JP2004226575A - Wiring board, electronic equipment, and led display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heat to raise the temperature of a desired electronic circuit component which needs to be heated when low in temperature up to within a recommended operation temperature range selectively in a short time with high heating efficiency. <P>SOLUTION: A heating body 3 and a heat-sensitive switch means 4 are mounted on a substrate 1 on the surface where the electronic circuit component 2 is mounted. The heating body 3 is arranged in contact with a GND line 6 for the electronic circuit component 2 and efficiently heats the electronic circuit component 2 through the GND line 6 up to a specified operating temperature range. The heat-sensitive switch means 4 supplies electric power to the heating body 3 when the temperature in a heat insulating cover 5 falls below specified temperature to generate heat and cuts off the electric power to the heating body 3 when the temperature in the heat insulating cover 5 rises above the specified temperature to keep the electronic circuit component 2 within the desire recommended operating temperature range. The electronic circuit component 2 which needs to be heated, the heating body 3, and a heat switch 4 are covered with the heat insulating cover 5 and no heat is conducted to the circumference of the heat insulating cover 5 to improve the heating efficiency. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring board capable of controlling the temperature of an electronic circuit component mounted on an insulating substrate, an electronic device using the wiring board, and an LED display.
[0002]
[Prior art]
Normally, a recommended operating temperature range is determined for electronic circuit components such as semiconductor devices as a temperature range suitable for use. The reason why such a recommended operating temperature range is set is that normal operation cannot be performed at a low temperature such as 0 ° C. or less. In particular, electronic circuit components such as high-performance programmable logic devices (PLDs) used as display control ICs in LED displays, for example, cannot operate normally at low temperatures outside the recommended operating temperature range.
[0003]
For this reason, in an electronic device using a high-performance PLD or the like, in a cold region where the temperature is 0 degrees Celsius or less, for example, individual electronic circuit components are placed in a special state at a temperature of 0 degrees Celsius or less. Either the operation is confirmed and only the one that normally operates is selected, or a heater is provided inside an electronic device in which a printed wiring board on which electronic circuit components are mounted is incorporated, and heating is performed by the heater.
[0004]
However, as described above, when confirming the operation of each semiconductor device, it is necessary to confirm the operation in a special state for a cold region, and prepare a semiconductor device suitable for it, and the There is a problem that it becomes expensive.
[0005]
In addition, when a heater is provided inside an electronic device to heat the electronic device, even if only electronic circuit components that need to be heated at a low temperature are part of the electronic device, the inside of the electronic device may be heated. There is a problem that the power efficiency becomes extremely poor because of the overall heating. Further, there is a problem that it takes time until the atmosphere around the electronic circuit components in the electronic device reaches a predetermined temperature.
[0006]
For this reason, Patent Document 1 (Japanese Patent Application Laid-Open No. 2000-188171) proposes a temperature control device for electronic circuit components. In this temperature control device, copper patterns are formed on the electronic circuit component mounting surface (front surface side) and the opposite surface (rear surface side) of the printed wiring board, respectively. Connected electrically. A power transistor that heats the copper pattern by heat loss and a thermal switch that performs a switching operation by detecting that the temperature has fallen below a predetermined temperature are mounted on the copper pattern on the back side. With this temperature control device, when the temperature becomes equal to or lower than the predetermined temperature, the thermal switch is operated to turn on the power transistor, and the power transistor generates heat by the heat loss. This heat is conducted from the copper pattern on the back side to the copper pattern on the front side via the through holes. Therefore, only the desired electronic circuit component can be selectively and efficiently heated by the copper pattern provided immediately below the lead of the electronic circuit component. As a result, the power efficiency is higher than in the above-described conventional configuration, and the temperature can be raised more quickly to a predetermined temperature within the recommended operating temperature range.
[0007]
[Patent Document 1]
JP 2000-188171 A
[Problems to be solved by the invention]
In the above-described conventional temperature control device for electronic circuit components, only the desired electronic circuit components can be selectively and efficiently heated, but the heat from the power transistor is also radiated into the air, so that the heat is released into the air. The heat does not easily contribute to the heating of the desired electronic circuit component, and in that sense, the heating efficiency is not good.
