A ceramic-based double-sided printed circuit board and a manufacturing method thereof

Abstract

The application discloses a ceramic-based double-sided printed circuit board and a manufacturing method thereof, and relates to the technical field of circuit board manufacturing. The method comprises the following steps: providing a metal carrier, manufacturing an unsintered ceramic layer on one side surface of the metal carrier, manufacturing an interconnection hole penetrating through the ceramic layer to the metal carrier at a preset position on the surface of the ceramic layer, sintering the ceramic layer, manufacturing a metal interconnection structure connecting the metal carrier and the surface of the ceramic layer in the interconnection hole, manufacturing a first circuit pattern contacting the metal interconnection structure on the surface of the ceramic layer, manufacturing a second circuit pattern on the other side surface of the metal carrier, connecting the first circuit pattern and the second circuit pattern through the metal interconnection structure and the metal carrier, and forming the ceramic-based double-sided printed circuit board. The method reduces the manufacturing cost of the ceramic-based double-sided printed circuit board.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, and in particular to a ceramic-based double-sided printed circuit board and its manufacturing method. Background Technology

[0002] Currently, the insulating dielectric material of printed circuit boards (PCBs) is mainly a mixture of organic resins and inorganic fillers, which generally has poor thermal conductivity, typically below 1 W / m·K. In contrast, ceramic materials possess extremely excellent thermal conductivity. Silicon nitride ceramics can achieve thermal conductivity above 10 W / m·K, alumina ceramics can reach 30 W / m·K, and aluminum nitride ceramics can reach up to 300 W / m·K. Therefore, using ceramics as the dielectric material for PCBs can significantly improve their thermal conductivity. However, ceramic materials present challenges in metallization, especially the metallization of interconnect holes, leading to significant difficulties in fabricating interlayer interconnects in double-sided ceramic boards and resulting in high costs for manufacturing ceramic-based double-sided PCBs. Summary of the Invention

[0003] Therefore, it is necessary to provide a ceramic-based double-sided printed circuit board and its manufacturing method to address the above-mentioned technical problems, so as to solve the problems of high manufacturing difficulty in fabricating interlayer interconnections of double-sided ceramic boards and high cost in manufacturing ceramic-based double-sided printed circuit boards.

[0004] In a first aspect, the present invention provides a method for manufacturing a ceramic-based double-sided printed circuit board, comprising:

[0005] A metal carrier is provided, an unsintered ceramic layer is formed on one side surface of the metal carrier, and an interconnection hole is formed at a predetermined position on the surface of the ceramic layer to penetrate the ceramic layer and reach the metal carrier.

[0006] The ceramic layer is sintered, and a metal interconnect structure connecting the metal carrier and the surface of the ceramic layer is formed in the interconnect hole;

[0007] A first circuit pattern is formed on the surface of the ceramic layer to contact the metal interconnect structure, and a second circuit pattern is formed on the other side surface of the metal carrier. The first circuit pattern and the second circuit pattern are connected to the metal carrier through the metal interconnect structure to form a ceramic-based double-sided printed circuit board.

[0008] The above solution has the following beneficial effects:

[0009] The method for manufacturing a ceramic-based double-sided printed circuit board of the present invention involves fabricating interconnect holes on an unsintered ceramic layer, then fabricating metal connection structures within the interconnect holes and circuit patterns on both sides. Fabricating metal connection structures on an unsintered ceramic layer greatly reduces the difficulty of fabricating interconnects between layers of the double-sided ceramic board and reduces the manufacturing cost of the ceramic-based double-sided printed circuit board.

[0010] Optionally, the ceramic layer is sintered, and a metal interconnect structure connecting the metal carrier and the surface of the ceramic layer is formed within the interconnect hole; a first circuit pattern contacting the metal interconnect structure is formed on the surface of the ceramic layer, and a second circuit pattern is formed on the other side surface of the metal carrier, including:

[0011] A metal paste is printed on the surface of the ceramic layer, and the metal paste fills the interconnect holes while simultaneously creating the first circuit pattern on the surface of the ceramic layer.

[0012] The ceramic layer is sintered, and photoresist layers are formed on the surface of the first circuit pattern and on the other side of the metal carrier, respectively, with the photoresist layer on the surface of the first circuit pattern completely covering the first circuit pattern.

[0013] A window is made at a predetermined position of the photoresist layer on the other side of the metal carrier, and the metal carrier at the window position is etched away using an etching method to remove the photoresist layer on the surface of the metal carrier, thereby obtaining the second circuit pattern.

