【発明の詳細な説明】[Detailed description of the invention]
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した特性を有する
銅合金に関するものである。
従来、半導体機器のリード材として、熱膨脹係
数が低く、素子およびモールド材との接着および
封着性の良好なコバール合金（Fe―29Ni―
16Co）、42合金（Fe―42Ni）等の高ニツケル合金
が好んで使われてきた。しかし、近年は半導体回
路の集積度の向上および家庭製品のIC制御の普
及に伴い、高消費電力型のICの需要が多くなつ
てきた。従つて、使用されるリード材も放熱性の
よい、すなわち熱伝導性の良好な銅基合金が使わ
れるようになつてきた。しかしながらリード材と
して熱伝導性が良い（放熱性がよい）、耐熱性が
よい（軟化点が高い）、ハンダ付け性、メツキ密
着性、及び加工性が良い、廉価である等の諸条件
をすべて満足した銅基合金は見当らない。
従来より使用されている無酸素銅、りん青銅、
すず入り銅などの銅基合金は何れも一長一短があ
り、必ずしも満足し得るものではない。たとえば
無酸素銅は優れた放熱性を示すが耐熱性、強度が
低く、りん青銅は優れた強度を示すが高価であり
放熱性が悪いという欠点をもつている。またすず
入り銅は優れた諸特性を示すがさらに耐熱性の向
上が望まれており、すずという高価な添加元素を
用いるため、他の廉価な成分系を用いることが要
望されている。本発明はかかる点に鑑み、従来の
無酸素銅、りん青銅、すず入り銅などの銅基合金
のもつ欠点を改良し、半導体機器のリード材とし
て好適な諸特性を有する導電材料として銅合金を
提供するものである。
本発明は、Ni0.01〜1.0重量％、P0.001〜0.1重
量％を含み、残部がCu及び不可避不純物から成
り、該不純物のうち酸素含有量が0.0010重量％以
下であることを特徴とする半導体機器のリード材
用銅合金である。
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、ハンダ付け性、メツキ密着
性等のすべてが良好なる合金である。
斯かる諸条件をすべて満たすために、本発明で
は合金の加工性、熱伝導性を著しく劣化すること
のないように、無酸素銅ベースに微量の添加元素
を含有させた。
添加元素のうち、Ｐは合金の強度と耐熱性の向
上に必要である。しかし多すぎると熱伝導性を害
したり粒界腐食が著しくなる。この点本発明では
無酸素銅ベースのため溶湯の脱酸は必要なく、微
量添加で目的を達成できる。
これは本発明の大きな特徴の一つである。
Niは強度と耐熱性の向上に寄与し、しかも著
しく熱伝導性を害することはない。なお、NiP共
存により、単独添加に比べ、熱伝導性が向上す
る。
次に本発明における合金組成範囲の限定理由を
説明する。Niの含有量を0.01〜1.0重量％とする
理由は、Ni含有量が0.01重量％未満ではＰを0.1
重量％まで添加しても期待する強度と耐熱性が得
られず、逆にNi含有量が1.0重量％をこえると熱
伝導性が低下するためである。また本発明の銅合
金においてＰ含有量を0.001〜0.1重量％とした理
由はＰ含有量が0.001重量％未満ではＰ含有によ
る強度と耐熱性の向上は顕著でなく、Ｐ含有量が
0.1重量％をこえると粒界に偏析し伸びが低下す
るとともに、熱伝導性の低下が著しいからであ
る。また、本発明の銅合金において酸素含有量を
0.0010重量％以下とした理由は、0.0010重量％を
超えるとメツキ密着性が低下するからである。さ
らに重要な特性であるハンダ付け性は上記範囲の
NiおよびＰの含有量において良好である。
本発明合金の製造法は、無酸素銅を不活性雰囲
気中で溶解し、或いはタフピツチ銅を還元性雰囲
気中で溶解することによつて得た酸素含有量の少
ない金属銅溶湯をベースとし、これに所定量のＰ
母合金およびNiを添加しインゴツトを製造す
る。熱間圧延、面削、冷間圧延および焼鈍は通常
の銅基合金と格別異なることはない。
実施例
第１表に示される本発明合金に係る各種成分組
成のインゴツトを不活性雰囲気中で溶製後、800
℃において熱間圧延し、厚さ４mmの板とした。次
にこの板を通常の酸洗処理をしたのち冷間圧延で
厚さ1.0mmとした。さらに500℃において１時間焼
鈍したのち冷間圧延で厚さ0.6mmの板とした。こ
のようにして調製された試料の評価として、強度
は引張強さおよび伸び、耐熱性は加熱時間30分間
における軟化（硬さ低下）開始温度、そして熱伝
導性は導電率（％IACS）によつて示した。熱伝
導性は導電率と比例関係にあるからである。ま
た、ハンダ付け性は垂直式浸漬法で230℃のハン
ダ浴（すず60―鉛40）に５秒間浸漬し、ハンダに
よるぬれの状態を目視観察した。メツキ密着性は
試料に厚さ３ミクロンの銀メツキを施し、450℃
にて５分間加熱し、表面に発生するフクレの有無
を目視観察した。
これらの結果を同様に試料調製および評価した
比較合金とともに第１表に示した。
第１表に示すごとく本発明に係る合金は、充分
な熱伝導性、秀れた耐熱性およびハンダ付け性を
兼ね具えることが明らかで、高い信頼性が要求さ
れる半導体のリード材として好適である特長を有
するものである。
なお、本発明合金は溶解、熱間圧延、冷間圧延
および中間熱処理等は全く容易でああり、何等技
術的困難は見られなかつた。
The present invention relates to a copper alloy having properties suitable for lead materials for semiconductor devices such as transistors and integrated circuits (ICs). Conventionally, Kovar alloy (Fe-29Ni-
High nickel alloys such as 16Co) and 42 alloy (Fe-42Ni) have been preferred. However, in recent years, with the improvement in the degree of integration of semiconductor circuits and the spread of IC control in household products, the demand for high power consumption ICs has increased. Therefore, copper-based alloys with good heat dissipation properties, that is, good thermal conductivity, have come to be used as lead materials. However, as a lead material, it meets all the requirements such as good thermal conductivity (good heat dissipation), good heat resistance (high softening point), good solderability, plating adhesion, good workability, and low price. No satisfactory copper-based alloy has been found. Conventionally used oxygen-free copper, phosphor bronze,
Copper-based alloys such as tin-containing copper all have advantages and disadvantages, and are not always satisfactory. For example, oxygen-free copper exhibits excellent heat dissipation but has low heat resistance and strength, while phosphor bronze exhibits excellent strength but has the drawbacks of being expensive and having poor heat dissipation. Further, although tin-containing copper exhibits excellent properties, it is desired to further improve heat resistance, and since tin, which is an expensive additive element, is used, it is desired to use other inexpensive component systems. In view of the above, the present invention improves the drawbacks of conventional copper-based alloys such as oxygen-free copper, phosphor bronze, and tin-containing copper, and develops a copper alloy as a conductive material with various properties suitable as a lead material for semiconductor devices. This is what we provide. The present invention is characterized in that it contains 0.01 to 1.0% by weight of Ni, 0.001 to 0.1% by weight of P, and the remainder consists of Cu and unavoidable impurities, and the oxygen content of the impurities is 0.0010% by weight or less. This is a copper alloy for lead material in semiconductor equipment. The alloy according to the present invention