CN217279340U

CN217279340U - Control circuit for enhancing PCB heat conduction and PCB board with same

Info

Publication number: CN217279340U
Application number: CN202221178036.5U
Authority: CN
Inventors: 翟让海; 张毅; 欧阳晓波; 魏蓉
Original assignee: Fiberhome Telecommunication Technologies Co Ltd
Current assignee: Fiberhome Telecommunication Technologies Co Ltd
Priority date: 2022-05-12
Filing date: 2022-05-12
Publication date: 2022-08-23
Anticipated expiration: 2032-05-12

Abstract

The application discloses a control circuit for enhancing PCB heat conduction and a PCB with the same, and relates to the technical field of chip heat dissipation, wherein the control circuit comprises a Central Processing Unit (CPU), at least one switch branch and at least one thermoelectric cooler (TEC) thermocouple element; the central processing unit CPU is connected with the control end of the switch branch; one end of the TEC thermocouple element is grounded after being connected with the switch branch in series, the other end of the TEC thermocouple element is connected with a forward power supply VCC, the refrigerating end of the TEC thermocouple element is used for being connected with a to-be-cooled area on the PCB, and the heating end of the TEC thermocouple element is used for being connected with a heat dissipation area on the PCB after the TEC conducts heat; meanwhile, the central processing unit CPU is configured to control the switch branch circuit to enable the TEC thermocouple element to conduct heat of the area to be cooled to the heat dissipation area when the temperature of the chip on the PCB exceeds a set temperature. According to the thermoelectric cooler and the manufacturing method thereof, the heat pump principle of the semiconductor cooler TEC is utilized, two areas with temperature difference on the PCB are connected through the TEC thermocouple element, the defect that the heat dissipation of the chip on the PCB is limited is overcome, and the heat conduction performance on the PCB is improved.

Description

Control circuit for enhancing PCB heat conduction and PCB board with same

Technical Field

The application relates to the technical field of chip heat dissipation, in particular to a control circuit for enhancing PCB heat conduction and a PCB with the circuit.

Background

Chips on a Printed Circuit Board (PCB) are often packaged on metal pads as one of the thermal paths for heat dissipation of the chips, and the heat of the chips is dissipated from the bottom pads and conducted to copper sheets of the PCB and then dissipated out through the copper sheets and via holes of the PCB. Wherein about 50-80% of the heat generated by the chip can be conducted through the PCB, and the rest heat can be dissipated through the surface of the package.

Disclosure of Invention

The embodiment of the application provides a control circuit for enhancing PCB heat conduction and a PCB with the control circuit, so as to solve the technical problem that the heat dissipation of a chip on the PCB is limited in the related art.

In a first aspect, a control circuit for enhancing heat conduction of a PCB is provided, which comprises a central processing unit CPU, at least one switching branch and at least one TEC thermocouple element;

the central processing unit CPU is connected with the control end of the switch branch;

one end of the TEC thermocouple element is grounded after being connected with the switch branch in series, the other end of the TEC thermocouple element is connected with a forward power supply VCC, the refrigerating end of the TEC thermocouple element is used for being connected with a to-be-cooled area on the PCB, and the heating end of the TEC thermocouple element is used for being connected with a heat dissipation area on the PCB after the TEC conducts heat;

meanwhile, the central processing unit CPU is configured to control the switch branch circuit to enable the TEC thermocouple element to conduct heat of the area to be cooled to the heat dissipation area when the temperature of the chip on the PCB exceeds a set temperature.

In some embodiments, if the number of the TEC thermocouple elements is multiple, the multiple TEC thermocouple elements are all controlled by the central processing unit CPU through the same switch branch.

In some embodiments, the central processor CPU supports junction temperature detection; alternatively, the first and second electrodes may be,

the control circuit also comprises a divider resistor R3 and a thermistor R with negative temperature coefficient _NTC (ii) a The voltage dividing resistor R3 and the thermistor R with negative temperature coefficient _NTC One end of the series resistor is connected with a positive power supply, the other end of the series resistor is grounded, and the thermistor R _NTC One end of the divider resistor R3 close to the divider resistor R is connected with a detection pin of the central processing unit CPU.

In some embodiments, the switch branch comprises an NMOS transistor, a gate of the NMOS transistor is connected to the output terminal of the CPU, a drain of the NMOS transistor is connected to the TEC thermocouple element, and a source of the NMOS transistor is grounded.