[0014] Optionally, a second circuit pattern is formed on the other side surface of the metal carrier, including:

[0015] A window is made at a predetermined position of the photoresist layer on the other side of the metal carrier. A metal material is electroplated at the window position using a pattern electroplating method, so that the metal at the window position is higher than the metal carrier by a predetermined distance. The photoresist layer on the other side of the metal carrier and the metal carrier covered by the photoresist layer are removed to obtain the second circuit pattern.

[0016] Optionally, a metal interconnect structure connecting the metal carrier and the surface of the ceramic layer is fabricated within the interconnect hole, including:

[0017] An electroplated protective film is attached to the other side of the metal carrier, and a metal material is electroplated inside the interconnect hole using the metal carrier as a conductive layer to obtain the metal interconnect structure.

[0018] Optionally, a first circuit pattern is formed on the surface of the ceramic layer to contact the metal interconnect structure, and a second circuit pattern is formed on the other side surface of the metal carrier, including:

[0019] Grind the metal interconnect structure that protrudes from the ceramic layer so that the end face of the metal interconnect structure is on the same plane as the surface of the ceramic layer;

[0020] A metal layer of a predetermined thickness is formed on the surface of the ceramic layer, and photoresist layers are formed on the surface of the metal layer and on the other side of the metal carrier, respectively.

[0021] Windowing is performed at preset positions of each photoresist layer, and the metal material at the windowed positions is etched away using an etching method to remove all photoresist layers, thereby obtaining the first circuit pattern located on the surface of the ceramic layer and the second circuit pattern located on the other side of the metal carrier.

[0022] Optionally, a metal layer of a predetermined thickness is formed on the surface of the ceramic layer, including:

[0023] A seed layer is formed by sputtering on the surface of the ceramic layer, and a metal material of a predetermined thickness is electroplated on the surface of the seed layer to form the metal layer.

[0024] Optionally, a first circuit pattern is formed on the surface of the ceramic layer to contact the metal interconnect structure, and a second circuit pattern is formed on the other side surface of the metal carrier, including:

[0025] Windowing is performed at preset positions of each of the photoresist layers, and metal material is electroplated at the window positions using a pattern electroplating method, so that the metal at the window positions is higher than the metal layer or the metal carrier by a preset distance.

[0026] Remove all the photoresist layers and the metal carrier covered by the photoresist layers to obtain the first circuit pattern located on the surface of the ceramic layer and the second circuit pattern located on the other side of the metal carrier.

[0027] Optionally, a metal interconnect structure connecting the metal carrier and the surface of the ceramic layer is formed within the interconnect hole; a first circuit pattern contacting the metal interconnect structure is formed on the surface of the ceramic layer, and a second circuit pattern is formed on the other side surface of the metal carrier, including:

[0028] A seed layer is formed on the surface of the ceramic layer and the inner wall of the interconnecting hole;

[0029] A photoresist pattern is fabricated on the surface of the ceramic layer, and metal is electroplated according to the photoresist pattern to obtain the metal interconnect structure and the first circuit pattern.

[0030] Remove the photoresist pattern and the seed layer below the photoresist pattern, and fabricate a photoresist layer on the surface of the ceramic layer and the surface of the metal carrier;

[0031] A window is made at a predetermined position on the photoresist layer on the surface of the metal carrier, and the metal carrier at the window position is etched away using an etching method to remove the photoresist layer on the surface of the metal carrier, thereby obtaining the second circuit pattern.

[0032] Optionally, an unsintered ceramic layer is formed on one side surface of the metal carrier, and an interconnecting hole penetrating the ceramic layer and reaching the metal carrier is formed at a predetermined position on the surface of the ceramic layer, including:

[0033] An unsintered ceramic layer of a predetermined thickness is formed on the surface of the metal carrier by casting or molding.

[0034] The interconnecting holes are made at predetermined positions on the surface of the ceramic layer by mechanical drilling or laser engraving, so that the interconnecting holes pass through the ceramic layer and reach but do not pass through the metal carrier.

[0035] In a second aspect, the present invention provides a ceramic-based double-sided printed circuit board, comprising:

[0036] Ceramic layer, metal carrier, first circuit pattern, and second circuit pattern;

[0037] The ceramic layer is located above the metal carrier, and a metal interconnect structure is provided within the ceramic layer. The first circuit pattern is located on one side of the ceramic layer, and the second circuit pattern is located on the other side of the ceramic layer. The first circuit pattern and the second circuit pattern are connected to the metal carrier through the metal interconnect structure.

