JP2010197163A - Thin-film temperature sensor and method for manufacturing the same - Google Patents
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Abstract
Description
本発明は、小型で熱応答特性の優れた薄膜温度センサ及びその製造方法に関するものである。 The present invention relates to a thin film temperature sensor having a small size and excellent thermal response characteristics, and a method for manufacturing the same.
例えば、情報機器、通信機器、医療用機器、住宅設備機器、自動車用伝送機器等の温度センサ、流量センサとして、大きな負の温度係数を有する酸化物半導体の焼結体からなるサーミスタチップがある。このサーミスタチップを用いた温度センサは、端子電極が形成されており、この電極面にはんだ付け等によってリード線を取り付けた構造のものである。又、サーミスタチップの寸法やリード線径を小さくすることによって、熱応答特性の良い温度センサとして使用されている。 For example, there is a thermistor chip made of an oxide semiconductor sintered body having a large negative temperature coefficient as a temperature sensor and a flow rate sensor for information equipment, communication equipment, medical equipment, housing equipment, automobile transmission equipment, and the like. A temperature sensor using the thermistor chip has a structure in which a terminal electrode is formed and a lead wire is attached to the electrode surface by soldering or the like. In addition, it is used as a temperature sensor with good thermal response characteristics by reducing the thermistor chip size and lead wire diameter.
しかし、上記のように製作された金属酸化物の焼結体からなるサーミスタチップは、強度面から、寸法を小さくするのに限界がある為、薄膜形成技術を用いた薄膜温度センサが開発され実用化されるようになった。この薄膜温度センサは、上記の金属酸化物の焼結体を、機械的強度の強い薄い基板上に成膜して、薄膜電極を形成することで、小型化が可能となり、チップに比べて熱容量が小さいために、熱応答特性の良い温度センサが可能となる。 However, the thermistor chip made of a sintered metal oxide manufactured as described above has a limit in reducing the size in terms of strength, so a thin film temperature sensor using thin film formation technology has been developed and put into practical use. Came to be. In this thin film temperature sensor, the above metal oxide sintered body is formed on a thin substrate with high mechanical strength, and a thin film electrode is formed, so that the size can be reduced and the heat capacity compared to the chip. Therefore, a temperature sensor with good thermal response characteristics can be achieved.
従来、薄膜温度センサにおけるリード線と引き出し電極とを接合するために、電極膜上にＮｉ／Ｓｎめっきを行い、リード線とのはんだ接合を行うか、金ワイヤー等を用いたワイヤーバンプ法を使用してバンプを形成した後、リード線を接合する方法が採用されている。例えば、特許文献１には、薄膜温度センサのＰｔ等の電極とリード線とを接続するために、電極上にワイヤーバンプ法でバンプを形成し、このバンプ上にリード線をレーザ溶接により接続する技術が提案されている。 Conventionally, in order to join the lead wire and lead electrode in the thin film temperature sensor, Ni / Sn plating is performed on the electrode film and soldering with the lead wire is used, or a wire bump method using a gold wire or the like is used. Then, after the bumps are formed, a method of joining the lead wires is adopted. For example, in Patent Document 1, in order to connect an electrode such as Pt of a thin film temperature sensor and a lead wire, a bump is formed on the electrode by a wire bump method, and the lead wire is connected to the bump by laser welding. Technology has been proposed.
上記従来の技術には、以下の課題が残されている。
すなわち、上記はんだ接合の場合、温度センサの使用温度範囲がはんだの融点以下に限定されてしまうと共に、はんだ接合部の肉盛りにより熱容量が増加して薄膜温度センサが持っている本来の熱応答速度の遅延につながってしまう不都合があった。
また、溶接のためにワイヤーバンプ法を用いてバンプを形成した場合も、同様にバンプの容積により素子の熱容量が増加して熱応答速度の遅延につながってしまう。さらに、バンプを形成してしまうと、リード線の最大高さが高くなり、後の工程での耐熱、耐熱応力、耐引っ張り応力強化のために素子表面にモールドする場合、さらに素子の容量及び熱容量が増加して熱応答速度の遅延につながってしまう不都合があった。特に、チップサイズが小さくなればなるほど、これらの問題が顕著に現れてしまう。また、ワイヤーバンプ法等では、電極のＰｔ膜の露出部分が多くあり、Ｐｔ膜が酸素透過性を有していることから、温度センサの感熱部分のセラミックス部分（サーミスタ薄膜）に保護膜を施しているのにかかわらず、酸素のやりとりが電極部分を介して行われてしまう不都合があった。特に、耐熱試験を行うと、抵抗値上昇等の電気特性が変化する現象が顕著に現れてしまう。
The following problems remain in the conventional technology.
That is, in the case of the above-mentioned solder joint, the temperature range of use of the temperature sensor is limited to the melting point of the solder or less, and the heat capacity increases due to the build-up of the solder joint, and the original thermal response speed of the thin film temperature sensor There was an inconvenience that led to a delay.
