JP2010199199A - Wire bonding method and wire bonding structure - Google Patents

Wire bonding method and wire bonding structure Download PDF

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JP2010199199A
JP2010199199A JP2009040708A JP2009040708A JP2010199199A JP 2010199199 A JP2010199199 A JP 2010199199A JP 2009040708 A JP2009040708 A JP 2009040708A JP 2009040708 A JP2009040708 A JP 2009040708A JP 2010199199 A JP2010199199 A JP 2010199199A
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wire
bonding
bonded
tapered surface
capillary
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Yoshio Fukuda
芳生 福田
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Yamaha Corp
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Yamaha Corp
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  • Wire Bonding (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire bonding method such that a wire and a base such as an external terminal have superior bonding strength and the wire has superior strength. <P>SOLUTION: The wire bonding method includes: preparing a capillary 1 comprising at least a projection part 3a having a lead-out hole for a wire 4 and a press surface for the wire 4 such that the press surface is provided nearby the lead-out hole, a first tapered surface 3b forming the projection part 3a, a second tapered surface 3c retreating to a base end side more than the first tapered surface 3b at an outer peripheral side of the first tapered surface 3b, and a step part 3d coupling the first tapered surface 3b and second tapered surface 3c to each other; causing the projection part 3a and first tapered surface 3b to stick in the base 11 together with the wire 4 and simultaneously pressing the wire 4 against a surface 12 to be bonded while deforming the wire 4 with the press surface; and joining the wire 4, having been pressed to be deformed, to the surface 12 to be bonded; and then cutting the wire 4 at the projection part 3a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、ワイヤボンディング方法及びワイヤボンディング構造に関する。   The present invention relates to a wire bonding method and a wire bonding structure.

従来、半導体チップのパッド電極とリードフレームのリード部とをＡｕまたはＡｌからなるワイヤで結線するワイヤボンディング技術が知られている。ワイヤボンディングは、キャピラリと呼ばれる器具を用いて行うのが一般的である。例えば、キャピラリの先端部に設けられたワイヤの導出口からワイヤを突出させ、ワイヤ先端を球状に加工してボール部を形成し、キャピラリの先端によってボール部を半導体チップのパッド電極に押し付け、熱圧着または超音波圧着等の手段でワイヤをパッド電極にボンディングする（ファーストボンディング）。その後、キャピラリによってワイヤをリード部まで引き回し、キャピラリの先端によってワイヤをリード部に押し付け、熱圧着または超音波圧着等の手段でワイヤをリード部にボンディングする（セカンドボンディング）。その後、キャピラリをリード部に押し当てた状態でワイヤを引っ張ることでワイヤを切断する。このようにして、リード部とパッド電極とをワイヤで接続している。   Conventionally, a wire bonding technique for connecting a pad electrode of a semiconductor chip and a lead portion of a lead frame with a wire made of Au or Al is known. Wire bonding is generally performed using an instrument called a capillary. For example, a wire protrudes from the wire outlet provided at the tip of the capillary, and the tip of the wire is processed into a spherical shape to form a ball portion. The tip of the capillary presses the ball portion against the pad electrode of the semiconductor chip, and heat The wire is bonded to the pad electrode by means such as pressure bonding or ultrasonic pressure bonding (first bonding). Thereafter, the wire is routed to the lead portion by the capillary, the wire is pressed against the lead portion by the tip of the capillary, and the wire is bonded to the lead portion by means such as thermocompression bonding or ultrasonic pressure bonding (second bonding). Thereafter, the wire is cut by pulling the wire while the capillary is pressed against the lead portion. In this way, the lead portion and the pad electrode are connected by the wire.

特許文献１には、従来のセカンドボンディング方法の一例が開示されている。この特許文献１の図１には、ワイヤの導出口、縁部及びステップ状の先端部周辺領域が設けられたキャピラリが開示されている。このキャピラリは、先端部周辺領域の高さが縁部よりも低くなっており、その高低差がワイヤの径よりも小さくなっている。また、縁部がワイヤを切る部分となっている。   Patent Document 1 discloses an example of a conventional second bonding method. FIG. 1 of Patent Document 1 discloses a capillary provided with a wire outlet, an edge, and a step-like tip peripheral region. In this capillary, the height of the peripheral region of the tip is lower than that of the edge, and the height difference is smaller than the diameter of the wire. Moreover, the edge part is a part which cuts a wire.

特許文献１に記載のボンディング方法では、半導体チップのパッド電極にワイヤを超音波圧着した後（ファーストボンディング）、ワイヤを繰り出しつつキャピラリを外部端子まで移動させる。次いで、キャピラリの先端によってワイヤを外部端子に押し当てて超音波圧着を行った後（セカンドボンディング）、縁部によってワイヤを擦り切っている。特許文献１の図２及び３には、ボンディングされたワイヤの先端形状が示されており、ワイヤが擦りきられる先端部分には、キャピラリの先端部周辺領域の形状に対応した所定の厚みｄ１を有する肉厚のステッチが形成され、このステッチの形成によってワイヤと外部端子との接合強度が高められている。また、ステッチ部分が厚いのでワイヤの断線も防止されている。   In the bonding method described in Patent Document 1, after a wire is ultrasonically pressure-bonded to a pad electrode of a semiconductor chip (first bonding), the capillary is moved to an external terminal while feeding the wire. Next, after the wire is pressed against the external terminal by the tip of the capillary and subjected to ultrasonic pressure bonding (second bonding), the wire is scraped off by the edge. 2 and 3 of Patent Document 1 show the tip shape of the bonded wire, and the tip portion where the wire is scraped has a predetermined thickness d1 corresponding to the shape of the peripheral region of the tip of the capillary. A thick-walled stitch is formed, and the bonding strength between the wire and the external terminal is enhanced by the formation of the stitch. Further, since the stitch portion is thick, wire breakage is prevented.

