JPH0821665B2 - Lead pin and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lead pin used for an external terminal of an IC ceramic package and a method for manufacturing the same.

(Prior Art) Conventionally, as a lead pin used as an external terminal of an IC ceramic package, there is known one in which a silver solder for brazing the lead pin to an electrode of the package is previously joined to one end of a lead pin body. The lead pin to which such a silver solder is joined is manufactured as follows. As shown in FIG. 6, with the silver brazing pieces 13 placed on the top surface 11a of the head of the lead pin body 11, after setting them on the refractory jig 15, raise them to a temperature not lower than the melting point of the silver brazing material. The silver wax piece 13 is melted by heating. Thereafter, the molten silver solder is solidified to form a silver solder portion 17 on the upper surface 11a of the lead pin body 11 as shown in FIG. 7, thereby obtaining the lead pin 19.

(Problems to be Solved by the Invention) However, the lead pin manufactured through the step of melting the silver solder as described above has the following problems.

(1) When a silver solder piece is heated to a temperature above its melting point and melted, the molten silver solder spreads in a bowl shape on the top surface 11a of the head of the lead pin body due to its surface tension, as shown in FIG. Ideally, the height should be constant. However, in reality, even if careful attention is paid to process control such as strict temperature control, part of the molten silver solder will vibrate and other factors, causing the upper surface of the head of the lead pin body to rise.
It overflows from 11a. For example, as shown in FIG.
The molten silver solder 17a flows to the outer peripheral surface 11b of the head portion of the lead pin body or, as shown in FIG. 9, wraps around the lower head portion 11c of the lead pin body. As a result, it is difficult to form an amount of silver brazing part sufficient for the main brazing at the time of mounting the lead pin, and the silver brazing consumed to form a sufficient silver brazing part. Is unnecessarily large, the height of the brazing portion is also varied, and as a result, the total length of the lead pin is varied, which is inconvenient during mounting.

(2) As described above, when the molten silver brazing material goes under the head of the lead pin body and solidifies there (see FIG. 9), the diameter of the lead pin body is reduced by the amount of the attached silver brazing material. Becomes thicker. It is difficult to detect such adhesion of silver brazing to the underside of the head, and if such a lead pin is used as it is, it is possible to fix the lead pin to a fixing jig that fixes the lead pin during brazing assembly. There is a problem that you cannot do it. Such an adverse effect becomes a major obstacle in automating the brazing and assembling work.

In addition, the silver brazing material attached to the unnecessary portion as described above causes so-called stress cracking, in which, when stress is applied to the portion at the time of mounting, it penetrates into the crystal grain boundaries of the texture of the portion and causes cracks therein. This may cause breakage of the lead pin, which may cause a serious defect in the mounting package.

(3) When the silver solder is once heated to a temperature equal to or higher than the melting point and then melted and solidified as in the conventional case, the fluidity of the silver solder tends to decrease when heated again. Especially, it is often used for external terminals of ceramic packages. It is remarkable in the silver-copper binary wax. That is, in the case of the conventional product, the excellent "wetting" property and the throwing power inherent to the silver brazing are hindered during the main brazing. SUMMARY OF THE INVENTION An object of the present invention is to provide a silver brazed lead lead pin and a method for manufacturing the same which solves the above problems.

(Means for Solving the Problems) In order to achieve the above object, in the lead pin of the present invention, the silver brazing member is supplied to one end surface of the lead pin body without completely melting it. The original shape of time is kept almost as it is and joined. As a suitable method for forming such a bonded state, there is the diffusion bonding method according to the present invention.

(Operation) In the lead pin of the present invention, when the silver brazing member is joined to the lead pin body, the silver brazing member does not substantially melt, and therefore the original shape is kept almost the same.
Since it does not melt like the conventional method, it does not flow down from the top surface of the top of the lead pin body, and all of the silver brazing material is used for the main brazing (bonding with the electrode during packaging). It will be.

In addition, since the silver braze is joined to the lead pin body without melting and solidifying, the silver braze retains its original flow characteristics as it is. At the same time, the flow occurs and the brazing is reliably performed without impairing the original characteristics of the brazing.

This point will be described by taking a silver-copper binary solder as an example. The structure of this binary wax is α rich in silver and β rich in copper.
Phase and (α + β) phase, and shows a substantially uniform structure by repeating the composition processing and annealing until the product. Therefore, when heated, melting starts at a melting point determined by the composition ratio of silver and copper, and at the same time when the pour point is reached, flow starts rapidly. However, as in the case of the conventional silver brazing clad lead pin, the brazing structure that has once undergone melting and solidification has an α phase rich in silver and a β rich in copper.
The phase and the (α + β) phase become a clearly separated macroscopic mixture. Therefore, melting starts from a eutectic composition phase and then gradually progresses to a phase with a high melting point, so that it begins to flow later in time as compared with the unmelted wax described above, and it is extremely high. Progress slowly. As a result, the fluidity and wettability of the solder are poor, and the probability of occurrence of brazing defects increases. On the other hand, since the wax attached to the lead pin body by the method of the present invention has a uniform structure, the flowability and wettability are maintained in a suitable state.

(Effect of the Invention) As described above, according to the lead pin of the present invention, since the silver brazing member is joined to the lead pin body without substantially undergoing melting and solidification, the conventional defect, that is, the molten silver brazing member, is prevented. It is possible to avoid the harmful effect of flowing from the top surface of the top of the main body and adhering to unnecessary parts,
There are few variations among the lead pins, automation at the time of mounting is performed with high yield, and advantages such as saving silver solder can be obtained.