In some embodiments, the switching branch includes a PMOS transistor and a transistor Q, where a source of the PMOS transistor is connected to the forward power VCC, a drain of the PMOS transistor is connected to the TEC thermocouple element, and a gate of the PMOS transistor is controlled by the CPU through the transistor Q.

In some embodiments, the switch branch further includes a voltage dividing resistor R1 and a voltage dividing resistor R2, the collector of the triode Q is sequentially connected in series with the voltage dividing resistor R1 and the voltage dividing resistor R2 and then connected to the forward power VCC, one end of the voltage dividing resistor R1, which is far away from the triode Q, is connected to the gate of the PMOS transistor, the base of the triode Q is connected to the output end of the central processing unit CPU, and the emitter is grounded.

In some embodiments, a current limiting resistor R0 is connected in series with a branch of the TEC thermocouple element in series with the switching branch.

In a second aspect, there is provided a PCB board having a control circuit as described above that enhances PCB thermal conduction.

In some embodiments, the cooling end of the TEC thermocouple element is welded to the area of the PCB where cooling is to be performed, and the heating end is welded to the heat dissipation area of the PCB.

In some embodiments, if the area to be cooled comprises a TOP layer, the heat dissipation area comprises a BOT layer, and the TEC thermocouple element is inserted into the PCB through hole; alternatively, the first and second electrodes may be,

if the temperature to be cooled comprises a chip end copper sheet, the heat dissipation area comprises a peripheral copper sheet, and the TEC thermocouple element is bridged between the chip end copper sheet and the peripheral copper sheet; alternatively, the first and second electrodes may be,

if the area to be cooled comprises the surface PCB, the heat dissipation area comprises a TCE top, and the TCE top is connected with the heat dissipation device.

The beneficial effect that technical scheme that this application provided brought includes: by utilizing the heat pump principle of the semiconductor cooler TEC, two areas with temperature difference on the PCB are connected through the TEC thermocouple element, the defect that the heat dissipation of the chip on the PCB is limited is overcome, and the heat conduction performance on the PCB is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is an electrical connection diagram of a first control circuit for enhancing PCB heat conduction according to an embodiment of the present application;

FIG. 2 is an electrical connection diagram of a second control circuit for enhancing PCB thermal conduction according to an embodiment of the present application;

FIG. 3 is a schematic diagram of the main structure of the control circuit in the application of heat conduction barrier between PCB layers;

fig. 4 is a PCB board with a control circuit for enhancing thermal conduction of the PCB according to an embodiment of the present application.

The implementation, functional features and advantages of the objectives of the present application will be further explained with reference to the accompanying drawings.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.

The flow diagrams depicted in the figures are merely illustrative and do not necessarily include all of the elements and operations/steps, nor do they necessarily have to be performed in the order depicted. For example, some operations/steps may be decomposed, combined or partially combined, so that the actual execution order may be changed according to the actual situation.

The embodiment of the application provides a TEC (thermoelectric cooler) control circuit for enhancing PCB heat conduction, which connects two areas with temperature difference on a PCB through a TEC thermocouple element by utilizing the heat pump principle of a semiconductor cooler TEC, solves the defect of limited heat dissipation of chips on the PCB, and improves the heat conduction performance on the PCB.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

As shown in fig. 1-2, an embodiment of the present application provides a control circuit for enhancing heat conduction of a PCB, including a central processing unit CPU, at least one switch branch, and at least one TEC thermocouple element;

meanwhile, the central processing unit CPU is configured to control the switch branch to enable the TEC thermocouple element to conduct heat of the region to be cooled to the heat dissipation region when the temperature of the chip on the PCB exceeds a set temperature.

In this embodiment, the number of the switch branch and the TEC thermocouple element is 1, and the switch branch and the TEC thermocouple element are connected in series to form a cooling end and a heating end on the TEC thermocouple element, where the cooling end of the TEC thermocouple element is connected to a region to be cooled with a higher temperature on the PCB, and the heating end is connected to a heat dissipation region with a lower temperature on the PCB.

