JP2005037316A - Gas sensor and its manufacturing method - Google Patents

Gas sensor and its manufacturing method Download PDF

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JP2005037316A
JP2005037316A JP2003276536A JP2003276536A JP2005037316A JP 2005037316 A JP2005037316 A JP 2005037316A JP 2003276536 A JP2003276536 A JP 2003276536A JP 2003276536 A JP2003276536 A JP 2003276536A JP 2005037316 A JP2005037316 A JP 2005037316A
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diameter
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JP4462864B2 (en
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Hiroshi Tone
宏 東根
Tomoyasu Honda
智靖 本田
Tokio Ogoshi
時夫 大越
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Figaro Engineering Inc
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/14—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature
    • G01N27/16—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature caused by burning or catalytic oxidation of surrounding material to be tested, e.g. of gas
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
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    • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
    • G01N21/783—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour for analysing gases
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/40—Concentrating samples
    • G01N1/4077—Concentrating samples by other techniques involving separation of suspended solids
    • G01N2001/4094—Concentrating samples by other techniques involving separation of suspended solids using ultrasound

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor and its manufacturing method capable of maintaining bonding strength even in parallel directions and in vertical directions to a substrate for a long period without covering a bonding part to a pad with a gold paste. <P>SOLUTION: Pt-based leads are arranged on gold alloy pads, and thermo-compression bonding is performed on gold-based bumps to sandwich and fix the leads between the bumps and the pads. The bumps are formed in a disk shape, and are six to twelve times larger than the leads in diameter, two to five times higher, and do not have any recession part in their upper surfaces. By this method, it is possible to facilitate bonding and maintain high bonding strength for a long period. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この発明はガスセンサとその製造方法に関する。   The present invention relates to a gas sensor and a manufacturing method thereof.

特許文献１は、アルミナ基板の１面の４隅に金合金パッドを形成し、Ｐｔ系合金線などをパッドに溶接することを開示している。しかしながら充分なボンディング強度を得るには、溶接部を金ペーストなどで被覆し、再焼成するのが好ましい。
日本特許３４０８９１０ Patent Document 1 discloses that a gold alloy pad is formed at four corners of one surface of an alumina substrate, and a Pt alloy wire or the like is welded to the pad. However, in order to obtain a sufficient bonding strength, it is preferable to cover the welded portion with a gold paste or the like and refire.
Japanese Patent 3408910

この発明の課題は、パッドへのボンディング部を金ペーストで被覆する必要がなく、基板に平行な方向にも垂直な方向にも、ボンディング強度を長期間維持できる、ガスセンサとその製造方法を提供することにある。   An object of the present invention is to provide a gas sensor and a method for manufacturing the same that do not require the bonding portion to the pad to be coated with a gold paste and can maintain the bonding strength in a direction parallel to or perpendicular to the substrate for a long period of time. There is.

この発明は、基板上にヒータ膜とガス感応部とパッドとを形成し、該基板を外部に接続するリードを、前記パッドにボンディングしたガスセンサにおいて、
前記リードを、金系のパッドと金系のバンプとの間に挟み込むようにしてボンディングし、
バンプは上面に凹部がない円盤状とし、その直径Ｒ、及びパッドの上面からバンプの上面までの高さＨに対して、リードの直径ｒとの比を、６≦Ｒ／ｒ≦１２，２≦Ｈ≦５とする、ことを特徴とする。 The present invention provides a gas sensor in which a heater film, a gas sensitive part, and a pad are formed on a substrate, and a lead for connecting the substrate to the outside is bonded to the pad.
Bonding the lead so as to be sandwiched between a gold-based pad and a gold-based bump,
The bump has a disk shape with no recess on the upper surface, and the ratio of the lead diameter r to the diameter R and the height H from the upper surface of the pad to the upper surface of the bump is 6 ≦ R / r ≦ 12,2 ≦ H ≦ 5.

好ましくは、バンプの直径Ｒ、及びパッドの上面からバンプの上面までの高さＨと、リードの直径ｒとの比を、７.５≦Ｒ／ｒ≦１１，２≦Ｈ≦４とする。
特に好ましくは、バンプの直径Ｒ、及びパッドの上面からバンプの上面までの高さＨと、リードの直径ｒとの比を、８≦Ｒ／ｒ≦１０，２.５≦Ｈ≦３とする。 Preferably, the ratio of the bump diameter R and the height H from the top surface of the pad to the top surface of the bump and the lead diameter r is 7.5 ≦ R / r ≦ 11, 2 ≦ H ≦ 4.
Particularly preferably, the ratio of the bump diameter R and the height H from the upper surface of the pad to the upper surface of the bump and the diameter r of the lead is 8 ≦ R / r ≦ 10, 2.5 ≦ H ≦ 3. .

また好ましくは、前記リードがバンプをパッドの上面に沿って貫通して、リード先端が該パッド上で前記バンプから突き抜けている。   Preferably, the lead penetrates the bump along the upper surface of the pad, and the tip of the lead penetrates the bump on the pad.

この発明はまた、基板上にヒータ膜とガス感応部とパッドとを形成し、該基板を外部に接続するリードを、パッドにボンディングしたガスセンサの製造方法において、
直径ｒのリードの先端を金系のパッド上に配置し、バンプ形成用の金系ワイヤで、その直径がｒの１.５倍以上のものの先端に、直径がｒの５倍以上１０倍以下のボールを形成し、
該ボールを前記バンプに超音波熱圧着して、ワイヤの残部を除いて上面が平坦なバンプを形成すると共に、前記リードを該バンプとパッドとの間に挟み込んでボンディングし、
かつバンプは円盤状で上面に凹部がなく、その直径をＲ、及びパッドの上面からバンプの上面までの高さをＨとして、リードの直径ｒとの比を、６≦Ｒ／ｒ≦１２，２≦Ｈ≦５としたことを特徴とする。 The present invention also provides a gas sensor manufacturing method in which a heater film, a gas sensitive portion, and a pad are formed on a substrate, and a lead that connects the substrate to the outside is bonded to the pad.
The tip of a lead with a diameter r is placed on a metal pad, and a gold wire for bump formation, whose diameter is 1.5 times or more of r, is 5 to 10 times the diameter of r. Forming a ball of
The ball is ultrasonically heat-bonded to the bump to form a bump having a flat upper surface excluding the remainder of the wire, and the lead is sandwiched between the bump and the pad and bonded,
The bump is disk-shaped and has no recess on the upper surface, the diameter is R, and the height from the upper surface of the pad to the upper surface of the bump is H, and the ratio to the lead diameter r is 6 ≦ R / r ≦ 12, It is characterized in that 2 ≦ H ≦ 5.