[0009]
The present invention solves the above-mentioned conventional problem, and selectively heats the temperature of a desired electronic circuit component requiring heating at a low temperature within a recommended operating temperature range with a short heating time and further higher heating efficiency. It is an object to provide a wiring board that can be raised, an electronic device and an LED display using the same.
[0010]
[Means for Solving the Problems]
The wiring board of the present invention is a temperature control means for controlling the temperature of an electronic circuit component within a predetermined recommended operating temperature range in a wiring board on which an electronic circuit component having a predetermined recommended operating temperature range is mounted on an insulating substrate. Is provided on the substrate surface side on which the electronic circuit components are mounted, thereby achieving the above object.
[0011]
Further, preferably, the temperature control means in the wiring board of the present invention has a heating element which is supplied with electric power and generates heat, and a heat-sensitive switch means which controls power supply to the heating element, in a position near the electronic circuit component. ing.
[0012]
Still preferably, in a wiring board according to the present invention, the heating element is disposed so as to be able to conduct heat to a ground line electrically connected to the electronic circuit component.
[0013]
Also, preferably, the heating element in the wiring board of the present invention is uniformly provided at a position near the periphery of the electronic circuit component.
[0014]
Still preferably, in a wiring board according to the present invention, the heat-sensitive switch means has a heat-sensitive element and a switch means, and the switch means is a transistor, and can output a drive voltage for driving the transistor based on an output from the heat-sensitive element. And a power supply to the heating element via the transistor when the ambient temperature is detected to be lower than the predetermined first temperature by the thermal element, and the ambient temperature is controlled to the predetermined second temperature by the thermal element. When it is detected that the temperature is equal to or higher than the temperature, the power supply to the heating element via the transistor is cut off. Preferably, the heat-sensitive switch means in the wiring board of the present invention has a heat-sensitive element for detecting an ambient temperature of the electronic circuit component, and a switch means for on / off control based on an output from the heat-sensitive element, The switch means is a transistor, and further includes bias means for outputting a drive voltage for driving the transistor based on the output from the thermal element, and the ambient temperature is equal to or lower than a predetermined first temperature by the thermal element. Is detected, the power is supplied to the heating element via the transistor, and when the ambient temperature is detected by the thermal element to be equal to or higher than the second predetermined temperature, the power is supplied to the heating element via the transistor. Cut off.
[0015]
More preferably, the wiring board of the present invention further includes a heat retaining cover that covers at least the electronic circuit components and the ambient temperature control unit.
[0016]
Further, preferably, the material of the heat retaining cover in the wiring board of the present invention is made of polycarbonate resin.
[0017]
Still preferably, in the wiring board of the present invention, the heat insulating cover has a two-layer structure in which an air layer is interposed therebetween.
[0018]
Further, preferably, the wiring board of the present invention is provided with flocks inside the heat retaining cover.
[0019]
Next, an electronic device according to the present invention includes the above-described wiring board, thereby achieving the above object.
[0020]
Further, the LED display of the present invention uses the wiring board as a control circuit board for controlling the driving of the LED panel, thereby achieving the above object. Further, in the LED display of the present invention, the wiring board according to claim 1, wherein the electronic circuit component is a display control IC, is used as a control circuit board for driving and controlling an LED panel. Is done.
[0021]
The operation of the present invention having the above configuration will be described below.
[0022]
In the present invention, for example, a wiring board on which an electronic circuit component requiring heating at a low temperature is mounted, such as a PLD which is a control IC for an LED display, is mounted on the board surface side on which the electronic circuit component is mounted. A heating element is provided. The heating element is provided in contact with a ground line electrically connected to the electronic circuit component. Heat from the heating element is conducted through the ground line and the leads of the electronic circuit components. Further, the heat radiated into the air from the heating element also contributes to an increase in the ambient temperature of the electronic circuit component. Accordingly, it is possible to selectively heat a predetermined electronic circuit component to a desired recommended operating temperature range in a shorter time and more efficiently. In addition, the surroundings of the electronic circuit components and the surrounding temperature control means (including the heating element and the heat-sensitive switch means) that need to be heated are covered with a heat insulating cover, and heat is hard to escape around the heat insulating cover. The heating efficiency can be further improved, and the electronic circuit component can be heated within the desired recommended operating temperature range in a short time with less power consumption.
