JPH06182580A - Low alpha-ray pb alloy solder material and solder film - Google Patents

Abstract

PURPOSE:To provide an inexpensive low alpha-ray Pb alloy solder material for a semiconductor device assembly. CONSTITUTION:The low alpha-ray Pb alloy solder material is made of a material obtained by incorporating one kind or two kinds or more of Na, Sr, K, Ga, Cr, Nb, Mn, V, Ta, Si, Zr and Ba by 10 to 5000ppm in total to a solder material constituted of a Pb alloy with compositions containing one kind or two kinds of 1-65% Sn and 1-65%, by wt., further containing one kind or two kinds of 1-15% Sb and 1-10% Ag if necessary, and the remainder Pb with inevitable impurities.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to die-bonding Si chips such as IC and LSI to substrates, lead frames, ceramic packages, etc., and ceramic packages made of metal or ceramics. Low α ray Pb for semiconductor device assembly used when sealing with a lid made of
The present invention relates to an alloy solder material and a solder film. 2. Description of the Related Art Conventionally, in the assembly of semiconductor devices such as ICs and LSIs, the count number of α particles emitted from the surface is 0.5 per cm ² for the purpose of preventing a memory error.
Count / hour (hereinafter referred to as CPH), Sn: 1 to 1
65%, In: 1 to 65%, 1 or 2 types, further, if necessary, Sb: 1 to 15%, Ag: 1 to 10
%, A solder material composed of a Pb alloy having a composition containing one or two of Pb and the balance Pb and inevitable impurities (above,% by weight and below% indicates% by weight) is known. (See JP-A-58-151037, JP-B-62-54597, JP-A-3-207596, etc.). To produce a Pb alloy solder material having a small number of α particles counted, ²³⁸ U of decay nuclide is used.
Special Pb obtained by carefully selecting ore from a mine with a small amount of ²¹⁰ Pb from the sampling stage, refining it while paying attention to contamination, and refining it by vacuum melting and zone melting is used as a Pb raw material. However, there is a limit to the reserves of ores having a low ²¹⁰ Pb content, and it is becoming difficult to find an ore in such a mine each year, and Pb obtained from this ore is difficult to find. The price also rises, which makes it difficult to supply a large amount of Pb alloy solder with a small number of radioactive α particles counted at low cost. Therefore, ²¹⁰ P contained in ordinary Pb raw materials is used.
b reduced to less than 5ppb by centrifugation device, the ²¹⁰
Pb: It is possible to manufacture a Pb alloy solder with a low count of radioactive α particles by using a Pb raw material of less than 5 ppb, but a Pb raw material with a reduced ²¹⁰ Pb content using such a method becomes too expensive. Therefore, it cannot be used in the field of consumer electronic devices. [0006] Therefore, the present inventors,
As a result of research to obtain a Pb alloy solder having a small radioactive α particle count number even when using a normal Pb raw material, a normal Pb raw material was used, and Sn: 1 to 65%, In: 1
1 to 2 of 60% to 65% is added, and further, if necessary, Sb: 1 to 15%, Ag: 1 to 10%
To the Pb alloy solder obtained by adding and melting one or two kinds, and further adding Na, Sr, K, Ga, Cr, Nb, M
Studies have shown that when one or more of n, V, Ta, Si, Zr, and Ba are contained in a total amount of 10 to 5000 ppm, the radioactive α particle count decreases to 0.5 CPH / cm ² or less. It was obtained. The present invention was made based on the results of such research, and Sn: 1 to 65%, In: 1 to
65%, 1 or 2 out of 65%, and if necessary,
Sb: 1 to 15%, Ag: 1 to 10%, one or two of them, and the balance is composed of a Pb alloy having a composition of Pb and inevitable impurities.
r, K, Ga, Cr, Nb, Mn, V, Ta, Si, Z
10 to 50 in total of 1 or 2 or more of r and Ba
This is a feature of the Pb alloy solder material containing 0.00 ppm. N contained in the Pb alloy solder of the present invention
a, Sr, K, Ga, Cr, Nb, Mn, V, Ta, S
The reason why one or more of i, Zr and Ba is limited to 10 to 5000 ppm in total is that these components are 1
