JP2516623C

JP2516623C -

Info

Publication number: JP2516623C
Authority: JP
Publication date: 1998-04-15

Description

【発明の詳細な説明】［産業上の利用分野］本発明は電子電気機器、特に半導体リード材、コネクター、スイッチ、リレー
などの接点ばね、端子等として強度、導電性、メッキ性、半田付け性等の実用特
性に優れた銅合金とその製造法に関するものである。［従来の技術］電子電気機器の部品や部材にはＣｕ合金が多用されているが、近時小型化、高
密度化、高精度化に加えて経済性が強く志向され、従来の純Ｃｕ、黄銅、リン青
銅に替ってより高性能と経済性が要求されるようになった。例えば黄銅に比べて
はるかに機械的特性が優れたリン青銅でも応力腐食割れ（ＳＣＣ）感受性に加え
て、電子電気用途に普遍的な半田接合の信頼性の問題が大きい。これと同種の欠
陥として電気接点や接続部に貴金属に代えてＳｎやＳｎ−Ｐｂ合金（半田）メッ
キを用いる場合、経時的に密着性が失われ、前記半田接合部と同様に剥離現象を
起こす。これはＣｕとＳｎとの拡散反応に起因する現象で、１００℃以下の低温
でも進行するため、特公昭５１−４１２２２号や特開昭４９−１０８５６２号に例示される如く厚いＣｕやＮｉのバリヤー層をメッキ等により予め形成する等余
分の工程を必要とする。このため一部ではＣｕ−Ｆｅ合金、例えばＣ１９４（２．３ｗｔ％Ｆｅ，０．
１２ｗｔ％Ｚｎ，０．０３ｗｔ％Ｐ，残部Ｃｕ）（以下ｗｔ％を％と略記）やＣ
１９５（１．５％Ｆｅ，０．６％Ｓｎ，０．２％Ｃｏ，０．０３％Ｐ，残部Ｃｕ
）等が用いられている。これ等合金は多量のＦｅ分をリン化物や金属単体状に析
出分散させたもので、精密な曲げ加工においてミクロクラックを起すばかりか、
前記半田接合の信頼性に劣る問題がある。［発明が解決しようとする問題点］このような状況下において、機械的強度や精密加工性の優れたＣｕ−Ｓｎ合金
について、下記の欠点欠陥の改善が強く望まれている。（１）高価なＳｎを節約して同等の強度を発揮させること。（２）強度と導電率は相反する関係にあるが、これをより高い値で両立させるこ
と。（３）ＳＣＣを起さないこと。（４）半田接合やＳｎ，Ｓｎ−Ｐｂ合金メッキの経時剥離を起さないこと。（５）熱間加工において割れなどの欠陥を起さない製造上有利な組成であること
。（６）特別な設備を必要としない大気溶解鋳造で造られること。［問題を解決するための手段］本発明はこれに鑑み種々検討の結果、電子電気機器、特に半導体リード材、コ
ネクター、スイッチ、リレーなどの接点ばね、端子等として強度、導電性、メッ
キ性、半田付け性等の実用特性に優れた銅合金とその製造法を開発したものであ
る。本発明銅合金としては、Ｓｎ０．０５〜８％，Ｐ０．１ｗｔ％以下，Ｚｎ０．
１〜１．０ｗｔ％，Ｍｎ０．０３〜０．５％を含み、更にＣｒ，Ｔｉ，Ｚｒの何
れか１種又は２種以上を合計０．０５〜１％を含み、残部Ｃｕからなることを特
徴とするものである。また本発明製造法は、Ｓｎ０．０５〜８％，Ｐ０．１ｗｔ％以下，Ｚｎ０．１
〜１．０ｗｔ％，Ｍｎ０．０３〜０．５％を含み、更にＣｒ，Ｔｉ，Ｚｒの何れ
か１種又は２種以上を合計０．０５〜１％を含み、残部Ｃｕからなる合金を７００〜１０５０℃で熱間加工してから、少なくとも４００℃まで１５℃／ｓｅｃ以
上の速度で冷却し、しかる後３０％以上の冷間加工を行なってから、４００〜６
５０℃で熱処理を施すことを特徴とするものである。即ち本発明は上記組成の合金からなり、そのインゴットを７００〜１０５０℃
で熱間加工してから、少なくとも４００℃まで１５℃／ｓｅｃ以上の速度で冷却
し、その後３０％以上の冷間加工を施し、しかる後４００〜６５０℃で熱処理を
施すことにより造られる。また本発明合金は上記熱処理後、更に加工して所望サ
イズに仕上げてから２００〜４００℃の低温焼鈍を施せば、強度を失うことなく
、伸びや応力緩和抵抗を向上することができる。更にコネクター、スイッチ、リ
レーなどのばね性を必要とする用途では、Ｓｎ含有量を２〜８％、特に４〜７％
とし、他方半導体リード材や電気機器類のように導電性及び耐熱性が重視される
ものではＳｎ含有量を０．０５〜３％、特に０．１〜２％とする。［作用］本発明合金はＣｒ，Ｔｉ，Ｚｒの析出を併用したＣｕ−Ｓｎ固溶体合金であり
、同一Ｓｎ量の合金に対し、強度、導電率を向上することができる。添加元素や
組成にもよるが大略Ｓｎ量の１〜２％分に相当するので、経済的にも有利である
。上記添加元素は金属単体、Ｐとの化合物、特にＺｒはＣｕ₃Ｚｒ，ＴｉはＴｉ
Ｓｎとして微小な析出物となり、Ｃｕ−Ｓｎ合金のＳＣＣ感受性を大巾に改善抑
制することができる。本発明ではＰを０．１％以下と通常のリン青銅のＰ量（０．１〜０．２５％）
より低濃度化し、替りにＺｎやＭｎを脱酸剤として利用したものである。Ｐの低
