Manifold-embedded microchannel LTCC (Low Temperature Co-Fired Ceramic) substrate additionally provided with microneedle fins

Abstract

The invention discloses an embedded manifold micro-channel LTCC substrate additionally provided with micro needle fins, which comprises a top cover plate layer, a middle micro-channel layer, a bottom substrate layer and an external driving assembly, and is characterized in that the top cover plate layer is provided with a radio frequency device unit, the middle micro-channel layer is provided with main and bypass manifold micro-channels, and the bottom substrate layer is provided with an external driving assembly; a plurality of flow dividing micro-needle fins are arranged on the input section of the main branch pipe micro-channel, a plurality of flow disturbing micro-needle fins are arranged on the bypass branch pipe micro-channel, a liquid inlet / outlet is formed in the bottom base plate layer, and the external driving assembly comprises a controller, a micro-pipe and a micro-pump. During working, a cooling working medium is transmitted through the micro-pipes, flows through the main branch pipe micro-channels of the middle micro-channel layer, is distributed to the bypass branch pipe micro-channels through the shunting micro-needle fins, is fully mixed under the action of the turbulence micro-needle fins, takes away heat generated by the high-power radio frequency device and is transmitted to the external environment. According to the invention, organic fusion of the LTCC substrate and the heat dissipation technology is realized, and efficient cooling of the high-heat-flux radio frequency device is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of heat dissipation, and in particular to an embedded manifold microchannel LTCC substrate with additional micro-needle fins. Background Art

[0002] Low Temperature Co-fired Ceramic (LTCC) packaging can integrate multiple types of chips and other components into the same package to achieve systemic functions. It is an important means to achieve the integration, multi-function and lightweight of RF microsystems. Due to its excellent high-frequency performance, LTCC substrate can meet the application requirements of RF microsystems in high frequency, low loss and high-speed transmission. However, the thermal conductivity of LTCC substrate is poor (<20W / (m·k)), which leads to the failure of heat generated by integrated power devices to dissipate in time, becoming a bottleneck problem that restricts the application of LTCC in high-power microwave components and multifunctional microsystems. At present, forced air cooling or liquid cooling is mostly used to solve the heat dissipation problem faced by LTCC substrates. However, forced air cooling has gradually failed to meet the thermal management requirements of device heat dissipation capacity and size; forced liquid cooling mainly solves the heat dissipation problem by setting a liquid cooling structure outside the shell, but its thermal control components are complex, costly and reliable. The emergence of embedded heat dissipation provides a new solution for near-junction heat dissipation. It has excellent heat dissipation performance, is easy to highly integrate, and can quickly and efficiently remove the heat generated by the heat-generating module. However, the use of embedded liquid cooling technology for thermal management of RF devices has many problems, such as a single microchannel topology, insufficient heat dissipation capacity, poor temperature consistency, and complex processes. Summary of the invention

[0003] The present invention proposes an embedded manifold microchannel LTCC substrate with additional micro-needle fins. The technical solution is to embed a regular hexagonal manifold microchannel in the LTCC substrate through an integrated stacking and sintering process. In order to effectively enhance its heat dissipation capacity and improve temperature consistency, diamond-shaped micro-needle fins are added in the manifold microchannel for flow diversion and disturbance.

[0004] The technical solution to realize the present invention is: an embedded manifold microchannel LTCC substrate with additional micro-needle fins, including: a top cover layer, a middle microchannel layer, a bottom substrate layer, and an external driving component.

[0005] The top cover layer is formed by stacking and sintering the first to fifth layers of raw ceramic sheets. The RF device unit is arranged on the top cover layer. Thermal conductive columns are buried between the top cover layers. The thermal conductive columns are made of metal copper material. The thermal conductive columns can assist the heat generated by the RF device unit to be quickly transferred to the middle microchannel layer.

[0006] The middle microchannel layer is formed by stacking and sintering the sixth to ninth layers of raw ceramic sheets. A main manifold microchannel and a bypass manifold microchannel are arranged in the middle microchannel layer. A plurality of single-row diversion micropin fins are arranged on the main manifold microchannel, and a plurality of multi-row staggered turbulence micropin fins are arranged on the bypass manifold microchannel.

