JP3772319B2

JP3772319B2 - Copper alloy for lead frame and manufacturing method thereof

Info

Publication number: JP3772319B2
Application number: JP17752997A
Authority: JP
Inventors: 樹新董; 敏裕神崎
Original assignee: Dowa Holdings Co Ltd; Dowa Mining Co Ltd
Current assignee: Dowa Holdings Co Ltd
Priority date: 1997-03-24
Filing date: 1997-05-29
Publication date: 2006-05-10
Anticipated expiration: 2017-05-29
Also published as: JPH10324935A

Description

【０００１】
【発明の属する技術分野】
本発明は、高強度で耐熱特性に優れ、導電率が高いリードフレーム用銅合金とその製造方法に関するものである。
【０００２】
【従来の技術】
一般に半導体機器用リードフレームには、次の特性が要求される。
（１）強度が高く、耐熱特性に優れていること。
（２）放熱性、即ち熱伝導性が高いこと。
（３）電気伝導性が高いこと。
（４）フレーム形成後の曲げ加工性が良いこと。
（５）メッキ密着性及び樹脂とのモールド性が良いこと。
（６）ハンダとの接合部の経時劣化がないこと。
【０００３】
従来、半導体機器用リードフレームには、Ｃｕ−Ｆｅ系合金が用いられている。この合金は引張強さが４７０ＭＰａ，導電率は６０％ＩＡＣＳ程度である。
【０００４】
近年、半導体素子は集積度の増大及び小型化と同時に高信頼性が求められるようになり、半導体素子用のリードフレームも薄肉・小型化され、さらに高強度及び高導電率が要求されるようになった。
【０００５】
即ち、薄肉化による構成部品の強度低下を防ぐための強度の向上と集積度の増大による放熱性向上のために、熱伝導性と同一特性である導電率の向上、更に優れた耐熱性と半導体のフレーム上の固定及び半導体からリードフレームの足部分の配線のボンディング前処理としてのリードフレーム表面のメッキ性及びメッキ密着性、更に封入樹脂とのモールド性の向上、更に信頼性の問題としてフレームと基板との接合におけるハンダ接合強度の経時劣化が無いことが望まれている。
【０００６】
しかしながら、従来の製造方法ではＣｕ−Ｆｅ系合金の析出物の存在比等の制御が不充分なため、導電率、強度等の特性を向上させることには限界がある。
【０００７】
【発明が解決しようとする課題】
本発明は、上記のような問題点を解決し、これまでのＣｕ−Ｆｅ系合金と同等以上の強度を有すると共に優れた導電性を有し、半導体機器用リードフレームに要求される上記諸特性を満足するリードフレーム用銅合金とその製造方法を提案するものである。
【０００８】
【課題を解決するための手段】
即ち、本発明は、
（１）質量％でＦｅ：０．５〜５％、Ｐ：０．０１〜０．２％を含有し、残部がＣｕ及び不可避的不純物からなり、析出粒子の粒径は１００Å以上の粒子個数と１００Å未満の粒子個数との比が０．００４〜１．０００であることを特徴とするリードフレーム用銅合金。
（２）質量％でＦｅ：０．５〜５％、Ｐ：０．０１〜０．２％を含有し、残部がＣｕ及び不可避的な不純物からなり、折出粒子の粒径は１００Å以上の粒子個数と１００Å未満の粒子個数との比が０．００４〜１．０００である銅合金であって、引張強度が５００ＭＰａ以上でかつ導電率が６５％ＩＡＣＳ以上であることを特徴とするリードフレーム用銅合金。
（３）質量％でＦｅ：０．５〜５％、Ｐ：０．０１〜０．２％を含み、Ｓｎ，Ｚｎ，Ｐｂのうちから選ばれる１種又は２種以上を合計で０．０５〜０．５％を含有し、残部がＣｕ及び不可避的不純物からなり、析出粒子の粒径は１００Å以上の粒子個数と１００Å未満の粒子個数との比が０．００４〜１．０００である銅合金であって、引張強度が５００ＭＰａ以上でかつ導電率が６５％ＩＡＣＳ以上であることを特徴とするリードフレーム用銅合金。
