JP2003273305A - Lead frame - Google Patents
Lead frameInfo
- Publication number
- JP2003273305A JP2003273305A JP2002066992A JP2002066992A JP2003273305A JP 2003273305 A JP2003273305 A JP 2003273305A JP 2002066992 A JP2002066992 A JP 2002066992A JP 2002066992 A JP2002066992 A JP 2002066992A JP 2003273305 A JP2003273305 A JP 2003273305A
- Authority
- JP
- Japan
- Prior art keywords
- plating
- plating layer
- lead frame
- layer
- multilayer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Landscapes
- Electroplating Methods And Accessories (AREA)
- Lead Frames For Integrated Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、リードフレームに
関し、特に、鉛を含まないめっきが施されたリードフレ
ームに関する。
【０００２】
【従来の技術】リードフレームには、通常、ワイヤボン
ディング性や半導体チップの接合性を向上させるため、
金、銀、ニッケル、パラジウムなどの金属めっきがアイ
ランドやインナーリードなどに部分的に施されている。
【０００３】そして、半導体チップをアイランド上に搭
載し、樹脂封止が施されたリードフレームには、さらに
外装半田めっきが施される。
【０００４】ところで、近年、環境保護の立場から多く
の化学物質の規制が強化されている。
【０００５】外装鉛半田めっきを施したリードフレーム
は、半田めっきを施す時に使用された鉛の処理問題や、
鉛が回収されることなく廃棄された製品から環境への流
出問題など、様々な課題を有している。
【０００６】また、ＩＣ組立工程での工程簡素化の流れ
で、外装半田めっきが必要ない、ＰＰＦ（ Pre Plated
Lead-Frame ）が注目されている。
【０００７】外装半田めっきを必要とせず、かつ鉛フリ
ーの半導体装置用ＰＰＦとしてのリードフレームには、
ワイヤボンディング性、半田濡れ性、耐食性、及び封止
樹脂との密着性等の機能が同時に要求されている。
【０００８】また、商品として製造コスト及び環境影響
をも考えなければならない。
【０００９】
【発明が解決しようとする課題】しかし、現在実用化さ
れているＰＰＦでこのような諸条件を満足することは非
常に困難である。
【００１０】例えば、Ｎｉ／Ｐｄの２層またはＮｉ／Ｐ
ｄ／Ａｕの３層めっきのＰＰＦは、高周波特性が悪いな
どの欠点があり、また、耐食性に難点があるためＡ４２
材には使用できない。
【００１１】また、Ｐｄの価格変動が大きいため、コス
ト面でも不安定である。
【００１２】そして、スポットＡｇめっきとスポット鉛
フリーの半田めっきの２色めっきのＰＰＦは、ワイヤボ
ンディング温度が制限されている。
【００１３】そこで本発明では、優れた特性を有しかつ
鉛を含まないめっき皮膜が形成されたリードフレームを
提供することを目的とする。
【００１４】
【課題を解決するための手段】本発明に係るリードフレ
ームは、表面にＡｕ−Ａｇめっきが形成されたリードフ
レームにおいて、Ａｕ−Ａｇめっきは、Ａｇの割合が異
なる複数のＡｕ−Ａｇめっき層が積層された多層Ａｕ−
Ａｇめっき層からなり、多層Ａｕ−Ａｇめっき層は、基
材側から最表面にかけてＡｇの割合が増加する傾斜組成
構造を有する。
【００１５】また、Ａｕ−Ａｇめっきは、銅からなる基
材表面に施されたニッケルめっき層上に形成されてい
る。
【００１６】また、Ａｕ−Ａｇめっきは、Ａ４２材から
なる基材表面に施されたニッケルめっき層上に形成され
ている。
【００１７】
【発明の実施の形態】図１は、本発明に係るリードフレ