In addition, when a bump is formed using the wire bump method for welding, the heat capacity of the element is similarly increased due to the volume of the bump, leading to a delay in the thermal response speed. Furthermore, if bumps are formed, the maximum height of the lead wire becomes high, and when molding on the element surface to strengthen heat resistance, heat stress, and tensile stress resistance in later processes, the capacity and heat capacity of the element are further increased. There is a disadvantage that the increase in the thermal response speed is delayed. In particular, as the chip size decreases, these problems become more apparent. In the wire bump method, etc., there are many exposed parts of the Pt film of the electrode, and the Pt film has oxygen permeability, so a protective film is applied to the ceramic part (thermistor thin film) of the heat sensitive part of the temperature sensor. In spite of this, there is a disadvantage that the exchange of oxygen is performed through the electrode portion. In particular, when a heat resistance test is performed, a phenomenon in which electrical characteristics change, such as an increase in resistance value, appears prominently.
本発明は、前述の課題に鑑みてなされたもので、熱容量の増加を抑制すると共に酸素の進行を防止して電気特性の変化を低減することができる薄膜温度センサ及びその製造方法を提供することを目的とする。 The present invention has been made in view of the above-described problems, and provides a thin film temperature sensor capable of suppressing an increase in heat capacity and preventing the progression of oxygen to reduce changes in electrical characteristics, and a method for manufacturing the same. With the goal.
本発明は、前記課題を解決するために以下の構成を採用した。すなわち、本発明の薄膜温度センサは、表面に絶縁層が形成された基板又は絶縁基板と、前記絶縁層又は前記絶縁基板の上面にパターン形成されたサーミスタ薄膜と、前記絶縁層又は前記絶縁基板の上面から前記サーミスタ薄膜の上面に亘ってＰｔでパターン形成されたＰｔ接合層と、該Ｐｔ接合層上にＮｉで形成されたＮｉめっき層と、該Ｎｉめっき層の表面に形成されたＮｉ酸化膜と、前記Ｎｉめっき層に接続されたリード線と、を備え、前記リード線が、前記Ｎｉ酸化膜よりも深い溶け込み深さで前記Ｎｉめっき層の途中まで溶接されていることを特徴とする。 The present invention employs the following configuration in order to solve the above problems. That is, the thin film temperature sensor of the present invention includes a substrate or an insulating substrate having an insulating layer formed on a surface thereof, a thermistor thin film patterned on the upper surface of the insulating layer or the insulating substrate, and the insulating layer or the insulating substrate. A Pt bonding layer patterned with Pt from the upper surface to the upper surface of the thermistor thin film, a Ni plating layer formed of Ni on the Pt bonding layer, and a Ni oxide film formed on the surface of the Ni plating layer And a lead wire connected to the Ni plating layer, wherein the lead wire is welded to the middle of the Ni plating layer with a deeper penetration depth than the Ni oxide film.
本発明の薄膜温度センサの製造方法は、基板上の絶縁層又は絶縁基板の上面にサーミスタ薄膜をパターン形成する薄膜形成工程と、前記絶縁層又は前記絶縁基板の上面から前記サーミスタ薄膜の上面に亘って、ＰｔによりＰｔ接合層をパターン形成する接合層形成工程と、前記Ｐｔ接合層上にＮｉめっきによりＮｉめっき層を形成すると共に該Ｎｉめっき層の表面にＮｉ酸化膜を形成する電極形成工程と、前記Ｎｉめっき層上にリード線をレーザ溶接するリード線溶接工程と、を備え、前記リード線を、前記Ｎｉ酸化膜よりも深い溶け込み深さで前記Ｎｉめっき層の途中まで溶接することを特徴とする。 The method of manufacturing a thin film temperature sensor according to the present invention includes a thin film forming step of patterning a thermistor thin film on an insulating layer on the substrate or the upper surface of the insulating substrate, and the upper surface of the thermistor thin film from the upper surface of the insulating layer or the insulating substrate. A bonding layer forming step of patterning a Pt bonding layer with Pt; and an electrode forming step of forming a Ni plating layer on the Pt bonding layer by Ni plating and forming a Ni oxide film on the surface of the Ni plating layer; And a lead wire welding step of laser welding a lead wire on the Ni plating layer, wherein the lead wire is welded to the middle of the Ni plating layer with a deeper penetration depth than the Ni oxide film. And
これらの薄膜温度センサ及びその製造方法では、リード線が、Ｎｉ酸化膜よりも深い溶け込み深さでＮｉめっき層の途中まで溶接されるので、Ｎｉめっき層上を覆うＮｉ酸化膜によって酸素の進行が防止されると共に、Ｎｉ酸化膜よりも深く溶け込んでリード線が溶接されるため、高い引っ張り強度を得ることができる。すなわち、耐熱試験時のＮｉの酸化による電気特性の変化や、センサの感熱部分のサーミスタ薄膜に対する酸素のやりとりによる電気特性の変化が低減されると共に、溶接がＰｔ接合層の途中までに制御されることで絶縁層又は絶縁基板との接合を受け持つＰｔ接合層のダメージが少なく、高い接合強度が得られる。特に、厚く成膜することが容易なめっき法でＮｉめっき層を厚く形成することで、溶接の溶け込み深さ制御も容易になると共に、Ｐｔ接合層へのダメージをより低減することができる。また、リード線がはんだやバンプ等を使用せずに溶接されるため、熱容量の増加を抑制でき、高い熱応答速度を維持することができる。 In these thin film temperature sensors and manufacturing methods thereof, the lead wire is welded to the middle of the Ni plating layer at a deeper penetration depth than the Ni oxide film, so that oxygen progresses by the Ni oxide film covering the Ni plating layer. In addition to being prevented, the lead wire is welded by melting deeper than the Ni oxide film, so that a high tensile strength can be obtained. That is, a change in electrical characteristics due to Ni oxidation during a heat resistance test and a change in electrical characteristics due to the exchange of oxygen with the thermistor thin film in the heat sensitive part of the sensor are reduced, and welding is controlled halfway through the Pt bonding layer. As a result, there is little damage to the Pt bonding layer responsible for bonding with the insulating layer or the insulating substrate, and high bonding strength can be obtained. In particular, by forming a thick Ni plating layer by a plating method that is easy to form a thick film, it is possible to easily control the penetration depth of welding and to further reduce damage to the Pt bonding layer. Moreover, since the lead wire is welded without using solder, bumps, or the like, an increase in heat capacity can be suppressed and a high thermal response speed can be maintained.