（４）質量％でＦｅ：０．５〜５％、Ｐ：０．０１〜０．２％含有し、残部がＣｕ及び不可避的不純物からなる銅合金に熱間加工後で冷間加工前に高温（５５０℃以上で０．１分間以上）−低温（５２０℃以下で１分間以上）の２段階時効処理を行うことを特徴とするリードフレーム用銅合金の製造方法。
以上を提供するものである。
【００１６】
【作用】
次に、本発明の内容を具体的に説明する。
本発明合金は上記組成からなり、Ｆｅ含有量を０．５〜５重量％の範囲内とし、析出粒子の粒径は１００Å以上の粒子個数と１００Å未満の粒子個数との比を０．００４〜１．０００の範囲内に制御したのは、充分な強度と導電率を有し、かつメッキ性、鋳造性及び加工性を良好なものとするためである。
【００１７】
次に、本発明合金を構成する合金成分の添加理由とその限定理由等を説明する。
（１）Ｆｅ：Ｆｅ含有量が０．５質量％未満では粒子析出による強化が不十分であり、５％を越えると、導電率が低下するので、含有量は０．５〜５．０質量％の範囲とする。
【００１８】
（２）Ｐ：Ｐは溶湯の脱酸剤として作用すると共にＦｅと化合物を形成して析出することにより、導電性を向上させ、かつ強度を向上させるが、０．０１質量％未満では効果が不充分であり、０．２質量％を越えると効果が飽和し、不経済である。したがって、含有量は０．０１−０．２０質量％の範囲とする。
【００１９】
（３）副成分（Ｓｎ，Ｚｎ，Ｐｂ）：Ｓｎ，Ｚｎ，Ｐｂのうちから選ばれる１種または２種以上の添加量を合計で０．０５〜０．５質量％に限定したのは、これらはハンダの経時劣化を抑制し、共有により、その効果を大きく、ハンダ付け性をより良好なものとするためであり、０．０５質量％未満では効果が不充分であり、一方０．５質量％を越えると導電率の低下が著しくなるためである。従って、上記副成分の含有量は０．０５〜０．５質量％の範囲とする。
【００２０】
（４）析出粒子径とその個数の比：
１００Å以上の析出粒子個数と１００Å未満の析出粒子個数との比が、０．００４より小さくなると時効処理後の冷間圧延時の導電率が大きく低下し、１．０００より大きくなると時効処理後の導電率も低く、製品の強度も低い。従って、その比は０．００４〜１．０００の範囲とする。
【００２１】
（５）２段階時効処理：
また、本発明に係る銅合金の製造方法で、熱間圧延後、冷間圧延前に、高温（５５０℃以上で０．１分間以上）−低温（５２０℃以下で１分間以上）の２段階時効処理を規定したのは、２段時効処理を行なわないと、１００Å以上の析出粒子個数と１００Å未満の析出粒子個数との比を０．００４〜１．０００の範囲に制御することができないからである。
【００２２】
また、高温段階での時効処理は、温度が５５０℃より低いと１００Å以上の析出粒子を形成させるために相当な時間が必要となって、生産性が悪くなり、一方低温段階での時効処理温度が５２０℃より高いと、時効析出が不完全で導電率も低くなる。
【００２３】
【発明の実施の形態】
表１にその化学成分値（質量％）を示す銅基合金を高周波溶解炉により大気中で溶解し、カーボン鋳型を用いて鋳造し、５０×５０×１５０ｍｍの鋳塊を得た。次いで、この鋳塊を９５０℃に加熱して厚さが１２ｍｍになるまで熱間圧延した。この熱間圧延材に面削を施して１０ｍｍの厚さにした上で、加工率８０％の冷間圧延を施して厚さ２ｍｍの板とした。この板材に表１に示す条件で２段または１段の時効処理を施した。その後、さらに加工率８７．５％の冷却圧延を行い、最終厚さが０．２５ｍｍの板とした。
【００２４】
このようにして、得られた試験片を用いて、引張強さ，導電率，伸び，硬度，ばね限界値，はんだ耐候性，析出粒子径及びその個数を測定した。
引張強さ及び導電率の測定はそれぞれＪＩＳ−Ｚ−２２４１，ＪＩＳ−ＳＨ−０５０５に従い、硬度及びばね限界値の測定はそれぞれＪＩＳ−Ｚ−２２５１，ＪＩＳ−Ｈ−３１３０−６．４に従って行った。
【００２５】
析出粒子径はＴＥＭ写真から測定した。この場合に、各方向から１つの粒子を平行線で挟んで最も長い線間距離を粒子の粒径とした。また、析出粒子の個数はＴＥＭ写真から１０００個以上の粒子を含む視野で２０視野数えた。
本発明と比較品の組成及び時効条件を表１に、また本発明品と比較品の析出粒子径及び特性値を表２に示す。
【００２６】
【表１】