[0038] The above solution has the following beneficial effects:

[0039] The ceramic-based double-sided printed circuit board of the present invention uses ceramic material as the substrate. Ceramic material has extremely good thermal conductivity. Using ceramic as the dielectric material of the printed circuit board can significantly improve the thermal conductivity of the printed circuit board, thereby improving the performance of the printed circuit board. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart of a method for manufacturing a ceramic-based double-sided printed circuit board according to an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of a structure for fabricating a ceramic layer on a metal carrier according to an embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of a structure for fabricating interconnect holes in a ceramic layer according to an embodiment of the present invention;

[0044] Figure 4(a) is a schematic diagram of the first method for fabricating a metal interconnect structure and a first circuit pattern provided in an embodiment of the present invention;

[0045] Figure 4(b) is a schematic diagram of the first type of sintered ceramic layer provided in an embodiment of the present invention;

[0046] Figure 4(c) is a schematic diagram of the structure of the first type of photoresist layer provided in an embodiment of the present invention;

[0047] Figure 4(d) is a schematic diagram of a first method for fabricating a second circuit pattern according to an embodiment of the present invention;

[0048] Figure 4(e) is a schematic diagram of a second structure for setting a photoresist layer provided in an embodiment of the present invention;

[0049] Figure 4(f) is a schematic diagram of a second method for fabricating a second circuit pattern provided in one embodiment of the present invention;

[0050] Figure 5(a) is a schematic diagram of a second type of sintered ceramic layer provided in an embodiment of the present invention;

[0051] Figure 5(b) is a schematic diagram of a method for manufacturing a metal connecting post according to an embodiment of the present invention;

[0052] Figure 5(c) is a schematic diagram of a ground metal connecting post provided in one embodiment of the present invention;

[0053] Figure 5(d) is a schematic diagram of a method for fabricating a metal layer according to an embodiment of the present invention;

[0054] Figure 5(e) is a schematic diagram of a third method of setting a photoresist layer according to an embodiment of the present invention;

[0055] Figure 5(f) is a schematic diagram of a first method for fabricating a first circuit pattern and a second circuit pattern according to an embodiment of the present invention;

[0056] Figure 5(g) is a schematic diagram of the fourth method of setting a photoresist layer provided in one embodiment of the present invention;

[0057] Figure 5(h) is a schematic diagram of a second method for fabricating the first circuit pattern and the second circuit pattern according to an embodiment of the present invention;

[0058] Figure 6(a) is a schematic diagram of a seed layer fabrication method provided in an embodiment of the present invention;

[0059] Figure 6(b) is a schematic diagram of the fifth method of setting a photoresist layer provided in one embodiment of the present invention;

[0060] Figure 6(c) is a schematic diagram of a second method for fabricating a metal interconnect structure and a first circuit pattern provided in an embodiment of the present invention;

[0061] Figure 6(d) is a schematic diagram of the sixth method of setting a photoresist layer provided in one embodiment of the present invention;

[0062] Figure 6(e) is a schematic diagram of a third method for fabricating the first and second circuit patterns according to an embodiment of the present invention;

[0063] Figure 6(f) is a schematic diagram of the seventh method of setting a photoresist layer provided in one embodiment of the present invention;

[0064] Figure 6(g) is a schematic diagram of a third method for fabricating a second circuit pattern provided in one embodiment of the present invention;

[0065] Figure 7 This is a schematic diagram of the structure of a ceramic-based double-sided printed circuit board provided in one embodiment of the present invention;

[0066] The symbols are explained as follows:

[0067] 100. Metal carrier; 200. Ceramic layer; 201. Interconnect hole; 202. Metal connecting post; 203. First circuit pattern; 204. Second circuit pattern; 205. Third circuit pattern; 301. First photoresist layer; 302. Second photoresist layer; 303. Third photoresist layer; 304. Fourth photoresist layer; 305. Fifth photoresist layer; 306. Sixth photoresist layer; 307. Seventh photoresist layer; 308. Eighth photoresist layer; 309. Ninth photoresist layer; 310. Tenth photoresist layer; 311. Eleventh photoresist layer; 312. Twelfth photoresist layer; 400. Metal layer; 500. Seed layer. Detailed Implementation

[0068] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0069] In one embodiment, a method such as Figure 1 The method for creating a ceramic-based double-sided suppression circuit board may include the following steps:

[0070] Step S100: Provide a metal carrier, form an unsintered ceramic layer on one side surface of the metal carrier, and form an interconnect hole that penetrates the ceramic layer and reaches the metal carrier at a predetermined position on the surface of the ceramic layer.

