JP2008241566A - Thin-film temperature sensor, and outgoing line connection method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the connection strength between an electrode for composing a thin-film temperature sensor and a leader line. <P>SOLUTION: The thin-film temperature sensor 1 comprises: an insulating substrate 11; a heat-sensitive film 12 formed on one surface of the insulating substrate 11; a pair of electrode films 13 connected to the heat-sensitive film 12 electrically; a bump 14 formed on the pair of electrode films; and the leader line 15 connected to the bump electrically. The bump 14 is formed by a well known wire bump technique. The size of the bump is made larger than the diameter of the leader line 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thin film temperature sensor used for temperature detection or temperature compensation of various electronic devices and parts used in the consumer and industrial fields.

  2. Description of the Related Art Conventionally, a sensor chip used for a heat sensitive part of a temperature sensor is a thermistor chip obtained by sintering a powder compact of a metal oxide such as manganese, cobalt, or nickel. The temperature sensor using the thermistor chip has a structure in which electrodes are formed on the front and back surfaces of the chip, and a lead wire is attached to the electrode surface by soldering or the like. The temperature sensor having such a structure can be used as a temperature sensor having excellent thermal responsiveness by reducing the shape of the thermistor chip.

  However, since the thermistor chip made of a sintered metal oxide produced as described above has a limit in reducing the shape and size, a thin film temperature sensor using a thin film formation technology has been developed and put into practical use. It became so. This thin film temperature sensor is a temperature sensor that is excellent in thermal response because it has a smaller heat capacity than a chip made of a sintered metal oxide. In this thin film temperature sensor, as shown in FIG. 4A, after a heat sensitive film 42 and an electrode 43 are formed on an insulating substrate 41 by a sputtering method or the like, a lead wire 44 is formed on the surface of the electrode 43 formed on one surface. After the heat-sensitive film 42 and the electrode 43 are formed on the insulating substrate 41 by a sputtering method or the like as shown in FIG. Some lead wires 44 are electrically connected to the electrode 43 surface by laser welding.

  In the conventional thin film temperature sensor having the structure as shown in FIG. 4A, when the electrode 43 and the lead wire 44 are connected, the electrode 43 and the lead wire 44 are positioned so that the lead wire 44 contacts the surface of the electrode 43, and the bonding material 45. Apply and fix so as to wrap around it. However, since the lead wire 44 is thin and has a diameter of about 100 μm, the lead wire 44 may be bent in the assembly process or in a poor storage condition. there were.

  Further, when the lead wire 44 is connected to the surface of the electrode 43 of the thin film temperature sensor, the surface of the electrode 43 is very small, so that the bonding material 45 cannot be applied with high positional accuracy, and the amount of application of the bonding material varies. In some cases, poor electrical continuity or short-circuiting may occur due to poor bonding due to the cause.

  Furthermore, in recent years, the dimensions of sensor chips forming thin film thermistors have become increasingly smaller, and recently, a chip having a size of 0.6 mm × 0.3 mm has appeared, and there is a trend toward further miniaturization in the future. Along with this, as shown in FIG. 6B, a method of electrically connecting a leader line to the electrode surface by laser welding is also performed, but the laser beam is mechanically applied to the electrode or the insulating substrate. Even if the electrode and the lead wire are electrically and mechanically connected, the insulating substrate is mechanically damaged, and when the lead wire is pulled, it breaks from the insulating substrate and obtains sufficient tensile strength. Sometimes it was not possible.

  In addition, the connection between the electrode surface and the leader line by laser welding must be performed by accurately positioning the leader line to the electrode and irradiating the laser, and as with the former method, the leader line is arranged on the electrode face with high positional accuracy. It was a problem.

  In view of the above problems, the present invention maintains a connection strength between the lead wire and the electrode, and can easily connect without requiring so severe positional accuracy, and a problem of a lead wire connection method of the thin film temperature sensor Is to eliminate.

  A thin film temperature sensor according to a first invention includes an insulating substrate, a heat sensitive film formed on one surface of the insulating substrate, a pair of electrode films electrically connected to the heat sensitive film, and the pair of electrode films. A thin-film temperature sensor comprising a bump formed on the lead wire and a lead line electrically connected to the bump.

  The thin film temperature sensor according to a second aspect of the present invention is the thin film temperature sensor according to the first aspect of the present invention, wherein the bump is formed by a wire bump.

  A thin film temperature sensor according to a third aspect of the present invention is formed on a thermal film formed on one surface of an insulating substrate, a pair of electrode films electrically connected to the thermal film, and the electrode film. In the thin film temperature sensor composed of a bump and a lead wire electrically connected to the bump, the lead wire is placed on the bump, and the lead wire is connected to the bump by means of laser welding. The present invention relates to a lead wire connecting method for a thin film temperature sensor.

  The thin film temperature sensor of the present invention is formed on an insulating substrate, a heat sensitive film formed on one surface of the insulating substrate, a pair of electrode films electrically connected to the heat sensitive film, and the pair of electrode films. Since the bump and the lead wire electrically connected to the bump are configured, the bump and the lead wire are electrically and mechanically connected to improve the tensile strength. Moreover, since the thin film temperature sensor of this invention forms a bump larger than the diameter of a leader line in an electrode, the connection area with an electrode surface is expanded and tensile strength improves. Moreover, since the thin film temperature sensor of the present invention forms bumps larger than the diameter of the lead wire on the electrode, laser welding can be easily performed without requiring strict lead wire position accuracy as in the prior art. Moreover, the thin film temperature sensor of this invention can improve heat resistance rather than the connection by soldering a conventional electrode and a leader line by laser-welding a bump and a leader line. In addition, since the thin film temperature sensor of the present invention can electrically and mechanically connect the bump and the lead wire, conventionally, the electrode and the insulating substrate can be improved from being mechanically damaged by the laser, and the tension can be improved. Strength can be improved.