好ましくは、３０μｍ≦ｒ≦５０μｍで、３００μｍ≦Ｒ≦４４０μｍ、
８０μｍ≦Ｈ≦１６０μｍとし、
前記ボールと前記パッドとの接合を超音波熱圧着で行い、かつ超音波熱圧着時の、ボンディング荷重を３〜６Ｎ，超音波パワーを３〜１０Ｗ，超音波の印加時間を５０〜２００ｍsec，基板温度を２００〜３５０℃とする。 Preferably, 30 μm ≦ r ≦ 50 μm, 300 μm ≦ R ≦ 440 μm,
80 μm ≦ H ≦ 160 μm,
Bonding of the ball and the pad is performed by ultrasonic thermocompression bonding, and at the time of ultrasonic thermocompression bonding, the bonding load is 3 to 6 N, the ultrasonic power is 3 to 10 W, the ultrasonic wave application time is 50 to 200 msec, the substrate The temperature is 200-350 ° C.

特に好ましくは、３２０μｍ≦Ｒ≦４００μｍ、１００μｍ≦Ｈ≦１２０μｍとし、
前記ボールと前記パッドとの接合を超音波熱圧着で行い、かつ超音波熱圧着時の、ボンディング荷重を４〜５Ｎ，超音波パワーを７〜８Ｗ，超音波の印加時間を１００〜１５０ｍsec，基板温度を２２０〜３００℃とする。 Particularly preferably, 320 μm ≦ R ≦ 400 μm, 100 μm ≦ H ≦ 120 μm,
Bonding of the ball and the pad is performed by ultrasonic thermocompression bonding, and at the time of ultrasonic thermocompression bonding, the bonding load is 4 to 5 N, the ultrasonic power is 7 to 8 W, the ultrasonic wave application time is 100 to 150 msec, the substrate The temperature is 220-300 ° C.

この発明では、リードを金系のバンプと金系のパッドの間に挟み込むようにしてボンディングする。そしてこのバンプを円盤状で上面には凹部がないようにし、リードの直径との比で、所定の高さと所定の直径とを備えたものにすると、同じサイズのボールから得られるバンプの範囲で、ボンディング強度を最大にできる。このため、金ペーストなどを塗布して再焼成する必要が無く、ガスセンサの製造工程が簡単になり、製造に要する時間も短縮される。バンプは金系のパッドへのボンディングを容易にするため金系のバンプとし、リードはＰｔ系等の高融点リードが適しているので、バンプとリードとの融着は困難であり、主としてバンプ／リード間での合金層の形成や摩擦力により、リードが保持される。バンプとパッドは共に金系で低融点なので、簡単に接合できる。   In this invention, the lead is bonded so as to be sandwiched between a gold bump and a gold pad. And if this bump is disk-shaped and has no recess on the upper surface, and it has a predetermined height and a predetermined diameter in the ratio to the diameter of the lead, it will be within the range of bumps obtained from balls of the same size , Bonding strength can be maximized. For this reason, it is not necessary to apply gold paste or the like and re-fire it, the manufacturing process of the gas sensor is simplified, and the time required for manufacturing is shortened. The bump is a gold bump to facilitate bonding to the gold pad, and a high melting point lead such as Pt is suitable for the lead. Therefore, it is difficult to fuse the bump and the lead. The leads are held by the formation of an alloy layer between the leads and the frictional force. The bumps and pads are both gold and have a low melting point, so they can be joined easily.

しかしながらリードのボンディング強度は時間と共に減少する。このことには、パッドが純金のパッドではなく、基板との付着力を増すため、厚膜の金合金パッドを用いることと関係がある。合金パッドでは、パッドとバンプとの界面の付着力、あるいはパッドが１層でなく複数の層からなる場合パッド内の層間での付着力が低下する。またこれ以外に、基板を加熱することや、基板温度を変化させることなども、リードとバンプとの付着力などを低下させる。そしてこのことに基づく、付着力の低下を補うため、バンプのサイズには制限が生じる。またバンプの厚さが薄いと、リードを基板に垂直な方向に引っ張った際に、リードがバンプの上面を破って剥離する現象が生じる。これらのことから、バンプの厚さＨはリードの直径ｒの２倍以上とし、厚すぎると金系のバンプを形成するための金系のボールの形成が困難になり、またバンプのボンディングも難しくなるので２≦Ｈ≦５とし、好ましくは２≦Ｈ≦４とし，最も好ましくは２.５≦Ｈ≦３とする。   However, the lead bonding strength decreases with time. This is related to the use of a thick gold alloy pad because the pad is not a pure gold pad but increases the adhesion to the substrate. In the case of the alloy pad, the adhesive force at the interface between the pad and the bump, or the adhesive force between the layers in the pad is reduced when the pad is composed of a plurality of layers instead of one layer. In addition to this, heating the substrate or changing the substrate temperature also reduces the adhesion between the leads and the bumps. In order to compensate for the decrease in adhesion force based on this, the bump size is limited. In addition, when the bump is thin, when the lead is pulled in a direction perpendicular to the substrate, the lead breaks the upper surface of the bump and peels off. Therefore, the thickness H of the bump is set to be twice or more the lead diameter r, and if it is too thick, it becomes difficult to form a gold ball for forming the gold bump, and it is difficult to bond the bump. Therefore, 2 ≦ H ≦ 5, preferably 2 ≦ H ≦ 4, and most preferably 2.5 ≦ H ≦ 3.

バンプの直径が小さいと、バンプがパッドから剥がれる、あるいはパッドが損壊して、パッドの一部がバンプに付着した状態でバンプとパッドが剥離する現象が生じる。これはバンプにリードは充分に付着しているが、バンプとパッドの付着力が不足するために、バンプがパッドから剥離する、あるいはパッドがバンプに引きずられて破損してしまうためである。バンプとパッドの付着力は、バンプの底面積により定まるため、バンプは大きな直径が好ましい。もちろんバンプの直径Ｒを大きくすると、バンプの前駆体の金ボールの形成も困難になり、ボンディングも困難になる。そこでバンプの直径Ｒとリードの直径ｒの比は６≦Ｒ／ｒ≦１２とし、好ましくは７.５≦Ｒ／ｒ≦１１とし、最も好ましくは８≦Ｒ／ｒ≦１０とする。バンプの高さや直径の効果は図１１〜図１４に示し、リードの直径との比で定まる。   When the diameter of the bump is small, the bump is peeled off from the pad, or the pad is damaged, and a phenomenon occurs in which the bump and the pad are separated while a part of the pad is attached to the bump. This is because the leads are sufficiently attached to the bumps, but the adhesive force between the bumps and the pads is insufficient, so that the bumps are peeled off from the pads or the pads are dragged by the bumps and damaged. Since the adhesive force between the bump and the pad is determined by the bottom area of the bump, the bump preferably has a large diameter. Of course, when the diameter R of the bump is increased, it becomes difficult to form a gold ball as a precursor of the bump, and bonding becomes difficult. Therefore, the ratio of the bump diameter R to the lead diameter r is 6 ≦ R / r ≦ 12, preferably 7.5 ≦ R / r ≦ 11, and most preferably 8 ≦ R / r ≦ 10. The effect of bump height and diameter is shown in FIGS. 11 to 14 and is determined by the ratio to the lead diameter.