ームの構成を示す断面図である。
【００１８】図１において、本発明に係るリードフレー
ム１０には、基材である銅材１の表面に下地めっきであ
るニケッルめっき層２が形成され、さらにニッケルめっ
き層２の表面に複数のＡｕ−Ａｇめっき層３、４、５が
積層された多層めっき層６を形成している。
【００１９】ここで、多層Ａｕ−Ａｇめっき層６を形成
する各Ａｕ−Ａｇめっき層の組成は異なり、図２に示す
ように、下地めっきであるニッケルめっき側から外表面
側にかけて各Ａｕ−Ａｇめっき層中のＡｇの割合が徐々
に高くなるように構成され、総合的には深さ方向の合金
組成が傾斜構造となる。
【００２０】なお、下地めっき表面に形成されたＡｕ−
Ａｇめっき層と外表面のＡｕ−Ａｇめっき層との組成の
傾斜量は、９０ｗｔ％Ａｇ以下とし、また、各Ａｕ−Ａ
ｇめっき層の平均組成は、２０〜７０ｗｔ％Ａｇとす
る。
【００２１】また、各めっき層の厚みは、完全な層を得
るため０.００１μｍ以上の厚みであることが好まし
く、また、多層化したＡｕ−Ａｇめっき層の厚みは合計
して０.２μｍ以下であることが好ましい。
【００２２】以下、図３を用いて、本発明に係るリード
フレームの製造方法について説明する。
【００２３】まず、図３（ａ）に示すように、リードフ
レームの基材である銅材１の表面に下地めっきであるニ
ッケルめっき層２を形成し、図３（ｂ）に示すように、
下地めっき層２の表面に第１のＡｕ−Ａｇめっき層３を
形成する。
【００２４】そして、図３（ｃ）に示すように、第１の
Ａｕ−Ａｇめっき層３よりもＡｇの割合が高い第２のＡ
ｕ−Ａｇめっき層４を第１のＡｕ−Ａｇめっき層３の表
面に形成し、さらに、図３（ｄ）に示すように、第２の
Ａｕ−Ａｇめっき層４よりもＡｇの割合が高い第３のＡ
ｕ−Ａｇめっき層５を第２のＡｕ−Ａｇめっき層４の表
面に形成して、多層Ａｕ−Ａｇめっき層６を形成する。
【００２５】ここで、基材や下地めっき表面にめっきを
施す方法としては、めっき用整流器の電流波形や電圧波
形の制御する方法や２セル以上の多セルで分段めっきす
る方法、またこれらの方法を同時に用いた方法や、他の
ドライプレーティング法（真空蒸着法など）など、既知
のめっき方法を適宜用いることができる。
【００２６】また、リードフレームの基材は銅に限られ
るものではなく、Ａ４２材など、他の材料を用いること
もできる。
【００２７】そして、多層Ａｕ−Ａｇめっき層を構成す
るＡｕ−Ａｇめっき層は、３層に限られるものではな
く、必要に応じてＡｇの割合が異なる少なくとも２層以
上のＡｕ−Ａｇ合金めっき膜を用いて形成することがで
きる。
【００２８】以下、実施例を用いてさらに詳細に説明す
る。
【００２９】
【実施例１】本実施例では、多段セル（２段）めっき法
を用い、次の工程に従って多層Ａｕ−Ａｇめっき層を形
成した。
【００３０】１）まず、ＡｕイオンとＡｇイオンとの濃
度比が異なる２種類のＡｕ−Ａｇ合金めっき溶液を２つ
のめっきセルに用意する。
２）次に、板厚０.１２５ｍｍのリードフレーム用銅材
を脱脂・酸洗した後、厚さが１μｍのニッケルめっき層
を下地めっきとして表面に形成する。
３）そして、まず、Ａｇ濃度が低いＡｕ−Ａｇ合金めっ
き溶液から順番に下地めっきが施されたリードフレーム
用銅材を浸漬させ、同じ電流密度でＡｕ−Ａｇめっき層
を形成し、多層Ａｕ−Ａｇめっき層を形成する。
【００３１】上記工程を用いることにより、平均組成２
５.４ｗｔ％Ａｇ、組成の傾斜量２８.９ｗｔ％、２層構
造の多層Ａｕ−Ａｇめっき層を持つリードフレームが得
られた。
【００３２】
【実施例２】本実施例では、めっき用整流器の電流波形
を制御し、次の工程に従って多層Ａｕ−Ａｇめっき層を
形成した。
【００３３】１）まず、一定濃度比のＡｕイオン及びＡ
ｇイオンを含有し、低い電流密度でＡｕの割合が高いＡ
ｕ−Ａｇ合金膜が形成されるＡｕ−Ａｇめっき溶液を用
意する。
２）次に、板厚０.１２５ｍｍリードフレーム用銅材を
脱脂・酸洗した後、厚さが１μｍのニッケルめっき層を
下地めっきとして表面に形成する。
３）そして、下地めっきが施されたリードフレームを先
ほど用意したＡｕ−Ａｇめっき溶液に浸漬し、図４に示
すように、通電時間（ＯＮ）０.５秒間、休み時間（Ｏ
ＦＦ）２秒間、最初の通電時の電流密度（Ｉｐ）が０.
