JP2013201182A - Method for manufacturing palladium coated copper bonding wire - Google Patents

Method for manufacturing palladium coated copper bonding wire Download PDF

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JP2013201182A
JP2013201182A JP2012067363A JP2012067363A JP2013201182A JP 2013201182 A JP2013201182 A JP 2013201182A JP 2012067363 A JP2012067363 A JP 2012067363A JP 2012067363 A JP2012067363 A JP 2012067363A JP 2013201182 A JP2013201182 A JP 2013201182A
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core material
palladium
heat treatment
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coated copper
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Kazufumi Fukuzaki
和文 福崎
Koichi Imazawa
公一 今澤
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Nippon Micrometal Corp
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Abstract

PROBLEM TO BE SOLVED: To suppress a coating layer of a palladium coated copper bonding wire from dropping off from its core material and to provide a bonding wire with a surface on which no copper exposure occurs.SOLUTION: A method for manufacturing a palladium coated copper bonding wire manufactured by forming in a plating step a palladium coated layer around a core material 10 whose main component is copper, comprises: a single wire drawing step P2 in which, before the plating step, the core material is single wire drawn; and a heat treatment step P3 for heat treating the core material thus single wire drawn. The heat treatment step is a batch type heat treatment step in nitrogen atmosphere. In the step the core material after being single wire drawn is placed for a prescribed amount in a heating oven 40 and sealed therein, then the heating oven is filled with nitrogen gas and heating inside the heating oven is started.

Description

本発明は、パラジウム被覆銅ボンディングワイヤの製造方法に関する。   The present invention relates to a method for producing a palladium-coated copper bonding wire.

従来から、半導体素子の実装に用いられるボンディングワイヤとして、銅を主成分とする芯材の周囲に、パラジウムからなる被覆層を形成したパラジウム被覆銅ボンディングワイヤが知られている（例えば、特許文献１参照）。   Conventionally, as a bonding wire used for mounting a semiconductor element, a palladium-coated copper bonding wire in which a coating layer made of palladium is formed around a core material mainly composed of copper is known (for example, Patent Document 1). reference).

市場で専ら使用されているパラジウム被覆銅ボンディングワイヤの線径は約２０μｍであり、ボールボンディングのボール潰し径は、パッケージの信頼性を確保するために４５μｍ以上となっている。また、半導体素子上のアルミニウムパッドの間隔、即ち、ダイパッドピッチは、６０μｍ以上の場合が多い。通常ボール潰し厚は、線径の半分程度としている組立メーカーが多いが、この規則に従うと、線径２０μｍのボンディングワイヤの場合には、潰し厚は１０μｍとなる。ボールの潰し厚が１０μｍで、潰し径を４５μｍ以上とするためには、ボンディング前のボール径は３２μｍを超えることが必要となる。こうした、線径の１．６倍を超える大きさの直径を有するボールをフォーミングガス中で形成すると、ワイヤ表面のパラジウムがボールの表面全体に分布する。そうすると、ボールボンディング時には、アルミニウムパッドとの接合部で銅とアルミニウムが直接接触することを防止できるため、ガルバニック腐食が防止される。また、樹脂モールド時には、エポキシ中の塩素が銅に直接接触することが無いため、ボール内部の銅腐食が防止され、パッケージの信頼性評価では、ベア銅線よりも寿命が長いという結果が得られている。   The wire diameter of the palladium-coated copper bonding wire used exclusively in the market is about 20 μm, and the ball crushing diameter of ball bonding is 45 μm or more in order to ensure the reliability of the package. In many cases, the distance between aluminum pads on a semiconductor element, that is, the die pad pitch, is 60 μm or more. Usually, there are many assembly manufacturers whose ball collapse thickness is about half of the wire diameter. However, according to this rule, in the case of a bonding wire having a wire diameter of 20 μm, the collapse thickness is 10 μm. In order to make the crushed thickness of the ball 10 μm and the crushed diameter 45 μm or more, the ball diameter before bonding needs to exceed 32 μm. When a ball having a diameter larger than 1.6 times the wire diameter is formed in the forming gas, palladium on the wire surface is distributed over the entire surface of the ball. Then, at the time of ball bonding, it is possible to prevent copper and aluminum from coming into direct contact at the joint portion with the aluminum pad, thereby preventing galvanic corrosion. Also, during resin molding, the chlorine in the epoxy does not come into direct contact with copper, so copper corrosion inside the ball is prevented and the reliability evaluation of the package has a longer life than bare copper wire. ing.

最近になり、金価格の上昇が一段と進み、金ボンディングワイヤからパラジウム被覆銅ボンディングワイヤへの置き換えも進んでいる。例えば、ダイパッドピッチが５０μｍ以下のファインダイパッドピッチのパッケージへも、パラジウム被覆銅ボンディングワイヤが展開されるようになり、これに伴い、線径も２０μｍから１８μｍや１５μｍへと細線化された。ダイパッドピッチが５０μｍの場合、アルミニウムパッドの開口部の幅は４５μｍであり、ボンディングの位置精度やボールつぶし径のばらつき等から、ボール潰し径は４０μｍ以下であることが要求される。上述のボール潰し形状の規則に従うと、線径１８μｍではボール潰し厚は９μｍとなり、この体積を得るためのボンディング前のボール径は約２８μｍ以下となり、線径の１．６倍以下となる、いわゆる小ボールでのボールボンディングが要求される。   Recently, the price of gold has further increased, and the replacement of gold bonding wires with palladium-coated copper bonding wires is also progressing. For example, a palladium-coated copper bonding wire has been developed even in a fine die pad pitch package having a die pad pitch of 50 μm or less, and accordingly, the wire diameter has been reduced from 20 μm to 18 μm or 15 μm. When the die pad pitch is 50 μm, the width of the opening of the aluminum pad is 45 μm, and the ball crushing diameter is required to be 40 μm or less due to variations in bonding position accuracy and ball crushing diameter. According to the above-mentioned rule of the ball crushing shape, when the wire diameter is 18 μm, the ball crushing thickness is 9 μm, and the ball diameter before bonding for obtaining this volume is about 28 μm or less, which is not more than 1.6 times the wire diameter. Ball bonding with small balls is required.

特開２００４−６４０３３号公報JP 2004-64033 A

しかしながら、こうした小ボールが要求されるパラジウム被覆銅ボンディンディングワイヤにおいて、被覆層が脱落し、芯材が露出することによって、ボンディングワイヤ表面の熱伝導性および金属流体への濡れ性が不均一となる。これにより、ボンディングにおけるボール形成時に、ボールの芯ズレや異形状を誘発するため、ワイヤボンディング工程での収率及び作業性を著しく悪化させるという問題があった。   However, in a palladium-coated copper bonding wire that requires such a small ball, the coating layer falls off and the core material is exposed, so that the thermal conductivity of the bonding wire surface and the wettability to the metal fluid become non-uniform. . As a result, there is a problem in that the yield and workability in the wire bonding process are remarkably deteriorated because a ball misalignment or irregular shape is induced when forming a ball in bonding.