また、本発明の薄膜温度センサは、前記リード線の溶接部分が、略球状に形成されていることを特徴とする。
また、本発明の薄膜温度センサの製造方法は、前記レーザ溶接のレーザ光の照射位置を、前記リード線の先端から離した位置に設定し、前記リード線の溶接部分を略球状に形成することを特徴とする。
The thin film temperature sensor of the present invention is characterized in that the welded portion of the lead wire is formed in a substantially spherical shape.
In the method for manufacturing a thin film temperature sensor of the present invention, the laser welding irradiation position of the laser welding is set at a position away from the tip of the lead wire, and the welded portion of the lead wire is formed in a substantially spherical shape. It is characterized by.
これらの薄膜温度センサ及びその製造方法では、リード線の溶接部分が略球状に形成されるので、溶接面積が増えると共に引っ張り強度の異方性が減少し、接合強度がさらに向上する。 In these thin film temperature sensors and manufacturing methods thereof, the welded portion of the lead wire is formed in a substantially spherical shape, so that the weld area increases, the anisotropy of the tensile strength decreases, and the joint strength further improves.
本発明によれば、以下の効果を奏する。
すなわち、本発明に係る薄膜温度センサ及びその製造方法によれば、リード線が、Ｎｉ酸化膜よりも深い溶け込み深さでＮｉめっき層の途中まで溶接されるので、熱容量の増加を抑制して高い熱応答速度を維持できると共に、酸素の進行が防止されて電気特性の変化を抑制できる。また、溶接部分がＮｉ酸化膜よりも深く溶け込むと共にＮｉめっき層の途中までに制御されるため、高い引っ張り強度及び接合強度を得ることができる。
したがって、はんだやバンプを使用せず、高い熱応答速度で安定した電気特性を確保することができ、品質及び信頼性の向上を図ることができる。
The present invention has the following effects.
That is, according to the thin film temperature sensor and the manufacturing method thereof according to the present invention, since the lead wire is welded to the middle of the Ni plating layer with a deeper penetration depth than the Ni oxide film, the increase in heat capacity is suppressed and high. The thermal response speed can be maintained, and the progress of oxygen can be prevented to suppress changes in electrical characteristics. In addition, since the welded portion melts deeper than the Ni oxide film and is controlled by the middle of the Ni plating layer, high tensile strength and bonding strength can be obtained.
Therefore, stable electrical characteristics can be ensured at a high thermal response speed without using solder or bumps, and quality and reliability can be improved.
以下、本発明に係る薄膜温度センサ及びその製造方法の一実施形態を、図１から図５を参照して説明する。なお、以下の説明に用いる各図面では、各部材又は構成を認識可能な大きさとするために、各部材の縮尺を適宜変更している。 Hereinafter, an embodiment of a thin film temperature sensor and a manufacturing method thereof according to the present invention will be described with reference to FIGS. In each drawing used for the following description, the scale of each member is appropriately changed in order to make each member or configuration recognizable.
本実施形態の薄膜温度センサ１は、図１に示すように、アルミナ基板の絶縁基板３と、絶縁基板３の上面にパターン形成されたサーミスタ薄膜４と、絶縁基板３の上面からサーミスタ薄膜４の上面に亘ってＰｔでパターン形成された一対のＰｔ接合層５と、これらＰｔ接合層５上にＮｉで形成された一対のＮｉめっき層６と、これらＮｉめっき層６の表面に形成された一対のＮｉ酸化膜７と、これらＮｉめっき層６に接続された一対のリード線８と、を備えている。 As shown in FIG. 1, the thin film temperature sensor 1 of this embodiment includes an insulating substrate 3 made of an alumina substrate, a thermistor thin film 4 patterned on the upper surface of the insulating substrate 3, and a thermistor thin film 4 formed from the upper surface of the insulating substrate 3. A pair of Pt bonding layers 5 patterned with Pt over the upper surface, a pair of Ni plating layers 6 formed of Ni on the Pt bonding layers 5, and a pair formed on the surfaces of these Ni plating layers 6 The Ni oxide film 7 and a pair of lead wires 8 connected to the Ni plating layer 6 are provided.