【００２７】
【表２】

【００２８】
表１〜２中のＮｏ．１〜７は本発明に係る発明品であり、合成組成は各規定範囲で、１００Å以上の析出粒子個数と１００Å未満の析出粒子個数との比も規定範囲内であり、その引張強さは５００ＭＰａ以上、導電率６５％ＩＡＣＳ以上であり、非常に優れたリードフレーム用銅合金である。
【００２９】
Ｎｏ．８〜１４は比較品であり、Ｎｏ．８は合金組成は規定範囲内であるが、高温時効処理段階での温度が５５０℃以下であり、引張強さが５００ＭＰａ以下で、導電率も６５％ＩＡＣＳ以下である。
【００３０】
Ｎｏ．９〜１０は合金組成は規定範囲内であるが、１段時効処理のため、析出粒子も規定範囲外で引張強さ及び導電率も低い。
【００３１】
Ｎｏ．１１はＦｅ含有率が規定範囲より高く、２段階時効処理条件は規定範囲内であるが、導電率が低く、Ｎｏ．１２はＦｅ含有率が規定範囲より低く、２段階時効処理条件は規定範囲内であるが、引張強さが非常に低い。
【００３２】
Ｎｏ．１３〜１４は合金組成は規定範囲内であるが、Ｎｏ．１３は高温時効処理段階での処理温度が５５０℃以下であり、引張強さ及び導電率も低く、Ｎｏ．１４は１段時効処理のため、析出粒子も規定範囲外で導電率も非常に低い。
【００３３】
【発明の効果】
本発明に係るリードフレーム用銅合金とその製造方法は、上記実施例からも分かるように優れた導電性と強度を併せ有し、高い信頼性が要求される電子機器用材料、特にリードフレーム用の銅合金として好適であり、その薄肉化と小型化を可能に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。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a copper alloy for lead frames having high strength, excellent heat resistance, and high electrical conductivity, and a method for producing the same.
[0002]
[Prior art]
In general, lead frames for semiconductor devices are required to have the following characteristics.
(1) High strength and excellent heat resistance.
(2) High heat dissipation, that is, high thermal conductivity.
(3) High electrical conductivity.
(4) Bending workability after frame formation is good.
(5) Good plating adhesion and moldability with resin.
(6) There is no deterioration with time of the joint portion with the solder.
[0003]
Conventionally, Cu—Fe based alloys have been used for lead frames for semiconductor devices. This alloy has a tensile strength of 470 MPa and an electrical conductivity of about 60% IACS.
[0004]
In recent years, semiconductor devices have been required to have higher reliability and at the same time higher integration, and lead frames for semiconductor devices have been made thinner and smaller, and higher strength and higher conductivity are required. became.
[0005]
That is, in order to improve strength to prevent the strength of component parts from being reduced due to thinning and to improve heat dissipation by increasing the degree of integration, improvement in conductivity, which is the same characteristic as thermal conductivity, and even better heat resistance and semiconductors Fixing on the frame of the lead frame and pre-bonding of the lead to the lead frame of the lead frame from the semiconductor, lead frame surface plating and plating adhesion, further improved moldability with the encapsulating resin, further reliability issues with the frame It is desired that there is no deterioration over time in the strength of solder bonding in bonding to a substrate.
[0006]
However, the conventional manufacturing method has insufficient control of the abundance ratio of precipitates of the Cu—Fe-based alloy, and thus there is a limit to improving characteristics such as conductivity and strength.
[0007]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, has the same or better strength as conventional Cu-Fe alloys, has excellent conductivity, and has the above characteristics required for lead frames for semiconductor devices. The present invention proposes a copper alloy for lead frames that satisfies the requirements and a method for producing the same.
[0008]
[Means for Solving the Problems]
That is, the present invention
(1) Fe: 0.5 to 5% by mass and P: 0.01 to 0.2%, with the balance being Cu and inevitable impurities, and the particle size of the precipitated particles is 100Å or more. The lead frame copper alloy is characterized in that the ratio of the number of particles less than 100% to 0.004 to 1.000.
(2) By mass%, Fe: 0.5-5%, P: 0.01-0.2%, the balance is made of Cu and inevitable impurities, and the particle size of the protruding particles is 100 mm or more A lead frame characterized in that the ratio of the number of particles to the number of particles less than 100% is 0.004 to 1.000, the tensile strength is 500 MPa or more, and the conductivity is 65% IACS or more. Copper alloy.
(3) Fe: 0.5 to 5% by mass, P: 0.01 to 0.2%, and one or more selected from Sn, Zn and Pb in total of 0.05 Copper containing 0.5%, the balance being Cu and inevitable impurities, and the ratio of the number of particles larger than 100 to the number of particles smaller than 100 is 0.004 to 1.000 A copper alloy for lead frames, which is an alloy and has a tensile strength of 500 MPa or more and an electrical conductivity of 65% IACS or more.
(4) Fe: 0.5 to 5% by mass, P: 0.01 to 0.2% contained, the remainder being a copper alloy consisting of Cu and unavoidable impurities before hot working and before cold working A method for producing a copper alloy for a lead frame, comprising performing a two-step aging treatment at a high temperature (above 550 ° C. for 0.1 minute or more) -low temperature (less than 520 ° C. for 1 minute or more).
The above is provided.
[0016]
[Action]
Next, the contents of the present invention will be specifically described.