ところで、パラジウム被覆銅ボンディングワイヤ表面において、被覆層が脱落して芯材が露出する原因は、パラジウムめっき後の製品表面に凹凸があり、めっき後の伸線工程にてダイス通過時に凸部のパラジウム被覆層が削り取られることにある。この凹凸部はめっき前の芯材に由来しており、めっき前の薬品による芯材表面の化学研磨や、化学研磨以前に発生する。化学研磨で芯材表面を研磨（例えば０．０１μｍ〜５μｍ）しても、研磨される箇所で偏りを生じ、完全には平滑な表面が得られないため、めっき前の芯材の伸線過程でどれだけ凹凸の無い表面を得られるかが課題であった。   By the way, on the surface of the palladium-coated copper bonding wire, the core layer is exposed because the coating layer falls off, and the surface of the product after palladium plating has irregularities, and the palladium on the projections passes through the die in the wire drawing process after plating. The coating layer is to be scraped off. This uneven part is derived from the core material before plating, and occurs before chemical polishing of the core material surface with chemicals before plating or before chemical polishing. Even if the surface of the core material is polished by chemical polishing (for example, 0.01 μm to 5 μm), unevenness occurs in the portion to be polished, and a completely smooth surface cannot be obtained. The problem was how to obtain an uneven surface.

そこで、本発明は、パラジウム被覆銅ボンディングワイヤの被覆層が芯材から脱落することを抑制し、表面に銅露出が発生しないボンディングワイヤを提供することを目的とする。   Then, an object of this invention is to provide the bonding wire which suppresses that the coating layer of a palladium covering copper bonding wire falls off from a core material, and copper exposure does not generate | occur | produce on the surface.

上記目的を達成するため、本発明の一態様に係るパラジウム被覆銅ボンディングワイヤの製造方法は、銅を主成分とする芯材の周囲にパラジウム被覆層をめっき工程で形成したパラジウム被覆銅ボンディングワイヤの製造方法であって、
前記めっき工程より前に、前記芯材を単引き伸線する単引き伸線工程と、
単引き伸線された前記芯材を熱処理する熱処理工程と、を有し、
該熱処理工程は、加熱炉内に単引き伸線された前記芯材を所定量設置して密封し、窒素ガスを前記加熱炉内に満たしてから前記加熱炉内の加熱を開始する、窒素雰囲気下のバッチ式熱処理工程であることを特徴とする。 In order to achieve the above object, a method for producing a palladium-coated copper bonding wire according to one aspect of the present invention is a method for producing a palladium-coated copper bonding wire in which a palladium coating layer is formed around a core mainly composed of copper by a plating process. A manufacturing method comprising:
Prior to the plating step, a single drawing step for single drawing the core material,
A heat treatment step of heat-treating the core drawn by single drawing,
In the heat treatment step, a predetermined amount of the core material drawn and drawn in a heating furnace is hermetically sealed and filled with nitrogen gas in the heating furnace, and then heating in the heating furnace is started. It is the following batch type heat treatment process.

本発明によれば、ボンディングにおけるボール形成時にボールの芯ズレや異形状を改善してワイヤボンディング工程での収率および作業性を著しく向上することができる。   According to the present invention, it is possible to improve the yield and workability in the wire bonding process by improving the misalignment and irregular shape of the ball when forming the ball in bonding.

本発明の実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法を含む全体工程の一例を示した図である。It is the figure which showed an example of the whole process including the manufacturing method of the palladium covering copper bonding wire which concerns on embodiment of this invention. 本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の太線伸線工程の一例を示した図である。It is the figure which showed an example of the thick wire drawing process of the manufacturing method of the palladium covering copper bonding wire which concerns on this embodiment. 本発明の実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の熱処理工程の一例を示した図である。It is the figure which showed an example of the heat processing process of the manufacturing method of the palladium covering copper bonding wire which concerns on embodiment of this invention. 本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の熱処理工程の窒素導入と加熱のタイミングの説明図である。It is explanatory drawing of the timing of nitrogen introduction | transduction and the heating of the heat processing process of the manufacturing method of the palladium covering copper bonding wire which concerns on this embodiment. キズの状態の第１の例を示した図である。It is the figure which showed the 1st example of the state of a crack. キズの状態の第２の例を示した図である。It is the figure which showed the 2nd example of the state of a crack. キズの状態の第３の例を示した図である。It is the figure which showed the 3rd example of the state of a crack. キズの状態の第４の例を示した図である。It is the figure which showed the 4th example of the state of a crack.

以下、図面を参照して、本発明を実施するための形態の説明を行う。   DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

図１は、本発明の実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法を含む全体工程の一例を示した図である。パラジウム被覆銅ボンディングワイヤの製造工程は、連続鋳造工程Ｐ１と、太線伸線工程（単引き伸線工程）Ｐ２と、熱処理工程Ｐ３と、エッチング工程Ｐ４と、伸線工程Ｐ５と、熱処理工程Ｐ６と、めっき工程Ｐ７と、伸線工程Ｐ８と、熱処理工程Ｐ９とを含む。   FIG. 1 is a diagram showing an example of the entire process including a method for producing a palladium-coated copper bonding wire according to an embodiment of the present invention. The manufacturing process of the palladium-coated copper bonding wire includes a continuous casting process P1, a thick wire drawing process (single drawing process) P2, a heat treatment process P3, an etching process P4, a wire drawing process P5, and a heat treatment process P6. Plating process P7, wire drawing process P8, and heat treatment process P9.

このうち、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法は、めっき工程Ｐ７より前に太線伸線工程Ｐ２及び熱処理工程Ｐ３を有し、必要に応じて、更にエッチング工程Ｐ４を有すればよく、他の工程は、必要に応じて種々変更することができる。つまり、太線伸線工程Ｐ２、熱処理工程Ｐ３及びめっき工程Ｐ７以外の他の工程は、必要が無ければ省略されてもよいし、工程内容が変更されてもよい。また、図１に示されていない新たな工程が更に追加されてもよい。   Among these, if the manufacturing method of the palladium covering copper bonding wire which concerns on this embodiment has the thick wire drawing process P2 and the heat treatment process P3 before the plating process P7, and if necessary, it further has the etching process P4. Well, other processes can be variously changed as needed. That is, processes other than the thick wire drawing process P2, the heat treatment process P3, and the plating process P7 may be omitted if necessary, or the process contents may be changed. Moreover, a new process not shown in FIG. 1 may be further added.