上記サーミスタ薄膜４は、Ｍｎ−Ｃｏ系複合金属酸化物（例えば、Ｍｎ3Ｏ4−Ｃｏ3Ｏ4系複合金属酸化物）又は、Ｍｎ−Ｃｏ系複合金属酸化物に、Ｎｉ、Ｆｅ、Ｃｕのうち少なくとも一種類の元素を含む複合金属酸化物（例えば、Ｍｎ3Ｏ4−Ｃｏ3Ｏ4−Ｆｅ2Ｏ3系複合金属酸化物）からなる複合金属酸化物膜である。 The thermistor thin film 4 is made of Mn—Co based composite metal oxide (for example, Mn 3 O 4 —Co 3 O 4 based composite metal oxide) or Mn—Co based composite metal oxide with Ni, Fe, or Cu. It is a composite metal oxide film made of a composite metal oxide containing at least one element (for example, Mn 3 O 4 —Co 3 O 4 —Fe 2 O 3 -based composite metal oxide).
本実施形態のサーミスタ薄膜４は、絶縁基板３の上面に、スパッタリング法により平面視略正方形状に成膜されたものである。
このサーミスタ薄膜４は、半導体の性状を呈し、温度が上昇すると抵抗が低くなる負特性、いわゆるＮＴＣサーミスタ（Negative Temperature Coefficient Thermistor）の性質を有している。
The thermistor thin film 4 of this embodiment is formed on the upper surface of the insulating substrate 3 in a substantially square shape in plan view by a sputtering method.
The thermistor thin film 4 has the properties of a semiconductor and has a negative characteristic in which the resistance decreases as the temperature rises, that is, a so-called NTC thermistor (Negative Temperature Coefficient Thermistor).
一対のＰｔ接合層５は、サーミスタ薄膜４の上面から絶縁基板３の上面に亘って形成されている。この一対のＰｔ接合層５は、一対のＮｉめっき層６の下地層となるものであり、成膜される面の材料（本実施形態では絶縁基板３及びサーミスタ薄膜４）との接合強度がＮｉめっき層６よりも高い。また、本実施形態のＰｔ接合層５は、サーミスタ薄膜４の上面に形成され互いに対向した一対の櫛歯部５ａと、各櫛歯部５ａに接続された一対の引き出し電極である電極パッド部５ｂと、を有している。このＰｔ接合層５の厚さは、１００〜１０００ｎｍに設定されている。 The pair of Pt bonding layers 5 is formed from the upper surface of the thermistor thin film 4 to the upper surface of the insulating substrate 3. The pair of Pt bonding layers 5 serves as an underlayer for the pair of Ni plating layers 6, and the bonding strength with the material of the surface to be formed (in this embodiment, the insulating substrate 3 and the thermistor thin film 4) is Ni. It is higher than the plating layer 6. Further, the Pt bonding layer 5 of the present embodiment includes a pair of comb teeth 5a formed on the upper surface of the thermistor thin film 4 and facing each other, and an electrode pad section 5b that is a pair of lead electrodes connected to the comb teeth 5a. And have. The thickness of the Pt bonding layer 5 is set to 100 to 1000 nm.
一対のＮｉめっき層６は、絶縁基板３上に形成されたＰｔ接合層５の電極パッド部５ｂ上に積層されて引き出し電極としての電極パッドを構成している。このＮｉめっき層６の厚さは、３０μｍ程度である。
上記Ｎｉ酸化膜７は、Ｎｉめっき層６の表面に形成された自然酸化膜又はＮｉめっき層６の表面を熱酸化処理して形成したものであり、厚さは、０．１μｍ程度である。
The pair of Ni plating layers 6 are stacked on the electrode pad portion 5b of the Pt bonding layer 5 formed on the insulating substrate 3 to constitute an electrode pad as a lead electrode. The thickness of the Ni plating layer 6 is about 30 μm.
The Ni oxide film 7 is a natural oxide film formed on the surface of the Ni plating layer 6 or formed by thermally oxidizing the surface of the Ni plating layer 6 and has a thickness of about 0.1 μm.
上記リード線８は、ステンレス（ＳＵＳ）線であって、図２に示すように、Ｎｉ酸化膜７よりも深い溶け込み深さでＮｉめっき層６の途中まで溶接されている。また、リード線８の溶接部分は、内部の溶け込み部分も含めて略球状に形成されている。なお、本実施形態のリード線８は、φ０．１ｍｍのＳＵＳ３０４線である。 The lead wire 8 is a stainless steel (SUS) wire and is welded to the middle of the Ni plating layer 6 with a deeper penetration depth than the Ni oxide film 7 as shown in FIG. Further, the welded portion of the lead wire 8 is formed in a substantially spherical shape including the internal melted portion. Note that the lead wire 8 of the present embodiment is a SUS304 wire having a diameter of 0.1 mm.
なお、サーミスタ薄膜４及び櫛歯部５ａ上には、これらを内部に封止する保護膜（図示略）が形成されている。この保護膜は、櫛歯部５ａ及びサーミスタ薄膜４を覆うように平面視略正方形状に形成されている。この保護膜は、例えば、厚さ１００〜１０００ｎｍのＳｉＯ2膜である。但し、これに限られず、絶縁性で外部雰囲気を遮断できれば、ガラスや耐熱樹脂等の膜でも構わない。 Note that a protective film (not shown) is formed on the thermistor thin film 4 and the comb teeth portion 5a to seal them inside. The protective film is formed in a substantially square shape in plan view so as to cover the comb tooth portion 5 a and the thermistor thin film 4. This protective film is, for example, a SiO 2 film having a thickness of 100 to 1000 nm. However, the present invention is not limited to this, and a film made of glass, heat-resistant resin, or the like may be used as long as it is insulating and can block the external atmosphere.