１Ａ／ｄｍ２で、以後２０％ずつ上昇する電流波形によ
り多層Ａｕ−Ａｇめっき層を形成する。
【００３４】上記工程を用いることにより、平均組成２
５.４ｗｔ％Ａｇ、組成の傾斜量２８.９ｗｔ％、１３層
構造の多層Ａｕ−Ａｇめっき層を持つリードフレームが
得られた。
【００３５】
【実施例３】本実施例では、多段セル（４段）分段めっ
き法を用い、次の工程に従って多層Ａｕ−Ａｇめっき層
を形成した。
【００３６】１）まず、ＡｕイオンとＡｇイオンとの濃
度比が異なる４種類のＡｕ−Ａｇ合金めっき溶液を４つ
のめっきセルに用意する。
２）次に、板厚０.１２５ｍｍのリードフレーム用銅材
を脱脂・酸洗した後、厚さが１μｍのニッケルめっき層
を下地めっきとして表面に形成する。
３）そして、Ａｇ濃度が最も低いＡｕ−Ａｇ合金めっき
溶液から順番にＡｇ濃度が高いＡｕ−Ａｇ合金めっき溶
液に下地めっきが施されたリードフレーム用銅材を浸漬
させ、同じ電流密度を用いてＡｕ−Ａｇめっき層を形成
する。
【００３７】上記工程を用いることにより、平均組成４
９.０ｗｔ％Ａｇ、組成の傾斜量６３.７ｗｔ％、４層構
造の多層Ａｕ−Ａｇめっき層を持つリードフレームが得
られた。
【００３８】
【実施例４】本実施例では、多段セル（２段）分段めっ
き法を用い、次の工程に従って多層Ａｕ−Ａｇめっき層
を形成した。
【００３９】１）まず、ＡｕイオンとＡｇイオンとの濃
度比が異なる２種類のＡｕ−Ａｇ合金めっき溶液を２つ
のめっきセルに用意する。
２）次に、板厚０.１２５ｍｍのリードフレーム用銅材
を脱脂・酸洗した後、厚さが１μｍのニッケルめっき層
を下地めっきとして表面に形成する。
３）そして、Ａｇ濃度が低いＡｕ−Ａｇ合金めっき溶液
に下地めっきが施されたリードフレーム用銅材を浸漬さ
せ、直流整流器を用いてＡｕ−Ａｇめっき層を形成す
る。
４）その後、Ａｇ濃度が高いＡｕ−Ａｇめっき溶液に浸
漬し、実施例２と同様に、図４に示すように、通電時間
（ＯＮ）０.５秒間、休み時間（ＯＦＦ）２秒間、最初
の通電時の電流密度（Ｉｐ）が０.１Ａ／ｄｍ２で、以
後２０％ずつ上昇する電流波形により多層Ａｕ−Ａｇめ
っき層を形成する。
【００４０】上記工程を用いることにより、平均組成６
９.３ｗｔ％Ａｇ、組成の傾斜量８７.４ｗｔ％、１４層
構造の多層Ａｕ−Ａｇめっき層を持つリードフレームが
得られた。
【００４１】
【実施例５】本実施例では、多段セル（４段）分段めっ
き法を用い、次の工程に従って多層Ａｕ−Ａｇめっき層
を形成した。
【００４２】１）まず、ＡｕイオンとＡｇイオンとの濃
度比が異なる４種類のＡｕ−Ａｇ合金めっき溶液を４つ
のめっきセルに用意する。
２）次に、板厚０.１２５ｍｍのリードフレーム用Ａ４
２材を脱脂・酸洗した後、厚さが１μｍのニッケルめっ
き層を下地めっきとして表面に形成する。
３）そして、実施例３と同様に、Ａｇ濃度が最も低いＡ
ｕ−Ａｇ合金めっき溶液から順番にＡｇ濃度が高いＡｕ
−Ａｇ合金めっき溶液に下地めっきが施されたリードフ
レーム用Ａ４２材を浸漬させ、同じ電流密度を用いてＡ
ｕ−Ａｇめっき層を形成する。
【００４３】上記工程を用いることにより、Ａ４２材上
に、実施例３と同様に、平均組成４９.０ｗｔ％Ａｇ、
組成の傾斜量６３.７ｗｔ％、４層構造の多層Ａｕ−Ａ
ｇめっき層を持つリードフレームが得られた。
【００４４】
【比較例１】本比較例では、直流電源を用いてＡｕ−Ａ
ｇめっき層を形成した。
【００４５】１）まず、Ａｕ−Ａｇ合金めっき溶液を１
つのめっきセルに用意する。