以下、簡単に各工程について説明する。連続鋳造工程Ｐ１は、銅板から、芯材となる銅線を鋳造する工程である。太線伸線工程Ｐ２は、単頭伸線機を用いて単引き伸線を行う工程であり、これで、例えば数ｍｍの線径を有する鋳造後の芯材が、１ｍｍ程度にまで縮径される。熱処理工程Ｐ３は、単引き伸線された芯材を加熱して熱処理する工程であり、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法においては、バッチ処理で熱処理が行われる。なお、熱処理工程Ｐ３の詳細については後述する。エッチング工程Ｐ４は、熱処理されて表面に酸化膜が形成された芯材の酸化膜をエッチングにより除去する工程である。伸線工程Ｐ５は、１ｍｍ程度に縮径された芯材を、連続伸線加工により更に数１００μｍ程度まで縮径する工程である。熱処理工程Ｐ６は、連続熱処理により、芯材を軟化する工程である。めっき工程Ｐ７は、銅を主成分とする芯材の表面にパラジウムをめっきし、芯材の周囲にパラジウム被覆層を形成する工程である。めっき工程Ｐ７は、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法では、必須の工程となる。なお、めっき工程Ｐ７は、必要に応じて、前処理工程、ストライクめっき工程等の関連工程を含んでよい。伸線工程Ｐ８は、めっき工程により形成されたパラジウム被覆銅ボンディングワイヤを伸線加工し、製品と同径まで縮径する工程である。熱処理工程Ｐ９は、伸線加工されたパラジウム被覆銅ボンディングワイヤを熱処理して軟化する工程である。熱処理工程Ｐ９が終了すると、出荷可能なパラジウム被覆銅ボンディングワイヤが完成する。   Hereinafter, each process is demonstrated easily. The continuous casting process P1 is a process of casting a copper wire serving as a core material from a copper plate. The thick wire drawing process P2 is a process of performing single wire drawing using a single-head wire drawing machine. With this, for example, a core material after casting having a wire diameter of several mm is reduced to about 1 mm. The The heat treatment process P3 is a process of heating and heat-treating the single drawn core material, and in the method for producing a palladium-coated copper bonding wire according to the present embodiment, heat treatment is performed by batch processing. Details of the heat treatment step P3 will be described later. The etching process P4 is a process of removing the oxide film of the core material that has been heat-treated and has an oxide film formed on the surface thereof by etching. The wire drawing step P5 is a step of further reducing the diameter of the core material reduced to about 1 mm to about several hundred μm by continuous wire drawing. The heat treatment step P6 is a step of softening the core material by continuous heat treatment. The plating step P7 is a step of plating palladium on the surface of the core material mainly composed of copper and forming a palladium coating layer around the core material. The plating step P7 is an essential step in the method for producing a palladium-coated copper bonding wire according to this embodiment. In addition, the plating process P7 may include related processes such as a pretreatment process and a strike plating process as necessary. The wire drawing step P8 is a step of drawing the palladium-coated copper bonding wire formed by the plating step and reducing the diameter to the same diameter as the product. The heat treatment process P9 is a process of heat-treating and softening the drawn palladium-coated copper bonding wire. When the heat treatment step P9 is completed, a shippable palladium-coated copper bonding wire is completed.

かかる銅被覆銅ボンディングワイヤは、一般的に、ワイヤ表面にパラジウムが分布することにより、ウェッジ接合性および耐酸化性の向上などが期待できる。半面、パラジウム被覆層が芯材から脱落した場合、ボンディング時に芯ズレやボール異形状を誘発し、ワイヤボンディングの収率及び作業性を著しく悪化させることが新たな問題となることが分かった。   In general, such copper-coated copper bonding wires can be expected to improve wedge bondability and oxidation resistance due to the distribution of palladium on the wire surface. On the other hand, it has been found that when the palladium coating layer is detached from the core material, a new problem arises in that the core misalignment and the ball irregular shape are induced at the time of bonding, and the yield and workability of wire bonding are remarkably deteriorated.

そこで、本願の発明者等は、パラジウム被覆層が芯材から脱落することのないよう伸線加工における条件を鋭意検討した結果、めっき工程の前に芯材の表面に発生する凹凸を抑制することが大切であり、かかる凹凸抑制のためには、太線伸線工程Ｐ２の後の熱処理工程Ｐ３における熱処理の条件と、熱処理で生じた酸化膜のエッチングが重要であることを見出した。以下、これらに関連する内容について具体的に説明する。   Therefore, the inventors of the present application, as a result of earnestly examining the conditions in the wire drawing process so that the palladium coating layer does not fall off from the core material, suppress the unevenness generated on the surface of the core material before the plating step. In order to suppress such unevenness, it has been found that the heat treatment conditions in the heat treatment step P3 after the thick wire drawing step P2 and the etching of the oxide film generated by the heat treatment are important. Hereinafter, the contents related to these will be described in detail.

図２は、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の太線伸線工程Ｐ２の一例を示した図である。太線伸線工程Ｐ２においては、単頭伸線機を用いて、単引き伸線加工を行う。図２に示すように、単頭伸線機は、キャプスタンロール２０、２１と、ダイス３０とを備え、巻き出し用のキャプスタンロール２０で巻き出された芯材１０を、ダイス３０を通過させて引き抜き、巻き取り用のキャプスタンロール２１で巻き取る。ダイス３０は、出口側の径が入口側の径よりも小さくなるようなテーパー形状の穴を有し、ダイス３０の穴を芯材１０が通過して引き抜かれることにより、線径が細くなるように構成されている。この単引き伸線は、芯材１０の線径がｍｍ単位で太く、引き抜きに大きな力を要するため、１つのダイス３０のみを用いて伸線加工が行われる。それ故、シングルダイドローイング又は単引き伸線と呼ばれている。単引き伸線は複数回行われ、一般的には、数１０回行われる。本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の熱処理工程Ｐ３は、かかる太線伸線工程Ｐ２の直後に行われる。   FIG. 2 is a diagram showing an example of a thick wire drawing step P2 of the method for producing a palladium-coated copper bonding wire according to the present embodiment. In the thick wire drawing process P2, single wire drawing is performed using a single-head wire drawing machine. As shown in FIG. 2, the single-head wire drawing machine includes capstan rolls 20, 21 and a die 30. The core material 10 unwound by the capstan roll 20 for unwinding is passed through the die 30. It is wound up with a capstan roll 21 for drawing and winding. The die 30 has a taper-shaped hole whose diameter on the outlet side is smaller than the diameter on the inlet side, and the core diameter 10 passes through the hole of the die 30 so that the wire diameter is reduced. It is configured. In this single drawing, the diameter of the core material 10 is large in mm units, and a large force is required for drawing, so that drawing is performed using only one die 30. Therefore, it is called single die drawing or single drawing. Single drawing is performed a plurality of times, and generally several tens of times. The heat treatment step P3 of the method for producing a palladium-coated copper bonding wire according to this embodiment is performed immediately after the thick wire drawing step P2.