リードの直径ｒを３０〜５０μｍとすると、バンプの直径や高さは、例えば３００μｍ≦Ｒ≦４４０μｍ、８０μｍ≦Ｈ≦１６０μｍが好ましく、このバンプをパッドと充分融着して、かつ上面に凹部が生じないように超音波熱圧着するには、超音波熱圧着時の、ボンディング荷重を３〜６Ｎ，超音波パワーを３〜１０Ｗ，超音波の印加時間を５０〜２００ｍsec，基板温度を２００〜３５０℃とすれば良い。   When the lead diameter r is 30 to 50 μm, the bump diameter and height are preferably 300 μm ≦ R ≦ 440 μm, 80 μm ≦ H ≦ 160 μm, and the bump is sufficiently fused with the pad, and a recess is formed on the upper surface. In order to avoid ultrasonic thermocompression, the ultrasonic thermocompression bonding has a bonding load of 3 to 6 N, an ultrasonic power of 3 to 10 W, an ultrasonic application time of 50 to 200 msec, and a substrate temperature of 200 to 350. It may be set to ℃.

ここで最も好ましくはバンプの直径や高さを、３２０μｍ≦Ｒ≦４００μｍ、１００μｍ≦Ｈ≦１２０μｍとし、このバンプをパッドと充分融着して、かつ上面に凹部が生じないように超音波熱圧着するため、超音波熱圧着時のボンディング荷重を４〜５Ｎ，超音波パワーを７〜８Ｗ，超音波の印加時間を１００〜１５０ｍsec，基板温度を２２０〜３００℃とすれば良い。   Most preferably, the diameter and height of the bump is set to 320 μm ≦ R ≦ 400 μm and 100 μm ≦ H ≦ 120 μm, and the ultrasonic thermocompression bonding is performed so that the bump is sufficiently fused to the pad and no concave portion is formed on the upper surface. Therefore, the bonding load at the time of ultrasonic thermocompression bonding is 4 to 5 N, the ultrasonic power is 7 to 8 W, the ultrasonic application time is 100 to 150 msec, and the substrate temperature is 220 to 300 ° C.

ここでリードの先端がバンプを貫通してパッド上に現れるようにすると、リードとバンプの接触面積を最大にし、バンプとリード間の摩擦力を大きくでき、ボンディング強度を増すことができる。   Here, if the tip of the lead penetrates the bump and appears on the pad, the contact area between the lead and the bump can be maximized, the frictional force between the bump and the lead can be increased, and the bonding strength can be increased.

図１〜図４に、実施例のガスセンサ２の構造を示す。図において、４はベースで、６は例えば４本のステムで、８はセンサ本体である。センサ本体８には、アルミナなどの絶縁性の基板１０と、パッド１２並びにバンプ１４があり、例えば４本のリード１６が、基板１０の１面の４隅に、パッド１２とバンプ１４との間に挟まれるようにして取り付けられ、他端はステム６に例えば溶接されている。なお図３，図４に示すように、リードの先端１７はバンプ１４を貫通して、パッド１２上に配置されている。   The structure of the gas sensor 2 of an Example is shown in FIGS. In the figure, 4 is a base, 6 is, for example, four stems, and 8 is a sensor body. The sensor body 8 includes an insulating substrate 10 such as alumina, a pad 12, and a bump 14. For example, four leads 16 are provided at four corners on one surface of the substrate 10 between the pad 12 and the bump 14. The other end is welded to the stem 6, for example. As shown in FIGS. 3 and 4, the lead tip 17 penetrates the bump 14 and is disposed on the pad 12.

４つのパッド１２のうち、例えば２つのパッドをヒータ膜２１に接続し、他の２つのパッドを基板の裏面の図示しないガス感応部に接続する。またガス感応部には、例えば金属酸化物半導体膜や固体電解質膜、あるいはこれらのチップなどを用いる。さらに実施例では、基板１０に４つのパッド１２を設けたが、例えば３パッドや５パッドなどとしてもよい。   Of the four pads 12, for example, two pads are connected to the heater film 21, and the other two pads are connected to a gas sensitive portion (not shown) on the back surface of the substrate. For the gas sensitive part, for example, a metal oxide semiconductor film, a solid electrolyte film, or a chip thereof is used. Further, in the embodiment, the four pads 12 are provided on the substrate 10, however, for example, three pads or five pads may be used.

パッド１２は例えば金と白金との合金パッド、あるいは下側を白金とし、上側を金とした２層のパッドなどとする。実施例では、パッド１２を下側１０μｍを白金、上側２０μｍを金とした２層パッドとし、上層と下層は部分的に合金化している。パッド１２はバンプ１４とのボンディングを容易にするため、金を含有することが必要で、少なくとも４０％以上の金を含有するパッドとする。   The pad 12 is, for example, an alloy pad of gold and platinum, or a two-layer pad in which the lower side is platinum and the upper side is gold. In the embodiment, the pad 12 is a two-layer pad in which the lower 10 μm is platinum and the upper 20 μm is gold, and the upper layer and the lower layer are partially alloyed. The pad 12 needs to contain gold in order to facilitate bonding with the bumps 14 and is a pad containing at least 40% or more of gold.

バンプ１４は金を主成分とし、これに５重量％（以下％は重量％）以下の範囲で銅などの他の金属を合金化させてもよい。金を主成分とするバンプ１４は、パッド１２への超音波熱圧着が容易である。図３，図４に示すように、バンプ１４は円盤状で、パッド１２の上面からバンプ１４の上面までの高さをＨとし、その直径をＲとする。バンプ１４の上面は、ワイヤの残部１９を除いて平坦で、図４に鎖線で示す凹部２０が生じないようにする。なお凹部２０が生じる場合、残部１９の周囲が窪むように生じ、凹部２０が生じるとは、バンプ１４の周面を基準とする深さがリード１６の直径ｒの１／２以上であることをいう。また残部１９は、キャピラリ中央のワイヤ挿通孔がボールに食い込むことや、キャピラリを上昇させた際にワイヤの上部が引きちぎられることにより生じる。   The bumps 14 are mainly composed of gold, and may be alloyed with other metals such as copper within a range of 5% by weight (hereinafter referred to as “%” by weight). The bump 14 mainly composed of gold is easy to be subjected to ultrasonic thermocompression bonding to the pad 12. As shown in FIGS. 3 and 4, the bump 14 is disk-shaped, and the height from the upper surface of the pad 12 to the upper surface of the bump 14 is H, and the diameter is R. The upper surface of the bump 14 is flat except for the remaining portion 19 of the wire so that the concave portion 20 shown by a chain line in FIG. 4 does not occur. When the recess 20 is formed, the periphery of the remaining portion 19 is recessed, and the recess 20 is generated when the depth based on the peripheral surface of the bump 14 is ½ or more of the diameter r of the lead 16. . The remaining portion 19 is generated when the wire insertion hole at the center of the capillary bites into the ball or when the upper portion of the wire is torn off when the capillary is raised.

