JPH036662B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing structure for electronic components, and in particular, a semiconductor element such as a diode or other electronic component element is sandwiched between the lead wire portions of both electrodes inserted through openings at both ends of a sleeve body. This relates to a structure in which both electrodes and a sleeve body are welded together while being attached and held.

An electronic component shown in FIG. 1 is known as an electronic component having a cylindrical leadless type sealing structure. Figure 1 shows the structure of a semiconductor diode.
Using a vertical jig (not shown), a T-shaped Fe-
Ni-Cu electrodes 3 and 4 are inserted, respectively, and at this time, a diode pellet 13 is clamped between each lead wire portion (dummet wire portion) 2 of both electrodes and heat treated, and each electrode 3 and 4 is heated. The sleeve 12 is welded and integrated with the sleeve 12. FIG. 2 shows this integrated structure, in which the Ag bump 7 on the upper surface side of the pellet 13 is fixed to the lead wire portion 2 of the electrode 3, and the back surface side is connected via a brazing material (not shown). While being fixed to the lead wire portion 2 of the electrode 4, the electrodes 3 and 4 themselves are fixed to the inner peripheral surface and upper and lower end surfaces of the sleeve 12.
When mounting this cylindrical leadless diode, it is placed horizontally on a printed circuit board, and solder is selectively applied between each header portion and the conductive pattern of the printed circuit board using a technique such as solder dip. Both can be electrically and mechanically connected. In order to improve the adhesive strength of the printed circuit board and the diode electrode by soldering, the header part 1 is sufficiently expanded by the lead wire part 2 in order to protect the sleeve 12 during assembly using the jig described above. , must be formed to have approximately the same diameter as the end surface of the sleeve 12.

As a result of the inventor's study of such a diode structure, it has been found that although it has the features of a leadless component, there are serious defects particularly arising from its assembly method.

That is, when cooling the sleeve 12 to room temperature after the above heat treatment for welding the sleeve 12 to the electrodes 3 and 4,
In particular, since the header portion 1 has a higher coefficient of thermal expansion (or contraction rate) than the sleeve 12, it contracts more than the sleeve 12. As a result, the end surface of the sleeve 12 is subjected to excessive stress from the header portion 1 fixed thereto, resulting in distortion and the formation of a crack 8 as shown in FIG. This phenomenon is caused in particular by the fact that the coefficient of thermal expansion of the sleeve 12 in the radial direction differs considerably from that of the header part 1. Although the drawings show that the crack 8 occurs in one electrode 4, a similar phenomenon occurs in the other electrode 3 as well.

The present invention aims to prevent the occurrence of cracks, improve mechanical strength, stabilize characteristics, and improve reliability in the assembly structure of leadless type electronic components sealed in glass sleeves. It is something to do.

To achieve this objective, according to the invention:
It is characterized in that the contact area between the header part of one of the electrodes inserted into the glass sleeve and the end face of the sleeve is reduced, and the other header part and the end face of the sleeve are not brought into contact with each other.
Therefore, in the structure according to the present invention, it is possible to prevent the sleeve side from being affected by shrinkage of the header portion during cooling after welding, and it is possible to provide a product with high yield and high reliability.

Hereinafter, an embodiment in which the leadless type sealing structure of the present invention is applied to a semiconductor diode will be described in detail. In the following embodiments, parts common to those in FIGS. 1 and 2 are designated by common reference numerals, and their explanations are omitted.

FIG. 3 is a sectional view showing an embodiment of the invention.
According to the example shown in FIG. 3, on the inside of each header portion 1 of both electrodes 3 and 4 inserted into the sleeve 12, there is a linearly elevated (slanted) line toward the lead wire portion 2 side.
A tapered portion 9 is provided respectively, and the sleeve 12 itself is made shorter than that shown in FIG. 2 so that a certain gap 10 is left between the sleeve 12 and the upper header 1 (specifically, the tapered portion 9). ing. The tapered portion 9 has a substantially truncated conical shape, and is integrated with the lead wire portion 2 at its tip. Note that the sleeve 12 has a coefficient of thermal expansion of, for example, 91×
10 ^-7 /°C, and a soft glass such as Corning # ₈₈₇₀ (trade name) having a softening point of about ₆₅₀ °C or less may be used. Further, the electrodes 3 and 4 may be made of Cu-coated Fe-Ni known as a composite wire, and in particular, the thermal expansion coefficient of the header portion 1 is the same as that of the sleeve 12 in the length direction, but in the radial direction. For example, it is 100×10 ^-7 /°C. In FIG. 4, the pellet 13 portion is shown in an enlarged view. In the figure, 11 is a copper (Cu) coating on the surface of the lead wire portion 2, and 11' is a suboxide formed by oxidizing the Cu coating. A copper coating, 14 is an insulating film on the surface of the pellet 13, and 15 is a brazing material such as Ag formed on the back surface of the pellet. Even if there is some copper coating on the cut surface of the lead wire portion 2 on which the pellet is placed, it is possible to adhere the pellet to the lead wire portion.

