JPH06269984A - Low melting solder alloy - Google Patents

Abstract

PURPOSE:To improve the joint strength of an Sn-Pb solder alloy by adding specific ratios of low melting elements, such as Bi and In, and Ge to this solder alloy. CONSTITUTION:Ge is incorporated at 0.1 to 1% by weigh and >=1 kinds of Ag and Pd at 0.01 to 3% by weight into the Sn-Pb solder alloy contg. 2.7 to 20% Bi by weight, by which the boundary strength of the alloy is improved and the joint strength is improved. A low melting solder alloy formed by adding 2.7 to 20% Bi to a solder alloy consisting of Sn in a 20 to 80% component range and Pb in a 20 to 80% component range has the m. p. falling with an increase in the amt. of the Bi to be added and the degradation in the joint strength is significant as well and, therefore, such defect is ameliorated by adding the Ge, Ge-Ag or Ge-Ag-Pb to this alloy The amt. of the Ge to be added at this time is most adequately 0.1 to 1.0%. There are substantially no effects of addition if the amt. is <=1.0%. The effect is lost at >=1.0%. The addition of the Ag leads to an improvement in the strength and elongation of the solder itself. The addition of the Pd contributes to an improvement in soldering strength by dispersing in the form of fine particles into the solder.

Description

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

【０００１】[0001]

【産業上の利用分野】本発明は従来のＳｎ−Ｐｂ系ハン
ダにＢｉ、Ｉｎを添加した低融点ハンダを用いた場合の
接合強さの低い欠点を、Ｇｅの単独添加、もしくはＡ
ｇ、ＰｄとＧｅの複合添加によって接合強さを改善した
ハンダ合金。BACKGROUND OF THE INVENTION The present invention has the disadvantage of low bonding strength when using a low melting point solder in which Bi and In are added to a conventional Sn-Pb-based solder.
Solder alloy with improved joint strength by the combined addition of g, Pd and Ge.

【０００２】[0002]

【従来の技術と問題点】電子部品は一般に素子等の個別
部品を印刷基板に搭載し、これをハンダ付けすることに
よって、はじめて回路が形成される。これらのハンダ付
けは通常Ｓｎ−Ｐｂ二元合金を主体とするハンダ合金が
用いられるが、素子は高温加熱することによって少なか
らずその特性が劣化する場合が多い。したがって現行の
Ｓｎ６３％−Ｐｂ３７％共晶ハンダの融点１８３℃より
さらに低い融点のハンダ合金が望まれている。また電子
回路の高密度化が進む中で基板の両面ハンダ付けを行な
う趨勢にあり、この場合片面をハンダ付けした後の反対
面をハンダ付けするには先の融点より低い融点のハンダ
合金を用いる方が有利である。その他最近コストダウン
の目的から耐熱性の低い素子、部品を採用する傾向にあ
り、この点からも低融点ハンダ合金が要望されている。
現在までに低融点ハンダ合金と称してＳｎ４６％−Ｐｂ
４６％−Ｂｉ８％の他にさらに低融点を目的としてＢｉ
１２％、Ｂｉ １４％のごとくＢｉを増加したハンダ
合金も一部実用化されているが、これらの低融点ハンダ
合金は従来のＳｎ−Ｐｂ共晶ハンダに比べ、接合強さが
劣ることが工業化を阻んでいる現況である。いまＳｎ６
３％−Ｐｂ３７％の共晶とＳｎ％−Ｐｂ４６％−Ｂｉ８
％及びＳｎ４３％−Ｐｂ４３％−Ｂｉ１４％ハンダ合金
の融点と銅を母材とし、重ね継手試験片によるせん断強
さの関係を第１表に示す。このようにＢｉを添加するこ
とによって融点は降下するが、半面接合強度の低下が顕
著である。2. Description of the Related Art Generally, electronic parts are mounted with individual parts such as elements on a printed board and soldered to form a circuit for the first time. For these soldering, a solder alloy mainly composed of a Sn-Pb binary alloy is usually used, but the characteristics of the element are often deteriorated to some extent by heating at a high temperature. Therefore, a solder alloy having a melting point lower than the melting point of 183 ° C. of the existing Sn63% -Pb37% eutectic solder is desired. In addition, there is a tendency to solder both sides of the board as the density of electronic circuits increases. In this case, to solder the opposite side after soldering one side, use a solder alloy with a melting point lower than the previous melting point. Is more advantageous. In addition, recently, there is a tendency to adopt elements and parts having low heat resistance for the purpose of cost reduction, and from this point as well, a low melting point solder alloy is demanded.
To date, Sn46% -Pb has been called a low melting point solder alloy.
In addition to 46% -Bi8%, Bi for the purpose of lower melting point
Some solder alloys with increased Bi such as 12% and 14% Bi have been put into practical use, but these low-melting-point solder alloys are industrialized because their bonding strength is inferior to the conventional Sn-Pb eutectic solder. It is the current situation that is blocking Now Sn6
3% -Pb 37% eutectic and Sn% -Pb 46% -Bi8
% And Sn43% -Pb43% -Bi14% solder alloy and the copper as the base material, the relationship between the shear strength by the lap joint test piece is shown in Table 1. Although the melting point is lowered by adding Bi as described above, the half-face bonding strength is remarkably lowered.