Further, the structure of the silver brazing member remains substantially in a uniform state before its attachment, and the main brazing can be performed while maintaining the fluidity and wettability of the silver brazing material in a good state. Suitable brazing can be achieved.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a diagram showing an example of a lead pin manufactured by the method of the present invention. As shown in the figure, the lead pin 1 is composed of a lead pin body 3 and a silver brazing member 5, and has a structure in which the silver brazing member 5 is diffusion-bonded to the top surface 31b of the lead pin body 3.

As shown in FIG. 2, the lead pin body 3 includes a disk-shaped head portion 31 and a cylindrical leg portion 33 coaxially formed on the lower surface 31a. To give an example of the dimensions of each part, the above head has a diameter of 0.75 mm and a thickness of 0.2 mm.
The leg has a diameter of 0.44 mm and a leg length of 4.5 mm.
Is. The lead pin body having such a shape is made of Kovar.

As shown in FIG. 3, the silver brazing member 5 is obtained by cutting from a wire 51 having a square cross section, and has a substantially cubic shape. The silver brazing member is sized to fit within the top surface of the top of the lead pin body. For a lead pin body having the above dimensions, one side of the silver brazing member may be 0.46 mm. The silver brazing material is made of 85 silver-copper alloy.

Next, a process of joining the lead pin body 3 and the silver brazing member 5 will be described. First, as shown in FIG. 4, the lead pin body 3 and the silver brazing member 5 are attached to the top surface 31 of the top of the lead pin body.
With the silver brazing member 5 placed on b, it is set in the refractory jig 7. After that, these are placed in an atmosphere furnace in which the mixing ratio of nitrogen and hydrogen is adjusted to 5: 1 and heated at 760 ° C. for 10 minutes. In this manner, the original shape of the silver brazing member 5 is kept almost unchanged, and the silver brazing member 5 is diffusion-bonded to the upper surface 31b of the top portion of the lead pin body without melting.

Here, the lead pin formed by the above method,
The fluidity with a conventional silver brazing lead pin having a silver brazing part formed by melting was compared by measuring the fillet height. That is, five lead pins of the present invention are used as the lead pins of the present invention, and the conventional example has the same amount as the silver brazing clad lead pin of the present invention (about 1).
As shown in FIG. 5, the fillet height H when the lead pins A were brazed to the nickel plate B was measured by using the same five pieces having silver braze of (milligram).

 The results of this comparison are shown in the table below.

As is clear from the above table, the fillet height of the present invention is more than twice as high as that of the conventional one, and the fluidity of the silver solder is maintained in a better state.

It is to be noted that the dimensions and compositions of the respective portions in the above-mentioned examples are shown, and the present invention is not intended to be limited to these.

In addition, for the joining of the silver brazing material, it is possible to use spot welding, ultrasonic welding, etc. in addition to the heating below the melting point of the silver brazing material in vacuum or atmosphere as described in the present embodiment. Even by the method, the original shape at the time of supplying the silver brazing material can be substantially maintained, and the bonding can be achieved while the structure of the silver brazing material is maintained almost the same as at the time of supplying the silver brazing material, and the same effects and functions as those in the above-described embodiment can be exhibited. .

[Brief description of drawings]

FIG. 1 is a perspective view showing a lead pin according to an embodiment of the present invention,
2 is a side view showing the lead pin body of FIG. 1, FIG. 3 is a perspective view showing the silver solder of FIG. 1, FIG. 4 is a cross-sectional view for explaining the joining process of the silver solder members, and FIG. Explanatory drawing showing the fillet height in a fluidity comparison test, FIG. 6 is a sectional view showing a conventional silver brazing method, FIG. 7 is a side view showing an ideal state of molten silver brazing, and FIG. And FIG. 9 is a side view showing a state of the silver solder flowing from the top surface of the top of the lead pin body. 1 ... Lead pin 3 ... Lead pin body 5 ... Silver brazing member 7 ... Jig 31 ... Top of lead pin body 31a ... Top bottom surface 31b ... Top top surface 33 ... Legs

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshio Sekine, Yoshino Sekine 2-9-12 Kajicho, Chiyoda-ku, Tokyo Inside Tokuriki Honten Co., Ltd. (72) Hironobu Yamamoto 2-9-12 Kajimachi, Chiyoda-ku, Tokyo Incorporated company Tokuriki main store (72) Inventor Takashi Nara 2-9-12 Kajimachi, Chiyoda-ku, Tokyo Incorporated company Tokuriki main store (56) Reference JP-A-60-166163 (JP, A) Sho-60-121063 (JP, A)

Claims (2)

[Claims] 1. A lead pin used for an external terminal of an IC ceramic package, which comprises a lead pin body and a silver brazing member attached to one end surface of the lead pin body, the silver brazing member being diffusion bonded to the lead pin body. A lead pin that is characterized by being. 2. A method of manufacturing a lead pin used for an external terminal of an IC ceramic package, wherein the lead pin comprises a lead pin body and a silver brazing member, wherein the lead pin body and the silver brazing member are in vacuum or non-oxidizing. Heating in an atmosphere to a temperature below the melting point of the silver solder,
A method for manufacturing a lead pin, characterized in that both of these materials are diffusion bonded.