[0071] See Figure 2 A metal carrier 100 is provided, which is selected as copper foil. The type, size and thickness of the copper foil can be adjusted according to the circuit pattern parameters of the design.

[0072] An unsintered ceramic layer 200 of a predetermined thickness is formed on a metal carrier 100. The manufacturing method can be tape casting or molding, or other manufacturing methods can be selected. The ceramic material type can be aluminum nitride, silicon nitride, boron nitride, aluminum oxide, beryllium oxide, silicon carbide, etc.

[0073] See Figure 3 Interconnecting holes 201 are made at predetermined positions on the surface of ceramic layer 200 by mechanical drilling or laser engraving. When making interconnecting holes 201, the interconnecting holes 201 pass through ceramic layer 200 and reach but do not pass through metal carrier 100.

[0074] Step S200: Sinter the ceramic layer and fabricate a metal interconnect structure connecting the metal carrier and the surface of the ceramic layer within the interconnect holes.

[0075] Step S300: A first circuit pattern for contacting the metal interconnect structure is formed on the surface of the ceramic layer, and a second circuit pattern is formed on the other side of the metal carrier. The first circuit pattern and the second circuit pattern are connected to the metal carrier through the metal interconnect structure to form a ceramic-based double-sided printed circuit board.

[0076] In this embodiment, three methods for fabricating metal interconnect structures, a first circuit pattern, and a second circuit pattern are provided. The first method includes the following steps:

[0077] Step S1001: Print metal paste on the surface of the ceramic layer. The metal paste fills the interconnect holes and simultaneously creates the first circuit pattern on the surface of the ceramic layer.

[0078] Referring to Figure 4(a), before sintering the ceramic layer 200, a metal paste is first printed on the surface of the ceramic layer 200. The metal paste can be copper paste or silver paste. While filling the interconnect holes 201, the metal paste creates a pattern of the first circuit pattern 203 on the surface of the ceramic layer 200.

[0079] Step S1002: Sintering ceramic layer, photoresist layer is formed on the surface of the first circuit pattern and on the other side of the metal carrier respectively, and the photoresist layer on the surface of the first circuit pattern completely covers the first circuit pattern.

[0080] Referring to Figure 4(b), the sintered ceramic layer 200 and the first circuit pattern 203 on the surface of the ceramic layer 200 are such that the metal paste in the interconnect hole forms a metal interconnect structure 202; referring to Figure 4(c), a first photoresist layer 301 and a second photoresist layer 302 are respectively fabricated on the surface of the first circuit pattern 203 and on the other side of the metal carrier 100. The photoresist material is preferably a dry film, but photoresist can also be selected; wherein, the second photoresist layer 302 on the surface of the first circuit pattern completely covers the first circuit pattern 203 to protect the fabricated first circuit pattern 203; the paste printing method has lower cost and benefits from the co-sintering of the paste and ceramic, resulting in better adhesion.

[0081] Step S1003: Open a window at a preset position of the photoresist layer on the other side of the metal carrier, and use an etching method to etch and remove the metal carrier at the window position, thereby removing the photoresist layer on the surface of the metal carrier and obtaining the second circuit pattern.

[0082] Referring to Figure 4(c), according to the design of the second circuit pattern, exposure and development are performed at a preset position on the surface of the first photoresist layer 301 to form the second circuit pattern. Then, the metal carrier at the opening position of the first photoresist layer 301 is removed by etching, and the first photoresist layer 301 is removed. Finally, surface treatment and cutting steps are performed to obtain the ceramic-based double-sided printed circuit board shown in Figure 4(d).

[0083] The above-described method for fabricating the second circuit pattern is a subtractive method, that is, using photoresist patterns to selectively etch the metal carrier; as another implementation, a semi-additive method can also be used to fabricate the second circuit pattern, the fabrication method including the following steps:

[0084] Step 2001: Open a window at a preset position on the photoresist layer on the other side of the metal carrier.