図３，図４により、各部の寸法を説明する。基板１０は例えば正方形状で、その１辺ａを例えば１.５ｍｍとし、パッド１２も正方形状でその１辺ｂを例えば０.５ｍｍとする。またヒータ膜２１は例えば０.７×０.７ｍｍとし、ガス感応膜も例えばほぼ同じサイズである。   The dimensions of each part will be described with reference to FIGS. The substrate 10 has a square shape, for example, and its one side a is set to, for example, 1.5 mm, and the pad 12 has a square shape, and its one side b has, for example, 0.5 mm. The heater film 21 is, for example, 0.7 × 0.7 mm, and the gas-sensitive film is, for example, approximately the same size.

リード１６には、例えばＰｔやＰｔ−Ｗ，Ｐｔ−Ｆｅ，Ｐｔ−Ｎｉ，Ｐｔ−Ｃｒ，Ｐｔ−ＺＧＳ（Ｐｔの結晶粒界にジルコニアを分散させたもの），あるいはＡｕ−Ｐｄ−Ｍｏなどの貴金属合金線を用いる。これらの合金は、パッド１２やバンプ１４とのボンディング性能が低いので、主としてバンプ１４との合金層の形成や摩擦力により固定される。   The lead 16 is made of, for example, Pt, Pt—W, Pt—Fe, Pt—Ni, Pt—Cr, Pt—ZGS (in which zirconia is dispersed in the Pt crystal grain boundary), Au—Pd—Mo, or the like. Use precious metal alloy wire. Since these alloys have low bonding performance with the pads 12 and the bumps 14, they are fixed mainly by forming an alloy layer with the bumps 14 or by a frictional force.

図２に、リード１６のボンディングの過程を示すと、リード１６はキャピラリ２７から繰り出され、先端がパッド１２内に収まるように配置され、キャピラリ２６からの金系ワイヤ２５のボール２４で、超音波熱圧着される。実施例ではほぼ１００％金の金ワイヤ２５を用いた。２８は放電針、２９は高圧電源、３０はスイッチで、ワイヤ２５の先端と放電針２８との間の放電により、ボール２４を形成する。キャピラリ２６には図示しない超音波源から超音波を加えることができる、また図示しないチャックを設けて、ボンディング後にキャピラリ２６を上昇させ、ワイヤ２５を引きちぎるようにする。このようにすると、ボール２４の上部に弱い箇所があるので、その部分でワイヤ２５は引きちぎられる。さらに基板１０を加熱できるようにし、ボール２４の超音波熱圧着を容易にする。   FIG. 2 shows the bonding process of the lead 16. The lead 16 is drawn out from the capillary 27, arranged so that the tip thereof is accommodated in the pad 12, and is ultrasonicated by the ball 24 of the gold wire 25 from the capillary 26. Thermocompression bonded. In the example, a gold wire 25 of almost 100% gold was used. 28 is a discharge needle, 29 is a high voltage power source, and 30 is a switch, and the ball 24 is formed by discharge between the tip of the wire 25 and the discharge needle 28. The capillary 26 can be applied with an ultrasonic wave from an ultrasonic source (not shown), and a chuck (not shown) is provided so that the capillary 26 is raised after bonding and the wire 25 is torn off. In this way, since there is a weak spot on the upper part of the ball 24, the wire 25 is torn at that part. Further, the substrate 10 can be heated to facilitate the ultrasonic thermocompression bonding of the balls 24.

実施例ではリード１６として直径４０μｍのＰｔ−Ｗ線（Ｗ８重量％）を用い、ワイヤ２５には直径約７５μｍの金線を用いた。ワイヤ２５の直径は、リード１６の直径の、例えば１．５〜２.５倍とする。そしてバンプの直径Ｒが３８０μｍ、バンプの高さＨが１１０μｍのものを代表例とした。なおボール２４は、例えば直径２８０μｍで、好ましい直径は２００〜４００μｍ（リードの直径との比で５〜１０倍）である。ボール２４の直径は通常はワイヤ２５の直径の２〜３倍程度とされているが、発明者の実験では、ワイヤ２５の直径の２〜４倍程度のものまで真球状のボールにできた。   In the example, a Pt-W wire (W8 wt%) having a diameter of 40 μm was used as the lead 16, and a gold wire having a diameter of about 75 μm was used as the wire 25. The diameter of the wire 25 is, for example, 1.5 to 2.5 times the diameter of the lead 16. A representative example is one having a bump diameter R of 380 μm and a bump height H of 110 μm. The ball 24 has a diameter of 280 μm, for example, and a preferable diameter is 200 to 400 μm (5 to 10 times the ratio to the lead diameter). The diameter of the ball 24 is usually about 2 to 3 times the diameter of the wire 25, but in the experiments by the inventors, a ball having a spherical shape up to about 2 to 4 times the diameter of the wire 25 was made.

図５，図６に、実施例のガスセンサでのリードの取り付け状況を示す。これらの図では、１個のガスセンサの４つのバンプを、それぞれ別に示している。図５，図６での値Ｘ、Ｙ，Ｄは画像解析により求めたもので、Ｘはバンプの直径に相当し、図５でのＹはバンプの高さに相当する。図６のＤはバンプ付近に引いた補助線による長方形の対角線の長さである。図５に示したように、バンプの上面は平坦で、その中央部にはワイヤの残部が見える。また図６に示すように、バンプは円盤状で、長軸と短軸の差は１０％程度である。   5 and 6 show how the leads are attached in the gas sensor of the example. In these figures, four bumps of one gas sensor are shown separately. The values X, Y, and D in FIGS. 5 and 6 are obtained by image analysis. X corresponds to the bump diameter, and Y in FIG. 5 corresponds to the bump height. D in FIG. 6 is the length of the diagonal line of the auxiliary line drawn near the bump. As shown in FIG. 5, the upper surface of the bump is flat, and the remainder of the wire is visible at the center. Further, as shown in FIG. 6, the bump is disk-shaped, and the difference between the major axis and the minor axis is about 10%.