特開２００１−２９１７３６号公報、図１、図２、図３Japanese Patent Laid-Open No. 2001-291736, FIG. 1, FIG. 2, FIG.

ところでワイヤボンディングの接合強度を高めるには、ワイヤと外部端子の間の接合強度のほかに接合面積も影響する。特許文献１においては、キャピラリの先端部周辺領域によってワイヤのステッチ部分を押圧して外部端子に接合する一方、キャピラリの縁部によってワイヤを擦り切っている。このように特許文献１では、面積が限られたキャピラリの先端箇所においてワイヤの接合と切断とを行うので、ワイヤの接合面積が相対的に小さくなり、ワイヤと外部端子の接合強度が結果的に低下する問題があった。   By the way, in order to increase the bonding strength of wire bonding, the bonding area influences in addition to the bonding strength between the wire and the external terminal. In Patent Document 1, a stitch portion of a wire is pressed by a peripheral region of the tip of a capillary and joined to an external terminal, while the wire is scraped by an edge of the capillary. As described above, in Patent Document 1, since the bonding and cutting of the wire are performed at the tip portion of the capillary having a limited area, the bonding area of the wire is relatively reduced, and the bonding strength between the wire and the external terminal is consequently increased. There was a problem of lowering.

本発明は、上記事情に鑑みてなされたもので、ワイヤとリード部のような基体との接合強度を高めるとともに、ワイヤの強度を高めることが可能なワイヤボンディング方法及びワイヤボンディング構造を提供することを目的とする。   The present invention has been made in view of the above circumstances, and provides a wire bonding method and a wire bonding structure capable of increasing the bonding strength between a wire and a substrate such as a lead portion and increasing the strength of the wire. With the goal.

上記の目的を達成するために、本発明は以下の構成を採用した。
本発明のワイヤボンディング方法は、被ボンディング面を有する基体に対してワイヤをセカンドボンディングするワイヤボンディング方法であって、先端部に設けられたワイヤの導出口と、前記導出口の周囲に設けられた前記ワイヤの押付面とを有し、前記押付面が、前記導出口の近傍に設けられた突起部と、前記突起部を構成する第１テーパー面と、前記第１テーパー面の外周側にあって、前記第１テーパー面よりも基端側に後退された第２テーパー面と、前記第１テーパー面と前記第２テーパー面とを連結する段部とから少なくとも構成されたボンディング用キャピラリを用意し、前記突起部及び前記第１テーパー面を前記ワイヤとともに前記基体にめり込ませつつ、前記押付面によって前記ワイヤを変形させながら前記被ボンディング面に押し付け、押し付けられて変形された前記ワイヤを前記被ボンディング面に接合し、その後、前記突起部において前記ワイヤを切断することを特徴とする。
また、本発明のワイヤボンディング構造は、被ボンディング面を有する基体にワイヤの一端部がボンディングされたワイヤボンディング構造において、前記被ボンディング面には、前記ワイヤの一端部が埋設される凹部が設けられ、前記ワイヤの一端部には、前記凹部にその全部が埋設されて前記基体に接合された最先端部と、前記最先端部よりも前記ワイヤの他端側にあって前記最先端部よりも厚さが大きく、かつその一部が前記凹部に埋設されて前記基体に接合された肉厚部とが形成されてなることを特徴とする。 In order to achieve the above object, the present invention employs the following configuration.
The wire bonding method of the present invention is a wire bonding method in which a wire is second-bonded to a substrate having a surface to be bonded, the wire outlet provided at the tip, and provided around the outlet. A pressing surface of the wire, and the pressing surface is provided on a protruding portion provided in the vicinity of the outlet, a first tapered surface constituting the protruding portion, and an outer peripheral side of the first tapered surface. A bonding capillary comprising at least a second taper surface that is retracted to the base end side from the first taper surface and a step portion that connects the first taper surface and the second taper surface is prepared. Then, while the protrusion and the first tapered surface are sunk into the base together with the wire, the wire is deformed by the pressing surface while the wire is deformed. The pressing, the wires are deformed pressed and bonded to the target bonding surface, then, it is characterized by cutting the wire at the protruding portions.
The wire bonding structure of the present invention is a wire bonding structure in which one end of a wire is bonded to a substrate having a surface to be bonded, and the surface to be bonded is provided with a recess in which one end of the wire is embedded. One end portion of the wire is embedded in the concave portion and bonded to the base body, and is located on the other end side of the wire with respect to the most distal end portion and more than the most distal end portion. A thick part is formed, and a part thereof is buried in the recess and joined to the base.

本発明によれば、ワイヤと基体との接合強度を高めるとともに、ワイヤの強度を高めることが可能なワイヤボンディング方法及びワイヤボンディング構造を提供できる。   ADVANTAGE OF THE INVENTION According to this invention, while improving the joint strength of a wire and a base | substrate, the wire bonding method and wire bonding structure which can raise the intensity | strength of a wire can be provided.

