【発明の詳細な説明】[Detailed description of the invention]
〔産業上の利用分野〕
本発明は、トランジスタや集積回路（IC）な
どの半導体機器のリード材に適する銅合金に関す
るものである。
〔従来技術と問題点〕
従来、半導体機器のリード材としては、熱膨張
係数が低く、素子およびセラミツクスとの接着お
よび封着性の良好なコバール合金、42合金などの
高ニツケル合金が好んで使われてきた。
しかし、近年、半導体回路の集積度の向上に伴
い、消費電力の高いICが多くなつてきたため、
使用されるリード材も放熱性、熱伝導性が良好な
銅基合金が使われるようになつてきた。
しかし、リード材としては、熱伝導性が良い、
耐熱性が良い、半田付け性、めつき密着性が良
い、強度が高い、耐食性がある、廉価である等の
広範な諸条件を全て満足する必要がある。
〔問題点を解決するための手段〕
そこで本出願人は、先に安価で諸特性が優れた
銅合金を開発した（特願昭55−183967→特開昭57
−109357、特願昭56−1630→特開昭57−116738）
が、本合金は析出硬化型合金であるため、マトリ
ツクスに析出物を生成させ、強度、熱伝導性を共
に改善しようとするものである。
しかし、析出物の存在は必ずしも特性改善に寄
与するとはかぎらず、特に半田付け性、めつき密
着性にとつては有害なものとなり得る。
近年、表面実装の進展が著しく、また、信頼性
の向上要求が一段と厳しくなつているため、半田
付け性、めつき密着性の改善が強く求められてい
る。また、半導体の集積度の向上にともない、リ
ードフレームのピン数が増加してきているのが現
状である。
従つて、プレス、エツチングといつたリード材
の加工性も一段と厳しくなつており、析出硬化型
合金はこの観点からも問題があつた。
そこで、本発明は、この合金を半導体機器のリ
ード材として用いるには、析出粒子の大きさを厳
密に調整する必要があり、特に、半田付け性、め
つき密着性を良好にするには、析出粒子を5μｍ
以下にする必要があることを見出した。
そして本発明は、ニツケル0.4〜4.0重量％、け
い素0.1〜1.0重量％、銅及び不可避不純物からな
るリード材用銅合金の酸素含有量が10ppm以下で
析出粒子が5μｍ以下である半導体機器用リード
材に関する。
本発明に係る合金は、リード材に要求される放
熱性、耐熱性、強度、半田付け性、めつき密着性
等のすべてが良好なるものである。
〔発明の具体的な説明〕
次に、合金成分の限定理由を説明する。ニツケ
ルの含有量を0.4〜4.0の重量％とする理由はニツ
ケルの含有量が0.4重量％未満では、けい素を0.1
重量％以上添加しても高強度でかつ高導電性を示
す合金が得られず、逆にニツケル含有量が4.0重
量％を超えると加工性が低下し、半田付け性も低
下する為である。
けい素含有量を0.1〜1.0重量％とした理由は、
けい素含有量が0.1重量％未満ではニツケルを0.4
重量％以上添加しても高強度でかつ高導電性を示
す合金が得られず、けい素含有量が1.0重量％を
超えると加工性、導電性の低下が著しくなり、ま
た半田付け性も低下する為である。
また酸素含有量を10ppm以下とした理由は、
10ppmを超えるとめつき密着性が低下するためで
ある。析出粒子を5μｍ以下にした理由は、5μｍ
を超えると析出粒子上に半田めつきが良好につか
ず半田付け性、めつき密着性が低下し、さらには
プレス時に金型の型摩耗を起こしたり、エツチン
グ面が析出物脱落等による荒れが生じるといつた
加工性が低下するめである。
以下、実施例について説明する。
〔実施例〕
第１表に示した組成の合金を溶解し、厚さ100
mmの鋳塊を得た。次に鋳塊を約800℃で熱間圧延
し、厚さ7.5mmにした後、表面を面削する。そし
て冷間圧延で厚さ1.5mmにした後800℃で５分焼鈍
し、最終冷間圧延で0.8mmにし、420℃で６時間熱
処理する。
なお、比較合金については時効処理等の条件を
変えることによつて析出粒子が第１表に示すよう
に粗大化したものである。
この試料を５重量％の硫酸で約10秒間酸洗し、
引張強さ、伸び、硬さを測定した。また半田付け
性は垂直式浸漬法で230℃の半田浴（スズ60−鉛
40）に５秒間浸漬し、ハンダのぬれの状態を目視
観察した。まためつき密着性は、材料表面に、め
つき厚さ5μｍ程度銀めつきし350℃で５分間加熱
し、放冷後目視にてふくれの有無で評価した。
第１表に示す如く本発明に係る合金１〜５は、
析出粒子が5μｍ以下で有り比較合金１〜５と比
べると、半導体機器のリード材として十分な強度
を具え、半田付け性、めつき密着性が良好である
ため、半導体機器のリード材として優れた合金で
あることがわかる。
［発明の効果］
本発明合金は優れた強度を具備し、また、リー
ドフレーム材として使用する際のポイントとなる
信頼性を低下させないという前提に対して重要な
技術項目である半田付け性、めつき密着性が著し
く良好な合金である。
[Industrial Application Field] The present invention relates to a copper alloy suitable as a lead material for semiconductor devices such as transistors and integrated circuits (ICs). [Prior art and problems] Traditionally, high nickel alloys such as Kovar alloy and 42 alloy have been preferred as lead materials for semiconductor devices because of their low coefficient of thermal expansion and good adhesion and sealing properties with elements and ceramics. It has been. However, in recent years, as the degree of integration of semiconductor circuits has improved, the number of ICs with high power consumption has increased.