また、図４の（ｂ）に示すように、この薄膜温度センサ１は、リード線８の先端部分及びサーミスタ薄膜４を含んで表面全体が封止材９によって覆われている。この封止材９は、表面に滴下したセラミックスモールド材又はガラスペーストを焼成してモールドしたものである。 Further, as shown in FIG. 4B, the thin film temperature sensor 1 includes the tip portion of the lead wire 8 and the thermistor thin film 4, and the entire surface is covered with a sealing material 9. The sealing material 9 is obtained by firing and molding a ceramic mold material or glass paste dropped on the surface.
次に、このように構成された薄膜温度センサ１の製造方法について、図３及び図４を参照して説明する。 Next, a manufacturing method of the thin film temperature sensor 1 configured as described above will be described with reference to FIGS.
まず、図３の（ａ）に示すように、絶縁基板３のウエハＷ表面にサーミスタ薄膜４をパターン形成する薄膜形成工程を行う。即ち、絶縁基板３の全面に所定のスパッタ条件で上述した複合金属酸化物膜をスパッタリング法で成膜する。 First, as shown in FIG. 3A, a thin film forming step is performed for patterning the thermistor thin film 4 on the surface of the wafer W of the insulating substrate 3. That is, the above-described composite metal oxide film is formed by sputtering on the entire surface of the insulating substrate 3 under predetermined sputtering conditions.
続いて、フォトリソグラフィ技術により、複合金属酸化物膜の上面であってサーミスタ薄膜４を形成する領域にフォトレジスト膜をパターニングする。そして、フォトレジスト膜をマスクとして、所定の溶液を利用したウェットエッチング加工によりマスクされていない複合金属酸化物膜を選択的に除去する。そして、マスクとしていたフォトレジスト膜を除去する。これにより、絶縁基板３の上面に平面視略正方形状のサーミスタ薄膜４をパターン形成することができる。この後、耐熱性向上のため必要に応じて所定温度及び所定時間でアニール処理を行う。 Subsequently, a photoresist film is patterned on the upper surface of the composite metal oxide film on the region where the thermistor thin film 4 is formed by photolithography. Then, using the photoresist film as a mask, the unmasked composite metal oxide film is selectively removed by wet etching using a predetermined solution. Then, the photoresist film used as the mask is removed. Thereby, the thermistor thin film 4 having a substantially square shape in plan view can be patterned on the upper surface of the insulating substrate 3. Thereafter, annealing is performed at a predetermined temperature and for a predetermined time as necessary to improve heat resistance.
次いで、サーミスタ薄膜４の上面から絶縁基板３の上面に亘って、一対のＰｔ接合層５をパターン形成する接合層形成工程を行う。すなわち、まず、サーミスタ薄膜４の上面から絶縁基板３の上面に亘って、一対のＰｔ接合層５が形成される領域以外の部分にリフトオフ法により、フォトレジスト膜を塗布する。続いて、Ｐｔをスパッタリング法により成膜する。これにより、一対のＰｔ接合層５をパターン形成することができる。 Next, a bonding layer forming step of patterning a pair of Pt bonding layers 5 from the upper surface of the thermistor thin film 4 to the upper surface of the insulating substrate 3 is performed. That is, first, a photoresist film is applied to the portion other than the region where the pair of Pt bonding layers 5 are formed from the upper surface of the thermistor thin film 4 to the upper surface of the insulating substrate 3 by a lift-off method. Subsequently, Pt is formed by sputtering. As a result, the pair of Pt bonding layers 5 can be patterned.
続いて、Ｎｉめっき時の櫛歯部５ａ上への析出を防ぐために、めっき用レジスト１０（図中のハッチング領域）を施し、Ｐｔ接合層５の電極パッド部５ｂ上に、スルファミン酸Ｎｉめっき浴によりＮｉめっきを３０μｍ程度成膜し、Ｎｉめっき層６を形成する。この際又はこの後の大気中においてＮｉめっき層６の表面には、自然酸化膜としてＮｉ酸化膜７が形成される。なお、酸素含有の雰囲気中で熱処理を施してＮｉめっき層６の表面に熱酸化膜のＮｉ酸化膜７を形成しても構わない。なお、Ｎｉ酸化膜７は、４００℃１２０ｈで０．１μｍ以上に成膜されるが、初期の数時間で０．１μｍまで達した後、微増に推移する成膜傾向がある。この後、図３の（ｂ）に示すように、ダイシングを行ってチップ状に切り出す。 Subsequently, in order to prevent precipitation on the comb teeth portion 5a during Ni plating, a plating resist 10 (hatched region in the figure) is applied, and a sulfamic acid Ni plating bath is formed on the electrode pad portion 5b of the Pt bonding layer 5 Thus, Ni plating is formed to a thickness of about 30 μm, and the Ni plating layer 6 is formed. At this time or in the air thereafter, a Ni oxide film 7 is formed on the surface of the Ni plating layer 6 as a natural oxide film. Alternatively, a thermal oxide Ni oxide film 7 may be formed on the surface of the Ni plating layer 6 by performing a heat treatment in an oxygen-containing atmosphere. The Ni oxide film 7 is formed to a thickness of 0.1 μm or more at 400 ° C. for 120 hours. However, after reaching 0.1 μm in the initial few hours, the Ni oxide film 7 tends to increase slightly. Thereafter, as shown in FIG. 3B, dicing is performed to cut out into chips.