即ち、本発明のワイヤボンディング方法によれば、突起部及び第１テーパー面をワイヤとともに基体にめり込ませることで、ワイヤの接合強度を高めることができる。
また、第１テーパー面と第２テーパー面によって変形されたワイヤには、第２テーパー面に対応する肉厚部が形成されるが、この肉厚部によってワイヤの強度が高められるので、ワイヤの断線を防止できる。
更に、ワイヤを突起部において切断するので、ワイヤを擦り切ることなくワイヤの形状が切断前後で変形しない。これにより、ワイヤと基体との接合面積が縮小されず、ワイヤと基体との接合強度を高めることができる。 That is, according to the wire bonding method of the present invention, the bonding strength of the wire can be increased by causing the protrusion and the first tapered surface to be recessed into the base body together with the wire.
In addition, the wire deformed by the first taper surface and the second taper surface has a thick portion corresponding to the second taper surface. This thick portion increases the strength of the wire. Disconnection can be prevented.
Furthermore, since the wire is cut at the protruding portion, the shape of the wire does not deform before and after cutting without rubbing the wire. As a result, the bonding area between the wire and the substrate is not reduced, and the bonding strength between the wire and the substrate can be increased.

また本発明のワイヤボンディング構造によれば、被ボンディング面の凹部にワイヤの一端部がめり込まれているので、ワイヤと基体との接合強度を高めることができる。
また、ワイヤの一端部に、最先端部より厚さが大きな肉厚部が設けられるので、ワイヤ４の一端部全体の強度が高められ、ワイヤ断線等の不良が生じる恐れがない。
更に、最先端部及び肉厚部が凹部に接合されるので、接合面積を従来に比べて広く確保することができ、ワイヤと基体の接合強度を更に高めることができる。 Further, according to the wire bonding structure of the present invention, since one end of the wire is recessed in the concave portion of the surface to be bonded, the bonding strength between the wire and the substrate can be increased.
Moreover, since the thick part thicker than the most advanced part is provided in the one end part of a wire, the intensity | strength of the whole one end part of the wire 4 is raised, and there is no possibility that defects, such as a wire disconnection, will arise.
Furthermore, since the most advanced part and the thick part are joined to the concave part, the joining area can be ensured wider than before, and the joining strength between the wire and the substrate can be further increased.

図１は、本発明の実施形態であるワイヤボンディング方法に用いるボンディング用キャピラリの先端形状を示す拡大断面図である。FIG. 1 is an enlarged cross-sectional view showing the tip shape of a bonding capillary used in a wire bonding method according to an embodiment of the present invention. 図２は、本発明の実施形態であるワイヤボンディング方法の工程を示す拡大断面図である。FIG. 2 is an enlarged cross-sectional view showing the steps of the wire bonding method according to the embodiment of the present invention. 図３は、本発明の実施形態であるワイヤボンディング方法の工程を示すとともに、本発明の実施形態であるボンディング構造を示す拡大断面図である。FIG. 3 is an enlarged cross-sectional view illustrating the steps of the wire bonding method according to the embodiment of the present invention and the bonding structure according to the embodiment of the present invention.

以下、本発明の実施の形態について図面を参照して説明する。
（ボンディング用キャピラリ）
図１には、本実施形態のワイヤボンディング方法に用いられるボンディング用キャピラリの先端形状を示す。図１では、ボンディング用キャピラリにワイヤを挿通させた状態を示している。図１に示すボンディング用キャピラリ１（以下、キャピラリ１という）は、キャピラリの先端部１ａに設けられたワイヤ４の導出口２と、導出口２の周囲に設けられた押付面３とを具備して構成されている。ワイヤ４は、導出口２から自在に繰り出せるようになっている。また、押付面３は、導出口２を囲む端面であって、ワイヤボンディングの際にワイヤ４を例えばリードフレームのリード部等の基体に押し付けて固定する面である。また、押付面３は、ワイヤ４を熱圧着する場合にワイヤ４を加熱する加熱面となり、ワイヤ４を超音波圧着する場合にはワイヤ４に超音波を印加するホーンとなる。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Capillary for bonding)
FIG. 1 shows the tip shape of a bonding capillary used in the wire bonding method of this embodiment. FIG. 1 shows a state in which a wire is inserted through a bonding capillary. A bonding capillary 1 (hereinafter referred to as a capillary 1) shown in FIG. 1 includes a lead-out port 2 for a wire 4 provided at the tip 1a of the capillary, and a pressing surface 3 provided around the lead-out port 2. Configured. The wire 4 can be freely drawn out from the outlet 2. The pressing surface 3 is an end surface that surrounds the outlet port 2 and is a surface that presses and fixes the wire 4 to a base such as a lead portion of a lead frame during wire bonding. The pressing surface 3 is a heating surface that heats the wire 4 when the wire 4 is thermocompression bonded, and a horn that applies ultrasonic waves to the wire 4 when the wire 4 is ultrasonically bonded.