[0085] Referring to Figure 4(e), a third photoresist layer 303 and a fourth photoresist layer 304 are respectively fabricated on the surface of the metal carrier 100 and the surface of the first circuit pattern 203. The photoresist material is preferably a dry film, but photoresist can also be selected. The fourth photoresist layer 304 completely covers the first circuit pattern 203 to protect the first circuit pattern 203. The third photoresist layer 303 is designed according to the pattern of the second circuit pattern, and is exposed and developed to open windows, exposing the positions of the second circuit pattern that need to be electroplated and covering the positions that need to be etched away.

[0086] Step S2002: Electroplating metal material at the window position using a pattern electroplating method, so that the metal at the window position is higher than the preset height of the metal carrier, removing the photoresist layer on the other side of the metal carrier and the metal carrier covered by the photoresist layer to obtain the second circuit pattern.

[0087] Referring to Figure 4(e), a patterned electroplating method is used to electroplat a metal material, which can be copper, at the window position of the third photoresist layer 303. The metal plated at the window position of the third photoresist layer 303 is higher than the preset height of the metal carrier 100, forming the third circuit pattern 205 as shown in Figure 4(f). Then, the third photoresist layer 303 and the metal carrier covered by the third photoresist layer 303 are removed, so that the metal carrier 100 forms the second circuit pattern 204. The second circuit pattern 204 and the third circuit pattern 205 are exactly the same pattern, and the two are superimposed to form an integrated circuit pattern. Finally, surface treatment and cutting steps are performed to obtain the ceramic-based double-sided printed circuit board as shown in Figure 4(f).

[0088] In this embodiment, the second method for fabricating the metal interconnect structure, the first circuit pattern, and the second circuit pattern includes the following steps:

[0089] Step S3001: An electroplated protective film is attached to the other side of the metal carrier, and a metal material is electroplated inside the interconnect hole using the metal carrier as a conductive layer to obtain a metal interconnect structure.

[0090] Referring to Figure 5(a), after the unsintered ceramic layer 200 is fabricated, the ceramic layer 200 is sintered. Then, an electroplated protective film is attached to the other side of the metal carrier 100 to prevent the surface of the metal carrier 100 from being electroplated with metal materials during electroplating. This electroplated protective film can be photoresist, dry film, or other photosensitive materials, or other non-photosensitive materials. Finally, a metal material is electroplated in the interconnect hole 201 with the metal carrier 100 as the conductive layer. This metal material can be copper, thus obtaining the metal interconnect structure 202 shown in Figure 5(b). The conductive interconnect structure fabricated by electroplating can be used for printed circuit boards for high-power devices. Compared with traditional brazed ceramic boards, the copper interconnect structure can further enhance its heat dissipation capacity.

[0091] Step S3002: Grind the metal interconnect structure protruding from the ceramic layer so that the end face of the metal interconnect structure is on the same plane as the surface of the ceramic layer.

[0092] In step S3001, in order for the metal interconnect structure 202 to completely fill the interconnect hole 201, it is necessary to protrude from the ceramic layer 200 by a predetermined height when electroplating the metal interconnect structure 202. Before making the first circuit pattern, the metal interconnect structure 202 protruding from the ceramic layer 200 needs to be ground, as shown in Figure 5(c), so that the end face of the metal interconnect structure 202 and the surface of the ceramic layer are on the same plane, so as to facilitate the making of the first circuit pattern.

[0093] Step S3003: A metal layer of a preset thickness is formed on the surface of the ceramic layer, and photoresist layers are formed on the surface of the metal layer and on the other side of the metal carrier.

[0094] A seed layer is formed on the surface of the ceramic layer 200. The preferred method for forming the seed layer is sputtering, but other methods such as vapor deposition, electroless copper plating, and paste coating can also be used. Then, copper of a predetermined thickness is electroplated on the surface of the seed layer to form a metal layer 400 as shown in Figure 5(d). When electroplating the metal layer, an electroplating protective film is attached to the surface of the metal carrier 100 to prevent the surface of the metal carrier 100 from being electroplated with metal materials during electroplating. This electroplating protective film can be a photosensitive material such as photoresist or dry film, or other non-photosensitive materials. A photoresist layer is formed on the surface of the metal layer 400 and on the other side of the metal carrier 100.

[0095] Step S3004: Open windows at preset positions of each photoresist layer, and use etching to remove the metal material at the window positions. Remove all photoresist layers to obtain a first circuit pattern on the surface of the ceramic layer and a second circuit pattern on the other side of the metal carrier.