is an alloy that exhibits good heat dissipation, heat resistance, strength, solderability, plating adhesion, etc. all required for lead materials. In order to satisfy all of these conditions, the present invention includes a trace amount of additional elements in the oxygen-free copper base so as not to significantly deteriorate the workability and thermal conductivity of the alloy. Among the additive elements, P is necessary to improve the strength and heat resistance of the alloy. However, if the amount is too high, thermal conductivity will be impaired and intergranular corrosion will become significant. In this regard, since the present invention is based on oxygen-free copper, there is no need to deoxidize the molten metal, and the purpose can be achieved by adding a small amount. This is one of the major features of the present invention. Ni contributes to improving strength and heat resistance, and does not significantly impair thermal conductivity. Note that the coexistence of NiP improves thermal conductivity compared to when NiP is added alone. Next, the reason for limiting the alloy composition range in the present invention will be explained. The reason why the Ni content is set to 0.01 to 1.0% by weight is that when the Ni content is less than 0.01% by weight, P is set to 0.1% by weight.
This is because even if the Ni content is added up to 1.0% by weight, the expected strength and heat resistance cannot be obtained, and on the other hand, if the Ni content exceeds 1.0% by weight, the thermal conductivity decreases. In addition, the reason why the P content is set to 0.001 to 0.1% by weight in the copper alloy of the present invention is that when the P content is less than 0.001% by weight, the improvement in strength and heat resistance due to the P content is not significant.
This is because if it exceeds 0.1% by weight, it will segregate at grain boundaries, resulting in a decrease in elongation and a significant decrease in thermal conductivity. In addition, the oxygen content in the copper alloy of the present invention is
The reason for setting the content to 0.0010% by weight or less is that if it exceeds 0.0010% by weight, plating adhesion will decrease. The solderability, which is an even more important property, is within the above range.
Good Ni and P contents. The method for producing the alloy of the present invention is based on a molten copper metal with a low oxygen content obtained by melting oxygen-free copper in an inert atmosphere or by melting tough pitch copper in a reducing atmosphere. a predetermined amount of P
A master alloy and Ni are added to produce an ingot. Hot rolling, facing, cold rolling and annealing are no different from normal copper-based alloys. Example After melting ingots having various compositions of the alloy of the present invention shown in Table 1 in an inert atmosphere,
It was hot rolled at ℃ to form a plate with a thickness of 4 mm. Next, this plate was subjected to a conventional pickling treatment and then cold rolled to a thickness of 1.0 mm. After further annealing at 500°C for 1 hour, it was cold rolled into a plate with a thickness of 0.6 mm. As for the evaluation of the samples prepared in this way, the strength was determined by tensile strength and elongation, the heat resistance was determined by the softening (hardness reduction) onset temperature at a heating time of 30 minutes, and the thermal conductivity was determined by electrical conductivity (%IACS). It was shown. This is because thermal conductivity is proportional to electrical conductivity. Further, solderability was determined by immersing the product in a solder bath (tin 60-lead 40) at 230°C for 5 seconds using the vertical dipping method, and visually observing the state of wetting by the solder. The plating adhesion was determined by applying silver plating to a thickness of 3 microns on the sample at 450°C.
The sample was heated for 5 minutes, and the presence or absence of blisters occurring on the surface was visually observed. These results are shown in Table 1 along with comparative alloys whose samples were similarly prepared and evaluated. As shown in Table 1, it is clear that the alloy according to the present invention has sufficient thermal conductivity, excellent heat resistance, and solderability, and is suitable as a lead material for semiconductors that require high reliability. It has the following characteristics. The alloy of the present invention was completely easily melted, hot rolled, cold rolled, intermediate heat treated, etc., and no technical difficulties were observed.
【表】【table】
【表】【table】