押付面３は、ワイヤ４の導出口２に隣接する突起部３ａと、突起部３ａを構成する第１テーパー面３ｂと、第２テーパー面３ｃと、第１テーパー面３ｂと第２テーパー面３ｃを結ぶ段部３ｄとから概略構成されている。また、キャピラリ１の先端部１ａには、キャピラリ１の側面１ｂと第２テーパー面３ｃとを連結する凸曲面３eが形成されており、この凸曲面３eも押付面３の一部を構成している。更に、導出口２と突起部３ａの間には第３テーパー面５が形成されている。第３テーパー面５は、第１、第２テーパー面３ｂ、３ｃに対して傾斜の向きが逆向きになっている。また、第３テーパー面５の水平方向に対する傾斜角度θ３は、第１，第２テーパー面３ｂ、３ｃの傾斜角度θ１、θ２よりも大きくなっている。この第３テーパー面５は、ファーストボンディングを行う際に、ワイヤ先端に形成したボール部を半導体チップのパッド電極等に押し当てる押当面となる。 The pressing surface 3 includes a protruding portion 3a adjacent to the lead-out port 2 of the wire 4, a first tapered surface 3b constituting the protruding portion 3a, a second tapered surface 3c, a first tapered surface 3b, and a second tapered surface 3c. And a step portion 3d connecting the two. In addition, a convex curved surface 3e that connects the side surface 1b of the capillary 1 and the second tapered surface 3c is formed at the tip 1a of the capillary 1, and this convex curved surface 3e also constitutes a part of the pressing surface 3. Yes. Furthermore, a third taper surface 5 is formed between the outlet 2 and the protrusion 3a. The third taper surface 5 is inclined in the opposite direction with respect to the first and second taper surfaces 3b and 3c. Further, the inclination angle θ 3 of the third tapered surface 5 with respect to the horizontal direction is larger than the inclination angles θ 1 and θ 2 of the first and second tapered surfaces 3 b and 3 c. The third tapered surface 5 serves as a pressing surface that presses the ball portion formed at the tip of the wire against the pad electrode of the semiconductor chip when performing the first bonding.

突起部３ａは、第１テーパー面３ｂと第３テーパー面５とによって区画されてなり、導出口２を囲むように形成されている。この突起部３ａは、第２テーパー面３ｃを基準としたときに、キャピラリ１の先端側に向けて突出した形状とされている。突起部３ａの先端は、ワイヤを切断しやすいように鋭角にされている。   The protrusion 3 a is defined by the first tapered surface 3 b and the third tapered surface 5, and is formed so as to surround the outlet port 2. The protruding portion 3a has a shape protruding toward the tip side of the capillary 1 when the second tapered surface 3c is used as a reference. The tip of the protruding portion 3a has an acute angle so that the wire can be easily cut.

次に、第１テーパー面３ｂは、突起部３ａと同様に導出口２を囲むように形成されている。また、第１テーパー面３ｂの傾斜角度θ１は、水平方向に対する相対角度として８°〜１０°の範囲とされている。
また、第２テーパー面３ｃは、第１テーパー面３ｂの外周側にあって、第１テーパー面３ｂよりもキャピラリ１の基端側に後退された面である。第２テーパー面３ｃの幅ｗ２は、第１テーパー面３ｂの幅ｗ１と同じ幅でもよいし異なる幅でもよい。また、第２テーパー面３ｃの傾斜角度θ２は、第１テーパー面３ｂの傾斜角度θ１と同じでもよいし異なってもよい。
更に、段部３ｄは、第１テーパー面３ｂと、第１テーパー面３ｂより基端側に後退された第２テーパー面３ｃとを連結する端面である。段部３ｄにおける第１、第２テーパー面３ｂ、３ｃの段差ｈは、例えば数μｍ程度でよい。 Next, the 1st taper surface 3b is formed so that the outlet 2 may be enclosed like the projection part 3a. In addition, the inclination angle θ 1 of the first tapered surface 3b is in the range of 8 ° to 10 ° as a relative angle with respect to the horizontal direction.
The second taper surface 3c is a surface that is located on the outer peripheral side of the first taper surface 3b and is receded to the proximal end side of the capillary 1 with respect to the first taper surface 3b. Width w 2 of the second tapered surface 3c may be a width w 1 may be the same width as the different widths of the first tapered surface 3b. The inclination angle theta 2 of the second tapered surface 3c may be different or may be the same as the inclination angle theta 1 of the first tapered surface 3b.
Further, the step portion 3d is an end surface that connects the first tapered surface 3b and the second tapered surface 3c that is retracted to the proximal end side from the first tapered surface 3b. The step h between the first and second tapered surfaces 3b and 3c in the step 3d may be, for example, about several μm.

また、凸曲面３eは、第２テーパー面３ｃとキャピラリ１の側面１ｂとを曲面で連結させる面であり、ワイヤボンディング後のワイヤのダメージを防止するために設けられる。凸曲面３eを省略して第２テーパー面３ｃとキャピラリの側面１ｂとを直接に連結すると、それぞれの面３ｃ、１ｂの相対角度に対応する角部が形成される。この角部によって変形されたワイヤボンディング後のワイヤは強度が著しく低下する。従って、押付面３の一部として凸曲面３eを設けた方がよい。   The convex curved surface 3e is a surface that connects the second tapered surface 3c and the side surface 1b of the capillary 1 with a curved surface, and is provided to prevent damage to the wire after wire bonding. When the convex surface 3e is omitted and the second tapered surface 3c and the side surface 1b of the capillary are directly connected, corners corresponding to the relative angles of the respective surfaces 3c and 1b are formed. The strength of the wire after wire bonding deformed by the corners is significantly reduced. Therefore, it is better to provide the convex curved surface 3e as a part of the pressing surface 3.