[0096] Referring to Figure 5(e), according to the design patterns of the first and second circuit patterns, a sixth photoresist layer 306 and a fifth photoresist layer 305 are fabricated on the surface of the metal layer 400 and the surface of the metal carrier 100, respectively. The metal material at the window position of the photoresist layer is etched away by etching method. The fifth photoresist layer 305 and the sixth photoresist layer 306 are removed to obtain the first circuit pattern 203 on the surface of the ceramic layer 200 and the second circuit pattern 204 on the other side of the metal carrier, as shown in Figure 5(f).

[0097] The above-described method for fabricating the first and second circuit patterns is a subtractive method, that is, using photoresist patterns to selectively etch the metal carrier and the metal layer; as another embodiment, a semi-additive method can also be used to fabricate the first and second circuit patterns, the fabrication method including the following steps:

[0098] Step S4001: Open windows at preset positions of each photoresist layer, and electroplate metal material at the window positions using a pattern electroplating method, so that the metal at the window positions is higher than the preset height of the metal layer or metal carrier.

[0099] Following step S3003, after fabricating the surface of the metal layer 400 and the photoresist layer on the other side of the metal carrier 100, according to the design patterns of the first and second circuit patterns, windows are made at the preset positions of the corresponding photoresist layers. The window positions are the circuit patterns, and the covered positions are the positions that need to be etched away, forming the seventh photoresist layer 307 and the eighth photoresist layer 308 as shown in Figure 5(g). A metal material is electroplated at the window positions of the seventh photoresist layer 307 and the eighth photoresist layer 308 using a pattern electroplating method. The metal material can be copper, so that the metal electroplated at the window positions of the photoresist layers is higher than the preset height of the metal layer or the metal carrier.

[0100] Step S4002: Remove all photoresist layers and the metal carrier covered by the photoresist layers to obtain a first circuit pattern located on the surface of the ceramic layer and a second circuit pattern located on the other side of the metal carrier.

[0101] Etching removes all photoresist layers and the metal carrier located below the seventh photoresist layer 307, resulting in a first circuit pattern 203 on the surface of the ceramic layer. After etching the metal carrier 100, a second circuit pattern 204 is formed, while the electroplated metal material forms a third circuit pattern 205. The second and third circuit patterns are identical, and the two are superimposed to form an integrated circuit pattern.

[0102] In this embodiment, the third method for fabricating the metal interconnect structure, the first circuit pattern, and the second circuit pattern includes the following steps:

[0103] Step S5001: Create a seed layer on the surface of the ceramic layer and the inner wall of the interconnect hole.

[0104] After the interconnect holes of the ceramic layer are fabricated and the ceramic layer is sintered, as shown in Figure 6(a), a seed layer 500 is fabricated on the surface of the ceramic layer 200 and the inner wall of the interconnect hole 201. The preferred method for fabricating the seed layer 500 is vapor deposition, but sputtering, electroless copper plating, coating adsorption, etc. are also acceptable.

[0105] Step S5002: A photoresist pattern is fabricated on the surface of the ceramic layer, and metal is electroplated according to the photoresist pattern to obtain a metal interconnect structure and a first circuit pattern.

[0106] Referring to Figure 6(b), a ninth photoresist pattern 309 is fabricated on the surface of the ceramic layer 200 according to the pattern of the first circuit pattern. A metal material, such as copper, is electroplated at the opening position of the ninth photoresist pattern 309, thereby obtaining the metal interconnect structure 201 and the first circuit pattern 203 as shown in Figure 6(c).

[0107] Step S5003: Remove the photoresist pattern and the seed layer below the photoresist pattern, and fabricate a photoresist layer on the surface of the ceramic layer and the surface of the metal carrier.

[0108] Referring to Figure 6(d), the ninth photoresist layer 309 and the seed layer covered by the ninth photoresist layer 309 are removed. A tenth photoresist layer 310 is then fabricated on the surface of the first circuit pattern 203 to completely cover the first circuit pattern 203. This photoresist layer can protect the fabricated first circuit pattern. Then, a photoresist layer is fabricated on the surface of the metal carrier 100. An eleventh photoresist layer 311 is fabricated according to the pattern of the second circuit pattern.

[0109] Step S5004: Open a window at a preset position of the photoresist layer on the surface of the metal carrier, and use an etching method to etch and remove the metal carrier at the window position to remove the photoresist layer on the surface of the metal carrier and obtain the second circuit pattern.