下は熱間加工時の割れの主因となるＣｕ−Ｐ、Ｃｕ−Ｓｎ−Ｐ等の低融点相の形
成を防止し、Ｓｎメッキや半田付け性を大巾に改善する。即ち剥離したメッキや
半田接合部は何れも黒色を呈し、ＣｕやＳｎの他に濃縮したＰが検出される。こ
れはメッキや半田とリン青銅との界面に形成されるＣｕとＳｎの金属間化合物（
η’相とε相）のうちリン青銅側のε相にリン青銅中のＰが拡散濃縮し、ε相が
一層脆化することにより、半田接合部の強度を低下するものである。本発明はＰを０．１％以下に抑えることにより上記脆化現象を防止したもので
、ＺｎとＭｎの添加は上記脆化現象を防止するばかりか、熱間加工性の向上や機
械的性質をも改善する。上記Ｚｎ、Ｍｎの作用のメカニズムは不明であるが、ＣｕとＳｎとの拡散反応に関与して脆化層の発生を防止するものと推される。熱間
加工性はＣｕ−Ｓｎ合金、特にＳｎ３〜８％の高Ｓｎ合金の課題であり、粒界に
おけるＳｎ偏析や、上記Ｐの作用に因る。Ｃｒ，Ｔｉ，Ｚｒ等の添加元素も結晶
微細化して上記偏析を防止し、熱間加工性を改善するものである。またＶ，Ｍｇ
，Ｂｅ，Ｆｅ，Ｔｅ，Ｓｂ，Ｂｉ，Ｙ，希土類元素についても同様な効果が見ら
れた。しかしてＺｎの含有量を０．１〜１．０ｗｔ％、Ｍｎの含有量を０．０３〜０
．５％と限定したのは、何れも下限未満では十分な効果が得られず、上限を越え
ると導電率を低下させたり、ＳＣＣ感受性を再起させるためである。またＣｒ，
Ｔｉ，Ｚｒの何れか１種又は２種以上（以下Ｃｒ等と略記）の合計含有量を０．
０５〜１％と限定したのは、０．０５％未満では上記効果を発揮し難く、１％を
越えると冷間等の加工性を阻害するためである。またＰ含有量を０．１％以下と
限定したのは、これを越える過剰の濃度では、上記改善効果が実用的に発現され
難いためである。即ち過剰のＰはＣｒ等と結合し、Ｃｒ等の添加効果を減少せし
めるばかりか、加工性を阻害する。本発明合金は析出硬化を利用したものであり、７００〜１０５０℃の高温熱間
加工後、１５℃／ｓｅｃ以上の速度で少なくとも４００℃まで冷却するのは上記
析出物の析出を抑制するためであり、冷却速度が１５℃／ｓｅｃ未満では粗大粒
状析出を起し、上記の効果が得られない。また３０％以上の冷間加工を施してか
ら４００〜６５０℃で熱処理するのは加工歪により均一微細な析出を起させるた
めであり、加工率３０％未満の加工歪では均一微細な析出が得られない。［実施例］第１表に示す組成の合金を木炭被覆の黒鉛ルツボにより溶解し、金型に鋳造し
て小型鋳塊（３ｋｇ）としてから外削し、厚さ１０ｍｍの板とした。これを９０
０℃に加熱してから厚さ１．２ｍｍまで熱間圧延した。上がり温度は７１０〜７
５０℃であり、これを直ちに水冷した。４００℃迄の冷却速度は約２０℃／ｓｅ
ｃであった。これを酸洗いしてから厚さ０．６ｍｍ迄冷間圧延し、５５０℃で３
０分間熱処理した。更にこれを０．２１ｍｍ迄圧延してから３１０℃で２０分間
低温焼鈍を行なった。これ等について導電率、引張強さ、伸び、曲げ性、半田接
合強度、ＳＣＣを調べ、その結果を第２表に示す。曲げ性は各種先端半径（Ｒ）の押し棒と９０°溝ダイスを用い、プレスにより
折り曲げ、角部のミクロクラックを検査し、割れ発生のない最小Ｒと板厚（ｔ）
の比で比較した。半田接合強度はリード線を半田付け（４．５ｍｍ²）した後、
１５０℃に３００時間エージングしてからプル強度を測定し、半田接合の経時劣
化を比較した。ＳＣＣはＪＩＳＣ８３０６に従い、３Ｖｏｌ％ＮＨ₃ガス中で４
０ｋｇ／ｍｍ²の定荷重をかけ、破断するまでの時間を求めた。【第１表】【第２表】第１表及び第２表から明らかなように本発明合金Ｎｏ．１〜３は何れの特性も
優れており、従来のリン青銅からなる比較合金Ｎｏ．４と比較し、同じ強度を得
るのにＳｎ量にして１％前後の節約ができ、かつ高い導電率を示すことが判る。
特に比較合金Ｎｏ．４では熱間圧延時にコバ割れを起すばかりか、ＳＣＣをも起
し、更に半田接合強度も劣るのに、本発明合金Ｎｏ．１〜３では、熱間圧延時に
コバ割れを起すことがなく、ＳＣＣも抑制され、半田接合強度も改善されること
が判る。これに対し本発明合金の組成範囲から外れる比較合金Ｎｏ．４〜６では、要求
される特性の何れか一つ以上が劣ることが判る。即ち、Ｚｎ等やＣｒ等を含まな
い比較合金Ｎｏ．４ではＳＣＣを起すばかりか、半田接合強度も劣り、またＺｎ
の含有量が多い比較合金Ｎｏ．５では導電率の低下が著しく、ＳＣＣを起す。ま
たＣｒ等の含有量が多い比較合金Ｎｏ．６では熱間圧延において割れが著しく、
その後の加工を中止した。尚比較のため第１表中本発明合金Ｎｏ．３について熱
間圧延後、空冷（２．１℃／ｓｅｃ）し、その後、冷間圧延と熱処理を施したも
のは、引張強度６１．４ｋｇ／ｍｍ²、伸び９．４％にすぎなかった。また上記
実施例において第１表中本発明合金Ｎｏ．３について、熱処理前の冷間加工率を
