Method for integrating embedded heat dissipation micro-channel in LTCC ceramic substrate

Abstract

The invention discloses a method for integrating an embedded heat dissipation micro-channel in an LTCC (Low Temperature Co-Fired Ceramic) substrate, and relates to the technical field of microelectronic integration. The method is used for sequentially blocking out micro-channels which do not need to be pressed, and comprises the following steps that firstly, a limiting assembly is poured through a mold; 2, manufacturing a circuit layer; 3, manufacturing the stand columns by using the limiting assemblies in sequence; and 4, mounting a ceramic substrate II between the top ends of the stand columns, separating a plurality of micro-channels, and sintering. According to the invention, the plurality of limiting assemblies are manufactured in advance, the spaces of the sub-columns are limited and blocked on the ceramic substrates by virtue of the limiting assemblies, so that the plurality of micro-channels are formed between the two adjacent ceramic substrates, and the sub-columns are formed by limiting and blocking, so that the sintered micro-channels are in a regular state; and pressing is not needed until sintering is completed, and the situation of deformation caused by pressure after sintering is effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field of microelectronic integration, and in particular to a method for integrating an embedded heat dissipation microchannel in a LTCC ceramic substrate. Background Art

[0002] LTCC stands for low-temperature co-fired ceramics. It is made by preparing a green porcelain tape with precise thickness and density, and then producing the required circuit graphics on the green porcelain tape through processes such as laser drilling, micropore injection, and precision conductor paste printing. It also integrates multiple passive components and is mainly used for passive integration, system-level packaging, and multi-layer circuit substrates. It enables electronic products to have a smaller shape and thinner size, while being more powerful. However, the high integration also leads to higher requirements for structural heat dissipation.

[0003] The patent specification with publication number CN105514060B discloses a method for integrating embedded heat dissipation microchannels in LTCC ceramic substrates, which includes step 1: dividing the LTCC raw ceramic sheets into N groups according to the structural requirements of the heat dissipation microchannels, and completing the production of interconnection through holes and circuit patterns on each LTCC raw ceramic sheet; step 2: laminating and pre-pressing them according to the grouping situation to obtain N sub-modules; step 3: processing positioning holes and microchannel required structures on the sub-modules, and then bonding the sub-modules with adhesives, laminating them under low pressure, and finally sintering and cutting the raw ceramic blocks.

[0004] This scheme divides the ceramic substrates into multiple groups, and processes positioning holes and local microchannels for assembly connection on each group of substrates, and then glues and collectively presses them to form a complete channel. The shortcomings of this technical scheme are: first, since the sub-channels are connected by adhesives, and the sub-channel bodies are only press-fitted, during unified sintering, the adhesive in the sub-channels will still cause obvious segmented deformation in the final product due to material differences. Secondly, the sub-channels in this scheme are composed of a large number of raw ceramic sheets stacked together. Therefore, after sintering, the raw ceramic sheets in the sub-channel group will still have channel deformation due to the existence of gaps, that is, the microchannels are formed by pressing multiple raw ceramic sheets before sintering, which causes the channels to deform after sintering, affecting the heat dissipation effect. Summary of the invention

[0005] The purpose of the present invention is to provide a method for integrating embedded heat dissipation microchannels in LTCC ceramic substrates. The technical problems to be solved are as follows: the microchannels embedded in the existing ceramic substrates are stacked and bonded structures before sintering, which leads to channel deformation after sintering, affecting the heat dissipation effect of the channels.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate is used to sequentially block out microchannels that do not require pressing, and the steps are as follows: Step 1 S10: Casting the limit assembly through a mold; Step 2 S20: making a circuit layer; Step 3 S30: using each limiting component in sequence to produce a column; Step 4 S40: Install the second ceramic substrate between the top ends of the pillars to isolate a plurality of microchannels and sinter them.

[0007] As a further solution of the present invention: the limiting assembly includes an outer casting, an inner casting 1, an inner casting 2, an inner casting 3 and a plurality of spacer castings.

[0008] As a further solution of the present invention: the specific implementation method of making the circuit layer in step 2 S20 is: Step 1 S21: Mix and melt the raw materials to form a slurry, press the slurry into a green sheet with the help of a scraper, and cut the green sheet into a single green sheet; Step 2 S22: Paste the green sheet onto the ceramic substrate 1; Step three S23: photolithography, development and electroplating of the raw film to form the circuit layer.