[0023]
Also, by providing ambient temperature control means in the heat retaining cover, when the temperature in the heat retaining cover falls below a predetermined temperature by the ambient temperature control means, power is supplied to the heating element to generate heat, and the electronic circuit is heated. The component can be heated in a short time to within the desired recommended operating temperature range. Further, when the temperature inside the heat retaining cover becomes equal to or higher than the predetermined temperature, the power supplied to the heating element can be cut off to stop the heat generation. Thus, the electronic circuit components can be kept within a desired recommended operating temperature range. Heat required for heating can be arbitrarily set by a voltage supplied to a heating element (for example, a resistance element or a transistor).
[0024]
As a material for the heat retaining cover, it is preferable to use a polycarbonate resin in consideration of heat resistance, cost, and the like. Further, in order to surely isolate the temperature between the outside and the inside of the heat insulating cover, the heat insulating property can be further improved by adopting a two-layer structure with an air layer interposed therebetween. Also, the heat retention can be further improved by implanting the hair inside the heat retention cover.
[0025]
By providing a plurality of heating elements evenly around the electronic circuit component, such as at positions near four directions around the electronic circuit component, variations in the ambient temperature can be reduced.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the printed wiring board of the present invention will be described with reference to the drawings.
[0027]
FIG. 1 is a sectional view schematically showing a schematic configuration example of an embodiment of a printed wiring board of the present invention, and FIG. 2 is a top view of the printed wiring board of FIG.
[0028]
1 and 2, the printed wiring board 10 of the present invention is provided on the substrate 1 and on the substrate 1, and a normal operation cannot be obtained at a low temperature such as a sub-zero temperature such as a PLD. An electronic circuit component 2 having a predetermined recommended operating temperature range; a temperature control means provided on the substrate 1 for controlling the temperature of the electronic circuit component 2 within the predetermined recommended operating temperature range; And a heat retaining cover 5 that covers the ambient temperature control means.
[0029]
The electronic circuit component 2 is, for example, a programmable logic device (PLD) and requires heating to maintain a predetermined recommended operating temperature range.
[0030]
Ambient temperature control means includes a heating element 3 such as a resistance element which is heated by power supply on the mounting substrate surface side of the electronic circuit component 2 and a position near the electronic circuit component 2, and a power supply to the heating element 3. A thermal switch means 4 for controlling the supply.
[0031]
The heating element 3 is in contact with a ground line (GND line) 6 made of a copper foil (copper pattern) or the like electrically connected to the lead 2a of the electronic circuit component 2 so as to be thermally conductive, and one or more heating elements 3 are provided. For example, a resistance element is mounted, and the electronic circuit component 2 is heated via the GND line 6 and the lead 2a. Further, the heat radiation from the heating element 3 into the air also contributes to the heating of the ionization circuit component 2.
[0032]
In the example of FIG. 2, each heating element 3 is arranged in four directions around the electronic circuit component 2. In this way, by arranging a plurality of heating elements 3 around the electronic circuit component 2 evenly, it is possible to reduce the temperature unevenness in a specific area (the area around the electronic circuit component 2 in the area on the one surface side of the substrate). And can be evenly heated.
[0033]
The thermal switch means 4 is provided at least one inside the heat retaining cover 5, detects an ambient temperature, and controls power supply / interruption to each of the plurality of heating elements 3 based on the detected ambient temperature.
[0034]
FIG. 3 is a circuit diagram showing a configuration example of a main part of the heating element 3 and the thermal switch means 4 of FIG.
[0035]
In FIG. 3, a thermal switch means 4 includes a thermal element 4a for detecting an ambient temperature by an output change according to the ambient temperature, and a bias means including a comparator means for outputting a bias drive output in accordance with an output from the thermal element 4a. 4b, and a power transistor 4c that is driven and controlled by outputting a bias driving output from the biasing means 4b to a control terminal. The power supply is supplied via the power transistor 4c that is driven and controlled based on the output of the thermosensitive element 4a. , Power is supplied to and cut off from the heating element 3. As the thermal element 4a, for example, a thermistor, a thermocouple, or the like can be used.
[0036]
In the above configuration, when the temperature inside the heat retaining cover 5 is detected by the thermosensitive element 4a to be equal to or lower than a predetermined first temperature (for example, equal to or lower than zero degrees Celsius), the bias means 4b causes the control terminal of the power transistor 4c to connect A predetermined bias drive output (bias voltage) corresponding to the output from the element 4a is applied. As a result, the power transistor 4c is turned on, power is supplied from the power supply to the heating element 3, the heating element 3 generates heat, and heating of the electronic circuit component 2 is started.
