JP2005351856A - Heat flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To lessen the dispersion by dispensing with an adhesive extrusion measure process for substrate alignment and substrate, and enhancing the output of a heat flowmeter. <P>SOLUTION: The heat flowmeter is sealed by using an insulation resin, in a shape incorporating an electric coupling line part after electrically connecting, adhering and fixing a signal removing read out electrode provided previously on a holding substrate and a thermocouple pattern end pad. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat flow meter for measuring a temperature difference between a high temperature object and a low temperature object at a thermocouple contact of a serial connection thermocouple pattern formed on an insulating sheet and deriving a heat flow. .

  The heat flow meter is installed between a high temperature object and a low temperature object, measures a temperature difference between the high temperature object and the low temperature object with a thermocouple provided inside the heat flow meter, and derives a heat flow. Thermocouples are connected in series, and a thermocouple pattern in which a contact for high temperature object temperature measurement and a contact for low temperature object temperature measurement are formed on one side of the insulating sheet. A voltage obtained by multiplying the temperature difference generated between the high temperature object temperature measurement contact and the low temperature object temperature measurement contact by the thermocouple electromotive force and the number of thermocouples becomes the heat flow meter output.

  In a conventional heat flow meter, a serial connection thermocouple pattern is formed on an insulating sheet, and the insulating sheet is sandwiched between the substrates and bonded, and then bonded and fixed on a holding substrate provided with a signal extraction electrode in advance. For the thermocouple pattern, a semiconductor process method is used. For example, a fine pattern of 0.05 mm per thermocouple is formed.

  For example, polycarbonate having a thickness of 1 mm is used as the substrate sandwiching the insulating sheet, and the substrate is bonded to the insulating sheet with an epoxy adhesive having a thickness of 0.05 mm, for example. As the insulating sheet, for example, soda lime glass having a thickness of 0.3 mm is used. After a large number of thermocouple patterns are formed on the insulating sheet, the substrate is sandwiched and bonded with a substrate such as a dicing saw. A procedure of cutting into a predetermined dimension such as millimeter height 1 millimeter is adopted.

Assuming that the holding substrate is attached to a curved object, for example, a flexible substrate made of polyimide material is used. The signal extraction electrode provided in advance on the holding substrate and the thermocouple pattern end pad on the insulating sheet sandwiched between substrates such as polycarbonate are connected with, for example, an epoxy-based conductive adhesive. In order to facilitate this conductive adhesive connection, a cut-off portion is provided in advance at the position of the thermocouple pattern end of the substrate bonded to the thermocouple pattern, and the thermocouple on the insulating sheet is provided. For example, a 0.35 mm square pad is provided at the end of the pair. That is, on a 3.5 mm long and 1 mm long insulating sheet, for example, 50 patterns of 0.05 mm per thermocouple and two pads of 0.35 mm square are provided.

  Further, in order to prevent a short circuit due to exposure of the conductive adhesive connecting portion, an insulating coating having a thickness of, for example, 0.05 mm is applied on the same portion. The insulating coating is also applied to all objects located on the holding substrate, that is, the substrate / insulating sheet bonded to the holding substrate in order to ensure an electrically insulating state. Therefore, a bonded product having a length of 3.5 mm and a height of 1.05 mm including the coating thickness is positioned on the holding substrate such as a flexible substrate.

FIG. 9 is a perspective view showing a conventional heat flow meter, and FIG. 10 is a structural perspective view.