（ワイヤボンディング方法）
次に、上記のキャピラリ１を用いたワイヤボンディング方法について、図２及び図３を参照して説明する。なお、図２及び図３においては、キャピラリ１の一部の図示を省略している。図２には、ワイヤボンディング対象となる基体１１を示している。この基体１１は、例えば、半導体パッケージの製造の際に用いられるリードフレームのリード部を例示できる。基体１１には、ワイヤ４が接合される被ボンディング面１２が設けられている。
本実施形態のワイヤボンディング方法は、ファーストボンディングに引き続いて行われるセカンドボンディングに適用される。先ず、ファーストボンディングとして、例えば半導体チップのパッド電極にワイヤをキャピラリ１を用いてワイヤボンディングする。 (Wire bonding method)
Next, a wire bonding method using the capillary 1 will be described with reference to FIGS. 2 and 3, a part of the capillary 1 is not shown. FIG. 2 shows a base 11 to be wire bonded. For example, the base 11 may be a lead portion of a lead frame used in manufacturing a semiconductor package. The substrate 11 is provided with a bonding surface 12 to which the wire 4 is bonded.
The wire bonding method of the present embodiment is applied to second bonding performed subsequent to first bonding. First, as first bonding, for example, a wire is bonded to a pad electrode of a semiconductor chip using a capillary 1.

次にセカンドボンディングとして、先ず、キャピラリ１の導出口２からワイヤ４を繰り出させつつ、リード部（基体１１）の近くまでワイヤ４を引き回す。そして、キャピラリ１を被ボンディング面１２の斜め上方から斜め下方向（図２中の矢印Ｍの方向）に向けて接近させる。そして、図２に示すように、押付面３のうち突起部３ａ及び第１テーパー面３ｂをワイヤ４とともに基体１１にめり込ませる。このとき、第２テーパー面３ｃが被ボンディング面１２にめり込まないように基体１１に対する押付面３の押込量を調整する。   Next, as the second bonding, first, the wire 4 is drawn out from the outlet 2 of the capillary 1 to the vicinity of the lead portion (base 11) while being fed out. Then, the capillary 1 is made to approach from a diagonally upper side of the bonding surface 12 in a diagonally downward direction (the direction of the arrow M in FIG. 2). Then, as shown in FIG. 2, the protrusion 3 a and the first taper surface 3 b of the pressing surface 3 are recessed into the base body 11 together with the wire 4. At this time, the pressing amount of the pressing surface 3 with respect to the base 11 is adjusted so that the second tapered surface 3 c does not dig into the bonded surface 12.

このように、被ボンディング面１２に対して突起部３ａ及び第１テーパー面３ｂをワイヤ４とともにめり込ませることで、被ボンディング面１２に凹部１２ａが形成されるとともに、突起部３ａ及び第１テーパー面３ｂの直下のワイヤ４が塑性変形される。一方、第２テーパー面３ｃ及び凸曲面３ｅは被ボンディング面１２にめり込ませないものの、第２テーパー面３ｃ及び凸曲面３ｅの直下に位置するワイヤ４は、第２テーパー面３ｃ及び凸曲面３ｅと被ボンディング面１２とに挟まれて塑性変形し、変形したワイヤの下部が凹部１２ａにめり込まれる。このようにして、キャピラリ１の押付面３によってワイヤ４及び被ボンディング面１２を変形させつつ、ワイヤ４を被ボンディング面１２に押し付ける。   As described above, the protrusion 3 a and the first tapered surface 3 b are inserted into the bonding surface 12 together with the wire 4, whereby the recess 12 a is formed in the bonding surface 12, and the protrusion 3 a and the first tape 3 b are formed. The wire 4 immediately below the tapered surface 3b is plastically deformed. On the other hand, although the second tapered surface 3c and the convex curved surface 3e are not sunk into the bonded surface 12, the wire 4 positioned immediately below the second tapered surface 3c and the convex curved surface 3e has the second tapered surface 3c and the convex curved surface. 3e and the to-be-bonded surface 12 are plastically deformed, and the lower part of the deformed wire is inserted into the recess 12a. In this way, the wire 4 is pressed against the bonding surface 12 while the wire 4 and the bonding surface 12 are deformed by the pressing surface 3 of the capillary 1.

凹部１２ａの断面形状は、第１傾斜面１２ｂと、第１傾斜面よりも傾斜角度が急な第２傾斜面１２ｃとにより区画された形状になっている。第１傾斜面１２ｂは、キャピラリ１によってワイヤ４が基体１１にめり込まれる際に、ワイヤ４が基体１１上を摺動することで形成される。   The cross-sectional shape of the recess 12a is a shape defined by a first inclined surface 12b and a second inclined surface 12c whose inclination angle is steeper than that of the first inclined surface. The first inclined surface 12 b is formed by sliding the wire 4 on the base 11 when the wire 4 is sunk into the base 11 by the capillary 1.

また、押付面３によってワイヤ４を被ボンディング面１２に押し付ける際に、第２テーパー面３ｃまで被ボンディング面１２にめり込ませると、基体１１が部分的に歪んでしまうので好ましくない。キャピラリ１の突起部３ａ及び第１テーパー面３ｂは、第２テーパー面３ｃを基準としたときにキャピラリ１の先端側に突出されているため、押付面３の押込量を調整することで、突起部３ａ及び第１テーパー面３ｂを被ボンディング面にめり込ませる一方、第２テーパー面をめり込ませないように制御できる。   Further, when the wire 4 is pressed against the surface to be bonded 12 by the pressing surface 3, it is not preferable that the substrate 11 is partially distorted if the wire 4 is pushed down to the second taper surface 3c. Since the protruding portion 3a and the first tapered surface 3b of the capillary 1 protrude toward the distal end side of the capillary 1 when the second tapered surface 3c is used as a reference, the protruding amount can be adjusted by adjusting the amount of pressing of the pressing surface 3. It is possible to control so that the portion 3a and the first tapered surface 3b are recessed into the surface to be bonded while the second tapered surface is not recessed.

