JPH0466105B2 - - Google Patents

Abstract

PURPOSE:To stabilize the connecting strength of a ceramic substrate and a pin by using a composite pin connected concentrically with a brazing material as a lead pin when opening the lead pin inserting hole at the substrate having a Cu- metallized layer on the surface and inserting the pin into the hole, thereby utilizing the brazing material for brazing with the metallized layer. CONSTITUTION:When a lead pin 4' is inserted and secured to a ceramic substrate 3 formed with a Cu-metallized layer 2 on the surface and a lead pin inserting hole 1, the pin 4' is not formed as a continuous pin, but formed as a composite pin made of Kovar, or Fe-Ni alloy. In other words, pins 4a, 4b are contacted concentrically, bonded with a brazing material 5' of Au or Ag, and the material 5' is swelled at the bonding end with the pins 4a, 4b. After thus constructed and the pin 4' is inserted into the hole 1, they are filled in a furnace, heated, the material 5' is melted, and bonded to the layer 2. Thus, even if the amount of the material 5' is excess or insufficient, it automatically becomes in a meniscus shape, and the pin 4' and the substrate 3 are rigidly coupled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bonding structure using composite lead pins that is attached to a ceramic container used for electronic components such as integrated circuits, diodes, and ceramic capacitors.

Traditionally, lead pins used in electronic components such as integrated circuits and power transistors have been made of Fe-based alloys such as Kovar and Permalloy, or alloys whose main component is Cu, but the characteristics required of lead pins are diversifying. Therefore, what is an advantage in one aspect becomes a disadvantage in another, and there is a problem that lead pins with required characteristics cannot be obtained.

For example, the characteristics required for lead pins include high electrical conductivity, high thermal conductivity, brazing properties,
It has good solderability, good wire bonding properties, good plating properties, good workability, low coefficient of thermal expansion, high strength as a structural material, good corrosion resistance, and is economical. However, a material that has all of these properties has not yet been found.

Materials with high conductivity are soft and easy to bend.
Materials with good corrosion resistance are generally expensive and have their own drawbacks.

Conventionally, in order to braze a lead pin, the lead pin and the Ag solder are made separately, and a metallized layer is placed on the inner circumferential surface of the lead pin insertion hole 1 as shown in Fig. 1.
The lead pins 4 are inserted and set into the lead pin insertion holes 1 of the ceramic substrate 3 formed with the
Ag wax 5 is supplied and heated in a furnace, and Ag wax 5
The lead pins 4 are melted and brazed to the ceramic substrate 3, but the surface of the metallized layer 2 is uneven, and as the alloying between the Ag solder 5 and the metal of the metallized layer 2 progresses, the lead pins 4 are used slightly depending on the respective conditions. The volume of Ag solder 5 required for this process varies, but since brazing is performed with a certain volume of Ag solder 5 supplied in advance, the second
As shown in the figure, the volume of Ag wax 5 is insufficient,
As shown in FIG. 3, poor brazing often occurred due to flow-out due to excessive volume of Ag solder 5, especially variations in the appearance of the brazed part, that is, the shape of the meniscus, and a decrease in brazing strength.

The present invention was made in view of the above circumstances, and
We provide a joint structure using composite lead pins that can automatically supply brazing material to the brazing part, maintain a constant meniscus shape, and stabilize brazing strength even when there is too much or too little brazing material. That is.

In the bonding structure using the composite lead pin of the present invention, in the lead pin that is inserted into the lead pin insertion hole and brazed to the ceramic substrate etc., two lead pins having approximately the same diameter are concentrically opposed with their tip surfaces facing each other. The lead pin is formed into a single lead pin by being brazed so that both ends thereof are wrapped in a brazing material, and the portion positioned within the lead pin insertion hole is brazed.

At least one of the two lead pins 4a and 4b is a lead pin made of Kovar, an iron-nickel alloy, an alloy mainly composed of iron-based alloy and copper such as stainless steel, or Fe, Co, Ni, Mo, W, Ti. , an alloy containing Cu as a main component, or a single lead pin of each of them is preferable.

The brazing material 5' is made of Au, Ag, Cu, Ni, Pd,
It is preferable to use an alloy or a single brazing filler metal whose main component is one of In, Sn, and Pb.

Next, a joining structure using the composite lead pin of the present invention having such a configuration will be explained.