This is because even if the content is less than 0 ppm, sufficient effect cannot be obtained to reduce the count number of the radioactive α particles, while if the content exceeds 5000 ppm, the solderability is deteriorated, which is not preferable. . Further, the Pb alloy solder material of the present invention is
It can also be used as a solder film such as a vapor deposition film or a plating film. Example 1 Pb having a purity of 99.9995% obtained by further purifying commercially available high-purity Pb by a zone melting method was prepared as a Pb raw material. On the other hand, all S having a purity of 5 nines
n, In, Sb, Ag are prepared, and Na, Sr, K, Ga, Cr, Nb, Mn, having a purity of 5 nines are prepared.
V, Ta, Si, Zr and Ba (hereinafter, these metals are collectively referred to as "other metals") were prepared. The above Pb, Sn, In, Sb, Ag and other metals are melted in an Ar atmosphere, melted to the composition shown in Tables 1 to 3 and cast into an ingot, which is then rolled. And a thickness of 1 mm, the Pb alloy solder material of the present invention (hereinafter referred to as the solder material of the present invention) 1 to
23, comparative Pb alloy solder materials (hereinafter referred to as comparative solder materials) 1 to 12 and conventional Pb alloy solder materials (hereinafter referred to as conventional solder materials) 1 to 4 were produced. The solder materials 1 to 23 of the present invention, the comparative solder materials 1 to 12 and the conventional solder materials 1 to 4 radiate 2 to
The count number of α particles of 10 MeV was measured by a gas flow type α ray counter, and the measurement result was used as α dose.
The results are shown in Table 3. [Table 1] [Table 2] [Table 3] From the results shown in Tables 1 to 3, the solder materials 1 to 12 of the present invention containing other metals have a significantly reduced α dose as compared with the conventional solder material 1 containing no other metals. I understand. However, as can be seen from the comparative solder materials 1 to 12, it can be seen that even if the total amount of other metals is less than 10 ppm, a sufficient α dose reduction effect cannot be obtained. Example 2 A 4-inch Si wafer was prepared, and on the surface of the 4-inch Si wafer, 1: 100 g of the conventional solder having the composition of Pb-10% Sn shown in Table 3 and each element of other metals: 0. 02 g was vapor-deposited at the same time to form solder vapor deposition films 1 to 12 of the present invention having the composition shown in Table 4. On the other hand, for comparison, the conventional solder of 1: 100 g in Table 3 was directly deposited on the surface of the 4-inch Si wafer to form the conventional solder deposition film 1. The α doses of the above-described solder vapor deposition films 1 to 12 of the present invention and the conventional solder vapor deposition film 1 were measured in the same manner as in Example 1, and the measurement results are shown in Table 4. [Table 4] From the results shown in Table 4, the solder vapor deposition films 1 to 12 of the present invention obtained by vapor deposition of other metals at the same time,
It can be seen that the α dose is remarkably reduced as compared with the conventional solder deposition film 1 containing no other metal. As for the solder film, the example of the vapor-deposited solder film was shown, but the same effect was obtained for the wet-plated solder film. As described above, according to the present invention, ordinary Pb is used.
Since a low α-ray Pb alloy solder can be produced by using as a raw material, a low α-ray Pb alloy solder material for semiconductor device assembly can be provided at low cost, which can greatly contribute to the development of the electronic device industry. .

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Claims (1)

Claims: 1% by weight of Sn: 1 to 65%, In: 1 to 65%, and if necessary, Sb: 1 to 15%, Ag 1-10% of 1 type or 2 types, and further contains Na, Sr, K, Ga, Cr, Nb, Mn, V, Ta,
1 or 2 or more of Si, Zr and Ba in total 1
A low α-ray Pb alloy solder material having a composition of 0 to 5000 ppm and the balance of Pb and inevitable impurities. 2. A solder film comprising a low α ray Pb alloy solder material having the component composition according to claim 1.