When the CPU detects that the temperature of the chip on the PCB exceeds a set temperature, the CPU sends a switch closing signal to the control end of the switch branch through the GPIO port, at the moment, the TEC thermocouple element is electrified and forms a cooling end in the area to be cooled, the heat dissipation area forms a heating end, and the TEC thermocouple element is used as a new heat conduction channel, so that heat is actively conducted from the area to be cooled to the heat dissipation area through the TEC thermocouple element, condensation on the PCB is avoided, and temperature control is further achieved.

When the central processing unit CPU detects that the temperature of the chip on the PCB does not exceed the set temperature, the temperature of the area to be cooled is still in a safe range, the central processing unit CPU sends a switch-off signal to the control end of the switch branch circuit through the GPIO port, at the moment, the TEC thermocouple element is not electrified, a new heat conduction channel between the area to be cooled and the heat dissipation area does not work, and unnecessary operation and energy loss of the thermocouple element for a long time are avoided.

Generally, the number of the TEC thermocouple elements on the PCB is generally multiple, and multiple TEC thermocouple elements may be controlled by one switching branch, or by at least two switching branches, or by one switching branch.

Preferably, if the number of the TEC thermocouple elements is multiple, the multiple TEC thermocouple elements are all controlled by the central processing unit CPU through the same switch branch.

On the PCB, areas needing enhanced heat conduction are not located, the areas are mainly divided into three types of heat conduction barriers according to the heat dissipation condition of the PCB, one is transverse heat conduction barrier, the other is heat conduction between PCB layers, and the other is local overheating of the PCB, the three conditions cause non-uniform temperature distribution on the PCB, and the PCB temperature distribution detected by infrared rays is taken as an example, the temperature difference between the upper and lower parts of the PCB can reach 20-40 ℃. Therefore, for the three types of heat conduction barriers, three TEC heat conduction channels are built in the present embodiment, and then, assuming that the number of the TEC thermocouple elements in the present embodiment is three, the three TEC thermocouple elements may be controlled by three switching branches respectively and independently, or may be synchronously controlled by one switching branch. To further reduce the number of components and keep the PCB board simple, it is preferable to have one switching leg connected to each of the three TEC thermocouple elements.

As shown in fig. 3, taking the thermal conduction block between PCB layers as an example, in the layout of the PCB, chips such as CPU, WIFI, FEM, etc. are usually laid out on TOP layer, and devices such as resistors, capacitors, magnetic beads, etc. are distributed on the bottom layer behind, where the TOP layer represents the outer surface layer of the PCB soldered chip, and the bottom layer represents the other outer surface layer corresponding to the TOP layer in the PCB. The TOP surface of the PCB is high in temperature due to the fact that a large amount of heat is generated by the chip, the typical value of the thermal conductivity of the FR-4 glass fiber material between the two layers in the z direction (thickness direction) is only 0.25W/mK, the TOP surface heat cannot be rapidly conducted to the BOT surface copper sheet to be dissipated due to the fact that the thermal conductivity of the FR-4 material between the two layers is low, and the TOP surface heat is accumulated to cause the chip to be over-temperature.

In this embodiment, the natural heat conduction efficiency between the TOP surface and the BOT surface of the PCB is very low, a TEC type thermocouple element is inserted and welded in the through hole of the TOP surface and the BOT surface, that is, the TOP surface and the BOT surface form a heat conduction channel through the TEC thermocouple element, and when the TEC thermocouple element is energized, the TEC thermocouple element can quickly conduct heat of the TOP surface to the BOT surface, thereby accelerating heat conduction between PCB board layers and improving heat dissipation performance of chips.

Use the horizontal heat-conduction of PCB to hinder as the example, now, the chip integrates the degree higher more, and PCB walks that the line is more intensive, and the device is arranged and also is inseparabler more, and then leads to PCB copper skin around the chip to be cut apart into the polylith for the heat of chip bottom is passed to the route to the outside unsmooth through the copper skin, and the heat gathering has led to the chip overtemperature. Meanwhile, as far as the peripheral PCB area away from the chip is concerned, the temperature of a large copper sheet is lower, the heat conduction path is separated by the PCB wiring, and the heat dissipation performance is not fully utilized.

Obviously, the copper sheets close to the heat source chip on the PCB are separated by the wiring, the heat transfer pins of the TEC thermocouple element are welded on the two separated copper sheets, namely the chip end copper sheet and the peripheral copper sheet form a heat transfer conduction channel through the TEC thermocouple element, and when the TEC thermocouple element is electrified, the TEC thermocouple element can rapidly conduct the heat of the chip end copper sheet to the peripheral copper sheet, so that the heat conduction of the PCB around the heat source chip is accelerated, and the heat dissipation performance of the chip is improved.