図３は、本発明の実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の熱処理工程Ｐ３の一例を示した図である。熱処理工程Ｐ３においては、加熱炉４０を用いて、芯材１０の熱処理（アニール）を行う。加熱炉４０は、ステージ４１と、ヒータ４２と、ガス供給路４３と、窒素ガス供給タンク４４と、バルブ４５と、排気路４６と、排気ポンプ４７と、バルブ４８とを備える。   FIG. 3 is a diagram showing an example of a heat treatment step P3 of the method for producing a palladium-coated copper bonding wire according to the embodiment of the present invention. In the heat treatment step P <b> 3, heat treatment (annealing) of the core material 10 is performed using the heating furnace 40. The heating furnace 40 includes a stage 41, a heater 42, a gas supply path 43, a nitrogen gas supply tank 44, a valve 45, an exhaust path 46, an exhaust pump 47, and a valve 48.

熱処理工程Ｐ３は、パラジウムめっき前の芯材１０の単引き伸線加工において形成される加工変質層を再結晶させることで、芯材１０を軟化させるために行われる。かかる熱処理工程Ｐ３において、芯材１０の表面に酸化膜が多く形成されてしまうと、後にエッチング工程Ｐ４を行い、酸化膜を除去しても、エッチング後の芯材１０の表面に凹凸が形成されてしまう。また、除去できなかった酸化膜が以後の伸線過程で異物としてダイスに噛み込む事で断線や表面外観を損なう原因となる。よって、熱処理工程Ｐ３では、酸化膜の芯材表面への形成を抑制しつつ、アニールを行うことが好ましい。以下、その具体的な内容について説明する。   The heat treatment step P3 is performed in order to soften the core material 10 by recrystallizing a work-affected layer formed in the single drawing and drawing of the core material 10 before palladium plating. In this heat treatment step P3, if a large amount of oxide film is formed on the surface of the core material 10, irregularities are formed on the surface of the core material 10 after etching even if the etching step P4 is performed later and the oxide film is removed. End up. In addition, the oxide film that could not be removed bites into the die as a foreign substance in the subsequent wire drawing process, which may cause breakage of the wire or the appearance of the surface. Therefore, in the heat treatment step P3, it is preferable to perform annealing while suppressing the formation of the oxide film on the surface of the core material. The specific contents will be described below.

加熱炉４０は、芯材１０をバッチアニール処理するための加熱炉４０として構成されている。熱処理工程Ｐ３においては、単引き伸線加工後の芯材１０を、巻回した環状の束の状態で加熱炉４０のステージ４１上に設置し、加熱炉４０を密閉し、窒素ガスをガス供給路４３から加熱炉４０内に導入し、加熱炉４０内を窒素雰囲気で満たしてからヒータ４２により加熱を行う。ガス供給路４３は、ガス供給タンク４４に接続され、ガス供給路４３に設けられたバルブ４５により流量を調整しながら窒素ガスを加熱炉４０内に供給できるように構成されている。また、加熱炉４０には、排気ポンプ４７に接続された排気路４６が設けられ、必要に応じて排気が可能に構成されている。また、排気路４６にもバルブ４８が設けられ、排気量の調整が可能に構成されている。加熱が終わったら、そのまま窒素雰囲気を維持した密閉状態で冷却し、室温まで冷却してから加熱炉４０を開放し、熱処理後の芯材１０を取り出すようにする。   The heating furnace 40 is configured as a heating furnace 40 for batch annealing the core material 10. In the heat treatment process P3, the core material 10 after the single drawing process is placed on the stage 41 of the heating furnace 40 in a wound annular bundle state, the heating furnace 40 is sealed, and nitrogen gas is supplied as a gas. It introduce | transduces in the heating furnace 40 from the path | route 43, and after the inside of the heating furnace 40 is satisfy | filled with nitrogen atmosphere, it heats with the heater 42. FIG. The gas supply path 43 is connected to a gas supply tank 44 and configured to supply nitrogen gas into the heating furnace 40 while adjusting the flow rate by a valve 45 provided in the gas supply path 43. Further, the heating furnace 40 is provided with an exhaust passage 46 connected to an exhaust pump 47 so that exhaust can be performed as necessary. Further, a valve 48 is also provided in the exhaust passage 46 so that the exhaust amount can be adjusted. When the heating is finished, it is cooled in a sealed state maintaining a nitrogen atmosphere as it is, cooled to room temperature, then the heating furnace 40 is opened, and the heat-treated core material 10 is taken out.

図４は、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の熱処理工程Ｐ３の窒素導入と加熱のタイミングを説明するための図である。図４において、横軸は時間を示し、縦軸は温度を示す。   FIG. 4 is a diagram for explaining the timing of nitrogen introduction and heating in the heat treatment step P3 of the method for producing a palladium-coated copper bonding wire according to the present embodiment. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates temperature.

本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の熱処理工程Ｐ３においては、常温状態（又は室温状態）で加熱炉４０の加熱炉４０内に芯材１０を設置する。そして、図４の下部に示すように、常温状態のまま窒素ガスを加熱炉４０内に導入し、加熱炉４０内が窒素で満たされてから加熱を開始するようにする。そして、窒素雰囲気下で熱処理を継続し、加熱を終了してからも、窒素雰囲気下を保ったまま加熱炉４０内の温度を徐々に低下させ、室温まで到達させる。そして、室温まで到達したら、加熱炉４０を開放し、加熱炉４０から芯材１０を取り出し、熱処理工程Ｐ３を終了する。これにより、芯材１０が大気に接触するのは常温状態にある時のみとなり、芯材１０が加熱されているときには、常に窒素雰囲気下にある状態にすることができる。常温下での芯材１０の表面に形成される酸化膜は非常に少量であるが、加熱時に形成される酸化膜の量は非常に多い。よって、加熱時には常に芯材１０が窒素雰囲気下にある状態を作ることにより、芯材１０の表面に形成される酸化膜の量を大幅に低減させることができる。   In the heat treatment step P3 of the method for producing a palladium-coated copper bonding wire according to the present embodiment, the core material 10 is installed in the heating furnace 40 of the heating furnace 40 in a normal temperature state (or a room temperature state). And as shown in the lower part of FIG. 4, nitrogen gas is introduce | transduced in the heating furnace 40 with a normal temperature state, and heating is started after the inside of the heating furnace 40 is filled with nitrogen. Then, after the heat treatment is continued in the nitrogen atmosphere and the heating is finished, the temperature in the heating furnace 40 is gradually lowered to reach room temperature while maintaining the nitrogen atmosphere. And if it reaches room temperature, the heating furnace 40 will be open | released, the core material 10 will be taken out from the heating furnace 40, and the heat processing process P3 will be complete | finished. As a result, the core material 10 comes into contact with the atmosphere only when it is at room temperature, and when the core material 10 is heated, it can always be in a nitrogen atmosphere. Although the amount of oxide film formed on the surface of the core material 10 at room temperature is very small, the amount of oxide film formed during heating is very large. Therefore, the amount of the oxide film formed on the surface of the core material 10 can be greatly reduced by making the core material 10 always in a nitrogen atmosphere during heating.