The alloy of the present invention has the above composition, the Fe content is in the range of 0.5 to 5% by weight, and the particle size of the precipitated particles is a ratio of the number of particles of 100Å or more to the number of particles of less than 100Å is 0.004 to The reason why it is controlled within the range of 1.000 is to have sufficient strength and conductivity, and to improve the plating property, castability and workability.
[0017]
Next, the reason for addition of the alloy components constituting the alloy of the present invention and the reason for limitation will be described.
(1) Fe: Fe content is less than 0.5% by mass, strengthening due to particle precipitation is insufficient, and if it exceeds 5%, the conductivity decreases, so the content is 0.5 to 5.0% by mass. % Range.
[0018]
(2) P: P acts as a deoxidizer for the molten metal and forms a compound with Fe to precipitate, thereby improving conductivity and improving strength. If it exceeds 0.2% by mass, the effect is saturated and uneconomical. Therefore, the content is in the range of 0.01-0.20 mass%.
[0019]
(3) Subcomponents (Sn, Zn, Pb): The amount of addition of one or more selected from Sn, Zn, Pb was limited to 0.05 to 0.5 mass% in total. These are for suppressing the deterioration of solder over time, and by sharing, the effect is increased, and the solderability is further improved. When the content is less than 0.05% by mass, the effect is insufficient. This is because when the content exceeds mass%, the electrical conductivity is remarkably lowered. Therefore, the content of the subcomponent is in the range of 0.05 to 0.5% by mass.
[0020]
(4) Ratio of precipitated particle size and number thereof:
When the ratio between the number of precipitated particles of 100% or more and the number of precipitated particles of less than 100% is smaller than 0.004, the electrical conductivity during cold rolling after the aging treatment is greatly lowered, and when the ratio is larger than 1.000, Low electrical conductivity and low product strength. Therefore, the ratio is in the range of 0.004 to 1.000.
[0021]
(5) Two-stage aging treatment:
Further, in the method for producing a copper alloy according to the present invention, after hot rolling and before cold rolling, two stages of high temperature (550 ° C. or higher and 0.1 minute or longer) -low temperature (520 ° C. or lower and 1 minute or longer) The reason for specifying the aging treatment is that if the two-stage aging treatment is not performed, the ratio of the number of precipitated particles of 100% or more to the number of precipitated particles of less than 100% cannot be controlled in the range of 0.004 to 1.000. It is.
[0022]
In addition, when the temperature is lower than 550 ° C., the aging treatment in the high temperature stage requires considerable time to form the precipitated particles of 100 mm or more, resulting in poor productivity, while the aging treatment temperature in the low temperature stage. When the temperature is higher than 520 ° C., the aging precipitation is incomplete and the conductivity is lowered.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The copper base alloy which shows the chemical component value (mass%) in Table 1 was melt | dissolved in air | atmosphere with the high frequency melting furnace, and it casted using the carbon casting_mold | template, and obtained the ingot of 50x50x150mm. Subsequently, this ingot was heated to 950 ° C. and hot-rolled until the thickness became 12 mm. The hot-rolled material was chamfered to a thickness of 10 mm, and then cold-rolled at a processing rate of 80% to give a plate having a thickness of 2 mm. This plate material was subjected to two-stage or one-stage aging treatment under the conditions shown in Table 1. Thereafter, cold rolling with a processing rate of 87.5% was further performed to obtain a plate having a final thickness of 0.25 mm.
[0024]
Thus, using the obtained test piece, tensile strength, electrical conductivity, elongation, hardness, spring limit value, solder weather resistance, precipitated particle diameter and the number thereof were measured.
Tensile strength and conductivity were measured according to JIS-Z-2241, JIS-SH-0505, and hardness and spring limit values were measured according to JIS-Z-2251, JIS-H-3130-6.4, respectively. .
[0025]
The precipitated particle size was measured from a TEM photograph. In this case, one particle from each direction was sandwiched between parallel lines, and the longest distance between the lines was defined as the particle size of the particle. Further, the number of precipitated particles was counted from 20 fields of view including 1000 or more particles from a TEM photograph.
Table 1 shows the compositions and aging conditions of the present invention and the comparative product, and Table 2 shows the precipitated particle sizes and characteristic values of the present product and the comparative product.
[0026]
[Table 1]