As shown in FIG. 5, a composite lead pin 4' having a bonding structure in the composite lead pin of the present invention is inserted into the lead pin insertion hole 1 of the ceramic substrate 3 in which a Cu metallized layer 2 is formed on the inner peripheral surface of the lead pin insertion hole 1.
is inserted into the lead pin insertion hole 1, and a brazing material 5' which is brazed to cover both tips of the two lead pins 4a and 4b is positioned in the lead pin insertion hole 1. Next, while maintaining this state, it is heated in a furnace to melt the brazing material 5', and as shown in FIG. do.

The ceramic substrate 3 of this composite lead pin 4'
During brazing, the volume of the brazing filler metal 5' is not constant, so if the volume of the brazing filler metal 5' is too large, the tip surfaces of the two lead pins 4a and 4b will be flush with each other as shown in FIG. If the gap 6 is automatically widened and the volume of the filler metal 5' is small, the upper and lower two lead pins 4 are
The gap 6 between the tip surfaces of a and 4b is automatically narrowed, the shape of the meniscus is kept constant, and the brazing strength is stabilized. That is, the shape of the meniscus is determined by the surface tension caused by the spread of the solder material 5' and the surfaces of the lead pins 4a, 4b and metallized layer 2, but the amount of solder material is sufficient to fill the gap 6 between the tip surfaces of the lead pins 4a, 4b. When 5' is insufficient or excessive, the positions of lead pins 4a and 4b are slightly moved up and down to maintain balance, so the shape of the meniscus is always kept constant and the brazing strength is stable. do.

Incidentally, the composite lead pin 4' having a joining structure in the composite lead pin of the present invention has upper and lower lead pins 4a,
4b with a brazing material 5', the material of the upper and lower lead pins 4a, 4b can be arbitrarily selected depending on the object to which the composite lead pin 4' is attached. For example, when attaching to a ceramic container, the lower lead pin 4b
For the upper lead pin 4a, a strong iron-nickel alloy or an alloy such as Kovar can be used, and for the upper lead pin 4a, a copper alloy having good bonding properties with Au wire or the like can be used.

As can be seen from the above explanation, the bonding structure using the composite lead pin of the present invention consists of two upper and lower lead pins with approximately the same diameter, with their tip surfaces facing each other concentrically and brazed so that both tips are wrapped in a brazing material. Therefore, by inserting the brazing material into the lead pin insertion hole, which is the part to be brazed to the ceramic substrate, etc., and brazing in the upper furnace with the brazing material positioned in the lead pin insertion hole, there is no material inside the lead pin insertion hole. Brazing filler metal can be supplied automatically, and if there is too much filler metal, the gap between the tip surfaces of the upper and lower lead pins will automatically widen, and if there is less filler metal, the gap will automatically narrow, forming a meniscus. It has excellent effects such as keeping the shape constant and stabilizing the brazing strength between the lead pin and the ceramic substrate.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a state in which a conventional lead pin is brazed to a ceramic substrate, Figure 2 is a diagram showing a brazing state when Ag solder is insufficient in brazing the lead pin in Figure 1, The figure shows the brazing state when there is too much Ag solder in the brazing of the lead pin in Figure 1, Figure 4 shows the composite lead pin of the joint structure of the composite lead pin of the present invention, and Figure 5. , FIG. 6 is a diagram showing the process of brazing the composite lead pin of the present invention with a bonding structure to a ceramic substrate,
Figure 7 is a diagram showing the situation when too much brazing material is used when brazing the composite lead pin shown in Figure 6;
This figure is a diagram showing a situation when there is a shortage of brazing material in brazing the composite lead pin of FIG. 6. 4a, 4b...lead pin, 5'...brazing metal,
4'...Composite lead pin.

Claims (1)

[Scope of Claims] 1. In a lead pin that is inserted into a lead pin insertion hole that is a part to be brazed to a ceramic substrate or the like for brazing, two lead pins having substantially the same diameter are concentrically arranged with their tip surfaces facing each other, A joining structure using a composite lead pin, characterized in that both ends are brazed so as to be wrapped in a brazing material to form a single lead pin, and a portion positioned in the lead pin insertion hole is brazed. 2. The joint structure using composite lead pins according to claim 1, wherein at least one of the two lead pins is a lead pin made of an alloy whose main components are copper and an iron-based alloy such as Kovar, iron-nickel alloy, or stainless steel. . 3 At least one of the two lead pins is Fe,
A joining structure using a composite lead pin according to claim 1, which is an alloy mainly composed of Co, Ni, Mo, W, Ti, and Cu or a single lead pin of each of them. 4 The brazing filler metal is Au, Ag, Cu, Ni, Pd, In,
The bonding structure using a composite lead pin according to claim 1, which is an alloy or a single brazing filler metal containing either Sn or Pb as a main component.