次に、図３の（ｃ）に示すように、平坦なＮｉめっき層６及びＮｉ酸化膜７上に配したリード線８の先端部分にレーザ溶接を行ってリード線８の先端部をＮｉめっき層６に溶接する。このとき、リード線８を、図２に示すように、Ｎｉ酸化膜７よりも深い溶け込み深さでＮｉめっき層６の途中まで溶接する。なお、本実施形態では、リード線８の溶接部分８ａが、１８μｍ程の溶け込み深さとなるように、レーザ溶接を制御している。 Next, as shown in FIG. 3C, laser welding is performed on the tip portion of the lead wire 8 disposed on the flat Ni plating layer 6 and the Ni oxide film 7, and the tip portion of the lead wire 8 is Ni-plated. Weld to layer 6. At this time, the lead wire 8 is welded to the middle of the Ni plating layer 6 at a penetration depth deeper than that of the Ni oxide film 7 as shown in FIG. In this embodiment, laser welding is controlled so that the welded portion 8a of the lead wire 8 has a penetration depth of about 18 μm.
また、図３の（ｃ）に示すように、レーザ溶接のレーザ光Ｌの照射位置を、リード線８の先端から若干離した位置に設定し、リード線８の溶接部分８ａを略球状に形成する。すなわち、レーザ光Ｌをリード線８の先端に照射すると、融液が線方向に逃げて肉盛りのない溶接部分となってしまうが、リード線８の先端から若干離した位置にレーザ光Ｌを照射することで、図４の（ａ）に示すように、レーザ光Ｌの照射位置からリード線８の先端までが液状化した融液が表面張力により線方向に移動して略球状になった状態で固化され、肉盛りのある溶接部分８ａとなる。なお、先端の略球状部分の容積は、レーザ光Ｌの照射位置（リード線８の先端からの距離）でコントロール可能であり、無駄な容積が存在せず、接合に最適な形状を得ることができる。 Further, as shown in FIG. 3C, the irradiation position of the laser beam L of laser welding is set to a position slightly separated from the tip of the lead wire 8, and the welded portion 8a of the lead wire 8 is formed in a substantially spherical shape. To do. That is, if the tip of the lead wire 8 is irradiated with the laser beam L, the melt escapes in the line direction and becomes a welded portion with no build-up, but the laser beam L is applied to a position slightly away from the tip of the lead wire 8. By irradiating, as shown in FIG. 4 (a), the liquefied melt from the irradiation position of the laser beam L to the tip of the lead wire 8 moved in the linear direction due to surface tension and became substantially spherical. It is solidified in a state and becomes a welded portion 8a with a build-up. Note that the volume of the substantially spherical portion at the tip can be controlled by the irradiation position of the laser beam L (distance from the tip of the lead wire 8), and there is no useless volume, and an optimum shape for joining can be obtained. it can.
この後、図４の（ａ）に示すように、めっき用レジスト１０を除去し、図４の（ｂ）に示すように、セラミックスモールド材又はガラスペーストを、リード線８の先端部を含む表面全体を覆うようにディスペンサーで表面に滴下、焼成し、封止材９としてモールドすることで、薄膜温度センサ１が作製される。 Thereafter, as shown in FIG. 4A, the plating resist 10 is removed, and as shown in FIG. 4B, a ceramic mold material or glass paste is applied to the surface including the tip of the lead wire 8. The thin film temperature sensor 1 is manufactured by dripping and baking on the surface with a dispenser so as to cover the whole, and molding as the sealing material 9.
このように本実施形態の薄膜温度センサ１及びその製造方法では、リード線８が、Ｎｉ酸化膜７よりも深い溶け込み深さでＮｉめっき層６の途中まで溶接されるので、Ｎｉめっき層６上を覆うＮｉ酸化膜７によって酸素の進行が防止されると共に、Ｎｉ酸化膜７よりも深く溶け込んでリード線８が溶接されるため、高い引っ張り強度を得ることができる。すなわち、耐熱試験時のＮｉの酸化による電気特性の変化や、センサの感熱部分のサーミスタ薄膜４に対する酸素のやりとりによる電気特性の変化が低減されると共に、溶接がＰｔ接合層５の途中までに制御されることで絶縁基板３との接合を受け持つＰｔ接合層５のダメージが少なく、高い接合強度が得られる。 As described above, in the thin film temperature sensor 1 and the manufacturing method thereof according to the present embodiment, the lead wire 8 is welded to the middle of the Ni plating layer 6 with a deeper penetration depth than the Ni oxide film 7. Since the progress of oxygen is prevented by the Ni oxide film 7 covering the lead wire 8 and the lead wire 8 is welded by being melted deeper than the Ni oxide film 7, high tensile strength can be obtained. That is, a change in electrical characteristics due to Ni oxidation during a heat resistance test and a change in electrical characteristics due to oxygen exchange with the thermistor thin film 4 in the heat sensitive part of the sensor are reduced, and welding is controlled halfway through the Pt bonding layer 5. As a result, damage to the Pt bonding layer 5 responsible for bonding to the insulating substrate 3 is small, and high bonding strength is obtained.