次に、図２に示すようにワイヤ４を押し付けた後、加熱圧着や超音波圧着等の手段によってワイヤ４を基体１１に接合する。これにより、押付面３によって変形されたワイヤ４が基体１１に接合される。このときのワイヤ４の接合面は少なくとも、突起部３ａ、第１テーパー面３ｂ及び第２テーパー面３ｃによって変形された部分になる。   Next, as shown in FIG. 2, after the wire 4 is pressed, the wire 4 is joined to the substrate 11 by means such as heat pressure bonding or ultrasonic pressure bonding. As a result, the wire 4 deformed by the pressing surface 3 is joined to the base 11. At this time, the bonding surface of the wire 4 is at least a portion deformed by the protrusion 3a, the first tapered surface 3b, and the second tapered surface 3c.

次に、キャピラリ１を固定したままワイヤ４を図２中の矢印Ｎの方向に引っ張ることでワイヤ４を切断する。塑性変形後のワイヤ４は、突起部３ａの直下において厚さが最も小さくなっており、この部分で強度が最も小さくなっている。従ってワイヤ４に引っ張り応力を印加することで突起部３ａの近傍で容易に切断される。このようにして、図３に示すワイヤボンディング構造が得られる。図３に示すように、ワイヤが切断されることによって凹部１２ａの第２傾斜面１２ｂが露出された状態になる。   Next, the wire 4 is cut by pulling the wire 4 in the direction of arrow N in FIG. The wire 4 after plastic deformation has the smallest thickness immediately below the protrusion 3a, and the strength is smallest at this portion. Therefore, by applying a tensile stress to the wire 4, the wire 4 is easily cut in the vicinity of the protrusion 3 a. In this way, the wire bonding structure shown in FIG. 3 is obtained. As shown in FIG. 3, when the wire is cut, the second inclined surface 12b of the recess 12a is exposed.

（ワイヤボンディング構造）
図３に示すワイヤボンディング構造は、被ボンディング面１２を有する基体１１にワイヤ４の一端部４ａがボンディングされたワイヤボンディング構造である。ここで、ワイヤ４の一端部４ａとは、図１または図２に示すキャピラリ１によって変形、切断されたワイヤの端部を指す。
被ボンディング面１２には、ワイヤ４の一端部４ａをめり込ませた凹部１２ａが設けられる。また、ワイヤ４の一端部４ａには、最先端部４ｂと、最先端部４ｂよりもワイヤの他端側に形成された肉厚部４ｃとが設けられている。なお、ワイヤ４の他端側とは、先の例で言うと、半導体チップとリード部とを接続するワイヤ４において、半導体チップ側を意味する。 (Wire bonding structure)
The wire bonding structure shown in FIG. 3 is a wire bonding structure in which one end portion 4 a of the wire 4 is bonded to the base body 11 having the bonded surface 12. Here, the one end 4a of the wire 4 refers to the end of the wire deformed and cut by the capillary 1 shown in FIG. 1 or FIG.
The bonding surface 12 is provided with a recess 12 a into which the one end 4 a of the wire 4 is recessed. The one end portion 4a of the wire 4 is provided with a most distal end portion 4b and a thick portion 4c formed on the other end side of the wire with respect to the most distal end portion 4b. Note that the other end side of the wire 4 means the semiconductor chip side in the wire 4 connecting the semiconductor chip and the lead portion in the above example.

図３に示すように、最先端部４ｂは、凹部１２ａにその全部をめり込ませた状態で基体１１に接合されている。最先端部４ｂは、キャピラリ１の第１テーパー面３ｂによって塑性変形された部分であり、第１テーパー面３ｂを基体１１にめり込ませたことにより形成された部分である。この最先端部４ｂは、凹部１２ａ内において基体１１に接合されている。   As shown in FIG. 3, the most distal end portion 4b is joined to the base body 11 in a state where the entire recess portion 12a is recessed. The most distal portion 4 b is a portion plastically deformed by the first tapered surface 3 b of the capillary 1, and is a portion formed by the first tapered surface 3 b being sunk into the base body 11. This most advanced portion 4b is joined to the base 11 in the recess 12a.

また、肉厚部４ｃは、最先端部４ｂよりもワイヤ４の他端側に設けられている。肉厚部４ｃは、キャピラリ１の第２テーパー面３ｃによって塑性変形された部分であり、第２テーパー面３ｃによってワイヤ４を基体１１側に押し付けたことで形成された部分である。肉厚部４ｃは最先端部４ｂと同様に、凹部１２ａ内において基体１１に接合されている。また、最先端部４ｂと肉厚部４ｃとの間には、キャピラリ１の段部３ｄに対応するワイヤ段部４ｄが設けられる。   Moreover, the thick part 4c is provided in the other end side of the wire 4 rather than the most advanced part 4b. The thick portion 4c is a portion that is plastically deformed by the second tapered surface 3c of the capillary 1, and is a portion that is formed by pressing the wire 4 toward the base 11 by the second tapered surface 3c. The thick part 4c is joined to the base body 11 in the recess 12a in the same manner as the foremost part 4b. Further, a wire step 4d corresponding to the step 3d of the capillary 1 is provided between the foremost portion 4b and the thick portion 4c.