[0009] As a further solution of the present invention: the column includes sub-column one, sub-column two, sub-column three and sub-column four.

[0010] As a further solution of the present invention: the specific implementation method of sequentially manufacturing the columns in step 3 S30 is: Step S31: placing one side of the outer casting against one side of the ceramic substrate, electroplating and growing a copper layer on the side away from the outer casting, and grinding the grown copper-shaped column to form a sub-column one; Step S32: remove the outer casting, place one side of the inner casting against one side of the column one, cooperate with the column one to block the electroplating space, and perform electroplating copper growth, and grind to form the column two; Step S33: remove the inner casting 1, place one side of the inner casting 2 against one side of the sub-column 2, place one side of one of the spacer castings against one side of the sub-column 1, block the electroplating space, electroplate copper and grind to form the sub-column 3; Step S34: remove the inner casting 2 and the spacer casting, place one side of the inner casting 3 against one side of the sub-column 2, place one side of one of the spacer castings against one side of the sub-column 3, block the electroplating space, electroplate copper and grind to form the sub-column 4; Step S35: remove the inner casting three and the spacer casting, place two of the spacer castings against the adjacent sides of the sub-column two and the sub-column four respectively to block the electroplating space, electroplate copper and grind to form the sub-column five, and remove the two spacer castings.

[0011] As a further solution of the present invention: the specific implementation method of installing the second ceramic substrate in step four S40 is: electroplating a green sheet between the top ends of the pillars, pasting the second ceramic substrate on the top ends of the green sheet, and the pillars blocking four microchannels.

[0012] Beneficial effects of the present invention: In the present invention, multiple limiting components are prefabricated, and each limiting component is used to limit and block each column space on the ceramic substrate. Each column space is electroplated and subsequently polished to produce evenly arranged columns on the top of the ceramic substrate. The ceramic substrate on the top is then installed and finally sintered to form multiple microchannels between two adjacent ceramic substrates. Since each column is formed by limiting and blocking, the microchannel after sintering is in a regular state, and no pressing is required until sintering is completed, which effectively avoids deformation after sintering due to pressure. Furthermore, since the height and width of each microchannel are preset when the limiting component is manufactured, when the electroplated sub-columns are used in sequence, only one sub-column needs to be manufactured at a time. During the subsequent grinding, the top of the sub-column can be ground according to the height of the limiting component. When its height is flush with the height of the limiting component, the manufacturing is completed, thereby avoiding the difficulty in unifying the height when multiple sub-columns are manufactured at a time, thereby improving the accuracy of the manufacturing height of the column and improving the flatness of the subsequent sintering and capping ceramic substrate; Furthermore, since each sub-column is grown by integrated electroplating during production, when the ceramic substrate is capped and sintered, the sub-columns are electroplated as a whole and the sides are restricted by adjacent limiting components. Therefore, the side edges will not have layered patterns caused by multiple stacking and batch production, which further reduces the deformation of the side walls after sintering, is more conducive to the smooth passage of the heat dissipation airflow, and improves the heat dissipation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described below in conjunction with the accompanying drawings.

[0014] Figure 1 It is a schematic diagram of the connection structure between the circuit layer and the ceramic substrate of the present invention; Figure 2 It is a schematic diagram of the structure of a column-electroplating layer of the present invention; Figure 3 It is a schematic diagram of the structure of the two electroplating layers of the column of the present invention; Figure 4 It is a schematic diagram of the structure of the three-electroplating layer of the column of the present invention; Figure 5 It is a schematic diagram of the structure of the four electroplating layers of the column of the present invention; Figure 6 It is a schematic diagram of the structure of the five electroplating layers of the column of the present invention; Figure 7It is a schematic diagram of the structure of the microchannels formed by the columns of the two stacked layers of the ceramic substrate of the present invention.

[0015] In the figure: 1. Circuit layer; 2. Ceramic substrate 1; 3. Pillar; 31. Sub-column 1; 32. Sub-column 2; 33. Sub-column 3; 34. Sub-column 4; 35. Sub-column 5; 4. Outer casting; 5. Inner casting 1; 6. Inner casting 2; 7. Spacer casting; 8. Inner casting 3; 9. Microchannel; 10. Ceramic substrate 2. DETAILED DESCRIPTION

[0016] 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.