【０００３】 [0003]

【０００４】ハンダ付け部の強さを試験する前に予めハ
ンダ自身の強さを測定した結果、Ｓｎ６３％．Ｐｂ３７
％共晶とＳｎ４６％−Ｐｂ４６％−Ｂｉ８％ハンダでは
殆ど差異がないことから、接合強さは母材と溶融ハンダ
との反応によって生成する合金層の影響が大きく関与
し、Ｂｉの添加によってこの合金層とハンダの境界が脆
弱になることを見いだした。The strength of the solder itself was measured in advance before the strength of the soldered portion was tested. Pb37
% Eutectic and Sn46% -Pb46% -Bi8% solder have almost no difference. Therefore, the bonding strength is greatly influenced by the alloy layer formed by the reaction between the base material and the molten solder, and the addition of Bi causes We found that the boundary between the alloy layer and the solder became weak.

【０００５】[0005]

【問題を解決するための手段】本発明の低融点ハンダ合
金にＧｅの単独添加、もしくはＡｇ、ＰｄとＧｅの複合
添加は脆弱になる合金層と界面の強化改善に効果があ
り、特許請求範囲の構成により上記問題点を解決した。The sole addition of Ge or the combined addition of Ge, Ag, Pd and Ge to the low melting point solder alloy of the present invention is effective in improving the strengthening of the brittle alloy layer and the interface. The above-mentioned problem is solved by the configuration.

【０００６】[0006]

【作用効果】Ｓｎ２０〜８０％、Ｐｂ２０〜８０％の成
分範囲からなるハンダ合金にＢｉ２．７〜２０％添加し
た低融点ハンダ合金は、Ｂｉの添加量の増加と共に融点
降下が大きくなるが、接合強さの低下も著しくなる。そ
の欠点を本発明合金に添加したＧｅおよびＧｅ−Ａｇ，
Ｇｅ−Ａｇ−Ｐｄ添加によって改善される。この際のＧ
ｅの添加量は０．１〜１．０％が最適で０．１％以下で
はまその効果がほとんどなく、１．０％以上では脆弱と
なりその効果を失う。Ａｇの添加はハンダ自身の強さ、
伸びの改善に効果があり、また若干の融点降下の作用も
ある。その添加量は０．５〜３％が適当である。Ｐｄの
添加量は０．０１〜１％が適当で、ハンダ中に微細粒子
として分散し、分散強化によってハンダ付け強度の向上
にも貢献する。０．１％以下ではその効果がほとんどな
く１％以上では脆くなってその効果を失う。本発明合金
では融点降下元素として主にＢｉが用いられるが、Ｂｉ
に代わってＩｎまたはＢｉを一部をＩｎに代替して用い
られることがあり、その最適量はＢｉ、Ｉｎの合計２．
７〜２０％にある。[Effect] The low melting point solder alloy obtained by adding 2.7 to 20% of Bi to the solder alloy consisting of 20 to 80% of Sn and 20 to 80% of Pb has a large melting point drop as the addition amount of Bi increases. The decrease in strength is also significant. The drawback is that Ge and Ge-Ag added to the alloy of the present invention,
It is improved by the addition of Ge-Ag-Pd. G at this time
The optimum addition amount of e is 0.1 to 1.0%, and if 0.1% or less, there is almost no effect, and if 1.0% or more, it becomes brittle and loses its effect. The addition of Ag is the strength of the solder itself,
It has the effect of improving elongation and also has the effect of slightly lowering the melting point. The appropriate amount of addition is 0.5 to 3%. An appropriate amount of Pd added is 0.01 to 1%, which is dispersed in the solder as fine particles, and dispersion strengthening also contributes to the improvement of soldering strength. If it is less than 0.1%, its effect is scarce, and if it exceeds 1%, it becomes brittle and loses its effect. In the alloy of the present invention, Bi is mainly used as the melting point lowering element.
In or Bi may be partially replaced with In, and the optimum amount of Bi and In is 2.
7 to 20%.

【０００７】[0007]

【実施例１】本実施例では銅の試験片をハンダ付けし、
その剥離強さから接合強さを測定した。第２表はＳｎ−
Ｐｂ共晶の従来ハンダとＢｉ８％含む従来の低融点ハン
ダを本発明によるＧｅ０．５％含むハンダ合金とを比較
したものである。Example 1 In this example, a copper test piece was soldered,
The bond strength was measured from the peel strength. Table 2 shows Sn-
It is a comparison between a conventional Pb eutectic solder and a conventional low melting point solder containing Bi 8% and a solder alloy containing 0.5% Ge according to the present invention.