特に、厚く成膜することが容易なめっき法でＮｉめっき層６を厚く形成することで、溶接の溶け込み深さ制御も容易になると共に、Ｐｔ接合層５へのダメージをより低減することができる。
また、Ｐｔ接合層５は１μｍ以下と薄いため、引き出し電極としてＰｔと接合性の良いＮｉを生産性の高いめっき法で厚く成膜してＮｉめっき層６とすることで、より高い接合強度及び酸化防止効果を得ることができる。
In particular, by forming the Ni plating layer 6 thickly by a plating method that is easy to form a thick film, it is possible to easily control the penetration depth of welding and to further reduce damage to the Pt bonding layer 5. .
Further, since the Pt bonding layer 5 is as thin as 1 μm or less, Ni having a good bonding property with Pt as a lead electrode is formed thickly by a highly productive plating method to form the Ni plating layer 6, so that higher bonding strength and An antioxidant effect can be obtained.
また、リード線８がはんだやバンプ等を使用せずに溶接されるため、熱容量の増加を抑制でき、高い熱応答速度を維持することができる。
さらに、リード線８の溶接部分８ａが略球状に形成されるので、溶接面積が増えると共に引っ張り強度の異方性が減少し、接合強度がさらに向上する。なお、ＳＵＳ線であるリード線８とＮｉめっき層６とは、溶接性が良好であり、特に耐応力性が高くなる。
Moreover, since the lead wire 8 is welded without using solder, bumps, or the like, an increase in heat capacity can be suppressed, and a high thermal response speed can be maintained.
Furthermore, since the welded portion 8a of the lead wire 8 is formed in a substantially spherical shape, the weld area increases, the anisotropy of the tensile strength decreases, and the joint strength is further improved. Note that the lead wire 8 and the Ni plating layer 6 that are SUS wires have good weldability and particularly high stress resistance.
次に、本発明に係る薄膜温度センサを上記実施形態の製造方法で実際に製造した実施例を、図５から図７を参照して具体的に説明する。
上記実施形態の製造方法に基づいて作製し、リード線を溶接した薄膜温度センサの実施例について、２００℃での耐熱試験を行って抵抗値変化率を調べた結果を図５に示す。また、比較例として、Ｐｔ接合層まで形成したチップ品を作製し、同様に耐熱試験を行った結果も併せて図５に示す。
Next, an example in which the thin film temperature sensor according to the present invention is actually manufactured by the manufacturing method of the above embodiment will be specifically described with reference to FIGS.
FIG. 5 shows a result of examining the resistance value change rate by conducting a heat resistance test at 200 ° C. for an example of a thin film temperature sensor manufactured based on the manufacturing method of the above embodiment and welded with a lead wire. Further, as a comparative example, a chip product formed up to the Pt bonding layer is produced, and the result of the heat resistance test similarly is also shown in FIG.
この結果からわかるように、Ｐｔ接合層が露出している比較例に対して、本実施例は、抵抗値変化率が少ない。 As can be seen from this result, the resistance value change rate is smaller in this example than in the comparative example in which the Pt bonding layer is exposed.
また、上記実施例について、溶接部分の断面のＳＥＭ像（二次電子像）及びＣＯＭＰ像（反射電子組成像）による観察結果を、図６に示す。この結果から、リード線の溶接部分が、Ｎｉめっき層の表面から１７μｍ深く溶接されていることがわかる。
なお、図７に示すように、リード線の先端部は、溶接部分が球形状となった肉盛りのある構造であることがわかる。なお、溶接部分の下部は、図６に示すように、半球状にＮｉめっき層内に埋まっている。
Moreover, about the said Example, the observation result by the SEM image (secondary electron image) and COMP image (reflection electron composition image) of the cross section of a welding part is shown in FIG. From this result, it can be seen that the welded portion of the lead wire is welded 17 μm deep from the surface of the Ni plating layer.
In addition, as shown in FIG. 7, it turns out that the front-end | tip part of a lead wire is the structure with the buildup in which the welding part became spherical shape. The lower part of the welded portion is hemispherically embedded in the Ni plating layer as shown in FIG.
なお、本発明の技術範囲は上記実施形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲において種々の変更を加えることが可能である。 The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
例えば、上記実施形態では、アルミナ基板の絶縁基板を用いた場合を例にしたが、これに限られず、石英基板等の絶縁基板や、表面に熱酸化によるＳｉＯ2層の絶縁層が形成されたシリコン基板又はその他の半導体基板でも構わない。 For example, in the above embodiment, the case where an insulating substrate of an alumina substrate is used is taken as an example. However, the present invention is not limited to this, and an insulating substrate such as a quartz substrate or a SiO 2 insulating layer formed by thermal oxidation is formed on the surface. A silicon substrate or another semiconductor substrate may be used.