When assembling, prepare a jig that can be inserted vertically in the same manner as described in FIG. Thereafter, heat treatment is performed at a predetermined temperature for a predetermined time to weld the joint surfaces of the sleeve 12 and each lead wire portion 2 (specifically, the inner surface of the sleeve) to each other, and at the same time, the pellet 13 is made of Ag.
Each lead wire portion 2 is connected via the bump 7 and the brazing material 15.
sticks to. Various conditions can be selected for this heat treatment, but for example, it may be about 650° C. for several tens of seconds in N ₂ or air.

After heat treatment, the whole is cooled to room temperature. As a result, the pellet 13 is formed between the sleeve 12 and the lead wire portion 2.
- The lead wire portions 2 are fixed to each other.

During this cooling, the header portion 1 contracts as described above, but as shown in FIG. Since the sleeve 12 is only in contact with the sleeve 12, the contraction of the header portion 1 has almost no effect on the sleeve 12 side. This prevents any cracks from occurring at the ends of the sleeve 12 as described above. In other words,
Since the end face of the sleeve 12 and the header portion 1 are not substantially welded, stress in the header portion 1 is not transmitted to the sleeve 12, and therefore no thermal strain occurs. Further, on the upper end side of the sleeve 12, since a taper part 9 similar to the above is provided in the header part 1 and a gap 10 is formed between the sleeve 12 and the upper end surface of the header part 1 and the sleeve 12. have little or no contact, and the gap 10 effectively absorbs thermal expansion along the length of the sleeve 12. Therefore, there is no problem of cracks on the upper end side, and the structure is such that heat treatment can be carried out effectively. electrode 3,
The sleeve 12 is fixed to the lead wire portion 2 substantially on the outer peripheral surface of the lead wire portion 2, which exhibits sufficient mechanical strength and can achieve a stable sealing structure.

The tapered part 9 of the header part 1 plays an important role in this way, and its inclination angle θ is 10 to 20°.
It is appropriate that the amount of inclination t is 0.1 to 0.2 mm.

Another point to note in this example is that
When each electrode is inserted into the sleeve 12 during the above-described assembly, the lower end surface (inner peripheral edge) of the sleeve 12 comes into contact with the tapered part 9 of the lower header part 1 and is positioned. Since 9 is a conical surface, the position of the sleeve 12 (that is, the alignment of the sleeve 12 and the header portion 1) can be accurately performed. As a result, the inner circumferential edge of the sleeve 12 contacts the tapered portion 9 uniformly over the entire circumference, making it possible to perform the assembly stably, and furthermore, the welding between the inner surface of the sleeve 12 and the lead wire portion 2 can be achieved over the entire circumference. It can also be done uniformly.

Furthermore, according to such an electronic component, the contact area between one header part and the sleeve end face is reduced, and the other header part and the sleeve body are configured to not come in complete contact with each other, so that conventional sealing is not possible. In the process, it is possible to prevent the problem of electrical failure caused by non-contact between the pellet and the lead wire portion, which was caused by dimensional errors in the sleeve.

FIG. 5 shows a sealing structure according to another embodiment of the present invention.

This example differs from the above-described embodiments in that a concentric stepped portion 19 is provided on the inner surface of the header portion 1 of each electrode 3, 4. The size (area) of this stepped portion 19 is set such that the contact area with the end surface of the sleeve 12 is smaller than the end surface area of the glass sleeve. The smaller the contact area with the end surface of the sleeve 12, the greater the effect can be obtained.

With this configuration, since the header portion 1 and the sleeve 12 come into contact only at the stepped portion 19, the area of contact or welding between them can be significantly reduced compared to the case shown in FIG. Therefore, in this case as well, it is possible to prevent the sleeve 12 from cracking during cooling after heat treatment. In addition, step part 1
The height of 9 is 0.1, which is the same as the taper part 9 described above.
It may be about 0.2 mm.

FIG. 6 shows still another embodiment of the present invention,
The same parts as those described above are given the same reference numerals. In this embodiment, electrodes 3 and 4 having the same shape as the conventional one are used, and a metal ring 2 is inserted between the lower electrode 4 and the glass sleeve 12 when assembled in the vertical direction.
0 was sandwiched and heat treated for welding. This ring 20 can be made of the same metal material as the header part 1, or can be made of other metal materials such as Cu.