Copper-based alloys, which have good heat dissipation and thermal conductivity, have come to be used as lead materials. However, as a lead material, it has good thermal conductivity.
It is necessary to satisfy a wide range of conditions such as good heat resistance, good solderability, good plating adhesion, high strength, corrosion resistance, and low price. [Means for solving the problem] Therefore, the present applicant first developed a copper alloy that was inexpensive and had excellent properties (Japanese Patent Application No. 55-183967 → Japanese Unexamined Patent Publication No. 57-1983).
−109357, Patent application 1984-1630→Patent application 1987-116738)
However, since this alloy is a precipitation hardening alloy, it is intended to improve both strength and thermal conductivity by forming precipitates in the matrix. However, the presence of precipitates does not necessarily contribute to the improvement of characteristics, and can be particularly harmful to solderability and plating adhesion. In recent years, there has been significant progress in surface mounting, and demands for improved reliability have become even stricter, so there is a strong demand for improvements in solderability and plating adhesion. Furthermore, as the degree of integration of semiconductors increases, the number of pins on lead frames is currently increasing. Therefore, the processability of lead materials, such as pressing and etching, has become even more difficult, and precipitation hardening alloys have had problems from this point of view as well. Therefore, in the present invention, in order to use this alloy as a lead material for semiconductor devices, it is necessary to strictly adjust the size of precipitated particles, and in particular, in order to improve solderability and plating adhesion, Precipitated particles are 5μm
I found that I needed to do the following. The present invention provides a lead for semiconductor devices in which the copper alloy for lead material is composed of 0.4 to 4.0% by weight of nickel, 0.1 to 1.0% by weight of silicon, copper, and unavoidable impurities, and the oxygen content is 10 ppm or less and the precipitated particles are 5 μm or less. Regarding materials. The alloy according to the present invention has good heat dissipation, heat resistance, strength, solderability, plating adhesion, etc. all required for lead materials. [Specific Description of the Invention] Next, the reasons for limiting the alloy components will be explained. The reason for setting the nickel content to 0.4 to 4.0% by weight is that if the nickel content is less than 0.4% by weight, the silicon content is 0.1% by weight.
This is because even if more than 4.0% by weight is added, an alloy with high strength and high conductivity cannot be obtained, and conversely, if the nickel content exceeds 4.0% by weight, workability and solderability will decrease. The reason why the silicon content was set at 0.1 to 1.0% by weight is as follows.
If the silicon content is less than 0.1% by weight, nickel is 0.4%.
Even if more than 1.0% by weight is added, an alloy with high strength and high conductivity cannot be obtained, and if the silicon content exceeds 1.0% by weight, the workability and conductivity will be significantly reduced, and the solderability will also be reduced. It is for the purpose of Also, the reason why the oxygen content was set to 10 ppm or less is as follows.
This is because if the content exceeds 10 ppm, the adhesion will decrease. The reason for reducing the precipitated particles to 5μm or less is that the 5μm
If it exceeds this value, solder plating will not adhere well to the precipitated particles, resulting in poor solderability and plating adhesion.Furthermore, die wear may occur during pressing, and the etched surface may become rough due to precipitates falling off, etc. This is because the processability is reduced. Examples will be described below. [Example] An alloy having the composition shown in Table 1 was melted to a thickness of 100 mm.
An ingot of mm was obtained. Next, the ingot is hot rolled at approximately 800°C to a thickness of 7.5mm, and then the surface is chamfered. After cold rolling to a thickness of 1.5 mm, it is annealed at 800°C for 5 minutes, final cold rolled to 0.8 mm, and heat treated at 420°C for 6 hours. As for the comparative alloys, the precipitated particles were coarsened as shown in Table 1 by changing the aging treatment and other conditions. This sample was pickled with 5% by weight sulfuric acid for about 10 seconds,
Tensile strength, elongation, and hardness were measured. In addition, solderability was tested using a vertical immersion method in a 230°C soldering bath (tin 60-lead).
40) for 5 seconds and visually observed the state of solder wetting. The plating adhesion was evaluated by silver plating the material surface to a thickness of approximately 5 μm, heating it at 350° C. for 5 minutes, and visually observing the presence or absence of blisters after cooling. As shown in Table 1, alloys 1 to 5 according to the present invention are:
The precipitated particles are 5 μm or less, and compared to Comparative Alloys 1 to 5, it has sufficient strength as a lead material for semiconductor devices, and has good solderability and plating adhesion, making it an excellent lead material for semiconductor devices. It can be seen that it is an alloy. [Effects of the Invention] The alloy of the present invention has excellent strength, and also has excellent solderability and mechanical properties, which are important technical items based on the premise that reliability, which is a key point when used as a lead frame material, does not deteriorate. This alloy has extremely good adhesion.
【表】【table】
【表】
＊１ ふくれの有無
[Table] *1 Presence or absence of swelling