２）次に、板厚０.１２５ｍｍのリードフレーム用銅材
を脱脂・酸洗した後、厚さが１μｍのニッケルめっき層
を下地めっきとして表面に形成する。
３）そして、Ａｕ−Ａｇ合金めっき溶液に下地めっきが
施されたリードフレーム用銅材を浸漬させ、Ａｕ−Ａｇ
めっき層を形成する。
【００４６】上記工程を用いることにより、組成２７.
６ｗｔ％Ａｇの単層のＡｕ−Ａｇめっき膜を持つリード
フレームが得られた。
【００４７】
【比較例２】本比較例では、定電流パルス電源を用いて
Ａｕ−Ａｇめっき層を形成した。
【００４８】１）まず、Ａｕ−Ａｇ合金めっき溶液を１
つのめっきセルに用意する。
２）次に、板厚０.１２５ｍｍのリードフレーム用銅材
を脱脂・酸洗した後、厚さが１μｍのニッケルめっき層
を下地めっきとして表面に形成する。
３）そして、Ａｕ−Ａｇ合金めっき溶液に下地めっきが
施されたリードフレーム用銅材を浸漬させ、Ａｕ−Ａｇ
めっき層を形成する。
【００４９】上記工程を用いることにより、組成２５.
１ｗｔ％Ａｇの単層のＡｕ−Ａｇ合金膜を持つリードフ
レームが得られた。
【００５０】ここで、実施例１乃至５及び比較例１及び
２で形成されたリードフレームに対して、次の方法で耐
食性テスト及び半田濡れ性テストを行った。
【００５１】耐食性テスト：５％ＮａＣｌ溶液を３５℃
の環境で２４時間噴霧する塩水噴霧加速テストを行い、
錆の発生を観察する。半田濡れ性テスト：３３０℃で３
０分間加熱後、Ｓｎ−３７Ｐｂを２３０℃で５秒間接触
させ、半田の濡れを観測した。
【００５２】耐食性テスト及び半田濡れ性テストの結果
を表１に示す。
【００５３】
【表１】
【００５４】ここで、濡れ率は、９５％を超えると○
で、耐食性は、錆が観察されない場合は、○で示してい
る。
【００５５】表１に示すように、実施例１乃至５では、
比較例１及び２に比べて薄い膜厚（０.１μｍ未満）で
半田濡れ性及び耐食性に優れた特性を得ている。
【００５６】このように、本発明に係るリードフレーム
は、耐食性及び半田濡れ性に優れたリードフレームを薄
く形成することが可能となる。
【００５７】また、外装半田めっきなど鉛を用いる必要
がないため、環境にやさしく、廃液処理などのコストを
押さえることができる。
【００５８】さらに、単層のＡｕ−Ａｇめっき層を形成
する場合に比べて低コストで優れた特性を得ることがで
きる。
【００５９】また、Ａｕ−Ａｇめっきを用いるため、パ
ラジウムめっきなどを用いた場合と比べて、高周波特性
に優れたリードフレームを形成することができる。
【００６０】加えて、Ｎｉ／Ｐｄの２層またはＮｉ／Ｐ
ｄ／Ａｕの３層めっきでは、耐食性に難点があるため基
材として持ちいることができなかったＡ４２材を基材と
して用いることができる。
【００６１】
【発明の効果】本発明では、優れた特性を有するめっき
皮膜が鉛を用いることなく薄く形成されたリードフレー
ムを得ることができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame, and more particularly to a lead frame plated with lead. 2. Description of the Related Art Usually, a lead frame is provided with a wire bonding property and a semiconductor chip bonding property to improve the bonding property.