なお、図４の上部には、比較例として、加熱炉４０内は窒素ガスで満たされているが、温度が上昇してから芯材１０を加熱炉４０内に搬入して設置し、高温状態で芯材１０の搬出を行った場合が記載されている。この場合には、窒素雰囲気下で熱処理を行ったとしても、芯材１０の表面には、多くの酸化膜が形成されてしまう。これは、たとえ加熱炉４０内が窒素で満たされていたとしても、芯材１０の搬入の際に加熱炉４０の扉を開放すると、多くの酸素が加熱炉４０内に混入してしまい、酸化膜が形成されるからであると考えられる。同様に、高温状態で芯材１０を加熱炉から搬出すると、高温状態を維持している搬出直後の芯材１０は、周囲の酸素と反応してしまい、酸化膜が表面に形成されるからであると考えられる。つまり、たとえ窒素雰囲気下でバッチアニールしても、その後に芯材１０を空冷したり、水中などへ急冷したりする方法では、芯材１０の表面に酸化膜を形成してしまい、酸化膜を除去した後の芯材表面に凹凸が形成されてしまう。また、除去できなかった酸化膜が以後の伸線過程で異物としてダイスに噛み込む事で断線や表面外観を損なう原因となる。   In addition, although the inside of the heating furnace 40 is filled with nitrogen gas as a comparative example in the upper part of FIG. 4, after the temperature rises, the core material 10 is carried into the heating furnace 40 and installed, and is in a high temperature state. The case where the core material 10 is carried out is described. In this case, even if heat treatment is performed in a nitrogen atmosphere, many oxide films are formed on the surface of the core material 10. This is because even if the inside of the heating furnace 40 is filled with nitrogen, if the door of the heating furnace 40 is opened when the core material 10 is carried in, a large amount of oxygen is mixed into the heating furnace 40 and oxidized. This is probably because a film is formed. Similarly, when the core material 10 is unloaded from the heating furnace in a high temperature state, the core material 10 immediately after unloading maintaining the high temperature state reacts with surrounding oxygen, and an oxide film is formed on the surface. It is believed that there is. That is, even if batch annealing is performed in a nitrogen atmosphere, an oxide film is formed on the surface of the core material 10 by a method in which the core material 10 is subsequently air-cooled or rapidly cooled to water or the like. Unevenness is formed on the surface of the core material after the removal. In addition, the oxide film that could not be removed bites into the die as a foreign substance in the subsequent wire drawing process, which may cause breakage of the wire or the appearance of the surface.

一方、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法の熱処理工程Ｐ３においては、最初に芯材１０を加熱炉４０内に搬入設置し、加熱炉４０内に窒素をパージして加熱炉４０内を窒素雰囲気で満たしてから加熱を開始する。そして、所定時間加熱保持し、更に室温まで炉内で冷却する間を窒素雰囲気に保つことにより、熱処理全体を窒素雰囲気下で行うことができ、芯材表面の酸化を抑制することができる。   On the other hand, in the heat treatment step P3 of the method for producing the palladium-coated copper bonding wire according to the present embodiment, the core material 10 is first carried into the heating furnace 40 and nitrogen is purged into the heating furnace 40 to heat the heating furnace 40. Heating is started after filling the inside with a nitrogen atmosphere. Then, the whole heat treatment can be performed in a nitrogen atmosphere by heating and holding for a predetermined time and further maintaining in the nitrogen atmosphere while cooling in the furnace to room temperature, and oxidation of the core material surface can be suppressed.

次に、必要に応じて設けられるエッチング工程Ｐ４について説明する。なお、エッチング工程Ｐ４は、理解が容易であるので、特に図面は参照しない。エッチング工程Ｐ４においては、熱処理工程Ｐ３において、芯材１０の表面に酸化膜が形成された場合に、酸化膜を除去するために芯材１０の表面をエッチングする工程である。よって、エッチング工程Ｐ４は、熱処理工程Ｐ３の直後であって、めっき工程よりも前に行われる。   Next, the etching process P4 provided as necessary will be described. Since the etching process P4 is easy to understand, no particular reference is made to the drawings. In the etching process P4, when an oxide film is formed on the surface of the core material 10 in the heat treatment process P3, the surface of the core material 10 is etched to remove the oxide film. Therefore, the etching process P4 is performed immediately after the heat treatment process P3 and before the plating process.

エッチング工程は、処理槽に貯留されたエッチング液に、熱処理された芯材１０を浸漬することにより行われる。エッチング液は、一般的には、塩化第二鉄の水溶液が用いられるが、本実施形態に係るパラジウム被覆銅ボンディングワイヤにおいては、塩化第二鉄の水溶液よりも、エッチング効果が低いエッチング液を用いる。塩化第二鉄を用いたエッチング液は、エッチング効果が高すぎて、選択的にエッチングされる箇所が生じてしまい、芯材表面の凹凸形成の要因となることを本願の発明者等は見出した。そこで、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法のエッチング工程Ｐ４においては、塩化第二鉄よりもエッチング効果が低く、エッチングレートが遅いエッチング液を用いる。そして、塩化第二鉄によるエッチングよりも長時間掛けてエッチングを行うようにする。これにより、熱処理工程Ｐ３で形成された酸化膜のみを適切に除去することができ、芯材１０の表面の凹凸発生を抑制することができる。   The etching process is performed by immersing the heat-treated core material 10 in an etching solution stored in a processing tank. Generally, an aqueous solution of ferric chloride is used as the etching solution. However, in the palladium-coated copper bonding wire according to this embodiment, an etching solution having an etching effect lower than that of the aqueous solution of ferric chloride is used. . The inventors of the present application have found that an etching solution using ferric chloride has an etching effect that is too high and a portion to be selectively etched is generated, which causes formation of irregularities on the surface of the core material. . Therefore, in the etching step P4 of the method for producing the palladium-coated copper bonding wire according to the present embodiment, an etching solution having an etching effect lower than that of ferric chloride and a slower etching rate is used. Then, the etching is performed for a longer time than the etching with ferric chloride. Thereby, only the oxide film formed in the heat treatment step P3 can be appropriately removed, and the occurrence of unevenness on the surface of the core material 10 can be suppressed.