１…薄膜温度センサ、３…絶縁基板、４…サーミスタ薄膜、５…Ｐｔ接合層、６…Ｎｉめっき層、７…Ｎｉ酸化膜、８…リード線、８ａ…リード線の溶接部分、Ｌ…レーザ光 DESCRIPTION OF SYMBOLS 1 ... Thin film temperature sensor, 3 ... Insulating substrate, 4 ... Thermistor thin film, 5 ... Pt joining layer, 6 ... Ni plating layer, 7 ... Ni oxide film, 8 ... Lead wire, 8a ... Welded part of lead wire, L ... Laser light
Claims (4)
前記絶縁層又は前記絶縁基板の上面にパターン形成されたサーミスタ薄膜と、
前記絶縁層又は前記絶縁基板の上面から前記サーミスタ薄膜の上面に亘ってＰｔでパターン形成されたＰｔ接合層と、
該Ｐｔ接合層上にＮｉで形成されたＮｉめっき層と、
該Ｎｉめっき層の表面に形成されたＮｉ酸化膜と、
前記Ｎｉめっき層に接続されたリード線と、を備え、
前記リード線が、前記Ｎｉ酸化膜よりも深い溶け込み深さで前記Ｎｉめっき層の途中まで溶接されていることを特徴とする薄膜温度センサ。 A substrate with an insulating layer formed on the surface or an insulating substrate;
A thermistor thin film patterned on the top surface of the insulating layer or the insulating substrate;
A Pt bonding layer patterned with Pt from the upper surface of the insulating layer or the insulating substrate to the upper surface of the thermistor thin film;
A Ni plating layer formed of Ni on the Pt bonding layer;
A Ni oxide film formed on the surface of the Ni plating layer;
A lead wire connected to the Ni plating layer,
The thin film temperature sensor, wherein the lead wire is welded to the middle of the Ni plating layer with a deeper penetration depth than the Ni oxide film.
前記リード線の溶接部分が、略球状に形成されていることを特徴とする薄膜温度センサ。 The thin film temperature sensor according to claim 1,
A thin film temperature sensor, wherein a welded portion of the lead wire is formed in a substantially spherical shape.
前記絶縁層又は前記絶縁基板の上面から前記サーミスタ薄膜の上面に亘って、ＰｔによりＰｔ接合層をパターン形成する接合層形成工程と、
前記Ｐｔ接合層上にＮｉめっきによりＮｉめっき層を形成すると共に該Ｎｉめっき層の表面にＮｉ酸化膜を形成する電極形成工程と、
前記Ｎｉめっき層上にリード線をレーザ溶接するリード線溶接工程と、を備え、
前記リード線を、前記Ｎｉ酸化膜よりも深い溶け込み深さで前記Ｎｉめっき層の途中まで溶接することを特徴とする薄膜温度センサの製造方法。 A thin film forming step of patterning a thermistor thin film on the insulating layer on the substrate or the upper surface of the insulating substrate;
A bonding layer forming step of patterning a Pt bonding layer with Pt from the upper surface of the insulating layer or the insulating substrate to the upper surface of the thermistor thin film;
Forming an Ni plating layer on the Pt bonding layer by Ni plating and forming an Ni oxide film on the surface of the Ni plating layer; and
A lead wire welding step of laser welding a lead wire on the Ni plating layer,
A method of manufacturing a thin film temperature sensor, wherein the lead wire is welded to the middle of the Ni plating layer with a deeper penetration depth than the Ni oxide film.
前記レーザ溶接のレーザ光の照射位置を、前記リード線の先端から離した位置に設定し、前記リード線の溶接部分を略球状に形成することを特徴とする薄膜温度センサの製造方法。 In the manufacturing method of the thin film temperature sensor according to claim 3,
A method of manufacturing a thin film temperature sensor, wherein an irradiation position of the laser beam of the laser welding is set at a position separated from a tip of the lead wire, and a weld portion of the lead wire is formed in a substantially spherical shape.
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| KR20190059910A (en) | 2016-10-07 | 2019-05-31 | 세미텍 가부시키가이샤 | Welding electronic components, mounting board and temperature sensor |
| JP6392487B2 (en) * | 2016-10-07 | 2018-09-19 | Ｓｅｍｉｔｅｃ株式会社 | Welding electronic components, mounting board and temperature sensor |
| US11215514B2 (en) | 2016-10-07 | 2022-01-04 | Semitec Corporation | Electronic component for welding, mounted board and temperature sensor |
| WO2018203475A1 (en) * | 2017-05-01 | 2018-11-08 | Ｓｅｍｉｔｅｃ株式会社 | Temperature sensor and device equipped with temperature sensor |
| JP6502588B2 (en) * | 2017-05-01 | 2019-04-17 | Ｓｅｍｉｔｅｃ株式会社 | Device equipped with temperature sensor and temperature sensor |
| JPWO2018203475A1 (en) * | 2017-05-01 | 2019-06-27 | Ｓｅｍｉｔｅｃ株式会社 | Device equipped with temperature sensor and temperature sensor |
| US11460353B2 (en) | 2017-05-01 | 2022-10-04 | Semitec Corporation | Temperature sensor and device equipped with temperature sensor |
| CN115036086A (en) * | 2018-10-31 | 2022-09-09 | 株式会社芝浦电子 | Thermistor sintered compact and temperature sensor element |
| WO2022145083A1 (en) * | 2020-02-19 | 2022-07-07 | 三菱マテリアル株式会社 | Temperature sensor and method for manufacturing same |
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