Metal plating such as gold, silver, nickel, and palladium is partially applied to islands, inner leads, and the like. [0005] A lead frame on which a semiconductor chip is mounted on an island and sealed with a resin is further subjected to external solder plating. In recent years, regulations on many chemical substances have been strengthened from the standpoint of environmental protection. [0005] The lead frame subjected to the outer lead solder plating has a problem in treating lead used in applying the solder plating,
There are various problems, such as the problem of spilling into the environment from products discarded without recovery of lead. Also, with the flow of process simplification in the IC assembly process, PPF (Pre Plated
Lead-Frame) is attracting attention. [0007] A lead frame as a PPF for a semiconductor device which does not require external solder plating and is lead-free,
Functions such as wire bonding properties, solder wettability, corrosion resistance, and adhesion to a sealing resin are simultaneously required. In addition, it is necessary to consider the production cost and environmental impact as a product. [0009] However, it is very difficult for PPFs currently in practical use to satisfy such conditions. For example, two layers of Ni / Pd or Ni / Pd
The d / Au three-layer plating PPF has drawbacks such as poor high-frequency characteristics, and has a problem in corrosion resistance.
Cannot be used for wood. [0011] Further, since the price fluctuation of Pd is large, the cost is also unstable. [0012] The two-color plating PPF of spot Ag plating and spot lead-free solder plating has a limited wire bonding temperature. Accordingly, an object of the present invention is to provide a lead frame having excellent characteristics and a lead-free plating film formed thereon. According to the present invention, there is provided a lead frame having Au-Ag plating formed on a surface thereof, wherein the Au-Ag plating comprises a plurality of Au-Ag plating layers having different Ag ratios. Multi-layer Au- with plating layer laminated
The multilayer Au—Ag plating layer is composed of an Ag plating layer and has a gradient composition structure in which the ratio of Ag increases from the substrate side to the outermost surface. The Au-Ag plating is formed on a nickel plating layer provided on the surface of a substrate made of copper. The Au-Ag plating is formed on a nickel plating layer applied to the surface of a base material made of A42 material. FIG. 1 is a sectional view showing the structure of a lead frame according to the present invention. In FIG. 1, a lead frame 10 according to the present invention has a nickel plating layer 2 as a base plating formed on a surface of a copper material 1 as a base material, and a plurality of Au platings on the surface of the nickel plating layer 2. -The multilayer plating layer 6 in which the Ag plating layers 3, 4, and 5 are laminated is formed. Here, the composition of each Au-Ag plating layer forming the multilayer Au-Ag plating layer 6 is different, and as shown in FIG. 2, each Au-Ag plating layer extends from the nickel plating which is the base plating to the outer surface side. The composition of the plating layer is such that the ratio of Ag in the plating layer is gradually increased, and the alloy composition in the depth direction has a gradient structure overall. It should be noted that the Au-
The gradient amount of the composition between the Ag plating layer and the Au—Ag plating layer on the outer surface is set to 90 wt% Ag or less.
The average composition of the g-plated layer is 20 to 70 wt% Ag. The thickness of each plating layer is preferably 0.001 μm or more in order to obtain a complete layer, and the total thickness of the multilayer Au—Ag plating layer is 0.2 μm or less. It is preferred that Hereinafter, a method for manufacturing a lead frame according to the present invention will be described with reference to FIG. First, as shown in FIG. 3 (a), a nickel plating layer 2 which is a base plating is formed on the surface of a copper material 1 which is a base material of a lead frame, and as shown in FIG.
The first Au-Ag plating layer 3 is formed on the surface of the base plating layer 2. Then, as shown in FIG. 3C, the second Au having a higher Ag content than the first Au-Ag plating layer 3 has.