  Examples of the present invention will be described below. FIG. 1 is a perspective view of a thin film temperature sensor of the present invention, and FIGS. As shown in FIG. 1, a thin film temperature sensor 1 of the present invention includes a heat sensitive film 12 formed on an insulating substrate 11 and a pair of sensors that detect a change in ambient temperature and take out a resistance change of the heat sensitive film 12 as a signal. The electrode film 13 is composed of a bump 14 formed on the surface of the electrode film, and a lead wire 15 electrically connected to the bump.

  Here, the insulating substrate 11 is made of a material having excellent heat resistance and electrical insulation, such as alumina, sapphire, zirconia, and aluminum nitride. In consideration of thermal conductivity and mechanical strength, the thickness of the substrate is preferably about 150 μm to 400 μm for an alumina substrate, for example. The heat sensitive film 12 is a thin film thermistor film formed on the insulating substrate 11 by a known sputtering method using a target made of a mixture of metal oxides such as manganese, nickel, copper, cobalt and iron. The electrode film 13 is formed of a single layer or a combination of the above metals on the insulating substrate 11 by a known sputtering method using a target made of a metal such as platinum, nickel, gold, or silver. The bump 14 is made of gold, copper, nickel or the like. Further, as a material used for the lead wire 15, a jumet wire, a copper-clad steel wire (CP wire), a nickel-plated wire or the like having a wire diameter of about 100 μm is suitable.

  Next, the assembly process of the thin film temperature sensor of the present invention will be described with reference to FIGS.

  FIG. 2A is a view showing a part of a substrate in which a thin film thermistor made up of a large number of heat-sensitive films 12 and electrode films 13 is formed in an array on the alumina substrate 11, and FIG. FIG. 2 is a perspective view of a thin film sensor chip in which bumps are formed by cutting each chip.

  First, as shown in FIG. 2A, using an alumina substrate 11 having a thickness of about 250 μm, a heat sensitive film 12 made of a thin film thermistor film and a resistance change of the heat sensitive film 12 are extracted by a known sputtering method or the like. An electrode film 13 as a terminal is formed. As described above, the thermosensitive film 12 is a thermistor film 12 made of a metal oxide, and the electrode film 13 is, for example, a platinum thin film or a laminated film in which a gold thin film is laminated on a platinum thin film. Used. An example of the configuration of the heat sensitive film 12 and the electrode film 13 is disclosed in Japanese Patent Application Laid-Open No. 6-61012 filed previously by the present applicant.

  Next, as shown in FIG. 2B, a wire bump is formed on the electrode film 13 using a gold wire. The bump is formed by a known wire bump technique. The size of the bump is made larger than the diameter of the leader line of 100 μm. By enlarging the bump, laser welding can be performed as long as the leader line is placed on the bump even if the position where the leader line is set is slightly shifted. Next, in order to obtain individual thin film sensor chips, the substrate 11 is cut by a dicing apparatus or the like as shown by the dotted lines in FIG. As shown in FIG. 2 (c), in this example, each was cut to a size of about 0.6 mm × 0.3 mm.

  Next, as shown in FIGS. 3A and 3B, a leader line 15 made of a jumet line having a diameter of about 100 μm is placed on the bump. Next, using a laser welding machine, the laser beam 21 is irradiated onto the lead wire 15 placed on the bump 14, and the lead wire 15 and the bump 14 are connected to complete the thin film temperature sensor 1.

  The tensile strength of the thin film temperature sensor completed by the above manufacturing method is to maintain an average strength of 150 grams as compared with the average thin film temperature sensor having the structure of FIG. I was able to.

  Although not shown, an exterior material such as glass covering the heat-sensitive film and the lead wire may be coated on the heat-sensitive film 12 and the lead wire 15 in order to improve the weather resistance. As a method of covering the heat sensitive film 12 and the lead wire 15 with glass, there is a method of applying paste-like glass on the heat sensitive film 12 and the lead wire 15 with a dispenser or the like and baking at high temperature. In addition, when the thin film temperature sensor 1 of the present invention is intended to be used in an environment of about 100 degrees, glass is not used as a covering material for the heat sensitive film 12 and the lead wire 15 but a resin material such as epoxy. May be used.

  In the present embodiment, although not shown, an example using a dumet wire as the lead wire 14 has been disclosed. A lead frame formed into a desired shape may be used, and a lead frame lead wire having a surface plated with gold, silver, nickel or the like may be used.

  INDUSTRIAL APPLICABILITY The present invention can be used for a thin film temperature sensor used for temperature detection or temperature compensation of various electronic devices and parts regardless of consumer or industrial fields.

It is a perspective view of the thin film temperature sensor of this invention. It is an assembly drawing of the thin film temperature sensor of this invention. It is an assembly drawing of the thin film temperature sensor of this invention. It is a perspective view of the conventional thin film temperature sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin film temperature sensor 11 Insulating substrate 12 Thermal film 13 Electrode film 14 Bump 15 Leader 21 Laser beam

Claims (3)

  An insulating substrate; a thermal film formed on one surface of the insulating substrate; a pair of electrode films electrically connected to the thermal film; a bump formed on the pair of electrode films; A thin-film temperature sensor comprising an electrically connected lead wire.   The thin film temperature sensor according to claim 1, wherein the bump is formed of a wire bump.   A heat-sensitive film formed on one surface of the insulating substrate, a pair of electrode films electrically connected to the heat-sensitive film, a bump formed on the electrode film, and a drawer electrically connected to the bump A thin film temperature sensor comprising a wire, wherein the lead wire is placed on the bump, and the lead wire is connected to the bump by means of laser welding. .

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