図３に示すように、肉厚部４ｃの厚さｔ２は最先端部４ｂの厚さｔ１よりも大きくなっている。厚さｔ２が厚さｔ１より大きい理由は、キャピラリ１において、肉厚部４ｃを形成する第２テーパー面３ｃが、最先端部４ｂを形成する第１テーパー面３ｂよりも基端側に後退されているためである。これにより、第２テーパー面３ｃが第１テーパー面３ｂに対して後退された分だけ肉厚部４ｃの厚さｔ２が最先端部４ｂよりも大きくなる。なお、肉厚部４ｃ及び最先端部４ｂの厚さがそれぞれ均一でない場合は、肉厚部４ｃ及び最先端部４ｂのそれぞれの平均厚さを厚さｔ２、ｔ１とすればよい。 As shown in FIG. 3, the thickness t 2 of the thick portion 4c is larger than the thickness t 1 of the leading edge portion 4b. The thickness t 2 is the thickness t 1 greater because in the capillary 1, the second tapered surface 3c forming the thick portion 4c is proximal to the first tapered surface 3b which forms the cutting edge portion 4b This is because it has been retreated. Accordingly, the second tapered surface 3c thickness t 2 of the amount corresponding to the thick portion 4c which is retracted relative to the first tapered surface 3b is greater than the cutting edge portion 4b. If the thicknesses of the thick part 4c and the most advanced part 4b are not uniform, the average thicknesses of the thick part 4c and the most advanced part 4b may be the thicknesses t 2 and t 1 .

また、ワイヤ４の肉厚部４ｃの他端側には、キャピラリ１の凸曲面３eに対応する断面視凹曲面状のネック部４ｅが形成されている。ネック部４ｅの断面厚みは、基端側に向けて徐々に厚くなっている。また、ネック部４ｅは全体に渡って肉厚部４ｃよりも厚くなっている。   Further, on the other end side of the thick portion 4 c of the wire 4, a neck portion 4 e having a concave curved surface shape corresponding to the convex curved surface 3 e of the capillary 1 is formed. The cross-sectional thickness of the neck portion 4e gradually increases toward the base end side. Moreover, the neck part 4e is thicker than the thick part 4c over the whole.

上記のワイヤボンディング構造によれば、被ボンディング面１２に凹部１２ａが設けられ、この凹部１２ａにワイヤ４の一端部４ａがめり込まれているので、ワイヤ４と基体１１との接合強度を高めることができる。
特に、ワイヤ４の一端部４ａに設けられた最先端部４ｂの全部が凹部１２ａにめり込んでいるので、ワイヤ４と基体１１の接合強度をより高めることができる。
更に、ワイヤ４の一端部４ａに、最先端部４ｂより厚さが大きな肉厚部４ｃが設けられるので、ワイヤ４の一端部４ａ全体の強度が高められ、ワイヤ断線等の不良が生じる恐れがない。
また、少なくとも最先端部４ｂ及び肉厚部４ｃが凹部１２ａの第１傾斜面１２ｂに接合されているので、接合面積を従来に比べて広く確保することができ、ワイヤ４と基体１１の接合強度を更に高めることができる。 According to the above-described wire bonding structure, the concave portion 12a is provided in the surface to be bonded 12, and the one end portion 4a of the wire 4 is recessed into the concave portion 12a, so that the bonding strength between the wire 4 and the substrate 11 is increased. Can do.
In particular, since the entire leading edge 4b provided at the one end 4a of the wire 4 is recessed into the recess 12a, the bonding strength between the wire 4 and the substrate 11 can be further increased.
Further, since the thick portion 4c having a thickness larger than that of the most distal end portion 4b is provided at the one end portion 4a of the wire 4, the strength of the entire one end portion 4a of the wire 4 is increased, and there is a possibility that defects such as wire breakage may occur. Absent.
In addition, since at least the most distal end portion 4b and the thick portion 4c are joined to the first inclined surface 12b of the recess 12a, the joining area can be secured wider than in the past, and the joining strength between the wire 4 and the substrate 11 can be ensured. Can be further increased.

また、上記のワイヤボンディング方法によれば、突起部３ａ及び第１テーパー面３ｂをワイヤ４とともに基体１１にめり込ませることで、第１テーパー面３ｂに対応する最先端部４ｂがワイヤ４に形成され、この最先端部４ｂが基体１１にめり込まれる。また、第１テーパー面３ｂよりもキャピラリの基端側に後退された第２テーパー面３ｃによって、ワイヤ４を変形させながら被ボンディング面１２に押し付けることで、第２テーパー面３ｃに対応する肉厚部４ｃがワイヤ４に設けられる。この肉厚部４ｃの形成によってワイヤ４の強度が低下することがなく、ワイヤ４の断線が避けられる。
また、最先端部４ｂと肉厚部４ｃが基体１１にめり込まれることで、ワイヤ４と基体１１との接合強度を向上できる。
更に、ワイヤ４を突起部３ａにおいて切断するので、ワイヤ４が擦り切れない。このため、凹部１２ｂにめり込まれた最先端部４ｂ及び肉厚部４ｃがワイヤ切断に伴って変形することなくそのままの形で残される。これにより、接合面積が縮小されることがなく、ワイヤ４と基体１１との接合強度を高めることができる。
また、ワイヤ４が基体にめり込まれる際に、ワイヤ４が基体１１上を摺動することで凹部１２ａの第１傾斜面１２ｂが形成されるが、この第１傾斜面１２ｂは被ボンディング面が剔られて形成された面なので、汚れや異物が付着していない清浄な面になる。この第１傾斜面１２ｂにワイヤ４が接合されるので、ワイヤ４の接合強度を更に高めることができる。 Further, according to the above wire bonding method, the protrusion 3 a and the first tapered surface 3 b are inserted into the base body 11 together with the wire 4, so that the most distal portion 4 b corresponding to the first tapered surface 3 b becomes the wire 4. The leading edge 4 b is formed and is embedded in the base 11. Further, by pressing the wire 4 against the surface to be bonded 12 while deforming the second tapered surface 3c that is retracted to the proximal end side of the capillary with respect to the first tapered surface 3b, the thickness corresponding to the second tapered surface 3c is obtained. The part 4 c is provided on the wire 4. The formation of the thick portion 4c does not reduce the strength of the wire 4 and avoids disconnection of the wire 4.
In addition, the bonding strength between the wire 4 and the base body 11 can be improved by the leading edge 4b and the thick part 4c being recessed into the base body 11.
Further, since the wire 4 is cut at the protrusion 3a, the wire 4 is not frayed. For this reason, the most distal end portion 4b and the thick portion 4c that are recessed into the recess 12b are left as they are without being deformed along with the wire cutting. Thereby, the joining area between the wire 4 and the substrate 11 can be increased without reducing the joining area.
Further, when the wire 4 is sunk into the substrate, the wire 4 slides on the substrate 11 to form the first inclined surface 12b of the recess 12a. The first inclined surface 12b is a surface to be bonded. Since the surface is formed by squeezing, it becomes a clean surface free from dirt and foreign matter. Since the wire 4 is bonded to the first inclined surface 12b, the bonding strength of the wire 4 can be further increased.