３５％と２０％にしたところ夫々強度６４．４ｋｇ／ｍｍ²、６０．１ｋｇ／ｍ
ｍ²であった。［発明の効果］このように本発明によれば、Ｃｕ−Ｓｎ合金の優れた機械的強度や精密加工性
を活かしつつ上記改善点（１）〜（６）のすべてを改善したもので電子電気機器
、特に半導体リード材、コネクター、スイッチ、リレーなどの接点ばね、端子と
して強度、導電性、メッキ性、半田付け性等の実用特性を満足することができる
等工業上顕著な効果を奏するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to strength, conductivity, plating property, and solderability of electronic and electrical devices, particularly, contact springs and terminals of semiconductor lead materials, connectors, switches, relays and the like. The present invention relates to a copper alloy excellent in practical characteristics such as the above and a method for producing the same. [Prior art] Although Cu alloys are frequently used for parts and members of electronic and electrical equipment, in recent years, economical efficiency has been strongly sought in addition to miniaturization, high density, and high precision. Higher performance and economy have come to be required instead of brass and phosphor bronze. For example, phosphor bronze, which has much better mechanical properties than brass, has a serious problem of solder joint reliability that is universal for electronic and electrical applications in addition to stress corrosion cracking (SCC) susceptibility. As a defect of the same type, when Sn or Sn—Pb alloy (solder) plating is used instead of a noble metal for an electric contact or a connection part, the adhesion is lost with time, and a peeling phenomenon occurs like the solder joint part. . This is a phenomenon caused by a diffusion reaction between Cu and Sn, and proceeds even at a low temperature of 100 ° C. or less. Therefore, as exemplified in JP-B-51-41222 and JP-A-49-108562, a thick Cu or Ni barrier is used. An extra step such as forming the layer in advance by plating or the like is required. For this reason, in part, a Cu—Fe alloy, for example, C194 (2.3 wt% Fe, 0.
12 wt% Zn, 0.03 wt% P, balance Cu) (hereinafter, wt% is abbreviated as%), C
195 (1.5% Fe, 0.6% Sn, 0.2% Co, 0.03% P, balance Cu
) Etc. are used. These alloys have a large amount of Fe precipitated and dispersed in the form of phosphides or metal elements, and not only cause microcracks in precision bending,