The u-Ag plating layer 4 is formed on the surface of the first Au-Ag plating layer 3, and the ratio of Ag is higher than that of the second Au-Ag plating layer 4 as shown in FIG. Third A
The u-Ag plating layer 5 is formed on the surface of the second Au-Ag plating layer 4 to form the multilayer Au-Ag plating layer 6. Here, as a method of plating the surface of the base material or the underlying plating, there are a method of controlling a current waveform and a voltage waveform of a rectifier for plating, a method of performing step plating with multiple cells of two or more cells, and a method of plating these. A known plating method such as a method using the methods simultaneously or another dry plating method (such as a vacuum evaporation method) can be appropriately used. Further, the base material of the lead frame is not limited to copper, and other materials such as A42 material can be used. The Au—Ag plating layer constituting the multilayer Au—Ag plating layer is not limited to three layers, and may be at least two or more Au—Ag alloy plating films having different Ag ratios as necessary. Can be formed. Hereinafter, the present invention will be described in more detail with reference to examples. Example 1 In this example, a multilayer Au—Ag plating layer was formed according to the following steps using a multi-stage cell (two-stage) plating method. 1) First, two types of Au—Ag alloy plating solutions having different concentration ratios of Au ions and Ag ions are prepared in two plating cells. 2) Next, a copper material for a lead frame having a thickness of 0.125 mm is degreased and pickled, and then a nickel plating layer having a thickness of 1 μm is formed on the surface as a base plating. 3) Then, first, a copper material for a lead frame on which a base plating is applied is immersed in order from an Au-Ag alloy plating solution having a low Ag concentration, and an Au-Ag plating layer is formed at the same current density to form a multilayer Au- An Ag plating layer is formed. By using the above process, the average composition 2
A lead frame having 5.4 wt% Ag, a composition gradient of 28.9 wt%, and a multilayer Au-Ag plating layer having a two-layer structure was obtained. Example 2 In this example, the current waveform of the plating rectifier was controlled, and a multilayer Au-Ag plating layer was formed according to the following steps. 1) First, a constant concentration ratio of Au ions and A
A containing g ions and having a high Au content at a low current density
An Au-Ag plating solution for forming a u-Ag alloy film is prepared. 2) Next, after the copper material for a lead frame having a thickness of 0.125 mm is degreased and pickled, a nickel plating layer having a thickness of 1 μm is formed on the surface as a base plating. 3) Then, the lead frame on which the base plating has been applied is immersed in the previously prepared Au-Ag plating solution, and as shown in FIG. 4, the energization time (ON) is 0.5 seconds, and the rest time (O
FF) For 2 seconds, the current density (Ip) at the time of the first energization is 0.
A multilayer Au-Ag plating layer is formed at a current waveform of 1 A / dm 2 and thereafter increasing by 20%. By using the above process, the average composition 2
A lead frame having 5.4 wt% Ag, a composition gradient of 28.9 wt%, and a multilayer Au-Ag plating layer having a 13-layer structure was obtained. Example 3 In this example, a multilayer Au—Ag plating layer was formed according to the following steps using a multi-stage cell (four-stage) step plating method. 1) First, four kinds of Au-Ag alloy plating solutions having different concentration ratios of Au ions and Ag ions are prepared in four plating cells. 2) Next, a copper material for a lead frame having a thickness of 0.125 mm is degreased and pickled, and then a nickel plating layer having a thickness of 1 μm is formed on the surface as a base plating. 3) Then, the lead-plated copper material for the underlayer is immersed in the Au-Ag alloy plating solution having the highest Ag concentration in order from the Au-Ag alloy plating solution having the lowest Ag concentration, and using the same current density. An Au-Ag plating layer is formed. By using the above process, the average composition 4
A lead frame having 9.0 wt% Ag, a composition gradient of 63.7 wt%, and a multilayer Au-Ag plating layer having a four-layer structure was obtained. Embodiment 4 In this embodiment, a multilayer Au—Ag plating layer was formed according to the following steps by using a multi-stage cell (two-stage) step plating method. 1) First, two types of Au—Ag alloy plating solutions having different concentration ratios of Au ions and Ag ions are prepared in two plating cells. 2) Next, a copper material for a lead frame having a thickness of 0.125 mm is degreased and pickled, and then a nickel plating layer having a thickness of 1 μm is formed on the surface as a base plating. 3) Then, the lead-framed copper material having the base plating is immersed in an Au-Ag alloy plating solution having a low Ag concentration, and an Au-Ag plating layer is formed using a DC rectifier. 4) Then, it is immersed in an Au-Ag plating solution having a high Ag concentration, and as in Example 2, as shown in FIG. 4, the energizing time (ON) is 0.5 seconds, the rest time (OFF) is 2 seconds, and The current density (Ip) at the time of energization is 0.1 A / dm 2 , and a multilayer Au—Ag plating layer is formed by a current waveform that increases by 20% thereafter. By using the above process, an average composition of 6