Japanese Patent Application No. 2004-21849

In the prior art, when the insulating sheet provided with the thermocouple pattern and the substrate opposite to the thermocouple pattern is bonded, it is necessary to bond the cut-off portion provided in advance and the thermocouple pattern end pad after alignment. Sex was low. In addition, an adhesive release agent or the like is applied on the thermocouple pattern end pad in advance so that the adhesive does not protrude from the thermocouple pattern end pad and prevent electrical connection. A process procedure for removing the mold and the like is necessary, and the process is complicated.
Furthermore, in consideration of the alignment accuracy between the cut-off portion provided in advance on the substrate facing the thermocouple pattern and the thermocouple pattern end pad and the adhesive protruding to the thermocouple pattern end pad, the thermocouple pattern end It was necessary to set the pad size to a large size, the number of thermocouple patterns formed on the insulating sheet was small, and as a result, the heat flow meter output was low.
Furthermore, since the conductive adhesive used for electrical connection with the holding substrate signal extraction electrode is a good heat conductive material, for example, when the holding substrate is located on the high temperature object side, the conductive adhesive application position / application Due to the amount difference, the amount of heat transferred from the holding substrate to the insulating sheet provided with the thermocouple pattern was different in each heat flow meter. Even when the holding substrate was positioned on the low temperature object side, the heat transfer direction was only reversed, and the amount of heat transferred was different for each heat flow meter. Due to this calorific value difference, the temperature difference between the high temperature object temperature measurement contact and the low temperature object temperature measurement contact varies, resulting in variations in the output of each heat flow meter, resulting in poor product stability.

The signal extraction electrode provided on the holding substrate and the thermocouple pattern end pad on the insulating sheet are electrically connected and bonded and fixed, and then the signal extraction electrode on the holding substrate and the thermocouple pattern end on the insulating sheet are fixed. Wire bonding is used for the electrical connection between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad on the insulating sheet that is sealed with an insulating resin in a shape that incorporates the electrical connection with the pad. .
Alternatively, a bump formed by vapor deposition or plating technique in which the electrical connection is provided on the thermocouple pattern end pad or a bump formed by a wire bumping method is melt-welded.
Alternatively, the electrical connection is performed by forming the signal extraction electrode on the holding substrate with a hard metal having sharp irregularities, and forming the thermocouple pattern end pad on the insulating sheet with a soft metal, and pressing the two together. .

According to the present invention, the step of sandwiching and bonding the insulating sheet between the substrates is reduced, so that the alignment operation between the cut-off portion provided in advance on the substrate and the thermocouple pattern end pad, and further, the thermocouple pattern end pad After the adhesive release agent or the like is previously applied on the adhesive, and then cured by adhesion, an adhesive protrusion work for removing the adhesive release agent or the like becomes unnecessary. Also, the conventional insulating coating on the electrical connection portion between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad is sealed with an insulating resin, so that no work is required. .
The thermocouple pattern end pad dimensions are determined by taking into account the precision of aligning the cut-off part provided on the substrate opposite the thermocouple pattern and the thermocouple pattern end pad and the adhesive protruding from the thermocouple pattern end pad. Therefore, even if the chip size is the same as the conventional chip size, the number of thermocouple patterns formed on the insulating sheet is increased, and as a result, the heat flow meter output is increased.
The thermocouple pattern end pad size is reduced, and the amount of heat transferred to the insulating sheet provided with the thermocouple pattern is reduced. In addition, since the heat transfer path between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad is controlled with high accuracy, the temperature difference variation between the high temperature object temperature measurement contact and the low temperature object temperature measurement contact becomes small. As a result, the output variation of each heat flow meter becomes small, and the product stability is improved.

A plurality of serially connected thermocouple patterns having pads at the end portions are formed on the insulating sheet, and then cut into a predetermined size with a dicing saw or the like. The thermocouple pattern end pad of the cut-out insulating sheet and the signal extraction electrode provided in advance on the holding substrate are electrically connected. Then, it seals using insulating resin in the shape which incorporates an electrical connection part.
The electrical connection between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad on the insulating sheet is wire bonding with a gold wire or the like.
Alternatively, the electrical connection is carried out by providing bumps formed by vapor deposition of solder or the like or plating bumps on the thermocouple pattern end pads, or bumps formed by a wire bumping method, and melt welding.
Alternatively, the signal connection electrode on the holding substrate is formed of a hard metal such as stainless steel having sharp irregularities, and the thermocouple pattern end pad on the insulating sheet is formed of a soft metal such as gold. We carry out pressure welding of both.

  Examples of the present invention will be described below.