図７，図８に用いたボールを示すと、図７は直径７５μｍの金線から作成したボールで、直径は約２８０μｍである。図８は直径５０μｍの金線から作成したボールで、直径は約１５０μｍである。直径７５μｍのワイヤからは直径２８０μｍのボールの他に、直径２５０μｍのボールと２００μｍのボールを作成した。直径５０μｍのワイヤから直径１５０μｍのボールを作り、このボールを１回超音波熱圧着してバンプとしたものの他に、同じ場所に垂直に２つのボールを重ねて超音波熱圧着し、２重のバンプとしたものを作成した。図９に２重のバンプの断面を示す。パッドの上部にリードが円形に見え、バンプの部分には試料作成の過程で用いた樹脂が黒い点状に見えている。またバンプの上部には、ワイヤの残部が部分的に煙のように見えている。図１０に最適実施例（バンプ高さ１１０μｍ、バンプ直径３８０μｍ）での、基板とバンプの断面電子顕微鏡写真を示す。バンプの上面は平面的で、その中央にワイヤの残部が見えている。   The balls used in FIGS. 7 and 8 are balls made from a gold wire having a diameter of 75 μm and having a diameter of about 280 μm. FIG. 8 shows a ball made of a gold wire having a diameter of 50 μm and a diameter of about 150 μm. In addition to the 280 μm diameter ball, a 250 μm diameter ball and a 200 μm ball were prepared from the 75 μm diameter wire. A ball having a diameter of 150 μm is made from a wire having a diameter of 50 μm, and this ball is subjected to ultrasonic thermocompression bonding once to form a bump. Created a bump. FIG. 9 shows a cross section of the double bump. Leads appear to be circular on top of the pads, and the resin used in the sample preparation process appears as black dots at the bumps. On the top of the bump, the remainder of the wire appears partially like smoke. FIG. 10 shows a cross-sectional electron micrograph of the substrate and the bump in the optimum example (bump height 110 μm, bump diameter 380 μm). The upper surface of the bump is flat and the remainder of the wire is visible in the center.

ガスセンサの場合、基板を吊すのに用いられるリードは、直径が３０〜５０μｍ程度のものが多いが、今後基板の小型化が進めば直径２０μｍのリードも考えられる。ここで重要なのはリードの直径と、バンプの高さやバンプの直径の比である。例えばバンプの高さとリードの直径との比が１.２〜１.３程度の場合（１５０μｍボールを重ねずに超音波熱圧着）、リードを基板に直角な方向に引っ張ると、バンプの上面をリードが破って抜けてしまう。バンプが充分な厚さを有し、リードがバンプにしっかりと固定されている場合、リードを支える力は、バンプとパッドとの間の界面に働く力である。この力はバンプの底面積に比例し、リードはバンプの底面を貫通しているので、リードとバンプの接触面積は一定となり、バンプの直径とリードの直径との比が問題となる。   In the case of a gas sensor, the leads used to suspend the substrate are mostly those having a diameter of about 30 to 50 μm, but if the substrate is further downsized, a lead having a diameter of 20 μm can be considered. What is important here is the ratio of the lead diameter to the bump height and bump diameter. For example, when the ratio of the bump height to the lead diameter is about 1.2 to 1.3 (ultrasonic thermocompression without superimposing 150 μm balls), pulling the lead in a direction perpendicular to the substrate causes the upper surface of the bump to The lead breaks away. When the bump has a sufficient thickness and the lead is firmly fixed to the bump, the force supporting the lead is the force acting on the interface between the bump and the pad. This force is proportional to the bottom area of the bump. Since the lead penetrates the bottom surface of the bump, the contact area between the lead and the bump is constant, and the ratio between the bump diameter and the lead diameter becomes a problem.

これ以外に、バンプはその上面が平坦であることが重要である。超音波パワーが大きすぎる場合や、超音波の印加時間が長すぎる場合、あるいは超音波熱圧着時の荷重が大きすぎる場合、ワイヤの残部を取り囲むように凹部が生じる。凹部が生じると、この部分でバンプの強度が低下し、バンプが破損しやすくなる。これ以外に、大きなボールは製造することが難しく、また超音波熱圧着にも大きな荷重や高い温度、あるいは大きな超音波パワーなどが必要になる。荷重を大きくすると、基板などに破損が生じやすくなる。また実施例では２５０℃程度での超音波熱圧着を行っており、これよりも高い温度に加熱するのは装置的に難しい。   In addition to this, it is important that the bump has a flat upper surface. When the ultrasonic power is too large, when the application time of ultrasonic waves is too long, or when the load during ultrasonic thermocompression bonding is too large, a recess is formed so as to surround the remainder of the wire. When the concave portion is generated, the strength of the bump is lowered at this portion, and the bump is easily damaged. In addition to this, it is difficult to produce a large ball, and a large load, a high temperature, or a large ultrasonic power is required for ultrasonic thermocompression bonding. When the load is increased, the substrate is easily damaged. Further, in the examples, ultrasonic thermocompression bonding at about 250 ° C. is performed, and it is difficult for the apparatus to heat to a temperature higher than this.

図１１〜図１４に、実施例での特性を示す。図１１では基板に直角な方向にリードを引っ張った際の剥離強度（垂直ピーリング強度）を測定し、１回の測定にガスセンサ８個を用いた。またセンサは５００℃に連続加熱してエージングした。垂直方向や水平方向の剥離強度は、ガスセンサが落下テストなどにさらされることを加味して余裕を見込むと、実用的には０.４Ｎ／リード以上が好ましい。   11 to 14 show characteristics in the embodiment. In FIG. 11, peel strength (vertical peeling strength) when a lead was pulled in a direction perpendicular to the substrate was measured, and eight gas sensors were used for one measurement. The sensor was aged by continuous heating to 500 ° C. The peel strength in the vertical direction and the horizontal direction is preferably 0.4 N / lead or more practically considering a margin considering that the gas sensor is exposed to a drop test or the like.