[0007] The bottom substrate layer is formed by stacking and sintering the tenth to fifteenth layers of raw ceramic sheets, and a liquid inlet and a liquid outlet are provided on the bottom substrate layer.

[0008] The external driving component comprises a controller, a liquid inlet micro-tube, a liquid outlet micro-tube and a micro-pump.

[0009] During operation, the cooling medium is controlled by the controller and is transmitted to the liquid inlet through the liquid inlet microtube via the action of the micropump, flows through the main manifold microchannel of the middle microchannel layer, and is distributed to the bypass manifold microchannel through the diversion microneedle fins. Then, it is fully mixed under the action of the turbulent microneedle fins to take away the heat generated by the RF device unit. Finally, the cooling medium is transmitted to the liquid outlet microtube through the liquid outlet and then transported to the external environment.

[0010] Furthermore, the cooling medium material includes but is not limited to deionized water and fluorinated liquid with insulating properties.

[0011] Furthermore, the manifold microchannels of the middle microchannel layer are generally centrosymmetric regular hexagonal flow channel structures.

[0012] Furthermore, the main manifold microchannel and the bypass manifold microchannel of the middle microchannel layer are located directly below the area where the radio frequency device unit is arranged on the top cover layer.

[0013] Furthermore, a main manifold microchannel and a plurality of bypass manifold microchannels are arranged in the middle microchannel layer.

[0014] Furthermore, the flow channel height of the manifold microchannels is uniformly about 400 μm, and the spacing between adjacent bypass manifold microchannels is uniformly about 500 μm.

[0015] Furthermore, the cross-sectional shapes of the flow-dividing micro-needle fin and the flow-disturbing micro-needle fin are both rhombuses with a sharp angle of 60° and the same circumference.

[0016] Furthermore, the flow-dividing micro-needle fins are arranged in the input section of the main manifold microchannel, and the flow-disturbing micro-needle fins are arranged in the entire flow path of the bypass manifold microchannel.

[0017] Furthermore, the main manifold microchannel has a trapezoidal structure, the input section is a gradually tightening trapezoidal shape, connected to the liquid inlet; the output section is a gradually expanding trapezoidal shape, connected to the liquid outlet.

[0018] Furthermore, the cooling medium flowing through the input section of the main manifold microchannel is evenly diverted to a number of bypass manifold microchannels through the diverter micro-needle fins, and then fully mixed through the diverter micro-needle fins in the bypass manifold microchannel. Finally, the cooling medium flows from the liquid outlet to the output section of the main manifold microchannel and flows out.

[0019] Furthermore, the contact points between the inlet and outlet liquid ports and the inlet and outlet micro-tubes are sealed by fasteners and sealants.

[0020] Furthermore, the controller is powered by DC 3.7V. After the circuit is started, the default operating frequency is 30Hz, and the operating frequency range is 1-60Hz. By adjusting the operating frequency of the controller, the flow rate of the micropump pressure cooling medium can be controlled.

[0021] Furthermore, the micro pump is a piezoelectric micro water pump, the liquid supply flow rate of which is greater than 50 ml / min and the maximum head is greater than 25 kPa.

[0022] The cooling medium that absorbs heat is discharged from the liquid outlet to the external environment under the driving action of the micropump, and after cooling, it is pumped back into the liquid inlet by the micropump to achieve the purpose of repeated heat dissipation.

[0023] Furthermore, the cooling medium that absorbs heat is discharged from the liquid outlet to the external environment under the driving action of the micropump, and is pumped back into the liquid inlet by the micropump after cooling, thereby achieving the purpose of repeated heat dissipation.

[0024] Furthermore, in order to ensure that the liquid-cooling circulation microchannel does not collapse and to solve the problem of stratification and bulging during sintering, the three parts of the raw ceramic sheets, namely the top cover layer, the middle microchannel layer and the bottom substrate layer, are stacked and pre-pressed respectively in the preparation process to obtain sub-modules of the top, middle and bottom parts. Then, the sub-modules are bonded with an organic adhesive to form an overall module at low temperature and low pressure. Finally, a multi-layer ceramic substrate is made by lamination and sintering to obtain an LTCC substrate with an integrated embedded manifold microchannel.

