JPH01273690A - Material for brazing - Google Patents

Abstract

PURPOSE:To provide a material for brazing which can securely braze two members having the coefft. of thermal expansion varying largely from each other by incorporating a specific ratio of In and specific ratio of Sb into Ag. CONSTITUTION:The material for brazing is constituted by incorporating at least one kind of In and Sb at 1.0-15.0wt.% into the Ag. The hardness of the material for brazing itself can be lowered by this compsn. The stress generated between the two members having the coefft. of thermal expansion varying largely from each other is absorbed and removed by deforming the soft material for brazing in case of brazing the two members by using this material for brazing. As a result, the two members are securely brazed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brazing material, and more particularly to an improvement in a brazing material used for brazing external lead terminals in electronic components.

(Prior art and its problems) Conventionally, silver solder made of an alloy of 70 to 90% by weight of silver and 10 to 30% by weight of copper is not subject to many restrictions on joining members and has a low operating temperature range (melting temperature range). It is widely used as a material for brazing external lead terminals in electronic components, such as semiconductor device storage packages and circuit wiring boards that house semiconductor devices.

However, because this conventional silver solder has a Pinkers hardness (Hν) of 82 to 90 and is hard, two materials with significantly different coefficients of thermal expansion, such as mullite, are used in packages for housing semiconductor devices. quality sintered body (thermal expansion coefficient = 4.0~4.5 Xl0-'
/ "C)" and an iron alloy such as Kovar (iron-nickel-cobalt alloy) or 42A11oy (i-nickel alloy) (thermal expansion coefficient: 11.5-13.0X
When external lead terminals made of 10-'/'C) are brazed, a large stress is generated in the brazed part due to the difference in coefficient of thermal expansion between the two, and as a result, a small external force is applied to the external lead terminal. Even when applied, the external force becomes large in combination with the above-mentioned intrinsic stress, and has the disadvantage that the external lead terminal is peeled off from the insulating container.

(Purpose of the Invention) In view of the above-mentioned drawbacks, the present inventors have conducted various experiments on alloy components with silver (Ag) to replace copper (Cu) in conventional brazing materials, and found that indium (In
), antimony (Sb) lowers the operating temperature range of the brazing filler metal, improves wettability with joining parts, and prevents migration of flu (Ag), the main component of the brazing filler metal (
In addition, the hardness of the brazing material is reduced, and when two components with significantly different coefficients of thermal expansion are brazed, the stress generated between the two components is absorbed and removed by deformation of the brazing material. It has been found that both members can be firmly joined by doing so.

The present invention is based on the above findings, and in addition to the advantages of conventional brazing in that the operating temperature range is low and there are no major restrictions on the parts to be joined, it is also possible to firmly braze two members with significantly different coefficients of thermal expansion. The aim is to provide a possible new brazing material.

The present invention is applicable to electronic components having external lead terminals, specifically, as a material for brazing external lead terminals of semiconductor element housing packages, hybrid IC wiring boards, capacitors, resistors, microswitches, etc. Preferably used.

(Means for Solving the Problems) The brazing material of the present invention is characterized by containing 1.0 to 15.0% by weight of at least one of indium and antimony in silver.

In the brazing material of the present invention, indium (In) and antimony (Sb) are added to reduce the hardness and operating temperature range of the brazing material, improve wettability with joining members, and serve as main components of the brazing material. It is a component for preventing the migration of the component ill(Ag), and if its content is less than 1.0% by weight, the desired properties will not be imparted, and if the content is less than 1.0% by weight, the desired properties will not be imparted. If it exceeds this, the hardness of the brazing material will increase, and when brazing two components with significantly different coefficients of thermal expansion, the brazing material will not be able to absorb the stress that occurs between the two components well, resulting in a decrease in brazing strength. Indium (In)
, antimony (Sb) has a content of 1.0 to 15.
It is specified in the range of 0% by weight.

(Example) Next, the present invention will be explained based on examples.

First, silver (Ag), indium (In), and antimony (Sb) were weighed as starting materials so that they had the compositions shown in Table 1, and they were heated and melted to form il (Ag), indium (In), and antimony (Sb). Sb) is alloyed and processed into a desired shape to obtain a collage material sample.