直径２８０μｍのボールを用いたガスセンサ（バンプ高さ１１０μｍ、バンプ直径３８０μｍ）では、垂直ピーリング強度の初期値は２.２Ｎ程度で、連続加熱を続けると、この強度は徐々に低下する。一方図９のように、直径１５０μｍのボールを２つ重ねたバンプでは、ほぼ同程度の垂直ピーリング強度が得られるが、強度の低下速度は直径２８０μｍのボールを用いた場合よりも速い。これに対して直径１５０μｍのボール１個でバンプを形成した場合、初期的な垂直ピーリング強度は１Ｎを超えているが、使用と共に強度が低下し、１８ヶ月程度経過すると、実用域を下回るサンプルも生じる。リードの外れ方を調べると、１５０μｍのボールを１回のみ用いたものでは、リードがバンプを破って上側に抜けているものが多かった。これに対して直径２８０μｍのボールを用いたものや、直径１５０μｍのボールを２個用いたものでは、リードが切れる、バンプが何らかの意味で破損する、バンプがパッドから外れる、あるいはパッドの一部がバンプに付着したままパッドから外れるなどのものが入り交じっていた。しかしながらリードがバンプの上部を破って外れるものは見当たらなかった。   In a gas sensor using a ball having a diameter of 280 μm (a bump height of 110 μm and a bump diameter of 380 μm), the initial value of the vertical peeling strength is about 2.2 N, and this strength gradually decreases when continuous heating is continued. On the other hand, as shown in FIG. 9, with the bumps in which two balls having a diameter of 150 μm are stacked, almost the same level of vertical peeling strength can be obtained, but the rate of decrease in the strength is faster than when using a ball having a diameter of 280 μm. On the other hand, when the bump is formed with one ball having a diameter of 150 μm, the initial vertical peeling strength exceeds 1N, but the strength decreases with use, and after about 18 months, some samples are less than the practical range. Arise. Examination of how the lead was removed revealed that when the ball of 150 μm was used only once, the lead broke the bump and slipped upward. On the other hand, in the case of using a ball having a diameter of 280 μm or using two balls having a diameter of 150 μm, the lead is cut, the bump is damaged in some way, the bump is detached from the pad, or a part of the pad is There were things such as coming off the pads while adhering to the bumps. However, no lead was found to break off the top of the bump.

図１２に、図１１と同様の条件での、基板の表面に平行な方向にリードを引っ張った際の剥離強度（水平ピーリング強度）を示す。この場合、直径１５０μｍのボール１個を用いたバンプと、１５０μｍのボールを２個用いたバンプとの差は小さく、１２ヶ月以上使用すると、直径２８０μｍのボールを用いたバンプとの強度差が著しくなる。直径２８０μｍのボールを用いたバンプでは、１２ヶ月後や１８ヶ月後の破損原因は、パッドが損傷するものが多い（１２ヶ月後に５／８，１８ヶ月後に６／８）。これに対して直径１５０μｍのボールを用いたものでは、ボールが１個でも２個でも、バンプが破損する、あるいはリードがバンプから外れるものが多く、バンプの底面積が不足すると水平ピーリング強度の耐久性が不足することが分かる。   FIG. 12 shows the peel strength (horizontal peeling strength) when the lead is pulled in a direction parallel to the surface of the substrate under the same conditions as in FIG. In this case, the difference between a bump using one ball having a diameter of 150 μm and a bump using two balls having a diameter of 150 μm is small, and when used for 12 months or more, there is a significant difference in strength between the bump using a ball having a diameter of 280 μm. Become. In bumps using a ball having a diameter of 280 μm, the cause of damage after 12 months or 18 months is that the pad is often damaged (5/8 after 12 months, 6/8 after 18 months). On the other hand, with balls having a diameter of 150 μm, even if one or two balls are used, the bump is damaged or the lead is often detached from the bump. It turns out that sex is insufficient.

図１３に、ボールの直径と水平ピーリング強度や垂直ピーリング強度を示す。横軸には用いたワイヤの直径とボールの直径とをμｍ単位で示し、バンプの直径やバンプの高さは図１４に黒抜きで示したサンプルのものである。ボールの直径２００μｍ程度で、１８ヶ月後のピーリング強度が信頼性のある範囲と信頼性のない範囲の境界に現れる。リードの直径は４０μｍなので、ボールの直径は好ましくはリードの直径の６倍以上８倍以下とし、より広くはリードの直径の５倍以上１０倍以下とする。   FIG. 13 shows the ball diameter, horizontal peeling strength and vertical peeling strength. The horizontal axis shows the diameter of the wire used and the diameter of the ball in μm units, and the bump diameter and bump height are those of the sample shown in black in FIG. When the ball diameter is about 200 μm, the peeling strength after 18 months appears at the boundary between the reliable range and the unreliable range. Since the diameter of the lead is 40 μm, the diameter of the ball is preferably 6 to 8 times the diameter of the lead, and more widely 5 to 10 times the diameter of the lead.

図１４にバンプの直径Ｒやバンプの高さＨに対する、１８ヶ月経過後の水平方向の強度や垂直方向の強度を示す。これらの値が共に１Ｎを超えるためには、バンプの高さＨは８０μｍ以上必要で、より好ましくは１００μｍ以上必要である。バンプの高さを無制限に大きくすると、ボールの形成も難しく、超音波熱圧着も困難になる。これらのことから、Ｈの値は２以上５以下が良く、より好ましくは２以上４以下とし、最も好ましくは２.５以上３以下とする。バンプの直径Ｒはリードの直径４０μｍに対して少なくとも２４０μｍ以上必要で、好ましくは３００μｍ以上とし、最も好ましくは３２０μｍ以上とする。なお、バンプ直径が４４０μｍで、バンプ高さ８５μｍのサンプルでは、バンプの上面に凹部が存在し、そのため垂直方向の強度が低下している。バンプの直径Ｒとリードの直径ｒの比Ｒ／ｒは、一般的には６〜１２とし、好ましくは７.５〜１１とし、最も好ましくは８以上１０以下とする。   FIG. 14 shows the strength in the horizontal direction and the strength in the vertical direction after 18 months with respect to the bump diameter R and the bump height H. In order for both of these values to exceed 1N, the height H of the bumps needs to be 80 μm or more, more preferably 100 μm or more. If the height of the bump is increased without limit, it is difficult to form a ball, and ultrasonic thermocompression bonding becomes difficult. Accordingly, the value of H is preferably 2 or more and 5 or less, more preferably 2 or more and 4 or less, and most preferably 2.5 or more and 3 or less. The bump diameter R needs to be at least 240 μm with respect to the lead diameter of 40 μm, preferably 300 μm or more, and most preferably 320 μm or more. Note that in the sample having a bump diameter of 440 μm and a bump height of 85 μm, a recess is present on the upper surface of the bump, and therefore the strength in the vertical direction is reduced. The ratio R / r of the bump diameter R to the lead diameter r is generally 6-12, preferably 7.5-11, and most preferably 8-10.