エッチング液としては、塩化第二鉄よりもエッチング効果が低い種々のエッチング液を用いることができるが、例えば、塩酸又は硫酸のいずれか１つをエッチング液として用いてもよい。塩酸及び硫酸は、塩化第二鉄よりもエッチング効果が低く、エッチングレートが低いエッチング液である。よって、塩酸又は硫酸をエッチング液として用い、塩化第二鉄をエッチング液として行うエッチングよりも長時間エッチングを行うことにより、熱処理工程Ｐ３で発生した酸化膜を適切に除去することができ、めっき工程Ｐ７より前に発生する芯材１０の表面の凹凸を抑制することができる。特に、本実施形態に係るパラジウム被覆銅ボンディングワイヤの製造方法においては、窒素雰囲気下で行う熱処理Ｐ３により、芯材１０の表面への酸化膜の形成が抑制されている。よって、直後のエッチング工程Ｐ４において、エッチングレートの低いエッチング液を用いることで、酸化膜を効果的かつ適切に除去することができ、芯材表面の凹凸を抑制する相乗効果を得ることができる。   As the etching solution, various etching solutions having an etching effect lower than that of ferric chloride can be used. For example, any one of hydrochloric acid and sulfuric acid may be used as the etching solution. Hydrochloric acid and sulfuric acid are etching solutions that have a lower etching effect and a lower etching rate than ferric chloride. Therefore, by using hydrochloric acid or sulfuric acid as an etching solution and performing etching for a longer time than etching using ferric chloride as an etching solution, the oxide film generated in the heat treatment step P3 can be appropriately removed, and the plating step Unevenness on the surface of the core material 10 generated before P7 can be suppressed. In particular, in the method for manufacturing a palladium-coated copper bonding wire according to this embodiment, the formation of an oxide film on the surface of the core material 10 is suppressed by the heat treatment P3 performed in a nitrogen atmosphere. Therefore, in the immediately subsequent etching process P4, by using an etching solution having a low etching rate, the oxide film can be effectively and appropriately removed, and a synergistic effect of suppressing the irregularities on the surface of the core material can be obtained.

次に、本発明の実施例に係るパラジウム被覆銅ボンディングワイヤの製造方法を比較例とともに説明する。   Next, the manufacturing method of the palladium covering copper bonding wire which concerns on the Example of this invention is demonstrated with a comparative example.

まず、本実施例及び比較例に係るパラジウム被覆銅ボンディングワイヤの製造方法を、以下のように実施した。   First, the manufacturing method of the palladium covering copper bonding wire which concerns on a present Example and a comparative example was implemented as follows.

約１５質量％のリン銅と、純度９９．９９％以上の銅を、リン濃度が７５質量ｐｐｍとなるように調合し、約１２００℃で真空溶解して株式会社アサバ製の連続鋳造機で約直径８ｍｍの丸棒状芯材インゴットを作製した。これを連続伸線によって直径約１ｍｍまで縮径した。この後、芯材の軟化を目的に窒素雰囲気の箱型電気炉内で４００℃６０分のバッチアニールを行った。この後、芯材をエッチング液に６０秒浸漬させて純水で洗浄した。その後、これを連続伸線によって直径約２００μｍまで縮径し、芯材の軟化を目的に線速約１２ｍ／ｍｉｎにて４００℃で約４秒の熱処理を行った。   About 15% by mass of phosphorous copper and 99.99% or more purity copper were prepared so that the phosphorous concentration would be 75 ppm by mass, and melted in vacuo at about 1200 ° C. with a continuous casting machine manufactured by Asaba Co., Ltd. A round bar-shaped core material ingot having a diameter of 8 mm was produced. This was reduced in diameter to about 1 mm by continuous wire drawing. Thereafter, batch annealing was performed at 400 ° C. for 60 minutes in a box-type electric furnace in a nitrogen atmosphere for the purpose of softening the core material. Thereafter, the core material was immersed in an etching solution for 60 seconds and washed with pure water. Then, the diameter was reduced to about 200 μm by continuous wire drawing, and heat treatment was performed at 400 ° C. for about 4 seconds at a linear speed of about 12 m / min for the purpose of softening the core material.

こうして得られた芯材にパラジウムめっきを行った。工程は脱脂、塩酸洗浄、化学研摩、ストライクめっきを行い、約０．７μｍ厚にパラジウムをめっきした。その後、連続伸線によって所定の線径まで縮径し、窒素ガス中で約１０％の伸び率となるように線速４０ｍ／ｍｉｎにて４２０℃で約１．２秒の連続焼鈍（又は熱処理、アニール）を行った。   The core material thus obtained was subjected to palladium plating. In the process, degreasing, hydrochloric acid cleaning, chemical polishing, and strike plating were performed, and palladium was plated to a thickness of about 0.7 μm. Thereafter, the wire is reduced to a predetermined wire diameter by continuous wire drawing, and is continuously annealed (or heat-treated for about 1.2 seconds at 420 ° C. at a line speed of 40 m / min so as to obtain an elongation of about 10% in nitrogen gas. , Annealing).

ここで、バッチアニール処理は、箱型電気炉に芯材を入れてから窒素雰囲気に置換し、加熱を開始して４００℃を６０分保持した後、室温まで炉冷却したものを実施例、６０分保持後に箱型電気炉から取り出して空冷したものを比較例とした。また、バッチアニール後のエッチングとして、５０℃の６０％硫酸水溶液、常温の４％塩酸水溶液、常温の塩化第二鉄水溶液（市販の塩化第二鉄水溶液２００ｍＬと塩酸８００ｍＬと純水３０００ｍＬの混合液）を上記実施例と比較例に組み合わせた。   Here, the batch annealing treatment was performed by putting the core material into a box-type electric furnace and then substituting it with a nitrogen atmosphere, starting heating, holding 400 ° C. for 60 minutes, and then cooling the furnace to room temperature. A comparative example was taken out of the box-type electric furnace after air retention and cooled by air. Etching after batch annealing is carried out by using a 60% sulfuric acid aqueous solution at 50 ° C., a 4% hydrochloric acid aqueous solution at room temperature, and a ferric chloride aqueous solution at room temperature (a mixture of 200 mL of a commercially available ferric chloride aqueous solution, 800 mL of hydrochloric acid, and 3000 mL of pure water). ) Was combined with the above examples and comparative examples.

種々の組み合わせで製造した実施例の結果を表１、比較例の結果を表２に示す。   Table 1 shows the results of Examples manufactured in various combinations, and Table 2 shows the results of Comparative Examples.

Figure 2013201182
Figure 2013201182

Figure 2013201182
表１において、「バッチアニール」の項目で「炉冷却」と記載されているのが、窒素雰囲気下の加熱炉内での冷却を意味する。また、「円周方向の最大幅」、「長手方向の合計長さ」とあるのは、銅が露出したキズの幅と長さを意味しているが、この点については後述する。
Figure 2013201182
 In Table 1, “furnace cooling” in the item “batch annealing” means cooling in a heating furnace in a nitrogen atmosphere. “Maximum width in the circumferential direction” and “total length in the longitudinal direction” mean the width and length of scratches from which copper is exposed. This will be described later.

