【発明の詳細な説明】[Detailed description of the invention]
(産業上の利用分野)
本発明はコネクター、スイツチ、リレー等の電
気機器用のばね材料として用いられる導電性とば
ね特性に優れたCu―Sn―P系の導電ばね材料に
関するものである。
(従来の技術)
従来、導電性とばね特性とに優れた導電ばね材
料として代表的なものは、JISに2種、3種とし
て規定されているSn5.5〜9.0%、P0.03〜0.3%を
含むりん青銅であるが、最近の小型化されて高い
信頼性が求められる電子部品として使用するには
曲げ成形性特に応力弛緩特性等が不十分であると
いう問題点があつた。
(発明が解決しようとする問題点)
ところが、前記のような応力弛緩特性は試験片
に例えば40Kg/cm2の最大曲げ応力が作用するよう
に荷重をかけてわん曲させ、200℃で100時間保持
後に荷重を解除して試験片の残留応力を測定する
方法により評価されるもので、電子部品の高い信
頼性を保障する重要な特性とされているが、従来
のりん青銅にあつては応力残留率が30%前後であ
つて、高い信頼性を得ることができなかつた。
(問題点を解決するための手段)
本発明は上記のような従来の問題点を解決する
ため、従来のりん青銅中のSnの一部をNiで置換
することにより組織の微細化とともに第2相の析
出によつてりん青銅の優れた機械的性質を失うこ
となく曲げ成形性、応力弛緩特性等の諸特性にも
優れた導電ばね材料としたものであつて、重量%
で、Sn5.5〜8.5%、P0.05〜0.35%、Ni1.5〜3.5
%、残部Cuおよび不可避的な不純物からなるも
のである。
次に本発明におけるSnおよびNi,Pの含有率
の限定理由を説明すると、Snは5.5%未満である
と十分な機械的強度が得られず、8.5%を越える
と伸びが減少して冷間圧延性等の加工性が低下す
るもので、5.5〜8.5%の範囲が最も好ましい。Ni
はこれを加えることにより結晶粒を微細化させる
とともにSnとの間に第2相を生成させて前記諸
特性の向上を図るための成分であり、Niが1.5%
未満では結晶粒の微細化効果が不十分で応力弛緩
特性の向上が得られず、3.5%を越えると冷間圧
延性や曲げ成形性が悪化するものであつて、1.5
〜3.5%の範囲が最も好ましい。脱酸剤であるP
は0.05%未満では溶湯の脱酸効果が不足して素材
の鋳造欠陥が多くなつて圧延加工性および機械的
特性を悪化させ、0.35%を越えると導電性を悪化
させるものであつて、0.05〜0.35%の範囲が最も
好ましい。
実施例
(Field of Industrial Application) The present invention relates to a Cu--Sn--P based conductive spring material that has excellent conductivity and spring properties and is used as a spring material for electrical equipment such as connectors, switches, and relays. (Prior art) Conventionally, typical conductive spring materials with excellent conductivity and spring properties are Sn5.5-9.0% and P0.03-0.3, which are specified as Types 2 and 3 by JIS. %, but it has had the problem that its bending formability, particularly its stress relaxation properties, etc., are insufficient for use in electronic components that have recently been miniaturized and require high reliability. (Problem to be Solved by the Invention) However, the above-mentioned stress relaxation properties cannot be obtained by bending a test piece under a load such that a maximum bending stress of 40 kg/cm 2 is applied, for example, and at 200°C for 100 hours. This is evaluated by measuring the residual stress in the test piece after the load is released after it is held, and is considered to be an important property to ensure high reliability of electronic components.However, with conventional phosphor bronze, stress The residual rate was around 30%, and high reliability could not be obtained. (Means for Solving the Problems) In order to solve the above-mentioned conventional problems, the present invention replaces a part of the Sn in the conventional phosphor bronze with Ni, thereby making the structure finer and producing a second A conductive spring material that has excellent properties such as bending formability and stress relaxation properties without losing the excellent mechanical properties of phosphor bronze due to phase precipitation.
So, Sn5.5~8.5%, P0.05~0.35%, Ni1.5~3.5
%, the balance consists of Cu and unavoidable impurities. Next, to explain the reason for limiting the content of Sn, Ni, and P in the present invention, if Sn is less than 5.5%, sufficient mechanical strength cannot be obtained, and if it exceeds 8.5%, elongation decreases and cold The most preferable range is from 5.5% to 8.5% since it reduces workability such as rolling properties. Ni
is a component that refines the crystal grains by adding it and generates a second phase between it and Sn to improve the various properties mentioned above.Ni is 1.5%
If it is less than 3.5%, the effect of grain refinement is insufficient and no improvement in stress relaxation properties can be obtained, and if it exceeds 3.5%, cold rollability and bending formability deteriorate.
A range of ~3.5% is most preferred. P, which is a deoxidizing agent
If it is less than 0.05%, the deoxidizing effect of the molten metal will be insufficient and the casting defects of the material will increase, deteriorating the rolling workability and mechanical properties, and if it exceeds 0.35%, the conductivity will deteriorate. A range of 0.35% is most preferred. Example
【表】
第1表に示される実施例1〜5及び従来のりん
青銅材料を高周波誘導炉で溶解鋳造し、焼鈍、冷
間圧延の繰り返しにより所定の板厚とし、最終軟
化焼鈍を550℃で2時間行い、次いで60%の冷間
圧延の後、200℃2時間の低温焼鈍を施して特性
を測定した。その結果を第2表に示す。なお、第
2表において応力弛緩特性は前記方法により測定
された応力残留率(%)で示し、ヤング率は(Kg
f/mm2)で、曲げ成形性は(クランクを生じずに
90゜曲げができる最少曲率半径/板厚)で、引張
強度、耐力、ばね限界値(kb値)はいずれも
(Kgf/mm2)で示した。また、0゜は圧延方向に
おける特性値を、90゜は圧延方向に直角方向の特
性値を示す。[Table] Examples 1 to 5 and conventional phosphor bronze materials shown in Table 1 were melted and cast in a high-frequency induction furnace, made to a predetermined thickness by repeated annealing and cold rolling, and final softening annealed at 550°C. Then, after 60% cold rolling, low-temperature annealing was performed at 200° C. for 2 hours, and the properties were measured. The results are shown in Table 2. In Table 2, the stress relaxation properties are expressed as the stress residual rate (%) measured by the above method, and the Young's modulus is expressed as (Kg
f/mm 2 ), and the bending formability is (without cranking).
Tensile strength, yield strength, and spring limit value (kb value) are all expressed in (Kgf/mm 2 ). Further, 0° indicates the characteristic value in the rolling direction, and 90° indicates the characteristic value in the direction perpendicular to the rolling direction.
【表】
(発明の効果)
本発明は以上の説明からも明らかなように、従
来のりん青銅中のSnの一部をNiで置換すること
により組織の微細化と第2相の析出によつて機械
的特性を劣化させることなく熱的安定性の向上を
図り、応力弛緩特性を向上させるとともに曲げ成
形性を向上させ、更に導電性、加工性等の諸特性
を改良したものであつて、従来の導電ばね材料の
問題点を解決したものとして産業の発展に寄与す
るところは極めて大である。[Table] (Effects of the invention) As is clear from the above explanation, the present invention achieves refinement of the structure and precipitation of the second phase by substituting a part of Sn in conventional phosphor bronze with Ni. It aims to improve thermal stability without deteriorating mechanical properties, improves stress relaxation properties, improves bending formability, and further improves various properties such as electrical conductivity and workability. It will greatly contribute to the development of industry as it solves the problems of conventional conductive spring materials.