[0025] Furthermore, the preparation process involves laser cutting on a raw ceramic sheet to produce a manifold microchannel structure with additional microneedle fins; sacrificial materials such as graphite and starch are filled in the manifold microchannel. The sacrificial materials can transmit pressure during lamination to support and protect the microchannel from or reduce the effects of molding pressure, thereby maintaining the stability of the microchannel structure and size to the greatest extent.

[0026] Compared with the prior art, the present invention has the following significant advantages:

[0027] (1) Microchannels are embedded in the LTCC substrate, and forced convection of the cooling medium is used to directly cool the heat-generating components, which can improve the heat dissipation effect of the packaged device and meet the heat dissipation requirements of miniaturized products.

[0028] (2) The micro-needle fin structure not only plays a role in diversion and disturbance, but also increases the heat dissipation surface area, effectively improving the heat exchange efficiency.

[0029] (3) The regular hexagonal manifold microchannel structure reduces thermal resistance, lowers temperature gradient, makes heat more evenly distributed and dissipated, and avoids local overheating.

[0030] (4) The embedded manifold microchannel design does not occupy the external space of the ceramic substrate, reducing the space occupancy of the product, making the entire system smaller and lighter, suitable for lightweight and miniaturized applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A cross-sectional view of an embedded manifold microchannel LTCC substrate with additional micro-pin fins provided in some embodiments of the present invention;

[0032] Figure 2 A flow channel diagram of an embedded manifold microchannel LTCC substrate with additional micro-pin fins provided in some embodiments of the present invention;

[0033] Figure 3 A working flow chart of an embedded manifold microchannel LTCC substrate with additional micro-pin fins provided in some embodiments of the present invention;

[0034] Figure 4 A flow chart for preparing an embedded manifold microchannel LTCC substrate with additional micro-needle fins provided in some embodiments of the present invention.

[0035] In the figure, 1. Top cover layer; 2. Heat-conducting column; 3. Middle microchannel layer; 4. Bottom substrate layer; 5. External drive component; 6. RF device unit; 7. Main manifold microchannel; 8. Bypass manifold microchannel; 9. Diverter microneedle fin; 10. Disturbing microneedle fin; 11. Liquid inlet; 12. Liquid outlet; 13. Controller; 14. Liquid inlet microtube; 15. Liquid outlet microtube; 16. Micropump. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a mechanical connection or an electrical connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] The following will further introduce the specific implementation method, as well as the technical difficulties and inventive points of this invention in combination with this design example.

[0042] In one embodiment, see Figure 1 and Figure 2 , provides an embedded manifold microchannel LTCC substrate with additional micro-needle fins, including a top cover layer 1, a middle microchannel layer 3, a bottom substrate layer 4 and an external driving component 5.

[0043] The top cover plate layer 1 is formed by stacking and sintering the first to fifth layers of raw ceramic sheets, and the top cover plate layer 1 includes a radio frequency device unit 6 and a heat conducting column 2 .

[0044] The middle microchannel layer 3 is formed by stacking and sintering the sixth to ninth layers of raw ceramic sheets, and the middle microchannel layer 2 includes a main manifold microchannel 7, a plurality of bypass manifold microchannels 8, a plurality of diversion micropin fins 9 and a plurality of turbulent micropin fins 10.

[0045] The bottom substrate layer 4 is formed by stacking and sintering the tenth to fifteenth layers of green ceramic sheets, and the bottom substrate layer 4 includes a liquid inlet 11 and a liquid outlet 12 .

[0046] The external driving component 5 includes a controller 13 , a liquid inlet microtube 14 , a liquid outlet microtube 15 and a micropump 16 .

[0047] The thickness of the LTCC substrate is at least 1.5 mm, that is, the total number of layers must be no less than 15 layers. The number of raw ceramic layers of the top cover layer 1, the middle microchannel layer 3, and the bottom substrate layer 4 is not fixed, but it must be ensured that the thickness of the middle microchannel layer 3 is no more than 1 / 3 of the total thickness, and the thickness of the top cover layer 1 and the bottom substrate layer 4 are equal.