[0110] The eleventh photoresist layer 311 is fabricated according to the pattern of the second circuit pattern. The metal carrier at the opening position of the eleventh photoresist layer 311 is etched away by etching method, and then all photoresist layers are removed to obtain the first circuit pattern 203 and the second circuit pattern 204 as shown in Figure 6(e).

[0111] The above-described method for fabricating the second circuit pattern is a subtractive method, that is, using photoresist patterns to selectively etch the metal carrier; as another implementation, a semi-additive method can also be used to fabricate the second circuit pattern, the fabrication method including the following steps:

[0112] Step 6001: Open windows at preset positions on the photoresist layer on the surface of the metal carrier.

[0113] After the first circuit pattern 203 is fabricated, referring to Figure 6(f), a tenth photoresist layer 310 and a twelfth photoresist layer 312 are fabricated on the surface of the metal carrier 100 and the surface of the first circuit pattern 203, respectively. The photoresist material is preferably a dry film, but photoresist can also be selected. The tenth photoresist layer 310 completely covers the first circuit pattern 203 to protect it. The twelfth photoresist layer 312 is designed according to the second circuit pattern, and is exposed and developed to open windows, exposing the areas of the second circuit pattern that need to be electroplated and covering the areas that need to be etched away.

[0114] Step S6002: Electroplating metal material at the window position using a pattern electroplating method, so that the metal at the window position is higher than the metal carrier by a preset distance, removing the photoresist layer on the other side of the metal carrier and the metal carrier covered by the photoresist layer to obtain the second circuit pattern.

[0115] Referring to Figure 6(f), a patterned electroplating method is used to electroplat a metal material, which can be copper, at the opening position of the twelfth photoresist layer 312. The metal plated at the opening position of the twelfth photoresist layer 312 is higher than the predetermined height of the metal carrier 100, forming the third circuit pattern 205 as shown in Figure 6(g). Then, the twelfth photoresist layer 312 and the metal carrier covered by the twelfth photoresist layer 312 are removed, so that the metal carrier 100 forms the second circuit pattern 204. The second circuit pattern 204 and the third circuit pattern 205 are exactly the same pattern, and the two are superimposed to form an integrated circuit pattern. Finally, surface treatment and cutting steps are performed to obtain the ceramic-based double-sided printed circuit board as shown in Figure 6(g).

[0116] The method for fabricating a ceramic-based double-sided printed circuit board in this embodiment has the following characteristics:

[0117] (1) Interconnect holes are made on the unsintered ceramic layer, and then metal connection structures are made in the interconnect holes and circuit patterns are made on both sides; the metal connection structure is made on the unsintered ceramic layer, which greatly reduces the difficulty of interconnection between the layers of double-sided ceramic board and reduces the manufacturing cost of ceramic-based double-sided printed circuit boards.

[0118] (2) Compared with the traditional method of manufacturing conductive interconnect structure by vapor deposition and double-sided pattern electroplating, the paste printing method is cheaper and has better bonding force due to the co-sintering of paste and ceramic.

[0119] (3) The conductive interconnect structure is made by electroplating and can be used in printed circuit boards for high-power devices. Compared with traditional brazing ceramic boards, the copper interconnect structure can further enhance its heat dissipation capacity.

[0120] In one embodiment, a method such as Figure 7 The ceramic-based double-sided printed circuit shown includes:

[0121] The circuit consists of a ceramic layer 200, a metal carrier 100, a first circuit pattern 203, and a second circuit pattern 204. The ceramic layer 200 is located above the metal carrier 100. A metal interconnect structure 202 is provided within the ceramic layer 200. The first circuit pattern 203 is located on one side of the ceramic layer 200, and the second circuit pattern 204 is located on the other side of the ceramic layer 200. The first circuit pattern 203 and the second circuit pattern 204 are connected to the metal carrier 100 through the metal interconnect structure 202, thereby forming a ceramic-based double-sided printed circuit board.

[0122] Furthermore, the ceramic material in the ceramic matrix can be aluminum nitride, silicon nitride, boron nitride, aluminum oxide, beryllium oxide, silicon carbide, etc. The above-mentioned ceramic materials have excellent thermal conductivity, which can effectively improve the thermal conductivity of the circuit board.

[0123] Furthermore, the materials of the first circuit pattern 203 and the second circuit pattern 204 are preferably copper, but other metal materials can also be selected.

[0124] In this embodiment, the ceramic-based double-sided printed circuit board uses ceramic material as the substrate. Ceramic material has extremely good thermal conductivity. Using ceramic as the dielectric material of the printed circuit board can significantly improve the thermal conductivity of the printed circuit board, thereby improving the performance of the printed circuit board.

