JPH08215880A - Leadless solder - Google Patents

Abstract

PURPOSE: To lower the melting temp. of leadless solder and to improve wettability and mechanical strength by composing the leadless solder of specific weight% of Ag, Cu and the balance Sn. CONSTITUTION: The leadless solder is formed of an Sn-Ag-Cu system. The compsn. thereof is formed of the balance Sn, 0.5 to 3.5wt.% Ag, 0.5 to 2.0wt.% Cu. There is an effect of lowering the melting temp. and improving the mechanical strength by adding the Ag to the essential component Sn. Further, the microstructures are formed and the mechanical strength is further improved by adding the Cu to the compsn. This leadless solder is used by molding the compsn. to various forms, such as rods, wires, ribbons, preforms and powders. As a result, the long-term stable supply is possible and the leadless solder is provided at a relatively low cost.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、電子機器や電機機器の
回路基板上に小型のチップ部品や半導体部品を精度良く
実装するために、主として用いられる無鉛はんだに関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-free solder mainly used for mounting small chip parts or semiconductor parts on a circuit board of electronic equipment or electric equipment with high accuracy.

【０００２】[0002]

【従来の技術】従来のはんだにおいて使用されている鉛
が毒性を有することから、現在それらの産業廃棄物によ
る環境汚染が問題視されてきている。それ故に、このよ
うな環境面を考慮した無鉛はんだの要求が高まりつつあ
るが、主に、無鉛はんだは、Ｓｎ（スズ）を主成分とし
ているため、従来のはんだに比べて一般的に、融点が高
くなり、ぬれ性も若干劣り、機械的強度が低くなる傾向
が認められる。2. Description of the Related Art Due to the toxicity of lead used in conventional solders, environmental pollution due to these industrial wastes has been regarded as a problem at present. Therefore, the demand for lead-free solder considering such environmental aspects is increasing. However, since lead-free solder mainly contains Sn (tin), it generally has a higher melting point than conventional solder. And the wettability is slightly inferior and the mechanical strength tends to be low.

【０００３】[0003]

【発明が解決しようとする課題】従来の無鉛はんだは、
Ｓｎを主成分としてそのほかにＺｎ、Ｉｎ、Ｓｂ、Ｂｉ
等の元素を添加して、欠点として考えられる融点が高く
なり、ぬれ性が劣り、機械的強度が低くなることを改善
してきた。しかしながら、個々の元素は、一長一短があ
り、たとえば、Ｚｎは、大気中で酸化を受けやすくぬれ
性も悪くなる。Ｓｂは、若干の毒性を有する元素であ
り、Ｉｎは、産出量が少なく供給に問題を有しコスト高
となる。Ｂｉは、主として鉛の副産物でありＢｉを取り
出すには鉛が産出される必要があり、鉛の使用制限に伴
って安定供給性の面で問題がある。従って、すべての欠
点を補足することができる組成を有するはんだは、未完
成のままである。The conventional lead-free solder is
In addition to Sn as the main component, Zn, In, Sb, Bi
By adding such elements as the above, it has been improved that the melting point, which is considered to be a defect, becomes high, the wettability becomes poor, and the mechanical strength becomes low. However, each element has merits and demerits, and, for example, Zn is susceptible to oxidation in the atmosphere and has poor wettability. Sb is an element having some toxicity, and In has a small amount of production and has a problem in supply, resulting in high cost. Bi is mainly a by-product of lead, and it is necessary to produce lead in order to take out Bi, and there is a problem in terms of stable supply due to restrictions on the use of lead. Therefore, a solder with a composition that can complement all the drawbacks remains unfinished.

【０００４】[0004]

【課題を解決するための手段】本発明の無鉛はんだは、
上記課題を解決するため、Ｓｎ−Ａｇ−Ｃｕ系はんだを
選定し、その組成が、Ｓｎ残部、Ａｇ０．５〜３．５重
量％、Ｃｕ０．５〜２．０重量％よりなることを特徴と
する。The lead-free solder of the present invention comprises:
In order to solve the above problems, a Sn-Ag-Cu solder is selected, and the composition thereof is the balance of Sn, Ag 0.5 to 3.5% by weight, and Cu 0.5 to 2.0% by weight. To do.

【０００５】[0005]

【作用】本発明は、上記の構成により、次のような作用
を有する。The present invention has the following functions due to the above-mentioned structure.

【０００６】主成分ＳｎにＡｇを添加することにより、
溶融温度を低下させると共に機械的強度を改善する効果
があるが、添加量が０．５重量％未満では、その効果は
不十分で、一方３．５重量％を超えると添加してもその
効果は少なく、コスト高となる。By adding Ag to the main component Sn,
It has the effect of lowering the melting temperature and improving the mechanical strength, but if the addition amount is less than 0.5% by weight, the effect is insufficient, while if it exceeds 3.5% by weight, the effect is obtained. Is less and costs more.