In the embodiment shown in FIG. 6, the glass sleeve 12 is formed short so that its upper end surface does not come into contact with the upper header part 1 (stud part of the electrode 3), thereby leaving a gap t' between them. has been established. As a result, the upper end surface of the glass sleeve is not welded to the header portion 1, and the occurrence of cracks at the upper end of the glass sleeve is prevented. Also, this gap t' is the gap t between the lower glass sleeve and the header part with the metal ring.
By setting a large distance (t'>t) to the polarity, it is possible to display polarity such as indicating the anode side of a diode. In the case of the example, t'>t was set so that it could be visually determined that t' was a larger gap, and the upper electrode was set on the anode side.

FIG. 7 shows a partial cross-sectional view showing yet another embodiment of the invention. The same parts mentioned above are given the same reference numerals, and the explanation thereof will be omitted. In this embodiment, the header portion 1' is made of a different metal material than the lead wire portion 2. The third mentioned above
In the embodiment shown in FIG. 5 and FIG.
The shape of the header part 1 is formed integrally with the lead wire part 2 from the same metal material by the hedging process, but in the embodiment shown in FIG.
The header portion 1' is made of a metal material such as Cu or steel, which is different from that of the lead wire portion. In this case, the header part 1' is welded to the composite wire 2 by welding technology, and a nugget (weld deformation part) 21 is formed at the joint between the header part 1' and the lead wire part 2 during welding. is used as a spacer to obtain a gap t. Since the header portion has a nugget in this manner, the glass sleeve 12 is not welded to the header portion 1, and the same effect as described above can be obtained. The metal header part 1 is made of a different material from the composite wire (lead wire part) 2 by welding, so when forming the header part with a composite wire, it is necessary to remove the cuprous oxide film required during soldering. The acid treatment (washing with dilute hydrochloric acid solution, etc.) can be omitted. That is, solder plating can be performed directly on the header portion 1'.

Although the present invention has been illustrated above, the embodiments described above can be further modified based on the technical idea of the present invention. For example, in the above-mentioned sealed structure, it is preferable that the shapes of both electrodes 3 and 4 are the same in consideration of their compatibility, but when used with the above-mentioned vertical jig, the sleeve 12 is always connected to the lower electrode. Header part 1 of 4
, the tapered portion 9 or step portion 19 of the upper electrode 3 is not necessarily necessary. Further, the size of the gap 10 between the upper electrode 4 and the sleeve 12 can be arbitrarily determined, and for example, the sleeve 12 may be in contact with the above-mentioned taper part 9 or step part 19. Furthermore, the shapes of the tapered portion 9 and the step portion 19 may be changed in various ways, and the processing or forming methods thereof may be various. The direction in which each electrode 3, 4 is inserted into the sleeve 12 is not limited to the above-mentioned vertical direction, but may also be in an oblique direction. It is possible to change the material, shape, and dimensions of each component of the structure described above.

Furthermore, although the above-described embodiments have shown the case of semiconductor diodes, the present invention can be applied to the case where other electronic components such as resistors and capacitors having two electrodes are formed into leadless types in addition to semiconductor diodes. .

[Brief explanation of drawings]

The drawings are for explaining the present invention, and
Fig. 1 is a perspective view showing each component separated when assembling a conventional cylindrical leadless part;
3 is a sectional view of a cylindrical leadless component according to an embodiment of the present invention, FIG. 4 is an enlarged view of the pellet portion in FIG. 3, and FIGS. The figure is a cross-sectional view of a cylindrical leadless component according to another embodiment. In addition, in the symbols shown in the drawings, 1 is a header part, 2 is a lead wire part, 3 and 4 are electrodes, 7 is a bump, 8 is a crack, 9 is a taper part, 12 is a glass sleeve, and 13 is a semiconductor element ( pellets),
19 is a stepped portion, 20 is a metal ring, and 21 is a nugget of a welded portion.

Claims (1)

[Claims] 1. Lead wire portions of the first and second electrodes each consisting of a lead wire portion and a header portion enlarged from the lead wire portion are respectively inserted into the inside of the glass sleeve body through openings at both ends thereof, 1
and an electronic component in which the sleeve body is welded to the first and second electrodes while holding a semiconductor element between each lead wire portion of the second electrode,
The contact area between the header portion of one of the first and second electrodes and the opening side end surface of the sleeve body is smaller than the area of the opening side end surface, and the first
and an electronic component characterized in that the other header portion of the second electrode and the sleeve body do not come into contact with each other.