[0017] like Figures 1 to 7 As shown, a method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate is used to sequentially separate microchannels 9 that do not need to be pressed. Step 1: casting a limiting component through a mold, the limiting component includes an outer casting 4, an inner casting 1 5, an inner casting 2 6, an inner casting 3 8 and a spacer casting 7; Specifically, since the size of the pillars 3 between the microchannels 9 is relatively small, usually about half a millimeter, it is impossible to directly connect with the ceramic substrate 2 after manufacturing, so it is necessary to cast a limiting component for blocking the pillars 3 through a copper mold (not shown) in advance. Through the sequential use of the limiting components, the subsequent electroplating of each sub-column is realized one by one. A baffle is set on one side of the outer casting 4 in the limiting component for clamping on one side of the ceramic substrate 2. The inner casting 1 5, the inner casting 2 6, the inner casting 3 8 and the spacer casting 7 are reduced in sequence. The spacer casting 7 needs to be cast and manufactured in multiples, and its width is the set channel width. The limiting components are used in order from large to small. Preferably, the limiting components are composed of inorganic gel material, cooled and formed after casting, and the height of each limiting component is the same as the set channel height.

[0018] Step 2, making the circuit layer 1, that is, after the preparation of the limiting component is completed, the bottom plate of the stacked ceramic substrate is made. Specifically, the raw materials of the circuit board are first mixed and melted to form a slurry, and then the slurry is pressed into a raw sheet strip by a scraper through a casting method, and then cut into a single raw sheet. The main material of the raw sheet is copper. Secondly, the prepared raw sheet is pasted on a ceramic substrate 2. Finally, the raw sheet is made into a circuit layer 1 through photolithography, development and electroplating of circuit layers.

[0019] Step 3, sequentially manufacturing each sub-column, wherein each sub-column is assembled into a column 3, the column 3 includes a sub-column 1 31, a sub-column 2 32, a sub-column 3 33 and a sub-column 4 34; Specifically, it includes making a sub-column 31 (see Figure 2 ), one side of the outer casting 4 is butted against one side of the ceramic substrate 2, and then copper is printed on the upper surface of the ceramic substrate 2 by a layer-by-layer printing and growth electroplating process on the side away from the outer casting 4. Since the width of the outer casting 4 is shorter than the upper surface of the ceramic substrate 2 by the width of a column, the grown copper-shaped column is ground after printing to form a column 31 that is finally elevated with the microchannel 9; Then make column 2 32 (see Figure 3 ), after the outer casting 4 is corroded and cleaned, one side of the inner casting 5 is pressed against the inner side of the generated and ground sub-column 31. Since the width of the inner casting 5 is equal to the width of the top of the ceramic substrate 2 minus the width of the two sub-columns, after the copper column is grown on the other side of the top of the ceramic substrate 2, the copper column is polished to form the sub-column 32; Then make the three sub-columns 33 (see Figure 4 ), after the inner casting 5 is corroded and cleaned, one side of the inner casting 2 6 is pressed against the inner side of the second column 32, and the width of the inner casting 2 6 is equal to the width of the top of the ceramic substrate 2 minus the width of the three columns and the microchannel 9, and at the same time, one side of the spacer casting 7 is pressed against the inner side of the first column 31, and then a slot with the width of the column is reserved at the top of the ceramic substrate 2, and finally the third column 33 is formed by electroplating a copper layer and polishing; Then make the four columns 34 (see Figure 5 ), the inner casting 2 6 and the outer spacer casting 7 are corroded and cleaned, and then one side of the inner casting 3 8 is pressed against the inner side of the second column 32, and the width of the inner casting 3 8 is equal to the width of the top of the ceramic substrate 1 2 minus the width of four columns and two microchannels 9, and at the same time, one side of the spacer casting 7 is pressed against one side of the third column 33, and then a slot with the width of a column is reserved at the top of the ceramic substrate 1 2, and then a copper layer is electroplated and polished to form a fourth column 34; Finally, make the column 5 35 (see Figure 6 ), the inner casting 3 8 and the spacer casting 7 are corroded and cleaned, and then two new spacer castings 7 are respectively placed against one side of the second sub-column 32 and one side of the fourth sub-column 34, and a space of the width of a sub-column is reserved between the two new spacer castings 7, and then a copper layer is electroplated and polished to form a fifth sub-column 35; After the sub-columns 5 35 are made, the last two spacer castings 7 are corroded and cleaned, and the sequential growth and electroplating of each sub-column is completed. Since each sub-column is formed by integrated electroplating, and is limited during the forming process, and is polished after forming, no pressing is required during the process, so that each micro-channel 9 finally separated out has a regular overall shape and accurate size. When the micro-channels 9 that are regular and accurately reach the predetermined size are subsequently sintered on the ceramic substrate, the accuracy of the size of the final product will not be affected, thereby improving the product yield; Preferably, each casting used to separate the sub-columns can be fixed by bonding.