【０００７】主成分ＳｎにＡｇを添加したものにＣｕを
添加することにより、組織の微小化を計り、機械的強度
は更に改善される。Ｃｕ添加量は、０．５重量％未満で
は、その効果は少なく、２．０重量％を超えると、溶融
温度が高くなり、部品やプリント基板に熱的損傷を与え
る。By adding Cu to the main component Sn to which Ag is added, the structure is made finer and the mechanical strength is further improved. If the added amount of Cu is less than 0.5% by weight, its effect is small, and if it exceeds 2.0% by weight, the melting temperature becomes high and the components and the printed circuit board are thermally damaged.

【０００８】本発明は、Ｓｎ、Ａｇ、Ｃｕの元素を上記
組成範囲で混合させることにより、溶融温度をＳｎ−Ｐ
ｂ共晶はんだの融点（１８３℃）にできるだけ近づける
ことができると共に、ぬれ性及び機械的強度の優れた無
鉛はんだを提供することができる。According to the present invention, the melting temperature is Sn-P by mixing the elements Sn, Ag and Cu in the above composition range.
b It is possible to provide a lead-free solder that is as close to the melting point (183 ° C.) of the eutectic solder as possible and that is excellent in wettability and mechanical strength.

【０００９】[0009]

【実施例】実施例１〜実施例６として、表１に示す組成
の無鉛はんだを製作した。そして、各溶融温度とぬれ性
とを評価した。EXAMPLES As Examples 1 to 6, lead-free solders having the compositions shown in Table 1 were manufactured. Then, each melting temperature and wettability were evaluated.

【００１０】[0010]

【表１】 [Table 1]

【００１１】比較例として、表２に示す組成のＳｎ−Ａ
ｇ系はんだを選定し、その溶融温度とぬれ性とを評価し
た。As a comparative example, Sn-A having the composition shown in Table 2 is used.
A g-based solder was selected and its melting temperature and wettability were evaluated.

【００１２】[0012]

【表２】 [Table 2]

【００１３】ぬれ性の評価は、各はんだ組成でフラック
ス３重量％を含有するやに入りはんだＪＩＳ特性Ｂ級
（線径１．６ｍｍ）を作成し、やに入りはんだの重量が
約３００ｍｇになるようにリング状に切断したものを試
験片とした。試験片は、酸化処理した銅板（３０×３０
×０．３ｍｍ）の上に置き、液相温度２５０℃のホット
プレート上に３０秒間のせた後、ＪＩＳ−Ｚ−３１９
７，６．１０．の広がり率により評価した。The wettability was evaluated by making a flux cored solder JIS characteristic class B (wire diameter 1.6 mm) containing 3 wt% of flux in each solder composition, and the flux weighted flux of approximately 300 mg. The test piece was cut into a ring shape. The test piece was an oxidized copper plate (30 × 30
(× 0.3 mm) and placed on a hot plate having a liquidus temperature of 250 ° C. for 30 seconds, and then JIS-Z-319.
7, 6.10. It was evaluated by the spread rate.

【００１４】○ 広がり率８０％以上 □ 広がり率７９〜７５％ △ 広がり率７４〜７０％ × 広がり率６９％以下 表１、表２から明らかなように、実施例１〜実施例６
は、いずれもぬれ性は比較例と同等以上に良く、溶融温
度も比較例より低くなっていた。○ Spreading rate 80% or more □ Spreading rate 79 to 75% △ Spreading rate 74 to 70% × Spreading rate 69% or less As apparent from Tables 1 and 2, Examples 1 to 6
In all cases, the wettability was better than or equal to that of the comparative example, and the melting temperature was lower than that of the comparative example.

【００１５】本発明の無鉛はんだは、棒、ワイヤ、リボ
ン、プリフォーム、粉末等の種々の形態に成形して用い
られる。The lead-free solder of the present invention is formed into various shapes such as rods, wires, ribbons, preforms and powders.

【００１６】[0016]

【発明の効果】本発明の無鉛はんだは、溶融温度を低く
でき、ぬれ性及び機械的強度も良好である。さらに入手
し易い元素を使用しているので、長期的に安定な供給が
可能で、比較的低コストで提供できるものである。The lead-free solder of the present invention can have a low melting temperature, and has good wettability and mechanical strength. Furthermore, since an easily available element is used, it is possible to provide stable supply for a long period of time and to provide it at a relatively low cost.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 尾本 多佳彦 大阪府堺市築港浜寺西町７番21号石川金属 株式会社内 (72)発明者 尾崎 仁一 大阪府堺市築港浜寺西町７番21号石川金属 株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiko Omoto 7-21 Chikkohama Nishimachi, Sakai City, Osaka Prefecture Ishikawa Metal Co., Ltd. Ishikawa Metal Co., Ltd.

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 はんだ組成が、Ｓｎ残部、Ａｇ０．５〜
３．５重量％、Ｃｕ０．５〜２．０重量％からなる無鉛
はんだ。1. A solder composition having a balance of Sn, Ag 0.5 to
Lead-free solder consisting of 3.5 wt% and Cu 0.5-2.0 wt%.