Taking the local overheating of the PCB as an example, in practice, a plurality of chips are concentrated in one area on the PCB, and the heat radiated to the air is too small, thereby causing the copper sheet of the PCB in the area to be over-heated, that is, the local overheating of the PCB. In this embodiment, a TEC thermocouple element is soldered to a copper sheet around a chip of a PCB, specifically, a cooling end of the TEC thermocouple element is attached to a surface PCB, a heating end is connected to a heat sink through a top of the TEC by using an interface material such as a thermal pad or a thermal grease, and after the TEC thermocouple element is powered on, the TEC thermocouple element conducts heat of the surface PCB to the top of the TEC, and then the thermal pad or the thermal grease is dissipated to the air through the heat sink, thereby further improving thermal conduction efficiency and improving heat dissipation performance of the chip.

Therefore, the proper number of TEC thermocouple elements are distributed on the PCB according to different requirements, and the heat conduction efficiency of the PCB can be realized in an all-around manner.

Preferably, the central processing unit CPU supports junction temperature detection; alternatively, the first and second electrodes may be,

the control circuit also comprises a voltage dividing resistor R3 and a thermistor R with negative temperature coefficient _NTC (ii) a The voltage dividing resistor R3 and the thermistor R with negative temperature coefficient _NTC One end of the series resistor is connected with a positive power supply, the other end of the series resistor is grounded, and the thermistor R _NTC One end of the divider resistor R3 close to the divider resistor is connected with a detection pin of the central processing unit CPU.

In a specific embodiment, the central processing unit CPU supports junction temperature detection, and outputs a corresponding MCU _ CTR signal through the GPIO port according to a result of the junction temperature detection; in this embodiment, the CPU has a junction temperature detection function.

However, in practical applications, not all the CPU can support junction temperature detection, and for a CPU without junction temperature detection capability, a temperature detection loop is established in this embodiment, and the temperature detection loop mainly includes a voltage dividing resistor R3 and a negative temperature coefficient thermistor R connected in series _NTC And a thermistor R _NTC The other end of the voltage divider resistor R3 is grounded, the other end of the voltage divider resistor R3 is connected with a forward power supply VCC, and the voltage divider resistor R3 and the thermistor R can be enabled to be connected with a forward power supply VCC through the resistance change of the thermistor along with the temperature _NTC The voltage change between the two is changed, then the ADC detection pin of the CPU detects the current temperature through the voltage change after voltage division, and compares the detected temperature with the set temperature to judge which level signal is sent out through the GPIO port.

In this embodiment, the switch branch is mainly composed of MOS transistors, and two embodiments of NMOS transistors and PMOS transistors are explained below.

As shown in fig. 1, in a preferred embodiment, the switch branch includes an NMOS transistor, a gate G of the NMOS transistor is connected to the output terminal of the central processing unit CPU, a drain D is connected to the TEC thermocouple element, and a source S is grounded. Specifically, the gate G of the NMOS transistor is connected to the GPIO port of the CPU through a resistor R4.

In this embodiment, if the GPIO port outputs a high level signal, the NMOS transistor is directly driven to conduct, and at this time, the TEC thermocouple element is powered on, and a TEC heat conduction channel is formed. If the GPIO port outputs a low level signal, the NMOS tube is directly driven to be cut off, at the moment, the TEC thermocouple element is not electrified, and a TEC heat conduction channel is not formed.

As shown in fig. 2, in another preferred embodiment, the switching branch includes a PMOS transistor and a transistor Q, a source S of the PMOS transistor is connected to the forward power VCC, a drain D is connected to the TEC thermocouple element, and a gate G is controlled by the CPU through the transistor Q.

Further, the switch branch circuit still includes divider resistance R1 and divider resistance R2, triode Q's collecting electrode C concatenates in proper order connect behind divider resistance R1 and the divider resistance R2 forward power VCC, just divider resistance R1 keeps away from triode Q's one end with the grid G of PMOS pipe links to each other, triode Q's base B with central processing unit CPU's output links to each other, and projecting pole E ground.