[0037]
Further, when the temperature inside the heat retaining cover 5 is detected by the thermosensitive element 4a to be equal to or higher than a predetermined second temperature (predetermined first temperature ≦ predetermined second temperature), the bias from the bias means 4b to the power transistor 4c is changed. The application of the bias voltage (output from the comparator means) is stopped. As a result, the power transistor 4c is turned off, the power from the power supply to the heating element 3 is cut off, and the heating element 3 does not generate heat. Therefore, the heating of the electronic circuit component 2 is stopped. Thus, the first temperature and the second temperature are set to have a predetermined hysteresis. That is, the second temperature is set higher than the first temperature by the hysteresis.
[0038]
In an electronic device such as an LED display, an electronic circuit component has a very small heat capacity and time constant as compared with the entire device. The electronic circuit component 2 that needs to be heated at a low temperature is often a part of all components mounted on the printed wiring board 10. Therefore, when there is an electronic circuit component that needs to be heated at a low temperature, power efficiency becomes extremely poor when the entire electronic device is heated as in the related art.
[0039]
Therefore, in the present embodiment, only the electronic circuit components 2 whose operating temperature range is narrow and the temperature management needs to be performed are collected and contacted with the GND line 6 electrically connected to the leads of the electronic circuit components 2. The heating element 3 is mounted in this state, and only necessary parts (electronic circuit components 2) are selectively heated. At this time, in order to prevent heat radiation from the heating element 3 to the air layer, a corresponding portion is covered with a heat retaining cover 5 and is shielded from outside air.
[0040]
For example, when an LED display is used outdoors as a display device, considering that the LED display is used in a wide temperature range such as a minimum temperature of −40 ° C. to a maximum temperature of 100 ° C. and costs, etc., the material of the heat retaining cover 5 is considered. It is optimal to use a polycarbonate resin having high heat resistance.
[0041]
Furthermore, as shown in FIG. 4, the heat insulation cover 5 has a two-layer structure in which an air layer is interposed therebetween, so that the heat insulation performance of the heat insulation cover 5 can be improved. Alternatively, convection of the air layer in the vicinity of the heat retaining cover 5 can also be prevented by implanting hairs (not shown) inside the heat retaining cover 5, so that the heat insulating performance of the cover 5 can be improved.
[0042]
FIG. 5 is a graph showing the relationship between the power consumption of the heating element 3 and the temperature rise of the electronic circuit component 2 and the substrate 1 in the printed wiring board of the present embodiment. The vertical axis in FIG. 5 indicates a temperature rise (ΔT ° C.), and the horizontal axis indicates power consumption W. In FIG. 5, a solid line connecting points indicated by ○ indicates a rise in temperature of the electronic circuit component 2, and a dotted line connecting points indicated by × indicates a rise in the substrate temperature of the substrate 1. These have been almost the same.
[0043]
As shown in FIG. 5, the power consumption of the heating element 3 is about 15 ° C. at 4.2 W, and about 20 ° C. at 6.0 W, so that the temperature of the electronic circuit component 2 can be increased. It can be seen that the electronic circuit component 2 can be efficiently heated to a desired operating temperature range in a short time and with low power consumption.
[0044]
In the printed wiring board 10 of the present embodiment, a PLD which is a display control IC is mounted as the electronic circuit component 2 to constitute a control board of an LED display. It was possible to display well up to −40 ° C. where the temperature was up to ° C.
[0045]
As described above, according to each embodiment of the present invention, the heating element 3 and the thermal switch means 4 are mounted on the electronic circuit component 2 mounting surface side of the substrate 1. The heating element 3 is arranged in contact with the GND line 6 for the electronic circuit component 2, and heats the electronic circuit component 2 to a predetermined operating temperature range efficiently through the GND line 6. The heat-sensitive switch means 4 supplies power to the heating element 3 to generate heat when the temperature inside the heat retaining cover 5 becomes lower than a predetermined temperature, and generates electric power to the heating element 3 when the temperature inside the heat retaining cover 5 becomes higher than the predetermined temperature. , The electronic circuit component 2 can be maintained in a desired recommended operating temperature range. The surroundings of the electronic circuit component 2, the heating element 3, and the heating switch 4 that need to be heated are covered with a heat insulating cover 5, and heat does not escape around the heat insulating cover 5, thereby further improving the heating efficiency. be able to.
