have a high-temperature leakage current of 1.0 μA or less, which is the specified value. However, the ones up to point E may cause poor contact after printed circuit board mounting and soldering on the customer side, so here, the one with polyimide resin coating between point C and point D should be a good product. And

The width 20 shown in FIG. 2 shows the variation in the result of measuring the high-temperature leakage current of a plurality of rectifiers. Example 2 As shown in FIG. 1, using a connection conductor 3 having an edge surface distance of 1 mm between a columnar laminate fixing end 31 b of a large-diameter header 31 and a connection conductor fixing end 3 a, 5 using a polyimide resin, replacing the edge surface distance with the application distance of the bonding coating resin 5, and applying an application distance of 0 mm (the same as the conventional example);
A plurality of rectifiers each coated with the joint coating resin 5 at five points of 0.5 mm, 1 mm (covered to the fixed end portion 3a of the connection lead wire), 1.5 mm, and 2 mm were manufactured. C.
Each high temperature leakage current after T50 hours was measured. The result is shown in FIG. According to this, it is understood that the high-temperature leakage current of the polyimide resin coated from 1 mm (the portion covered with the connecting wire fixed end 3a) to 2 mm is not more than the specified value of 1.0 μA.

From the viewpoint of the coating method, the connection conductor fixing end 3
Covering up to a is easier than covering up a part of the outer periphery of the connection conductor 3 in order to lengthen the edge surface distance. Therefore, the connecting wire 3 having an edge surface distance of 1 mm between the columnar laminate fixing end 31b of the large header 31 and the connecting wire fixing end 3a.
It can be determined that it is better to cover the connection conductor fixed end 3a by using.

[0014]

According to the present invention, the bonding coating resin is a polyimide resin, and the bonding coating resin is moved from the columnar laminate to the resin.
Since was Rukoto be coated until connecting wire beyond Dda, prevents moisture rectifying body that enters, 1.0 .mu.A of leakage current at high temperature is a specified value as described in Example
As described below, a rectifier having high moisture resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rectifier showing this embodiment.

FIG. 2 is an explanatory diagram showing a change in a high-temperature leakage current when the bonding coating resin of this embodiment is coated on each position of a connection conductor.

FIG. 3 is an explanatory diagram showing changes in edge distance and high-temperature leakage current of a header according to another embodiment.

FIG. 4 is a sectional view of a rectifier showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diode chip 2 Solder 3 Connection lead 3a Connection lead fixed end 4 Solder 5 Join coating resin 5a Bond coating resin tip 6 Mold resin 6a Mold resin end face 10 Column laminated body 20 Width 31 Header 31a Flat surface 31b Column laminated body fixed end

Continuation of the front page (56) References JP-A-58-48955 (JP, A) JP-A-51-12777 (JP, A)

Claims (3)

(57) [Claims] 1. A columnar laminated body in which diode chips having a PN junction formed are laminated via solder, and an end face of the columnar laminated body .
To a connecting conductor having a header larger in diameter than the diagonal
Fixing a Dda across the columnar laminate, the bond coat resin is applied to the peripheral region of the columnar laminate, the more epoxy resin
In a high-voltage semiconductor rectifier, which is sealed with a molding resin, the bonding resin is a polyimide resin,
Resin covering from columnar laminate to connection conductor beyond header
High semiconductor rectifier device which is characterized that you coated. 2. A high-voltage semiconductor rectifier according to claim 1, wherein an edge surface distance between the fixed end of the columnar laminate and the fixed end of the connection conductor of the header is at least 1 mm. . 3. The high-voltage semiconductor rectifier according to claim 1, wherein the connection conductor is a silver-plated conductor.