[0048] Specifically, the controller is powered by DC 3.7V, and the default operating frequency is 30Hz after the circuit is started. The operating frequency of the controller is adjusted to control the flow rate of the cooling medium pumped by the micropump. Through the action of the micropump, the cooling medium is transmitted to the liquid inlet through the liquid inlet microtube, flows through the main manifold microchannel of the middle microchannel layer, and is distributed to the bypass manifold microchannel through the diversion microneedle fins. Then, it is fully mixed under the action of the turbulent microneedle fins to take away the heat generated by the RF device unit. Finally, the cooling medium is transmitted to the liquid outlet microtube through the liquid outlet and then transported to the external environment.

[0049] The cooling medium material includes but is not limited to water and fluorinated liquid with insulating properties.

[0050] In one embodiment, see Figure 1 , with regard to the radio frequency device unit, it is the prior art, and generally includes a connected switch, a power amplifier, a limiter, and a low noise amplifier.

[0051] In one embodiment, see Figure 1 The contact between the inlet and outlet liquid ports and the inlet and outlet micro-tubes is sealed by fasteners and sealants; by adjusting the working frequency of the controller, the flow rate of the micropump pressure cooling working fluid can be controlled.

[0052] In one embodiment, see Figure 2 The main manifold microchannel and bypass manifold microchannel of the middle microchannel layer are located directly below the RF device unit on the top ceramic cover layer. The manifold microchannel of the middle microchannel layer is a centrally symmetrical regular hexagonal flow channel structure. The main manifold microchannel is a trapezoidal structure, with the input section being a gradually tightening trapezoidal shape connected to the liquid inlet; the output section being a gradually expanding trapezoidal shape connected to the liquid outlet.

[0053] In one embodiment, see Figure 2 The centrally symmetrical regular hexagonal flow channel structure includes a main manifold microchannel and a plurality of bypass manifold microchannels, and the plurality of manifold microchannels are in the shape of a regular hexagon with increasing side lengths from the inside to the outside.

[0054] In one embodiment, see Figure 2The manifold microchannels have the same height, and the spacing between adjacent bypass manifold microchannels is consistent; the diverter micropin fins are arranged in the input section of the main manifold microchannel, and the spoiler micropin fins are arranged in the bypass manifold microchannel. The cross-sectional shape of the micropin fins can be diamond, triangle, circle or teardrop-shaped. Considering the process difficulty and heat dissipation effect, a diamond with a sharp angle of 60° is adopted.

[0055] In one embodiment, see Figure 3 , which is the working flow chart of the external drive component. The DC power supply is turned on and the controller starts the power supply. The circuit starts to work normally. The default frequency of the initial state is 30Hz. The pump pressure flow is controlled by changing the frequency by touching the relay button. Long press the relay button to save the current working state, and the micropump continues to work according to this state.

[0056] In one embodiment, see Figure 4 , is a flow chart of preparing an embedded manifold microchannel LTCC substrate with additional micro-needle fins provided in some embodiments of the present invention. The raw ceramic sheets for making the LTCC substrate can be Dupont 951 or Dupont 940, etc. The thickness of each layer of raw ceramic sheet is about 114μm, the shrinkage rate in the X-axis and Y-axis directions is 12.7±0.3%, the shrinkage rate in the Z-axis direction is 15±0.5%, and the density of the raw ceramic sheet is 3g / cm 3 , thermal conductivity is 3.3W / (m·k). First, screen printing is used to complete the production of circuit graphics and electrical interconnection through holes on the raw ceramic sheets; then, positioning holes, conductive holes, and heat dissipation holes are punched on the raw ceramic sheets; secondly, cavities and microchannel structures are produced on the multi-layer raw ceramic sheets by laser cutting; then, sacrificial materials such as graphite and starch are filled in the microchannels. The sacrificial materials can transmit pressure during lamination to support and protect the microchannels from or reduce the influence of molding pressure, thereby maintaining the stability of the microchannel structure and size to the greatest extent, and the deformation problem can be solved; the raw ceramic sheets are stacked and aligned through the positioning holes; the top, middle, and bottom three parts of the raw ceramic sheets are stacked and pre-pressed respectively to obtain sub-modules of the top, middle, and bottom parts; then the sub-modules are bonded with organic adhesives to form an overall module at low temperature and low pressure; finally, the multi-layer ceramic substrate is laminated and sintered, and the sacrificial materials are vaporized and discharged during the sintering process to form a microchannel cavity, thereby obtaining an LTCC substrate with integrated circuits and heat dissipation with embedded microchannels.