超音波熱圧着の条件を説明すると、超音波パワーが大きく、超音波の印加時間が長く、荷重が大きく、基板の加熱温度が高いほど、超音波熱圧着自体は容易になる。しかしこれらの条件が強すぎる場合、バンプに凹部が生じることがある。また基板の温度を高くするのは、ボンディング装置の構造上困難である。さらに荷重を大きくすると、基板の損傷などが生じやすい。一方超音波パワーやその印加時間、荷重、基板温度などが低すぎると、バンプとパッドとの付着強度が不足する上、バンプの形状が半球状となり、バンプの直径が不足したサンプルが生じやすかった。   Explaining the conditions of ultrasonic thermocompression bonding, the ultrasonic thermocompression bonding itself becomes easier as the ultrasonic power is larger, the application time of ultrasonic waves is longer, the load is larger, and the heating temperature of the substrate is higher. However, if these conditions are too strong, the bumps may be recessed. In addition, it is difficult to increase the substrate temperature because of the structure of the bonding apparatus. If the load is further increased, the substrate is likely to be damaged. On the other hand, if the ultrasonic power, its application time, load, substrate temperature, etc. are too low, the adhesion strength between the bump and the pad will be insufficient, and the bump shape will be hemispherical, and it will be easy to produce a sample with insufficient bump diameter. .

リードの直径ｒを３０〜５０μｍとすると、バンプの直径は例えば３００〜４４０μｍ、より好ましくは３２０〜４００μｍが良く、バンプの高さは８０〜１６０μｍが好ましく、より好ましくは１００〜１５０μｍとなる。このような直径や高さのバンプを直径２８０μｍや２５０μｍのボールから形成するには、バンプの直径が３００〜４４０μｍ、高さが８０〜１６０μｍの範囲で、超音波熱圧着時のボンディング荷重を３〜６Ｎ、超音波パワーを３〜１０Ｗ，超音波の印加時間を５０〜２００ｍsec、基板温度を２００〜３５０℃とすると、良かった。またバンプの直径を３２０〜４００μｍとし、その高さを１００〜１２０μｍとするには、ボンディング荷重を４〜５Ｎ、超音波パワーを７〜８Ｗ，その印加時間を１００〜１５０ｍsec、基板温度を２２０〜３００℃とすれば良かった。なおこのボンディング条件は、直径２５０〜２８０μｍのボールから、最適形状のバンプを作るための条件で、リードの直径とは独立した値である。   If the lead diameter r is 30-50 μm, the bump diameter is, for example, 300-440 μm, more preferably 320-400 μm, and the bump height is preferably 80-160 μm, more preferably 100-150 μm. In order to form a bump having such a diameter or height from a ball having a diameter of 280 μm or 250 μm, the bonding load at the time of ultrasonic thermocompression bonding is 3 in the range of the bump diameter of 300 to 440 μm and the height of 80 to 160 μm. -6N, ultrasonic power of 3 to 10 W, application time of ultrasonic waves of 50 to 200 msec, and substrate temperature of 200 to 350 ° C. were good. In order to set the bump diameter to 320 to 400 μm and the height to 100 to 120 μm, the bonding load is 4 to 5 N, the ultrasonic power is 7 to 8 W, the application time is 100 to 150 msec, and the substrate temperature is 220 to It should have been 300 degreeC. This bonding condition is a condition for making an optimally shaped bump from a ball having a diameter of 250 to 280 μm, and is a value independent of the lead diameter.

実施例では、長期間にわたって水平方向にも垂直方向にもリードの剥離強度が高いガスセンサを、簡単に製造することができる
In the embodiment, it is possible to easily manufacture a gas sensor having high lead peel strength both in the horizontal direction and in the vertical direction over a long period of time.

実施例のガスセンサの平面図Plan view of the gas sensor of the embodiment 実施例のガスセンサでの、パッドへのリードのボンディング工程を模式的に示す図The figure which shows typically the bonding process of the lead to the pad in the gas sensor of an Example. 実施例での基板やリード、パッド、バンプの配置を示す平面図The top view which shows arrangement | positioning of the board | substrate in an Example, a lead, a pad, and bump 実施例でのパッドとバンプ及びリードの関係を示す要部側面図Side view of main part showing relationship between pad, bump and lead in the embodiment 実施例のガスセンサの側面視写真Side view photograph of the gas sensor of the example 実施例のガスセンサの平面視写真Plan view photograph of the gas sensor of the example 実施例で用いたボールの３００倍電子顕微鏡写真300 times electron micrograph of the balls used in the examples 比較例で用いたボールの５００倍電子顕微鏡写真500 times electron micrograph of the ball used in the comparative example 比較例のガスセンサでのボンディング部の２５０倍電子顕微鏡写真250x electron micrograph of the bonding part of the gas sensor of the comparative example 実施例でのバンプと基板の断面を示す電子顕微鏡写真Electron micrograph showing the cross section of the bump and substrate in the example １８ヶ月間の連続加熱（５００℃）でのリードの基板に垂直な方向での剥離強度の変化を示す特性図： サンプル数は各８個、バンプは２８０μｍボール（実施例）、１５０μｍボールを垂直方向に２個重ねて形成、１５０μｍボール（比較例）の３種類Characteristic diagram showing changes in peel strength in the direction perpendicular to the substrate of the lead after 18 months of continuous heating (500 ° C): 8 samples each, bumps 280 μm balls (Example), 150 μm balls perpendicular 3 types of 150μm balls (comparative example) １８ヶ月間の連続加熱（５００℃）でのリードの基板表面に平行な方向での剥離強度の変化を示す特性図： サンプル数は各８個、バンプは２８０μｍボール（実施例）、１５０μｍボールを垂直方向に２個重ねて形成、１５０μｍボール（比較例）の３種類Characteristic diagram showing changes in peel strength in the direction parallel to the substrate surface of the lead after 18 months of continuous heating (500 ° C.): 8 samples each, 280 μm balls (Example), 150 μm balls Three types of 150μm balls (comparative example) formed by overlapping two vertically. １８ヶ月間の連続加熱（５００℃）でのリードの剥離強度の変化を示す特性図： バンプ形成に用いたボールの直径は、 ２８０μｍ，２５０μｍ（実施例） ２００μｍ，１５０μｍ（比較例）Characteristic diagram showing change in peel strength of lead after 18 months of continuous heating (500 ° C.): The diameter of the ball used for bump formation is 280 μm, 250 μm (Example) 200 μm, 150 μm (Comparative Example) １８ヶ月間の連続加熱後（５００℃）での、リードの剥離強度（Ｎ単位）をバンプの直径とバンプの高さに対して示す特性図：Characteristic diagram showing lead peel strength (in N units) against bump diameter and bump height after 18 months of continuous heating (500 ° C.):

符号の説明Explanation of symbols

２ ガスセンサ
４ ベース
６ ステム
８ センサ本体
１０ 基板
１２ パッド
１４ バンプ
１６ リード
１７ ワイヤの先端
１８ 上面
１９ ワイヤの残部
２０ 凹部
２１ ヒータ膜
２４ ボール
２５ ワイヤ
２６，２７ キャピラリ
２８ 放電針
２９ 高圧電源
３０ スイッチ
ａ 基板の１辺
ｂ パッドの１辺
Ｒ バンプの直径
ｒ リードの直径
Ｈ バンプの高さ 2 Gas sensor 4 Base 6 Stem 8 Sensor body 10 Substrate 12 Pad 14 Bump 16 Lead 17 Wire tip 18 Upper surface 19 Remaining wire 20 Recess 21 Heater film 24 Ball 25 Wire 26, 27 Capillary 28 Discharge needle 29 High-voltage power supply 30 Switch a substrate One side b One side of the pad R Bump diameter r Lead diameter H Bump height