There is a problem that the reliability of the solder joint is inferior. [Problems to be Solved by the Invention] Under such circumstances, it is strongly desired to improve the following defects in Cu-Sn alloys having excellent mechanical strength and precision workability. (1) To save the expensive Sn and exhibit the same strength. (2) The strength and the electrical conductivity are in a conflicting relationship, but they must be compatible at a higher value. (3) Do not cause SCC. (4) Solder bonding and peeling over time of Sn, Sn—Pb alloy plating should not occur. (5) The composition is advantageous in production without causing defects such as cracks in hot working. (6) Being made by air melting casting that does not require special equipment. [Means for Solving the Problems] In view of this, the present invention has been subjected to various studies, and as a result, the strength, conductivity, plating property, and the like of electronic and electrical devices, particularly, contact springs and terminals of semiconductor lead materials, connectors, switches, relays and the like, A copper alloy having excellent practical properties such as solderability and a method for producing the same have been developed. As the copper alloy of the present invention, Sn 0.05 to 8%, P 0.1 wt% or less, Zn0.
1 to 1.0 wt%, Mn 0.03 to 0.5%, and further contains any one or more of Cr, Ti, and Zr in a total of 0.05 to 1%, with the balance being Cu. It is a feature. In addition, the production method of the present invention comprises: Sn 0.05 to 8%, P 0.1 wt% or less, Zn 0.1
Alloy containing 1.0 to 1.0 wt%, Mn of 0.03 to 0.5%, and further containing any one or more of Cr, Ti, and Zr in a total of 0.05 to 1% and a balance of Cu of 70%. After hot working at 0 to 1050 ° C., cooling to at least 400 ° C. at a rate of 15 ° C./sec or more, and then performing cold working of 30% or more,
The heat treatment is performed at 50 ° C. That is, the present invention comprises an alloy having the above composition, and the ingot is heated at 700 to 1050 ° C.