Specifically, the base B of the triode Q is connected with the GPIO port of the central processing unit CPU through a resistor R4. The transistor Q is an NPN transistor.

In this embodiment, if the GPIO port outputs a high level signal, the NPN type triode is turned on, and the level at the collector C is a low level, that is, the gate S of the PMOS transistor receives the low level signal, and the PMOS transistor is turned on, at this time, the TEC thermocouple element is turned on, and the TEC heat conduction channel is formed. On the contrary, if the GPIO port outputs a low-level signal, the NPN type triode is cut off, the level at the collector C is high level, the PMOS tube is cut off, at the moment, the TEC thermocouple element is not electrified, and the TEC heat conduction channel is not formed.

Furthermore, a current limiting resistor R0 is further serially connected to a branch line of the TEC thermocouple element and the switch branch line in series.

The current limiting resistor R0 may be connected in series to a line where the TEC thermocouple element is connected to the positive power supply VCC, or may be connected in series to a line where the TEC thermocouple element is grounded.

In this embodiment, a current limiting resistor R0 is serially connected to the output line of the forward power supply VCC, and the maximum current flowing through the TEC thermocouple element is adjusted by the combination of the current limiting resistor R0 and the forward power supply VCC.

In the embodiment, a PCB micro heat dissipation channel, which is also a micro heat conduction channel, is constructed by utilizing the heat pump principle of a TEC thermocouple element, so that the heat conduction performance of PCB interlayer or PCB transverse heat conduction or PCB local overheating is enhanced, and the temperature distribution on the PCB is balanced; the TEC thermocouple elements are active heat conduction channels, heat flows from the refrigerating end to the heating end rapidly according to the preset heat conduction channels, the heat conduction performance is higher than that of natural heat flowing, the temperature of a PCB (printed circuit board) around the chip can be reduced rapidly in a short time, and the TEC thermocouple elements are suitable for being applied to integrated, miniaturized or thin integrated circuits, products with high heat density and poor heat convection or products with small heat dissipation space, and can also adopt a plurality of TEC thermocouple elements to dissipate heat in a distributed mode on the PCB to rapidly transfer the heat.

As shown in fig. 4, the present application also provides a PCB board having a control circuit for enhancing PCB heat conduction as described above.

Furthermore, the refrigerating end of the TEC thermocouple element is welded in the area of the PCB to be cooled, and the heating end is welded in the heat dissipation area of the PCB.

In this embodiment, the TEC couple elements have pins, such as electrode pins 1 and 2, and heat transfer pins 3 and 4, which are soldered to appropriate locations.

Preferably, if the area to be cooled comprises a TOP layer, the heat dissipation area comprises a BOT layer, and the TEC thermocouple element is inserted into the PCB through hole; alternatively, the first and second electrodes may be,

if the area to be cooled comprises a chip end copper sheet, the heat dissipation area comprises a peripheral copper sheet, and the TEC thermocouple element is bridged between the chip end copper sheet and the peripheral copper sheet; alternatively, the first and second electrodes may be,

if the area to be cooled comprises the surface PCB, the heat dissipation area comprises a TEC top, and the TEC top is connected to the heat dissipation device.

The heat dissipation device can be a heat sink on a PCB, a fan, a metal housing, or the like.

In the embodiment, according to the heat dissipation condition of the PCB, three types of heat conduction obstacles are mainly divided, one is heat conduction between PCB layers, the other is transverse heat conduction obstacle, and the other is local overheating of the PCB, which cause non-uniform temperature distribution on the PCB, and taking the PCB temperature distribution detected by infrared rays as an example, the high-low temperature difference on the PCB can reach 20-40 ℃. Therefore, for the three types of heat conduction obstacles, three TEC heat conduction channels are built in the present embodiment, and then, assuming that the number of the TEC thermocouple elements in the present embodiment is three, the three TEC thermocouple elements may be controlled by three switching branches respectively and independently, or may be synchronously controlled by one switching branch. To further reduce the number of components and keep the PCB board simple, it is preferable to have one switching leg connected to each of the three TEC thermocouple elements.