A lead frame having 9.3 wt% Ag, a composition gradient amount of 87.4 wt%, and a multilayer Au-Ag plating layer having a 14-layer structure was obtained. Embodiment 5 In this embodiment, a multilayer Au—Ag plating layer was formed according to the following steps using a multi-stage cell (four-stage) step plating method. 1) First, four kinds of Au—Ag alloy plating solutions having different concentration ratios of Au ions and Ag ions are prepared in four plating cells. 2) Next, A4 for a 0.1125 mm thick lead frame
After the two materials are degreased and pickled, a nickel plating layer having a thickness of 1 μm is formed as a base plating on the surface. 3) As in Example 3, A having the lowest Ag concentration
Au having a high Ag concentration in order from the u-Ag alloy plating solution
-An A42 material for a lead frame, which has been subjected to base plating, is immersed in an Ag alloy plating solution.
A u-Ag plating layer is formed. By using the above process, the average composition was 49.0 wt% Ag on A42 material in the same manner as in Example 3.
63.7 wt% of composition gradient, multilayer Au-A having a four-layer structure
g A lead frame having a plating layer was obtained. Comparative Example 1 In this comparative example, Au-A
g A plating layer was formed. 1) First, the Au—Ag alloy plating solution was
Prepare one plating cell. 2) Next, a copper material for a lead frame having a thickness of 0.125 mm is degreased and pickled, and then a nickel plating layer having a thickness of 1 μm is formed on the surface as a base plating. 3) Then, the copper material for the lead frame on which the base plating is applied is immersed in an Au-Ag alloy plating solution, and the Au-Ag alloy is plated.
Form a plating layer. By using the above process, the composition 27.
A lead frame having a single-layer Au-Ag plating film of 6 wt% Ag was obtained. Comparative Example 2 In this comparative example, an Au—Ag plating layer was formed using a constant current pulse power supply. 1) First, an Au-Ag alloy plating solution was
Prepare one plating cell. 2) Next, a copper material for a lead frame having a thickness of 0.125 mm is degreased and pickled, and then a nickel plating layer having a thickness of 1 μm is formed on the surface as a base plating. 3) Then, the copper material for the lead frame on which the base plating is applied is immersed in an Au-Ag alloy plating solution, and the Au-Ag alloy is plated.
Form a plating layer. By using the above process, the composition 25.
A lead frame having a single-layer Au-Ag alloy film of 1 wt% Ag was obtained. Here, the lead frames formed in Examples 1 to 5 and Comparative Examples 1 and 2 were subjected to a corrosion resistance test and a solder wettability test by the following methods. Corrosion resistance test: 5% NaCl solution at 35 ° C.
Salt spray acceleration test spraying for 24 hours in the environment of
Observe the formation of rust. Solder wettability test: 3 at 330 ° C
After heating for 0 minutes, Sn-37Pb was contacted at 230 ° C. for 5 seconds, and wetting of the solder was observed. Table 1 shows the results of the corrosion resistance test and the solder wettability test. [Table 1] Here, when the wetting rate exceeds 95%,
The corrosion resistance is indicated by a circle when no rust is observed. As shown in Table 1, in Examples 1 to 5,
Compared to Comparative Examples 1 and 2, thinner films (less than 0.1 μm) have excellent solder wettability and corrosion resistance. As described above, according to the lead frame of the present invention, it is possible to form a thin lead frame having excellent corrosion resistance and solder wettability. Further, since there is no need to use lead such as external solder plating, it is environmentally friendly and the cost of waste liquid treatment and the like can be suppressed. Further, excellent characteristics can be obtained at low cost as compared with the case where a single Au-Ag plating layer is formed. Further, since Au-Ag plating is used, a lead frame having excellent high frequency characteristics can be formed as compared with the case where palladium plating or the like is used. In addition, two layers of Ni / Pd or Ni / Pd
In the three-layer plating of d / Au, an A42 material that could not be used as a base material because of its poor corrosion resistance can be used as a base material. According to the present invention, it is possible to obtain a lead frame in which a plating film having excellent characteristics is formed thin without using lead.