[0020] Step 4: electroplate a green sheet between the tops of each column, and then paste a ceramic substrate 2 10 on the top of the green sheet. Then, each column blocks four microchannels 9 with the help of ceramic substrate 1 2 and ceramic substrate 2 10. Finally, print the circuit layer 1 on the ceramic substrate 2 10. When multi-layer printing and multi-layer heat dissipation are required, the heat dissipation channel layer can still be replicated between the two ceramic substrates by re-electroplating the green sheet and superimposing the ceramic substrates, thereby realizing the embedded heat dissipation channel function of the multi-layer structure ceramic substrate. After production, the green ceramic blocks are centrally sintered to complete the overall production of the ceramic substrate. Each column of each layer of heat dissipation channel is integrally formed and is not affected by sintering deformation.

[0021] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate, characterized in that: The steps for sequentially blocking out the microchannels (9) that do not need to be pressed are as follows: Step 1 S10: Casting the limit assembly through a mold; Step 2 S20: making a circuit layer (1); Step 3 S30: using each limiting component in sequence to produce a column (3); Step 4 S40: Install the second ceramic substrate (10) on the top of the pillar (3), block a plurality of microchannels (9) and sinter.

2. A method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate according to claim 1, characterized in that: The limiting assembly comprises an outer casting (4), an inner casting 1 (5), an inner casting 2 (6), an inner casting 3 (8) and a plurality of spacer castings (7).

3. A method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate according to claim 2, characterized in that: The specific implementation method of manufacturing the circuit layer (1) in step 2 S20 is: Step 1 S21: Mix and melt the raw materials to form a slurry, press the slurry into a green sheet with the help of a scraper, and cut the green sheet into a single green sheet; Step 2 S22: Paste the green sheet onto the ceramic substrate 1 (2); Step three S23: photolithography, development and electroplating of the raw film to form the circuit layer (1).

4. The method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate according to claim 3, characterized in that: The column (3) comprises a sub-column 1 (31), a sub-column 2 (32), a sub-column 3 (33) and a sub-column 4 (34).

5. The method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate according to claim 4, characterized in that: The specific implementation method of sequentially manufacturing the pillars (3) in step 3 S30 is: Step S31: placing one side of the outer casting (4) against one side of the ceramic substrate (2), electroplating and growing a copper layer on the side away from the outer casting (4), and grinding the grown copper-shaped column to form a branch column (31); Step S32: removing the outer casting (4), placing one side of the inner casting (5) against one side of the first column (31), cooperating with the first column (31) to block the electroplating space, and performing electroplating copper growth, and grinding to form the second column (32); Step S33: remove the inner casting 1 (5), place one side of the inner casting 2 (6) against one side of the second branch column (32), place one side of one of the spacer castings (7) against one side of the first branch column (31), block the electroplating space, electroplate copper and grind to form the third branch column (33); Step S34: remove the second inner casting (6) and the spacer casting (7), place one side of the third inner casting (8) against one side of the second branch column (32), place one side of one of the spacer castings (7) against one side of the third branch column (33), block the electroplating space, electroplate copper and grind to form the fourth branch column (34); Step S35: remove the inner casting three (8) and the spacer casting (7), place two of the spacer castings (7) against the adjacent sides of the sub-column two (32) and the sub-column four (34) respectively to block the electroplating space, electroplate copper and grind to form the sub-column five (35), and remove the two spacer castings (7).

6. A method for integrating embedded heat dissipation microchannels in a LTCC ceramic substrate according to claim 5, characterized in that: The specific implementation method of installing the second ceramic substrate (10) in the step 4 S40 is: electroplating a green sheet between the top ends of the pillars (3), pasting the second ceramic substrate (10) on the top ends of the green sheet, and the pillars (3) blocking four microchannels (9).

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