Incidentally, sample number 14 is a comparative sample for comparison with the product of the present invention, and is a conventionally commonly used silver solder (silver wax: 2% by weight, fl: 28% by weight).

Next, using each obtained brazing material sample, the coefficient of thermal expansion of the mullite sintered body = 4.0 to 4.5 xlO-'/'c
) with a width of 0.4 mm, a length of 20 mm, and a thickness of 0.15 mm on 20 tungsten metallized metal layers of 5 mm x 2 mm (area: 10 mm).
Kovar (coefficient of thermal expansion: 11.5-13.OX 10
-h/℃) at one end of the external lead terminal.
The brazing condition was observed using a microscope, and an external force was applied perpendicular to the brazing surface to one end of the external lead terminal opposite to the brazing part. The number of particles peeled off from the substrate consisting of aggregates was investigated.

The brazing area of the external lead terminal is 0.4 m wide.
m, length 2.5 mm x 1.0 mm'', and nickel (Ni) and gold (Au) are applied to the tungsten metallized metal layer provided on the substrate made of mullite sintered body and the outer surface of the external lead terminal, respectively. It is layered by plating.

The above results are shown in Table 1.

(Hereinafter, blank space) As is clear from the above experimental results, the conventional silver solder (sample number 14) has a hardness (Vickers hardness) of 82 and is hard, so two members with significantly different coefficients of thermal expansion were brazed together. In this case, if a force of 3 kg is applied to one member after brazing, both members will completely peel off, and the brazing strength of the brazing material is extremely low, whereas the brazing material of the present invention Its hardness (Vickers hardness) is 67
It is clear that the brazing strength of the brazing material is extremely high, as even if an external force of 4 kg is applied to one of the members after brazing, the two members do not peel off at all because the brazing material is soft.

Next, the migration of each brazing material sample (
(transition) is investigated by the acceleration test shown below.

To investigate, first, a pair of rectangular metallized metal layers with a width of 2.7 mm and a length of 20 mm are formed on a substrate made of a mullite sintered body so that their tips face each other with an interval of 0.7 mm. At the same time, about 900 of each brazing material sample shown in Table 1 was applied to the entire outer surface of the metallized metal layer.
It is applied by heating and melting at a temperature of 30°F.

Next, pure water of 50μβ was dropped between the pair of metallized metal layers to which each brazing material sample was adhered, and a DC voltage of 10V was applied to transfer silver from each brazing material sample at an accelerated rate. The time required for both metallized metal layers to become short-circuited due to migration was determined, and the length of time was used to evaluate the migration resistance of each brazing material sample.

The metallized metal layer provided on the mullite sintered body was made of tungsten, and a layer of nickel (Ni) was deposited on the surface of the metallized metal layer by plating.

The above results are shown in Table 2.

(Hereinafter, blank space) Sample numbers marked with * in Table 2 are outside the scope of the present invention. As is clear from the above experimental results, indium (In), antimony ( When the amount of Sb) is small, the migration of silver (Ag) contained in the brazing material is rapid, resulting in a short circuit between metallized metal layers in a short period of time, whereas indium (In)
The products of the present invention (sample numbers 3 to 12) with an antimony (Sb) content of 1.0 to 15.0% by weight have slow silver (Ag) migration, similar to conventional silver wax. , insulation between two adjacent metallized metal layers can be maintained for a long time.

(Effects of the Invention) As described above, according to the brazing material of the present invention, silver (Ag
) containing 1.0 to 15.0% by weight of at least one of indium (In) and antimony (Sb), the brazing material itself can have a low hardness, and When two members with significantly different coefficients of thermal expansion are brazed using materials, the stress generated between the two members is absorbed and removed each time the soft brazing material is deformed, and as a result, the stress between the two members is reduced. It becomes possible to braze extremely firmly.

In addition, the brazing material of the present invention has excellent wettability and migration resistance with bonding members, and, like conventional silver solder,
It can also be suitably used as a material for brazing external lead terminals of electronic components in which a large number of external lead terminals are brazed in close proximity.

Claims (1)

[Claims] Silver with at least one of indium and antimony at 1.0
A brazing material characterized by containing from 15.0% by weight.