[0057] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. An embedded manifold microchannel LTCC substrate with additional micro-pin fins, characterized in that: include: A top cover layer (1), a middle microchannel layer (3), a bottom substrate layer (4) and an external drive component (5); a radio frequency device unit (6) is arranged on the top cover layer (1), and a plurality of heat-conducting columns (2) are arranged therein; the heat-conducting columns (2) are used to conduct heat generated by the radio frequency device unit (6); the middle microchannel layer (3) is provided with a main manifold microchannel (7) and a bypass manifold microchannel (8); a plurality of flow-dividing micro-needle fins (9) are arranged on the input section of the main manifold microchannel (7); a plurality of flow-disrupting micro-needle fins (10) are arranged on the bypass manifold microchannel (8); a liquid inlet (11) and a liquid outlet (12) are opened on the bottom substrate layer (4); and the external drive component (5) is composed of a controller (13), a liquid inlet microtube (14), a liquid outlet microtube (15) and a micropump (16); When in operation, the cooling medium is controlled by the controller (13) and is transferred to the liquid inlet (11) through the liquid inlet microtube (14) via the action of the micropump (16), flows through the main manifold microchannel (7) of the middle microchannel layer (3), and is distributed to the bypass manifold microchannel (8) via the diversion micropin fin (9). Then, the cooling medium is fully mixed under the action of the turbulent micropin fin (10) to remove the heat generated by the radio frequency device unit (6). Finally, the cooling medium is transferred to the liquid outlet microtube (15) through the liquid outlet (12) and then transported to the external environment.

2. The LTCC substrate with embedded manifold microchannels and additional micro-pin fins according to claim 1, characterized in that: The LTCC substrate is formed by stacking and sintering a plurality of raw ceramic sheets, the thickness of the middle microchannel layer (3) is no more than 1 / 3 of the total thickness, and the thickness of the top cover layer (1) and the bottom substrate layer (4) are equal.

3. The LTCC substrate with embedded manifold microchannels and additional micro-pin fins according to claim 1, characterized in that: A radio frequency device unit (6) and a heat-conducting column (2) are arranged on the top cover plate layer (1); the heat-conducting column (2) is made of a metallic copper material, and the heat-conducting column (2) can assist in efficiently transferring the heat of the radio frequency device unit (6) to the middle microchannel layer (3).

4. The LTCC substrate with embedded manifold microchannels and additional micro-pin fins according to claim 1, characterized in that: The main manifold microchannel (7) and the bypass manifold microchannel (8) of the middle microchannel layer (3) are located directly below the area where the radio frequency device unit (6) is arranged on the top cover layer (1).

5. The LTCC substrate with embedded manifold microchannels and additional micro-pin fins according to claim 4, characterized in that: The microchannels of the middle microchannel layer (3) are generally centrally symmetrical regular hexagonal flow channel structures, the flow channel heights of the microchannels are consistent, and the spacings between adjacent bypass manifold microchannels (8) are consistent.

6. The LTCC substrate with embedded manifold microchannels and additional micro-pin fins according to claim 1, characterized in that: The cross-sectional shapes of the flow-dividing micro-needle fin (9) and the flow-disturbing micro-needle fin (10) are both rhombus-shaped with a sharp angle of 60° and the same circumference.

7. The LTCC substrate with embedded manifold microchannels and additional micro-pin fins according to claim 6, characterized in that: The flow-dividing micro-needle fin (9) is arranged at the input section of the main manifold micro-channel (7), and the flow-disturbing micro-needle fin (10) is arranged at the entire flow path of the bypass manifold micro-channel (8).

8. The LTCC substrate with embedded manifold microchannels and additional micro-pin fins according to claim 1, characterized in that: The main manifold microchannel (7) has a trapezoidal structure, wherein the input section is a gradually tightening trapezoidal shape connected to the liquid inlet (11); and the output section is a gradually expanding trapezoidal shape connected to the liquid outlet (12).

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