And then cooled to at least 400 ° C. at a rate of 15 ° C./sec or more, then subjected to cold working of 30% or more, and then heat-treated at 400 to 650 ° C. In addition, if the alloy of the present invention is further processed to a desired size after the heat treatment and then subjected to low-temperature annealing at 200 to 400 ° C., elongation and stress relaxation resistance can be improved without losing strength. In applications requiring spring properties, such as connectors, switches, and relays, the Sn content is reduced to 2 to 8%, particularly 4 to 7%.
On the other hand, in the case where conductivity and heat resistance are important such as semiconductor lead material and electric equipment, the Sn content is set to 0.05 to 3%, particularly 0.1 to 2%. [Action] The alloy of the present invention is a Cu-Sn solid solution alloy in which precipitation of Cr, Ti, and Zr is used in combination, and can improve the strength and electrical conductivity with respect to an alloy having the same Sn amount. Although it depends on the additive element and the composition, it is approximately equivalent to 1 to 2% of the Sn amount, which is economically advantageous. The additive element is a simple metal, a compound with P, particularly Zr is Cu ₃ Zr, Ti is Ti
It becomes fine precipitates as Sn, and can greatly improve and suppress the SCC sensitivity of the Cu-Sn alloy. In the present invention, the P content is 0.1% or less and the P content of ordinary phosphor bronze (0.1 to 0.25%).
The concentration is reduced, and Zn or Mn is used instead as a deoxidizing agent. The decrease in P prevents the formation of low melting point phases such as Cu-P and Cu-Sn-P, which are the main causes of cracking during hot working, and significantly improves Sn plating and solderability. That is, the peeled plating and solder joints are all black, and concentrated P is detected in addition to Cu and Sn. This is an intermetallic compound of Cu and Sn formed at the interface between plating and solder and phosphor bronze (
Of the η 'phase and ε phase), P in phosphor bronze diffuses and concentrates in the ε phase on the phosphor bronze side, and the ε phase is further embrittled, thereby reducing the strength of the solder joint. In the present invention, the above embrittlement phenomenon is prevented by suppressing P to 0.1% or less. The addition of Zn and Mn not only prevents the above embrittlement phenomenon but also improves the hot workability and mechanical properties. Also improve. The mechanism of the action of Zn and Mn is unknown, but is presumed to be involved in the diffusion reaction between Cu and Sn to prevent the generation of an embrittlement layer. Hot workability is a problem of Cu—Sn alloys, particularly high Sn alloys having a Sn content of 3 to 8%, and is caused by Sn segregation at grain boundaries and the action of P. Additional elements such as Cr, Ti, and Zr are also refined to prevent the segregation and improve hot workability. V, Mg
, Be, Fe, Te, Sb, Bi, Y, and rare earth elements have the same effect. Thus, the content of Zn is 0.1 to 1.0 wt%, and the content of Mn is 0.03 to 0%.
. The reason why the content is limited to 5% is that if the content is less than the lower limit, a sufficient effect cannot be obtained, and if the content exceeds the upper limit, the conductivity is reduced or SCC sensitivity is re-established. Cr,
The total content of any one or more of Ti and Zr (hereinafter abbreviated as Cr etc.) is set to 0.1.
The reason why the content is limited to 0.05 to 1% is that if the content is less than 0.05%, the above effect is hardly exhibited, and if it exceeds 1%, workability such as cold work is impaired. The reason why the P content is limited to 0.1% or less is that if the concentration is excessively higher than this, the above-mentioned improvement effect is hardly practically exhibited. That is, excessive P bonds with Cr and the like, and not only reduces the effect of adding Cr and the like, but also impairs workability. The alloy of the present invention utilizes precipitation hardening, and the purpose of cooling to at least 400 ° C. at a rate of 15 ° C./sec or more after high-temperature hot working at 700 to 1050 ° C. is to suppress precipitation of the precipitates. If the cooling rate is lower than 15 ° C./sec, coarse and granular precipitation occurs, and the above effects cannot be obtained. Further, the reason why the heat treatment is performed at 400 to 650 ° C. after performing the cold working of 30% or more is to cause uniform fine precipitation due to the processing strain, and to obtain the uniform fine precipitation with the working strain of less than 30%. I can't. Example An alloy having the composition shown in Table 1 was melted in a charcoal-coated graphite crucible, cast into a mold to form a small ingot (3 kg), and then externally cut into a 10 mm-thick plate. This is 90
After being heated to 0 ° C., it was hot-rolled to a thickness of 1.2 mm. The rise temperature is 710-7
It was 50 ° C. and immediately cooled with water. The cooling rate to 400 ° C is about 20 ° C / sec.
c. This is pickled and then cold rolled to a thickness of 0.6 mm.