  As an example of the insulating sheet, a plurality of thermocouple patterns connected in series having thermocouple patterns and pads at the ends are formed on soda lime glass having a thickness of 0.3 mm. For the thermocouple, for example, two materials such as nichrome on one side and bismuth antimony on the other are used. The thermocouple pattern uses a semiconductor process method such as film formation, exposure, and etching. For example, a fine pattern of 0.05 mm is formed per thermocouple. The thermocouple pattern end pad dimensions take into consideration the alignment accuracy between the cut-off portion provided on the substrate facing the thermocouple pattern and the thermocouple pattern end pad, and the protrusion of the adhesive to the thermocouple pattern end pad. Since it is not necessary, it is formed with, for example, a 0.1 millimeter square or a diameter of 0.1 millimeter.

  After forming the thermocouple pattern, it is cut into chips of a predetermined size with a dicing saw or the like. In the case of 3.5 mm high and 1 mm long with the same dimensions as the prior art, there is a space margin of 0.5 mm for the two pads together. The heat flow meter output which is a voltage obtained by multiplying the temperature difference generated between the high temperature object temperature measurement contact and the low temperature object temperature measurement contact by the thermocouple electromotive force and the number of thermocouples is 1.2 times.

  A thermocouple pattern end pad of the cut-out chip is electrically connected to a signal extraction electrode provided in advance on a holding substrate such as a flexible substrate made of polyimide, for example. After that, in the shape that incorporates the electrical connection part between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad on the insulating sheet, a die made of silicon rubber or the like with an insulating resin such as an epoxy adhesive is used. Use to seal. In order to completely seal the insulating sheet on which the thermocouple pattern is formed, the height of the sealing portion is higher than the height of the insulating sheet of 1 mm, but this thickness is, for example, 0.05 mm and the conventional total thickness is used. The same thickness as 1.05 millimeters.

As an example of electrical connection, after a cut chip is fixed on a holding substrate such as a flexible substrate using a die bonder, a 0.1 mm square thermocouple pattern end pad and a flexible substrate such as a flexible substrate are formed on the chip. The signal extraction electrode is wire-bonded using a wire bonder with a gold wire having a diameter of 0.025 mm. Gold or the like is selected as the surface material of the signal extraction electrode on the holding substrate, and aluminum or the like is selected as the surface material of the thermocouple pattern end pad on the chip.
For example, if the holding substrate is located on the high-temperature object side, the wire length and bonding ball position, etc., serving as a heat transfer path from the signal extraction electrode of the holding substrate to the thermocouple pattern end pad are controlled with high accuracy by the wire bonder. The FIG. 1 is a perspective view showing a heat flow meter according to an embodiment of the present invention when wire bonding is used, and FIG. 2 is a structural perspective view thereof.

As another example of the electrical connection, bumps having a diameter of 0.1 mm and a height of 0.07 mm are provided on a thermocouple pattern end pad formed on the chip, for example, with a 0.1 mm square. The bumps are easily formed with high accuracy by bumps formed by vapor deposition or plating techniques, or by wire bumping. The bumps on the chip are placed at positions facing the signal extraction electrodes on the holding substrate such as a flexible substrate, and heated while applying a certain pressure to melt and press the bumps. In the case of a solder bump, gold, copper, solder plating or the like is used for the signal extraction electrode on the holding substrate. In the case of gold bumps, solder plating or the like is used for signal extraction electrodes on the holding substrate.
For example, if the holding substrate is located on the high-temperature object side, the bump position and shape after melting, which becomes the heat transfer path from the signal extraction electrode of the holding substrate to the thermocouple pattern end pad, is highly accurate depending on the bump application pressure and temperature. Controlled. FIG. 3 is a perspective view showing a heat flow meter according to an embodiment of the present invention when wiring is made using bumps, and FIG. 4 is a structural perspective view thereof. FIG. 5 shows the bump connection part.