また、表２において、「バッチアニール」の項目で「空冷」と記載されているのが、冷却を加熱炉外の空気中で行ったことを意味している。   Further, in Table 2, “air cooling” in the item “batch annealing” means that cooling was performed in the air outside the heating furnace.

また、表１は実施例、表２は比較例の結果であるが、実施例か比較例かは、本実施例に係るパラジウム被覆銅ボンディングワイヤの必須構成要素とされているバッチアニールの冷却が炉冷却か空冷かにより分類している。よって、実施例には、バッチアニールが炉冷却であれば、エッチング液が塩化第二鉄の場合も含めて実施例としている。同様に、比較例は、バッチアニールの冷却が空冷であることに基づいて分類している。よって、比較例にも、エッチング液が硫酸の場合と塩酸の場合も含めて記載されている。   Table 1 shows the results of the examples, and Table 2 shows the results of the comparative examples. Whether the examples or the comparative examples is the cooling of batch annealing, which is an essential component of the palladium-coated copper bonding wire according to the present example. It is classified according to furnace cooling or air cooling. Therefore, in the examples, if batch annealing is furnace cooling, the examples include the case where the etching solution is ferric chloride. Similarly, the comparative example classifies based on the fact that the cooling of batch annealing is air cooling. Therefore, the comparative example also includes the case where the etching solution is sulfuric acid and hydrochloric acid.

表１、２に示すように、被覆層が芯材から脱落する種々の状態の製品が得られた。２００倍の光学顕微鏡観察では銅露出の違いは確認できなかったものの、ワイヤを金属製ＡＬ２スプールへ整列して５０ｍ巻取り、大気中２００℃で焼鈍することによって、銅露出の部分が酸化変色して赤くなり、光学顕微鏡でも銅露出の状態を容易に確認できるようになった。   As shown in Tables 1 and 2, products in various states in which the coating layer dropped from the core material were obtained. Although the difference in copper exposure could not be confirmed by observation with an optical microscope of 200 times, the exposed wire was oxidized and discolored by aligning the wires on a metal AL2 spool, winding 50m, and annealing in air at 200 ° C. As a result, the copper exposed state can be easily confirmed even with an optical microscope.

なお、銅露出の状態については以下のように測定した。   In addition, about the state of copper exposure, it measured as follows.

円周方向の最大幅については、ワイヤが巻かれたＡＬ２スプールの任意のワイヤ表面を観察し、酸化変色した部分の最大幅を５００倍の光学顕微鏡で測定した。   Regarding the maximum width in the circumferential direction, the surface of an arbitrary wire of the AL2 spool around which the wire was wound was observed, and the maximum width of the portion that was oxidized and discolored was measured with an optical microscope of 500 times.

図５乃至７は、キズの状態の例を示した図である。図５は、キズの状態の第１の例を示した図であり、図６は、キズの状態の第２の例を示した図である。同様に、図６は、キズの状態の第３の例を示した図であり、図７は、キズの状態の第４の例を示した図である。   5 to 7 are diagrams showing examples of scratched states. FIG. 5 is a diagram illustrating a first example of a scratched state, and FIG. 6 is a diagram illustrating a second example of a scratched state. Similarly, FIG. 6 is a diagram illustrating a third example of the scratch state, and FIG. 7 is a diagram illustrating a fourth example of the scratch state.

長手方向の合計長さについては、図５のように、全てのキズ１３１が線径の２．５倍の距離１２１以内にある場合には、任意の位置でのキズ１３１の長さを測定してその平均長さとした。図６のように、キズ１３２の長さが線径の２．５倍の距離１２２を超える場合には、最小値を線径の２．５倍とした。図７のように、線径の２．５倍の距離１２３以内に複数のキズ１４３、１５３が存在する場合には、長い方のキズ１５３の長さ１７３ともう一方のキズ１４３の長さ１８３との合計値とした。図８のように、任意の位置での線径の２．５倍の距離１２４内に複数のキズ１４４、１５４が長手方向では重なっている場合、キズ１４４、１５４の長さの最小値を、線径の２．５倍とした。   As for the total length in the longitudinal direction, as shown in FIG. 5, when all the scratches 131 are within a distance 121 that is 2.5 times the wire diameter, the length of the scratches 131 at an arbitrary position is measured. The average length. As shown in FIG. 6, when the length of the scratch 132 exceeds the distance 122 that is 2.5 times the wire diameter, the minimum value is set to 2.5 times the wire diameter. As shown in FIG. 7, when a plurality of scratches 143 and 153 exist within a distance 123 that is 2.5 times the wire diameter, the length 173 of the longer scratch 153 and the length 183 of the other scratch 143. And the total value. As shown in FIG. 8, when a plurality of scratches 144 and 154 overlap in the longitudinal direction within a distance 124 that is 2.5 times the wire diameter at an arbitrary position, the minimum value of the lengths of the scratches 144 and 154 is expressed as follows: The wire diameter was 2.5 times.

こうしたキズ１３１、１３２、１４３、１５３、１４４、１５４の状態によって試料を分類し、キューリックソファ製ワイヤボンダーＩＣｏｎｎを使用して連続ボンディング性とボールの偏芯について評価して、キズの状態との関係についてまとめた。   Samples are classified according to the state of such scratches 131, 132, 143, 153, 144, and 154, and the continuous bondability and the eccentricity of the ball are evaluated using a wire bonder IConn made of curic sofa, The relationship was summarized.

実施例の評価結果を表３、比較例の評価結果を表４に示す。   Table 3 shows the evaluation results of the examples, and Table 4 shows the evaluation results of the comparative examples.

Figure 2013201182
Figure 2013201182

Figure 2013201182
表３に示すように、実施例に係るパラジウム被覆銅ボンディングワイヤの製造方法により製造されたワイヤは、ワイヤボンディング時におけるボンダー停止率が極めて低く、殆どがゼロである。試料６、２１、３７のボンダー停止率がゼロではないが、それぞれ０．５、０．２、０．６と、総てゼロに近い値となっている。一方、比較例に係るパラジウム被覆銅ボンディングワイヤの製造方法により製造されたワイヤは、ワイヤボンディング時におけるボンダー停止率が、実施例と比較して高くなっている。試料８、１０、２２、２５、４０がゼロであり、試料３７が０．６であるが、他は３．０以上であり、３３．３に達している試料も存在する。
Figure 2013201182
 As shown in Table 3, the wire produced by the method for producing a palladium-coated copper bonding wire according to the example has a very low bonder stop rate during wire bonding, and is almost zero. The bonder stop rates of Samples 6, 21, and 37 are not zero, but are 0.5, 0.2, and 0.6, respectively, which are all close to zero. On the other hand, the wire produced by the method for producing a palladium-coated copper bonding wire according to the comparative example has a higher bonder stop rate at the time of wire bonding than that of the example. Samples 8, 10, 22, 25, and 40 are zero and sample 37 is 0.6, but others are 3.0 or more, and there are also samples that have reached 33.3.

