JPS5964790A - Tin with low count nunber of radioactive alpha particle and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain tin suitable for an electronic material, by a method wherein an electrolyte containing a tin salt and sulfamic acid each in a predetermined concn. is used and high purity tin is used as an anode to perform electrolysis under a predetermined condition. CONSTITUTION:An electrolyte having a liquid composition containing 30-50g/l of tin and 30-200g/l of sulfamic acid is prepared. This electrolyte and an anode containing 99.95wt% or more of tin are used to perform electrolysis under such a condition that cathode current density is 0.5-2A/dm<2> and a liquid temp. is 15-50 deg.C. The tin with radioactive isotope content of less than 30 ppb and a radioactive alpha-particle count number of 0.2CPH/cm<2> or less is obtained. This tin is especially used in an alloy with gold as the bonding solder material of a semiconductor apparatus member.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low radioactive alpha particle count suitable for electronic materials and a method for producing the same.

In recent years, the use of tin as an electronic material has been expanding.1 For example, tin is used as a device component when assembling not only ICs but also memories such as 64KRAM, which is a large capacity sewing memo + 7-element, and semiconductor devices such as 1 LSI each. As a brazing material for bonding, in particular, 80% AU-20% Sn is used as a brazing material for Ceramic Pack-948.

However, conventionally commercially available f-! ilJm or imported tin has a large amount of violet containing radioactive isotopes, especially U and Th, so the alpha particle d is 2~I OCPH/
Cm2 and Nao (, due to this influence the future 256 KRA
When using a VLSI button such as M'PI megabit RAM, which requires higher 1D orderliness, it is highly likely that II problems that will cause soft errors will occur.

The inventors of the present invention have made all the above points, and have investigated the radioactive properties of tin suitable for the above-mentioned boko material. As a result of 41 studies, the acid content of radioactive isotopes in tin as a product was less than 30 ppb, and the radioactive alpha particle count was 0.2 CPH/
cm'' or less, and solved the problem by applying the N,1 method in which sulfamic acid is dissolved in 1 to create a blue tint in a tin device having such radioactive properties, and completed the present invention. In other words, the gist of non-invention.

ill 99.95＠It has a quality of 99.95 @ or better, the content of radioactive isotopes is 30 ppb, and the count of radioactive α particles is 0.2 CPIi or more. Low alpha particle count tin.

+21 99.95 A fan with a quality of superior or better, AT composition is 8n: 30-130't/
13. In the sulfamine family 30-20011/no, the tortoise shearing is cathode X flow: d+f: 0.5-2.0 Am
p/den', aailt: Furrow x at 15-50°C
The special feature lies in the method of producing a nuisance with a low count of emissive α particles.

Sulfamine + d, which is used as an uninvented and relaxing bath
Even if it is a +11 sales crystal, the late sealing element gold is almost 100.
Therefore, the f pressure is llj phase and 1 grade is 99.95.
Tin r゛r node binding for electrician JT staff and above,
Amin-t-block folding is reversed. Under CC Kanakura 1 self-inspection, that is, γ node: S with quality 99.954t or more
nV & IM configuration: 8n 30~1B0f/e #sulfamine branch 30~20Of-/J Viewing conditions: Sathode current aKO, 5~2.0 Amp
/dm", the radioactive isotopes present in the anode are removed,
One cathode with a low radioactive alpha particle count is clearly visible.

The tin obtained by the lit solution has a quality of 99.95 Arashirokuchi or higher, and the content of radioactive isotopes is 30 ppb.
The number of radioactive α particles is less than 0.2 and the CPH7 is less than 2, making it fully applicable to upper ml electronic materials.

An example of the manufacturing method according to the present invention will be explained using the drawing buttons.

That is, a tin anode 2 having a grade of 99.95% by weight or more and an insoluble cathode plate 3 are inserted into an electrolytic cell 1, and a sulfamic acid aS solution 7 is refluxed by a reflux pump 4, and a direct current is generated.
4 is energized and electrolyzed by the taku device 6.1. I: Tin with a low radioactive α particle count suitable for each Mi electronic material can be obtained.

As described above, the present invention provides tin that is suitable for use as the above-mentioned single-layer material and a method for using it in IA. I will explain in detail.

Example than self-sulfamic acid bath? The measurement results of radioactive isotopes in the Sn cathode and radioactive α particle counting are shown in the table below as Examples 1 to 4. The numerical values in the Sn cathode obtained from hydroxide X acid are shown as Comparative Examples 1 to 4, respectively, together with exa.

As is clear from the following table, the cathode obtained by the method of the present invention has a significantly lower radioisotope concentration and a reduced number of radioactive α particles compared to the anode. was confirmed to be significant.

In the RF1 example, the anode ratio is 9, and the cathode content increases both the [1 and α particle counts of radioactive isotopes. This is thought to be due to the high content of .

4, 1.11 of 1M11ni: jJ-: Explanation Is
+Opening is a tree j:4'J &) 1 island・1'jj 1 row of IH Shi 1 mi demon map 1, n If 1. '16 and 1, 1 φ...Okiichi: jIIf Monk 2 So.
II 11 J+,” (flow pump 5... Akimata + V4
Container 6 ψ・l μ; 1 t L+V, 1 ζ device NN7・11 sulfuric acid liquid

Claims (1)

[Scope of Claims] (Has a quality of 1199,95i or higher, has a radioactive isotope content of less than aoppb, and has a radioactive α particle count of 0.2 CP H/cm” or less. Tin with a low count of radioactive α particles characterized by: (2) Tin with a grade of 99.95 → i highest as an anode;
The liquid composition is 8n: 30-150 f/4. Su, +1
/7 Ami/[[30~200 Ff/6 Te1141.
) l/# line note is cathode 'torque end 11 60, 5~2.
OAmp/dm'', liquid 4[: -m gold at 15 to 50°C, a method for producing tin with a low radioactive alpha particle count;