As another embodiment of the electrical connection, the material of the end pad of the thermocouple pattern formed with 0.1 mm square on the chip is made of a soft metal such as gold or indium. A signal extraction electrode on a holding substrate such as a flexible substrate is formed of a hard metal such as stainless steel or tungsten having sharp irregularities. When the thermocouple pattern end pad on the chip is placed at a position facing the signal extraction electrode on the holding substrate such as a flexible substrate, when sharp pressure is applied to the hard metal such as stainless steel and tungsten, soft metal such as gold and indium The electrical connection is obtained by pressure welding. Further, the chip is fixed using an insulating resin such as an epoxy-based adhesive in the pressure contact state.
For example, if the holding substrate is located on the high temperature object side, the heat transfer path from the signal extraction electrode on the holding substrate to the thermocouple pattern end pad is the signal extraction electrode itself with sharp irregularities, and the dimensions and The position is controlled with high accuracy. FIG. 6 is a perspective view showing a heat flow meter according to an embodiment of the present invention when a hard metal having sharp irregularities is used for connection, and FIG. 7 is a structural perspective view thereof. FIG. 8 shows a connection portion using a hard metal having sharp irregularities.

  In all the above three embodiments, the thermocouple pattern edge pad size of 0.35 mm square of the prior art is 0.1 mm square, which is an area of 1/10 or less. The amount of heat transferred to the insulating sheet provided with the pattern is reduced. Furthermore, when the holding substrate is located on the high temperature object side as described above, the heat transfer path from the signal extraction electrode of the holding substrate to the thermocouple pattern end pad is controlled with high accuracy in all three embodiments. The amount of heat variation, which is the cause of meter output variation, is also reduced.

It is a perspective view which shows the heat flow meter of the Example of this invention which carried out wire bonding connection and resin-sealed. It is a structure perspective view of the heat flow meter of the present invention example wire-bonded and resin-sealed. It is a perspective view which shows the heat flow meter of the Example of this invention which connected by bump and was resin-sealed. It is a structure perspective view of the heat flow meter of the example of the present invention connected with a bump and resin-sealed. It is a bump connection part structure conceptual diagram. It is a perspective view which shows the heat flow meter of the Example of this invention which pressed the hard metal which has sharp unevenness | corrugation to the soft metal, was connected, and was resin-sealed. 1 is a structural perspective view of a heat flow meter of an embodiment of the present invention in which a hard metal having sharp irregularities is pressed against a soft metal, connected, and resin-sealed. It is a structure conceptual diagram of the part which pressed and connected the hard metal which has sharp unevenness to the soft metal. It is a perspective view of the heat flow meter of a prior art. It is a structure perspective view of the heat flow meter of a prior art.

Explanation of symbols

1 Insulating Sheet 2 Thermocouple Pattern 3 Thermocouple Pattern End Pad 4 Bonding Wire 5 Insulating Resin 6 Holding Substrate 7 Holding Substrate Signal Extraction Electrode 8 Holding Substrate Pattern 9 Bump Melting Pressure Weld 10 Bump 11 Hard metal electrode 12 Soft metal electrode 13 Substrate 14 Adhesive 15 Cut-off portion 16 Insulating coating layer 17 Conductive adhesive

Claims (4)

  A thermocouple pattern in which a thermocouple is connected in series to form a high temperature object temperature measurement contact and a low temperature object temperature measurement contact is formed on an insulating sheet and adhered and held on a holding substrate. After electrically connecting and fixing the signal extraction electrode provided and the thermocouple pattern end pad on the insulating sheet, the electrical connection between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad on the insulating sheet A heat flow meter characterized by sealing with an insulating resin in a shape having a built-in connection portion.   The heat flow meter according to claim 1, wherein the electrical connection between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad on the insulating sheet is wire bonding.   The electrical connection between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad on the insulating sheet is formed by a bump or wire bumping method formed by vapor deposition or plating technology provided on the thermocouple pattern end pad. The heat flow meter according to claim 1, wherein the bumps are subjected to melt pressure welding.   An electrical connection between the signal extraction electrode on the holding substrate and the thermocouple pattern end pad on the insulating sheet is formed by a hard metal having sharp irregularities on the insulating substrate, and the signal extraction electrode on the holding substrate is formed on the insulating sheet. 2. The heat flow meter according to claim 1, wherein the thermocouple pattern end pad is made of a soft metal, and the two are pressed together.

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