[0125] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a ceramic-based double-sided printed circuit board, characterized in that, include: A metal carrier is provided, an unsintered ceramic layer is formed on one side surface of the metal carrier, and an interconnection hole is formed at a predetermined position on the surface of the ceramic layer to penetrate the ceramic layer and reach the metal carrier. The ceramic layer is sintered, and a metal interconnect structure connecting the metal carrier and the surface of the ceramic layer is formed in the interconnect hole; A first circuit pattern is formed on the surface of the ceramic layer to contact the metal interconnect structure, and a second circuit pattern is formed on the other side surface of the metal carrier. The first circuit pattern and the second circuit pattern are connected through the metal interconnect structure to form a ceramic-based double-sided printed circuit board. The ceramic layer is sintered, and a metal interconnect structure connecting the metal carrier and the surface of the ceramic layer is formed in the interconnect hole; A first circuit pattern is formed on the surface of the ceramic layer to contact the metal interconnect structure, and a second circuit pattern is formed on the other side surface of the metal carrier, including: A metal paste is printed on the surface of the ceramic layer, and the metal paste fills the interconnect holes while simultaneously creating the first circuit pattern on the surface of the ceramic layer. The ceramic layer is sintered, and photoresist layers are formed on the surface of the first circuit pattern and on the other side of the metal carrier, respectively, with the photoresist layer on the surface of the first circuit pattern completely covering the first circuit pattern. A window is made at a predetermined position on the photoresist layer on the other side of the metal carrier. An etching method is used to remove the metal carrier at the window position, thus removing the photoresist layer from the surface of the metal carrier, to obtain the second circuit pattern; or Fabricating a metal interconnect structure within the interconnect hole to connect the metal carrier and the surface of the ceramic layer includes: An electroplated protective film is attached to the other side of the metal carrier. Metal material is electroplated inside the interconnect holes, using the metal carrier as a conductive layer, to obtain the metal interconnect structure. The metal interconnect structure protruding from the ceramic layer is ground so that the end face of the metal interconnect structure is on the same plane as the surface of the ceramic layer. A metal layer of a predetermined thickness is formed on the surface of the ceramic layer. Photoresist layers are formed on the surface of the metal layer and on the other side of the metal carrier. Windows are made at predetermined positions on each photoresist layer. The metal material at the windowed positions is etched away using an etching method. All photoresist layers are removed, resulting in the first circuit pattern on the surface of the ceramic layer and the second circuit pattern on the other side of the metal carrier; or A metal interconnect structure connecting the metal carrier and the surface of the ceramic layer is fabricated within the interconnect hole; a first circuit pattern contacting the metal interconnect structure is fabricated on the surface of the ceramic layer, and a second circuit pattern is fabricated on the other side surface of the metal carrier, including: A seed layer is formed on the surface of the ceramic layer and the inner wall of the interconnecting hole; A photoresist pattern is fabricated on the surface of the ceramic layer, and metal is electroplated according to the photoresist pattern to obtain the metal interconnect structure and the first circuit pattern. Remove the photoresist pattern and the seed layer below the photoresist pattern, and fabricate a photoresist layer on the surface of the ceramic layer and the surface of the metal carrier; A window is made at a predetermined position on the photoresist layer on the surface of the metal carrier, and the metal carrier at the window position is etched away using an etching method to remove the photoresist layer on the surface of the metal carrier, thereby obtaining the second circuit pattern.

2. The method for manufacturing a ceramic-based double-sided printed circuit board according to claim 1, characterized in that, Forming a metal layer of a predetermined thickness on the surface of the ceramic layer includes: A seed layer is formed by sputtering on the surface of the ceramic layer, and a metal material of a predetermined thickness is electroplated on the surface of the seed layer to form the metal layer.

3. The method for manufacturing a ceramic-based double-sided printed circuit board according to claim 1, characterized in that, An unsintered ceramic layer is formed on one side surface of the metal carrier, and an interconnecting hole penetrating the ceramic layer and reaching the metal carrier is formed at a predetermined position on the surface of the ceramic layer, including: An unsintered ceramic layer of a predetermined thickness is formed on the surface of the metal carrier by casting or molding. The interconnecting holes are made at predetermined positions on the surface of the ceramic layer by mechanical drilling or laser engraving, so that the interconnecting holes pass through the ceramic layer and reach but do not pass through the metal carrier.

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