[0027]
[Table 2]

[0028]
No. in Tables 1-2. 1 to 7 are invention products according to the present invention, the composition is in each specified range, the ratio of the number of precipitated particles of 100 Å or more and the number of precipitated particles of less than 100 も is also in the specified range, and the tensile strength is 500 MPa. As described above, the electrical conductivity is 65% IACS or more, and it is a very excellent lead frame copper alloy.
[0029]
No. Nos. 8 to 14 are comparative products. Although the alloy composition is within the specified range, the temperature at the high temperature aging treatment stage is 550 ° C. or lower, the tensile strength is 500 MPa or lower, and the conductivity is 65% IACS or lower.
[0030]
No. Although the alloy compositions of 9 to 10 are within the specified range, the precipitated particles are also outside the specified range and the tensile strength and conductivity are low because of the one-stage aging treatment.
[0031]
No. No. 11 has a Fe content higher than the specified range, and the two-stage aging treatment condition is within the specified range, but the conductivity is low. In No. 12, the Fe content is lower than the specified range, and the two-stage aging treatment condition is within the specified range, but the tensile strength is very low.
[0032]
No. Nos. 13 to 14 have alloy compositions within the specified range. No. 13 has a treatment temperature in the high temperature aging treatment stage of 550 ° C. or lower, and has low tensile strength and electrical conductivity. Since No. 14 is a one-step aging treatment, the precipitated particles are also outside the specified range and the conductivity is very low.
[0033]
【The invention's effect】
The copper alloy for lead frames and the method for producing the same according to the present invention have excellent conductivity and strength, as can be seen from the above-described embodiments, and materials for electronic devices that require high reliability, particularly for lead frames. It is suitable as a copper alloy, and it is possible to reduce the thickness and size of the copper alloy.

Claims

Fe: 0.5 to 5% in mass%, P: 0.01 to 0.2%, the remainder is made of Cu and inevitable impurities, and the particle size of the precipitated particles is 100 or more and less than 100% A copper alloy for lead frames, characterized in that the ratio to the number of particles is 0.004 to 1.000.

Fe: 0.5 to 5% by mass, P: 0.01 to 0.2%, the balance is made of Cu and inevitable impurities, and the particle size of the bent particles is 100 or more. A copper alloy for lead frames, wherein the ratio of the number of particles less than 100% is 0.004-1.000, and the tensile strength is 500 MPa or more and the electrical conductivity is 65% IACS or more. .

Fe: 0.5 to 5% by mass, P: 0.01 to 0.2%, and one or more selected from Sn, Zn, and Pb are added in a total amount of 0.05 to 0.00. The copper alloy contains 5%, the balance is made of Cu and inevitable impurities, and the particle size of the precipitated particles is a ratio of the number of particles of 100 mm or more and the number of particles of less than 100 mm of 0.004 to 1.000. A lead frame copper alloy having a tensile strength of 500 MPa or more and an electrical conductivity of 65% IACS or more.

Fe: 0.5 to 5% in mass%, P: 0.01 to 0.2% contained, and a copper alloy consisting of Cu and unavoidable impurities in the balance is subjected to a high temperature (550) after hot working and before cold working. A method for producing a copper alloy for a lead frame, comprising performing a two-stage aging treatment at a temperature of not less than 0.1 ° C for not less than 0.1 minutes and a low temperature (not less than 520 ° C for not less than 1 minute).