【０００８】 [0008]

【０００９】従来のＳｎ６３％−Ｐｂ３７％の共晶ハン
ダの接合強さには及ばないがＢｉ８％を含む従来の低融
点ハンダよりは本発明のハンダ合金による接合強さは２
割ほど増加するAlthough it does not reach the joint strength of the conventional Sn63% -Pb37% eutectic solder, the joint strength of the solder alloy of the present invention is 2 as compared with the conventional low melting point solder containing 8% of Bi.
Increase about

【００１０】[0010]

【実施例２】Ｇｅの添加はＢｉ８％の低融ハンダに限ら
ずＢｉ２．７〜２０％まで効果がある。第３表はＳｎ６
３％−Ｐｂ３７％の組成にＢｉ３％、８％、１４％添加
した従来の低融ハンダ合金と同組成にさらにＧｅ０，５
％添加した本発明ハンダ合金２、３４の剥離強さを比較
して示した。Example 2 Addition of Ge is effective not only for low melting solder of Bi 8% but for Bi 2.7 to 20%. Table 3 shows Sn6
3% -Pb 37% composition with Bi 3%, 8%, and 14% added to the same composition as the conventional low-melting solder alloy.
%, The peel strengths of the solder alloys 2 and 34 of the present invention added are shown in comparison.

【００１１】 [0011]

【００１２】Ｂｉの添加と共に剥離強さが低下する傾向
は著しいが、Ｇｅを０．５％添加した本発明合金は約２
割の、強度増加が認められる。Although the peel strength tends to decrease with the addition of Bi, the alloy of the present invention containing 0.5% of Ge has about 2%.
However, an increase in strength is recognized.

【００１３】[0013]

【実施例３】Ｐｂ−Ｓｎ−Ｂｉ系の低融点ハンダにＧｅ
の単独添加も有効であるが、Ｇｅと同時にＡｇ、Ｐｄの
複合添加は更に接合強さの改善に効果がある。Ａｇおよ
びＡｇ、Ｐｄを同時添加した本発明ハンダ合金による剥
離強さを第４表に示す。Example 3 Pb-Sn-Bi based low melting point solder Ge
It is also effective to add Ag alone, but the combined addition of Ge and Ag and Pd is effective for further improving the bonding strength. Table 4 shows the peel strength of the solder alloy of the present invention in which Ag and Ag and Pd were simultaneously added.

【００１４】 [0014]

【００１５】実施例１で示した本発明ハンダ合金１のＳ
ｎ４５．８５％−Ｐｂ４６％−Ｂｉ８％−Ｇｅ０．１５
％の剥離強さ２１．８ｋｇｆ／ｃｍに比べ、Ａｇを同時
添加した本発明ハンダ合金５のＳｎ４４．８５％−Ｐｂ
４５％−Ｂｉ８％−Ｇｅ０．５％−Ａｇ２％は２２．３
ｋｇｆ／ｃｍに剥離強さが向上し、Ａｇ、Ｐｄを複合添
加した本発明ハンダ合金６のＳｎ４４．７５％−Ｐｂ４
５％−Ｂｉ８％−Ｇｅ０．１５％−Ａｇ２％−Ｐｄ０．
１％では２３．８ｋｇｆ／ｃｍに達する。このようにＡ
ｇ、Ｐｄの複合添加は有効で、これらを含まない本発明
ハンダ合金に比べ剥離強さが約１割向上する。S of the solder alloy 1 of the present invention shown in Example 1
n45.85% -Pb46% -Bi8% -Ge0.15
% Peel strength of 21.8 kgf / cm, compared to Sn44.85% -Pb of the solder alloy 5 of the present invention to which Ag was added at the same time.
45% -Bi8% -Ge0.5% -Ag2% is 22.3.
The peel strength was improved to kgf / cm, and Sn44.75% -Pb4 of the solder alloy 6 of the present invention in which Ag and Pd were added in combination.
5% -Bi8% -Ge0.15% -Ag2% -Pd0.
At 1%, it reaches 23.8 kgf / cm. Like this
The combined addition of g and Pd is effective, and the peel strength is improved by about 10% as compared with the solder alloy of the present invention not containing them.

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】Ｓｎ−Ｐｂハンダ合金に、Ｂｉ、Ｉｎ等の
低融点元素を少なくても一種以上、重量比で２．７〜２
０％を含む低融点ハンダ合金中に重量比でＧｅを０．１
〜１％（但し０．１％は含まない）添加することを特徴
とするハンダ合金。1. A Sn-Pb solder alloy containing at least one low-melting point element such as Bi or In in a weight ratio of 2.7 to 2.
Ge in a low melting point solder alloy containing 0% by weight ratio of 0.1
A solder alloy characterized by being added in an amount of ˜1% (not including 0.1%). 【請求項２】請求項１記載の低融点ハンダ合金中にＡ
ｇ、Ｐｄのうち一種以上、重量比で０．０１〜３％含む
ことを特徴とするハンダ合金。2. The low melting point solder alloy according to claim 1, wherein A
A solder alloy containing at least one of g and Pd in a weight ratio of 0.01 to 3%.