１…キャピラリ（ボンディング用キャピラリ）、１ａ…先端部、２…導出口、３…押付面、３ａ…突起部、３ｂ…第１テーパー面、３ｃ…第２テーパー面、３ｄ…段部、４…ワイヤ、４ａ…ワイヤの先端部、４ｂ…最先端部、４ｃ…肉厚部、１１…基体、１２…被ボンディング面、１２ａ…凹部。   DESCRIPTION OF SYMBOLS 1 ... Capillary (bonding capillary) 1a ... Tip part, 2 ... Outlet port, 3 ... Pressing surface, 3a ... Projection part, 3b ... 1st taper surface, 3c ... 2nd taper surface, 3d ... Step part, 4 ... Wires, 4a: wire tip, 4b: cutting edge, 4c: thick part, 11: substrate, 12: surface to be bonded, 12a: recess.

Claims (2)

被ボンディング面を有する基体に対してワイヤをセカンドボンディングするワイヤボンディング方法であって、
先端部に設けられたワイヤの導出口と、前記導出口の周囲に設けられた前記ワイヤの押付面とを有し、前記押付面が、前記導出口の近傍に設けられた突起部と、前記突起部を構成する第１テーパー面と、前記第１テーパー面の外周側にあって、前記第１テーパー面よりも基端側に後退された第２テーパー面と、前記第１テーパー面と前記第２テーパー面とを連結する段部とから少なくとも構成されたボンディング用キャピラリを用意し、
前記突起部及び前記第１テーパー面を前記ワイヤとともに前記基体にめり込ませつつ、前記押付面によって前記ワイヤを変形させながら前記被ボンディング面に押し付け、
押し付けられて変形された前記ワイヤを前記被ボンディング面に接合し、
その後、前記突起部において前記ワイヤを切断することを特徴とするワイヤボンディング方法。 A wire bonding method in which a wire is second bonded to a substrate having a surface to be bonded,
A wire outlet provided at the tip, and a pressing surface of the wire provided around the outlet, the pressing surface provided in the vicinity of the outlet, and the protrusion A first taper surface constituting a protrusion, a second taper surface located on an outer peripheral side of the first taper surface and retracted to a base end side with respect to the first taper surface; the first taper surface; A bonding capillary comprising at least a stepped portion connecting the second tapered surface is prepared;
While pressing the protrusion and the first taper surface together with the wire into the base, pressing the bonding surface while deforming the wire by the pressing surface,
Bonding the wire deformed by being pressed to the surface to be bonded;
Thereafter, the wire is cut at the protruding portion. 被ボンディング面を有する基体にワイヤの一端部がボンディングされたワイヤボンディング構造において、
前記被ボンディング面には、前記ワイヤの一端部をめり込ませる凹部が形成され、
前記ワイヤの一端部には、前記凹部にその全部がめり込まれて前記基体に接合された最先端部と、前記最先端部よりも前記ワイヤの他端側にあって前記最先端部よりも厚さが大きく、かつその一部が前記凹部にめり込まれて前記基体に接合された肉厚部とが形成されてなることを特徴とするワイヤボンディング構造。 In a wire bonding structure in which one end of a wire is bonded to a substrate having a surface to be bonded,
On the surface to be bonded, a concave portion is formed to engage one end of the wire,
At one end of the wire, the most advanced part that is all indented into the recess and joined to the base, and at the other end of the wire from the most advanced part, than the most advanced part A wire bonding structure characterized in that a thickness is large and a thick part joined to the base is formed by being partially embedded in the recess.
JP2009040708A 2009-02-24 2009-02-24 Wire bonding method and wire bonding structure Pending JP2010199199A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT201900024295A1 (en) * 2019-12-17 2021-06-17 St Microelectronics Srl WIRE BONDING TOOL, PROCEDURE AND CORRESPONDING BOND STRUCTURE

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT201900024295A1 (en) * 2019-12-17 2021-06-17 St Microelectronics Srl WIRE BONDING TOOL, PROCEDURE AND CORRESPONDING BOND STRUCTURE

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