Heat treated for 0 minutes. Further, this was rolled to 0.21 mm and then subjected to low-temperature annealing at 310 ° C. for 20 minutes. The conductivity, tensile strength, elongation, bendability, solder joint strength, and SCC were examined for these, and the results are shown in Table 2. Bendability is determined by using a push rod of various tip radii (R) and a 90 ° groove die, bending by press and inspecting micro cracks at corners, minimum R without cracking and plate thickness (t)
Were compared. After soldering the lead wire (4.5mm ² ),
After aging at 150 ° C. for 300 hours, the pull strength was measured, and the aging of the solder joint was compared. SCC conforms to JIS C8306 and is performed in 4% by volume NH ₃ gas.
A constant load of 0 kg / mm ² was applied, and the time until breaking was determined. [Table 1] [Table 2] As is clear from Tables 1 and 2, the alloy No. 1 of the present invention was used. Nos. 1 to 3 are all excellent in characteristics, and comparative alloy Nos. As compared with No. 4, it can be seen that the amount of Sn can be saved by about 1% in order to obtain the same strength, and high conductivity is exhibited.
In particular, the comparative alloy No. No. 4 not only causes edge cracking during hot rolling but also causes SCC and further deteriorates the solder joint strength. In Nos. 1 to 3, it is found that edge cracking does not occur during hot rolling, SCC is suppressed, and solder joint strength is improved. On the other hand, the comparative alloy No. which is out of the composition range of the alloy of the present invention. In Nos. 4 to 6, one or more of the required characteristics are inferior. That is, the comparative alloy No. containing no Zn or Cr or the like. No. 4 causes not only SCC, but also inferior solder joint strength.
Comparative Alloy No. In No. 5, the conductivity is remarkably reduced, causing SCC. In addition, Comparative Alloy No. In No. 6, cracks are remarkable in hot rolling,
Subsequent processing was stopped. For comparison, alloy No. 1 of the present invention in Table 1 was used. Sample No. 3 was hot-rolled, air-cooled (2.1 ° C./sec), and then subjected to cold-rolling and heat treatment. The tensile strength was 61.4 kg / mm ² and the elongation was only 9.4%. In the above examples, alloy No. 1 of the present invention in Table 1 was used. For No. 3, when the cold working ratio before the heat treatment was 35% and 20%, the strength was 64.4 kg / mm ² and 60.1 kg / m, respectively.
m ² . [Effects of the Invention] As described above, according to the present invention, all of the above improvements (1) to (6) are improved while taking advantage of the excellent mechanical strength and precision workability of a Cu-Sn alloy. It has industrially remarkable effects such as the ability to satisfy practical properties such as strength, conductivity, plating properties, solderability, etc. as equipment, especially contact springs for semiconductor lead materials, connectors, switches, relays, etc. is there.

Claims

Claims: (1) Sn 0.05 to 8 wt%, P 0.1 wt% or less, Zn 0.1 to 1.0 wt
%, Mn 0.03 to 0.5 wt%, and further contains any one or more of Cr, Ti and Zr in a total amount of 0.05 to 1 wt%, and the balance is Cu. (2) Sn 0.05 to 8 wt%, P 0.1 wt% or less, Zn 0.1 to 1.0 wt
%, Mn 0.03 to 0.5 wt%, and further contains one or more of Cr, Ti and Zr in a total amount of 0.05 to 1 wt%, and the balance of Cu is 700 to
After hot working at 1050 ° C., cooling to at least 400 ° C. at a rate of 15 ° C./sec or more, and then performing cold working of 30% or more, and then 400 to 650
A method for producing a copper alloy for electronic and electrical equipment, wherein the method comprises heat-treating at a temperature of ° C.