また、ボール偏芯率（ボール偏芯の発生率）も、実施例に係るワイヤにおいては、試料７〜９、２２、２４、２５、３８〜４０がゼロとなっており、半数以上の試料がゼロとなっている。一方、比較例に係るワイヤにおいては、ボール偏芯率がゼロの試料は１つだけである。   In addition, in the wire according to the example, the samples 7 to 9, 22, 24, 25, and 38 to 40 are zero in the ball eccentricity (the occurrence rate of the ball eccentricity), and more than half of the samples are It is zero. On the other hand, in the wire according to the comparative example, there is only one sample with a ball eccentricity of zero.

このように、実施例に係るパラジウム被覆銅ボンディングワイヤの製造方法により製造されたワイヤと比較例に係るパラジウム被覆銅ボンディングワイヤの製造方法により製造されたワイヤとを比較すると、実施例に係るワイヤの方が良好なワイヤボンディングが可能となっていることが分かる。   Thus, when the wire manufactured by the method for manufacturing the palladium-coated copper bonding wire according to the example and the wire manufactured by the method for manufacturing the palladium-coated copper bonding wire according to the comparative example are compared, It can be seen that better wire bonding is possible.

以上、本発明の好ましい実施形態及び実施例について詳説したが、本発明は、上述した実施形態及び実施例に制限されることはなく、本発明の範囲を逸脱することなく、上述した実施形態及び実施例に種々の変形及び置換を加えることができる。   The preferred embodiments and examples of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments and examples, and the above-described embodiments and examples can be performed without departing from the scope of the present invention. Various modifications and substitutions can be made to the embodiments.

１０ 芯材
２０、２１ キャプスタン
３０ ダイス
４０ 加熱炉
４１ ステージ
４２ ヒータ
４３ ガス供給炉
４４ 窒素ガス供給タンク DESCRIPTION OF SYMBOLS 10 Core material 20, 21 Capstan 30 Dies 40 Heating furnace 41 Stage 42 Heater 43 Gas supply furnace 44 Nitrogen gas supply tank

Claims (7)

銅を主成分とする芯材の周囲にパラジウム被覆層をめっき工程で形成したパラジウム被覆銅ボンディングワイヤの製造方法であって、
前記めっき工程より前に、前記芯材を単引き伸線する単引き伸線工程と、
単引き伸線された前記芯材を熱処理する熱処理工程と、を有し、
該熱処理工程は、加熱炉内に単引き伸線された前記芯材を所定量設置して密封し、窒素ガスを前記加熱炉内に満たしてから前記加熱炉内の加熱を開始する、窒素雰囲気下のバッチ式熱処理工程であることを特徴とするパラジウム被覆銅ボンディングワイヤの製造方法。 A method for producing a palladium-coated copper bonding wire in which a palladium coating layer is formed in the plating step around a core material mainly composed of copper,
Prior to the plating step, a single drawing step for single drawing the core material,
A heat treatment step of heat-treating the core drawn by single drawing,
In the heat treatment step, a predetermined amount of the core material drawn and drawn in a heating furnace is hermetically sealed and filled with nitrogen gas in the heating furnace, and then heating in the heating furnace is started. A method for producing a palladium-coated copper bonding wire, which is a batch heat treatment step below. 前記熱処理工程において、加熱終了後は、前記加熱炉内が常温になるまで前記芯材を窒素雰囲気下に保持することを特徴とする請求項１に記載のパラジウム被覆銅ボンディングワイヤの製造方法。   2. The method for producing a palladium-coated copper bonding wire according to claim 1, wherein in the heat treatment step, after the heating is finished, the core material is held in a nitrogen atmosphere until the inside of the heating furnace reaches room temperature. 前記熱処理工程の直後に、前記熱処理工程で前記芯材の表面に形成された酸化膜を除去するエッチング工程を更に有することを特徴とする請求項１又は２に記載のパラジウム被覆銅ボンディングワイヤの製造方法。   3. The production of a palladium-coated copper bonding wire according to claim 1, further comprising an etching step for removing an oxide film formed on a surface of the core material in the heat treatment step immediately after the heat treatment step. Method. 前記エッチング工程は、塩化第二鉄よりもエッチング速度が遅いエッチング液を用いて、塩化第二鉄でエッチングを行う時間よりも長時間かけてエッチングを行うことを特徴とする請求項３に記載のパラジウム被覆銅ボンディングワイヤの製造方法。   4. The etching process according to claim 3, wherein the etching step is performed using an etchant having a slower etching rate than ferric chloride and taking a longer time than etching with ferric chloride. A method for producing a palladium-coated copper bonding wire. 前記エッチング液は、塩酸又は硫酸であることを特徴とする請求項４に記載のパラジウム被覆銅ボンディングワイヤの製造方法。   The method for producing a palladium-coated copper bonding wire according to claim 4, wherein the etching solution is hydrochloric acid or sulfuric acid. 前記エッチング工程と前記めっき工程との間には、前記芯材を連続伸線する連続伸線工程と、該連続伸線工程により連続伸線された前記芯材を連続的に熱処理する連続熱処理工程とを含むことを特徴とする請求項３乃至５のいずれか一項に記載のパラジウム被覆銅ボンディングワイヤの製造方法。   Between the etching step and the plating step, a continuous wire drawing step for continuously drawing the core material, and a continuous heat treatment step for continuously heat-treating the core material continuously drawn by the continuous wire drawing step. The method for producing a palladium-coated copper bonding wire according to any one of claims 3 to 5, wherein: 前記連続熱処理工程は、窒素雰囲気下で行われることを特徴とする請求項５に記載のパラジウム被覆銅ボンディングワイヤの製造方法。   The method for producing a palladium-coated copper bonding wire according to claim 5, wherein the continuous heat treatment step is performed in a nitrogen atmosphere.
JP2012067363A 2012-03-23 2012-03-23 Method for manufacturing palladium coated copper bonding wire Pending JP2013201182A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115556440A (en) * 2021-07-02 2023-01-03 青岛海尔电冰箱有限公司 Acid treatment process of core material and vacuum insulation panel with acid-treated core material

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115556440A (en) * 2021-07-02 2023-01-03 青岛海尔电冰箱有限公司 Acid treatment process of core material and vacuum insulation panel with acid-treated core material
CN115556440B (en) * 2021-07-02 2024-01-05 青岛海尔电冰箱有限公司 Acid treatment process of core material and vacuum insulation panel with acid treated core material

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