As shown in fig. 3, taking the thermal conduction block between PCB layers as an example, in the layout of the PCB, chips such as CPU, WIFI, FEM, etc. are usually laid out on TOP layer, and devices such as resistors, capacitors, magnetic beads, etc. are distributed on the bottom layer behind, where the TOP layer represents the outer surface layer of the PCB soldered chip, and the bottom layer represents the other outer surface layer corresponding to the TOP layer in the PCB. The chip generates a large amount of heat to cause the surface temperature of the TOP layer of the PCB to be high, and the typical value of the thermal conductivity of the FR-4 glass fiber material between the two layers in the z direction (thickness direction) is only 0.25W/mK, so that the TOP layer heat cannot be quickly conducted to the BOT surface copper sheet to be dissipated due to the low thermal conductivity of the FR-4 material between the two layers, and the TOP surface heat is accumulated to cause the chip to be over-heated.

Use the horizontal heat-conduction of PCB to hinder as the example, now, the chip integrates the degree higher more, and PCB walks that the line is more intensive, and the device is arranged and also is inseparabler more, and then leads to PCB copper skin around the chip to be cut apart into the polylith for the heat of chip bottom is passed to the route to the outside unsmooth through the copper skin, and the heat gathering has led to the chip overtemperature. Meanwhile, as for the peripheral PCB area far away from the chip, the temperature of a large copper sheet is low, the heat conduction path is isolated by the PCB wiring, and the heat dissipation performance is not fully utilized.

Therefore, the proper number of TEC thermocouple elements are distributed on the PCB according to different requirements, and the heat conduction efficiency of the PCB can be realized in an all-round manner.

In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are merely for convenience of describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as the case may be.

It is noted that, in this application, relational terms such as "first" and "second," and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The previous description is only an example of the present application, and is provided to enable any person skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control circuit for enhancing PCB heat conduction is characterized by comprising a Central Processing Unit (CPU), at least one switch branch and at least one TEC thermocouple element;

2. The PCB thermal conduction enhancement control circuit of claim 1, wherein if the number of the TEC thermocouple elements is plural, the plurality of TEC thermocouple elements are controlled by the CPU through the same switching branch.

3. The control circuit for enhancing PCB thermal conduction according to claim 1, wherein the central processing unit CPU supports junction temperature detection; alternatively, the first and second electrodes may be,

the control circuit also comprises a voltage dividing resistor R3 and a thermistor R with negative temperature coefficient _NTC (ii) a The voltage dividing resistor R3 and the thermistor R with negative temperature coefficient _NTC One end of the series resistor is connected with a positive power supply, the other end of the series resistor is grounded, and the thermistor R _NTC One end of the divider resistor R3 close to the divider resistor R is connected with a detection pin of the central processing unit CPU.

4. The PCB thermal conduction enhancement control circuit of claim 1, wherein the switching branch comprises an NMOS transistor, and the gate of the NMOS transistor is connected to the output of the CPU, the drain of the NMOS transistor is connected to the TEC thermocouple element, and the source of the NMOS transistor is grounded.

5. The PCB heat conduction enhanced control circuit of claim 1, wherein the switching branch comprises a PMOS transistor and a transistor Q, the source of the PMOS transistor is connected to the forward power VCC, the drain is connected to the TEC thermocouple element, and the gate is controlled by the CPU through the transistor Q.

6. The PCB of claim 5, wherein the switch branch further comprises a voltage dividing resistor R1 and a voltage dividing resistor R2, the collector of the transistor Q is serially connected with the voltage dividing resistor R1 and the voltage dividing resistor R2 in sequence and then connected to the forward power VCC, one end of the voltage dividing resistor R1 far away from the transistor Q is connected to the gate of the PMOS transistor, the base of the transistor Q is connected to the output terminal of the CPU, and the emitter is grounded.

7. A control circuit for enhancing PCB heat conduction as recited in claim 1, wherein a current limiting resistor R0 is connected in series with a leg of said TEC thermocouple element in series with said switching leg.

8. A PCB board having a control circuit for enhancing PCB thermal conduction as claimed in any one of claims 1 to 7.

9. The PCB of claim 8, wherein the cooling end of the TEC thermocouple element is soldered to the area of the PCB to be cooled, and the heating end is soldered to the heat dissipation area of the PCB.

10. The PCB board of claim 9, wherein:

if the area to be cooled comprises the TOP layer, the heat dissipation area comprises the BOT layer, and the TEC thermocouple element is inserted into the PCB through hole; alternatively, the first and second electrodes may be,