Claims (7)

基板上にヒータ膜とガス感応部とパッドとを形成し、該基板を外部に接続するリードを前記パッドにボンディングしたガスセンサにおいて、
前記リードを金系のパッドと金系のバンプとの間に挟み込むようにしてボンディングし、
バンプは上面に凹部がない円盤状とし、その直径Ｒ、及びパッドの上面からバンプの上面までの高さＨと、リードの直径ｒとの比を、６≦Ｒ／ｒ≦１２，２≦Ｈ≦５とする、
ことを特徴とする、ガスセンサ。 In a gas sensor in which a heater film, a gas sensitive part, and a pad are formed on a substrate, and a lead that connects the substrate to the outside is bonded to the pad.
Bonding the lead so as to be sandwiched between a gold-based pad and a gold-based bump,
The bump has a disk shape with no recess on the upper surface, and the ratio of the diameter R and the height H from the upper surface of the pad to the upper surface of the bump and the diameter r of the lead is 6 ≦ R / r ≦ 12, 2 ≦ H. ≦ 5,
A gas sensor. バンプの直径Ｒ、及びパッドの上面からバンプの上面までの高さＨと、リードの直径ｒとの比を、７.５≦Ｒ／ｒ≦１１，２≦Ｈ≦４としたことを特徴とする、請求項１のガスセンサ。 The ratio of the bump diameter R and the height H from the upper surface of the pad to the upper surface of the bump and the diameter r of the lead is set to 7.5 ≦ R / r ≦ 11, 2 ≦ H ≦ 4. The gas sensor according to claim 1. バンプの直径Ｒ、及びパッドの上面からバンプの上面までの高さＨと、リードの直径ｒとの比を、８≦Ｒ／ｒ≦１０，２.５≦Ｈ≦３としたことを特徴とする、請求項２のガスセンサ。 The ratio of the diameter R of the bump and the height H from the upper surface of the pad to the upper surface of the bump and the diameter r of the lead is 8 ≦ R / r ≦ 10, 2.5 ≦ H ≦ 3, The gas sensor according to claim 2. リードがバンプをパッドの上面に沿って貫通して、リードの先端が該パッド上で前記バンプを突き抜けていることを特徴とする、請求項１〜３のいずれかのガスセンサ。 4. The gas sensor according to claim 1, wherein the lead penetrates the bump along the upper surface of the pad, and the tip of the lead penetrates the bump on the pad. 基板上にヒータ膜とガス感応部とパッドとを形成し、該基板を外部に接続するリードを、パッドにボンディングしたガスセンサの製造方法において、
直径ｒのリードの先端を金系のパッド上に配置し、直径がｒの１.５倍以上のバンプ形成用の金系ワイヤの先端に、直径がｒの５倍以上１０倍以下のボールを形成し、
該ボールを前記バンプに超音波熱圧着して、ワイヤの残部を除いて上面が平坦なバンプを形成すると共に、前記リードを該バンプとパッドとの間に挟み込んでボンディングし、
かつバンプは円盤状で上面に凹部がなく、その直径をＲ、及びパッドの上面からバンプの上面までの高さをＨとして、リードの直径ｒとの比を、６≦Ｒ／ｒ≦１２，２≦Ｈ≦５としたことを特徴とする、ガスセンサの製造方法。 In the method of manufacturing a gas sensor, a heater film, a gas sensitive part, and a pad are formed on a substrate, and a lead that connects the substrate to the outside is bonded to the pad.
The tip of a lead with a diameter r is placed on a metal pad, and a ball with a diameter of 5 to 10 times the diameter r is placed on the tip of a gold wire for bump formation with a diameter 1.5 or more times r. Forming,
The ball is ultrasonically heat-bonded to the bump to form a bump having a flat upper surface excluding the remainder of the wire, and the lead is sandwiched between the bump and the pad and bonded,
The bump is disk-shaped and has no recess on the upper surface, the diameter is R, and the height from the upper surface of the pad to the upper surface of the bump is H, and the ratio to the lead diameter r is 6 ≦ R / r ≦ 12, 2. A gas sensor manufacturing method, wherein 2 ≦ H ≦ 5. リードの直径ｒを３０μｍ≦ｒ≦５０μｍとし、
バンプの直径Ｒ及びバンプの高さＨを、３００μｍ≦Ｒ≦４４０μｍ、
８０μｍ≦Ｈ≦１６０μｍとし、
前記ボールと前記パッドとの接合を超音波熱圧着で行い、かつ超音波熱圧着時の、ボンディング荷重を３〜６Ｎ，超音波パワーを３〜１０Ｗ，超音波の印加時間を５０〜２００ｍsec，基板温度を２００〜３５０℃とすることを特徴とする、請求項５のガスセンサの製造方法。 The lead diameter r is 30 μm ≦ r ≦ 50 μm,
Bump diameter R and bump height H are set to 300 μm ≦ R ≦ 440 μm,
80 μm ≦ H ≦ 160 μm,
Bonding of the ball and the pad is performed by ultrasonic thermocompression bonding, and at the time of ultrasonic thermocompression bonding, the bonding load is 3 to 6 N, the ultrasonic power is 3 to 10 W, the ultrasonic wave application time is 50 to 200 msec, the substrate 6. The method of manufacturing a gas sensor according to claim 5, wherein the temperature is 200 to 350 [deg.] C. ３２０μｍ≦Ｒ≦４００μｍ、１００μｍ≦Ｈ≦１２０μｍとし、
前記ボールと前記パッドとの接合を超音波熱圧着で行い、かつ超音波熱圧着時の、ボンディング荷重を４〜５Ｎ，超音波パワーを７〜８Ｗ，超音波の印加時間を１００〜１５０ｍsec，基板温度を２２０〜３００℃とすることを特徴とする、請求項６のガスセンサの製造方法。 320 μm ≦ R ≦ 400 μm, 100 μm ≦ H ≦ 120 μm,
Bonding of the ball and the pad is performed by ultrasonic thermocompression bonding, and at the time of ultrasonic thermocompression bonding, the bonding load is 4 to 5 N, the ultrasonic power is 7 to 8 W, the ultrasonic wave application time is 100 to 150 msec, the substrate The method for manufacturing a gas sensor according to claim 6, wherein the temperature is 220 to 300 ° C.
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