[0046]
In each of the above embodiments, the heat retaining cover 5 is used. However, even when the heat retaining cover 5 is not used, the temperature control means is disposed on the same substrate surface side as the electronic circuit component 2 so that the heating element 3 can be provided. The heat radiated into the air also contributes to an increase in the ambient temperature of the electronic circuit component 2, so that the effect of the present invention with higher heating efficiency can be obtained as compared with the related art.
[0047]
【The invention's effect】
As described above, according to the present invention, it is not necessary to provide a heater in a device as in a conventional electronic device, and at a position near the same substrate side of an electronic circuit component that needs to be heated at a temperature lower than a recommended operating temperature range. By causing the heating element to generate heat, the electronic circuit component can be efficiently heated to a desired recommended operating temperature range from the ground pattern on the wiring board to the desired recommended operating temperature range via the lead of the electronic circuit component and the air layer. it can. In addition, since the periphery of the electronic circuit component is covered by the heat retaining cover, heat hardly escapes from the heat retaining cover to the outside, and the power consumption required for heating can be reduced. The amount of heat required for heating can be arbitrarily set by, for example, a power supply voltage supplied to the heating element.
[0048]
In an LED display using the wiring board of the present invention as a control board, excellent display is possible with minimum power consumption even in an area where the temperature is -40 ° C, such as Hokkaido, which is an extremely cold region, and it is very effective. is there.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically illustrating a schematic configuration example of an embodiment of a printed wiring board of the present invention.
FIG. 2 is a top view of the printed wiring board of FIG. 1;
FIG. 3 is a circuit diagram showing a configuration example of a main part of a heating element and a thermal switch of FIG. 1;
FIG. 4 is a cross-sectional view illustrating another configuration example of the printed wiring board of the present embodiment.
FIG. 5 is a graph showing the relationship between the power consumption of the heating element 3 and the temperature rise of the electronic circuit component 2 and the substrate 1 in the printed wiring board of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Electronic circuit component 2a Lead 3 Heating element 4 Thermal switch 4a Thermal element 4b Bias 4c Power transistor (switch)
5 Heat insulation cover 6 GND pattern

Claims (11)

A circuit board on which an electronic circuit component having a predetermined recommended operating temperature range is mounted on an insulating substrate, a temperature control means for controlling the temperature of the electronic circuit component within the predetermined recommended operating temperature range; A wiring board provided on the board surface side on which components are mounted. The wiring board according to claim 1, wherein the temperature control unit includes a heating element that is heated by power supply and generates heat, and a heat-sensitive switch unit that controls power supply to the heating element, at a position near the electronic circuit component. The wiring board according to claim 2, wherein the heating element is disposed so as to be able to conduct heat to a ground line electrically connected to the electronic circuit component. 4. The wiring board according to claim 2, wherein the heating element is evenly provided at a position near the periphery of the electronic circuit component. 5. The thermal switch means has a thermal element and a switch means,
The switch means is a transistor, and further includes bias means capable of outputting a drive voltage for driving the transistor based on an output from the thermosensitive element, wherein the ambient temperature is set to a predetermined first temperature by the thermosensitive element. When it is detected that the temperature is below, power is supplied to the heating element through the transistor, and when it is detected that the ambient temperature is equal to or higher than a predetermined second temperature by the thermal element, the power is supplied through the transistor. The wiring board according to claim 2, wherein power supply to the heating element is cut off. 2. The wiring board according to claim 1, further comprising a heat retaining cover that covers at least the electronic circuit component and the ambient temperature control unit. 7. The wiring board according to claim 6, wherein a material of the heat retaining cover is made of a polycarbonate resin. 7. The wiring board according to claim 6, wherein the heat retaining cover has a two-layer structure in which an air layer is interposed therebetween. 7. The wiring board according to claim 6, wherein flocking is performed inside the heat retaining cover. An electronic device comprising the wiring board according to claim 1. An LED display using the wiring board according to any one of claims 1 to 9 as a control circuit board for driving and controlling an LED panel.

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