【図面の簡単な説明】
【図１】本発明に係るリードフレームの構成を示す断面
図
【図２】本発明に係るリードフレームの製造方法を示す
断面図
【図３】多層Ａｕ−Ａｇめっき層のＡｇ含有量の変化を
示す概念図
【図４】実施例２における電流波形の制御を示す概略図
【符号の説明】
１…銅材
２…ニッケルめっき層
３…第１のＡｕ−Ａｇめっき層
４…第２のＡｕ−Ａｇめっき層
５…第３のＡｕ−Ａｇめっき層
６…多層Ａｕ−Ａｇめっき層
１０…リードフレームBRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a configuration of a lead frame according to the present invention. FIG. 2 is a cross-sectional view showing a method for manufacturing a lead frame according to the present invention. FIG. 3 is a multilayer Au-Ag plating layer. FIG. 4 is a conceptual diagram showing a change in the Ag content of FIG. 4. FIG. 4 is a schematic diagram showing the control of a current waveform in Example 2. Description of reference numerals 1... Copper material 2. Nickel plating layer 3. 4. Second Au-Ag plating layer 5 Third Au-Ag plating layer 6 Multi-layer Au-Ag plating layer 10 Lead frame
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 4K024 AA03 AA24 AB03 AB04 AB19 BA09 BB13 GA04 GA14 GA16 5F067 DC11 DC17 DC18 EA02 ────────────────────────────────────────────────── ─── Continuation of front page F term (reference) 4K024 AA03 AA24 AB03 AB04 AB19 BA09 BB13 GA04 GA14 GA16 5F067 DC11 DC17 DC18 EA02
Claims (1)
ードフレームにおいて、 前記Ａｕ−Ａｇめっきは、Ａｇの割合が異なる複数のＡ
ｕ−Ａｇめっき層が積層された多層Ａｕ−Ａｇめっき層
からなり、 前記多層Ａｕ−Ａｇめっき層は、基材側から最表面にか
けてＡｇの割合が増加することを特徴とするリードフレ
ーム。Claims: 1. A lead frame having a surface on which Au-Ag plating is formed, wherein the Au-Ag plating comprises a plurality of A having different Ag ratios.
A lead frame comprising a multilayer Au-Ag plating layer on which a u-Ag plating layer is laminated, wherein the multilayer Au-Ag plating layer has a ratio of Ag increasing from the substrate side to the outermost surface.
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|---|---|---|---|
| JP2002066992A JP3707548B2 (en) | 2002-03-12 | 2002-03-12 | Lead frame and lead frame manufacturing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002066992A JP3707548B2 (en) | 2002-03-12 | 2002-03-12 | Lead frame and lead frame manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003273305A true JP2003273305A (en) | 2003-09-26 |
| JP3707548B2 JP3707548B2 (en) | 2005-10-19 |
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| JP2002066992A Expired - Fee Related JP3707548B2 (en) | 2002-03-12 | 2002-03-12 | Lead frame and lead frame manufacturing method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004049415A1 (en) * | 2002-11-26 | 2004-06-10 | Sharp Kabushiki Kaisha | Alloy material for semiconductor, semiconductor chip using such alloy material, and method for manufacturing same |
-
2002
- 2002-03-12 JP JP2002066992A patent/JP3707548B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004049415A1 (en) * | 2002-11-26 | 2004-06-10 | Sharp Kabushiki Kaisha | Alloy material for semiconductor, semiconductor chip using such alloy material, and method for manufacturing same |
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| JP3707548B2 (en) | 2005-10-19 |
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