CN115955758A - High heat conduction circuit board with embedded ceramic heat conduction block and hollowed-out copper-coated layer - Google Patents

Abstract

The invention discloses a high heat conduction circuit board with embedded ceramic heat conduction blocks and hollow copper-clad layers, which mainly comprises: the circuit board comprises a circuit board body, a heat dissipation ceramic block correspondingly embedded into a through hole of the circuit board body, a fixing part for embedding and fixing the heat dissipation ceramic block into the through hole of the circuit board body, a metal circuit layer and a hollow high-heat-conductivity metal layer. The circuit substrate body comprises a dielectric material layer, a metal circuit layer and a hollowed high-heat-conductivity metal layer are plated on the dielectric material layer respectively, the hollowed part of the hollowed high-heat-conductivity metal layer corresponds to the fixing part and part of the heat dissipation ceramic block, in addition, the heat conductivity coefficient of the heat dissipation ceramic block is higher than that of the dielectric material layer, the heat conductivity coefficient of the hollowed high-heat-conductivity metal layer is higher than that of the heat dissipation ceramic block, the heat dissipation ceramic block is exposed outside through the fixing part and part of the heat dissipation ceramic block, and therefore the problem of board explosion when high-temperature baking is conducted is effectively solved.

Description

High heat conduction circuit board with embedded ceramic heat conduction block and hollowed-out copper-coated layer

Technical Field

The invention relates to a high-thermal-conductivity circuit board, in particular to a high-thermal-conductivity circuit board with embedded ceramic heat-conducting blocks and hollow copper-clad layers.

Background

A Printed Circuit Board (PCB) is formed by using a copper foil substrate as a main key base material for mounting electronic components, wherein the copper foil substrate generally uses a dielectric material as an insulating layer, a conductive wire formed by a copper foil as a conductive material layer, and the conductive material layer is disposed on the dielectric insulating layer. The dielectric material is mainly made of paper, bakelite board, glass fiber board, rubber and other insulating materials such as polymer through resin impregnation.

Since the insulating layer of the copper clad laminate of a printed circuit board is mostly made of dielectric materials and is not a good thermal conductor, the heat generated by the high-power components is accumulated near the high-power components, and the operating environment is not ideal. Meanwhile, excessive heat accumulation usually causes the expansion of the printed circuit board, but the thermal expansion coefficient between the printed circuit board and the circuit element is different, which inevitably causes the risk of damaging the contact points due to thermal stress.

To solve the above problems, taiwan patent nos. I670998 and I690246 disclose an embedded structure, in which a high heat-conducting ceramic block is embedded into a dielectric material, such as an FR4 board, and a high heat-generating element is disposed above the high heat-conducting ceramic block, so that heat generated by the high heat-generating element can be effectively conducted out through a high heat-conducting layer (i.e., copper) at the bottom, thereby effectively improving the overall heat dissipation effect. Therefore, when a printed circuit board with the heat dissipation ceramic block is manufactured at present, epoxy resin glue is mainly filled into a gap between the outer periphery of the heat dissipation ceramic block and the FR-4 dielectric material layer, and after the glue material is cured, the heat dissipation ceramic block can be firmly combined with the FR-4 dielectric material layer. However, in the implementation process, after the printed circuit board is disposed with the heat dissipation ceramic block and enters the reflow machine, the high temperature of the reflow machine may cause the water that may be buried in the high thermal conductivity ceramic block or the epoxy resin glue to be vaporized and/or released by a part of the compound material, and further, the FR-4 dielectric material layer embedded with the ceramic block and the copper-clad layer below expand and spread to form a board explosion state due to the partial release of gas or moisture.

In order to solve the problem that the FR-4 dielectric material layer and the copper-clad layer expand and expand to form a plate explosion state due to the generation of gas and moisture, the applicant gradually modifies the situation, and as shown in figure 1, the applicant tries to screen the copper-clad plate, namely, a large number of holes are punched in the copper-clad plate, so that the copper plate 1 (high heat conduction layer) at the bottom is screened, the screened copper plate 1 is provided with a plurality of holes 10 and gaps, wherein the holes 10 and the gaps corresponding to the heat dissipation ceramic blocks 2 in the middle can quickly discharge the gas and the moisture, and therefore the plate explosion situation cannot occur; however, the copper plate is meshed, so that the amount of copper capable of conducting heat is reduced, and the heat conduction effect is greatly reduced, which cannot solve the problem that the heat energy generated by the high-power element is accumulated near the high-power element to generate a high-temperature operating environment.

Considering the above structural problem of avoiding board explosion but reducing heat conduction effect, please refer to fig. 2, the applicant further changes the copper-clad plate into a vertical and horizontal slotted structure, mainly to let gas and water gas be discharged quickly on the copper plate 1 in a slotted 12 way, and the position of the slotted 12 passes through each heat dissipation ceramic block 2 in a horizontal and vertical way, so the copper plate 1 presents a cross slotted 12 style corresponding to the position of the heat dissipation ceramic block 2. Although the above-mentioned problem of board explosion caused by gas and moisture can be solved by the criss-cross slots 12 of the copper plate 1 corresponding to the positions of the heat dissipation ceramic blocks 2, the problem of heat conduction degradation caused by a large reduction of copper cladding in the former solution is also reduced, but the following two disadvantages are still caused: firstly, the central position of the heat dissipation ceramic block 2, which is usually the core position of the layout of the high heating elements above, cannot radiate heat through the copper plate 1 due to the passing of the slot 12, so that heat accumulation and uneven heat flow distribution in a local area still occur, the heat conduction effect is relatively reduced, and the risk of damage caused by heat accumulation generated by the high heating elements in the prior art cannot be effectively improved; it should be noted that, since the slots 12 are cross-shaped and connected in series with each of the heat dissipation ceramic blocks 2, the heat dissipation independent area 3 is generated between every four heat dissipation ceramic blocks 2 under the influence of the cross-shaped division of the slots 12, and once the heat dissipation independent area 3 is not fixed by screws or is not properly adhered to the rear heat dissipation fins (not shown), the heat dissipation efficiency of each independent area is different, and the copper plate 1 is divided into a plurality of heat isolated islands, so that the average heat dissipation in a large range cannot be ensured.

Therefore, the object of the present invention is to provide a printed circuit board that does not explode due to the release of gas or moisture after the heat dissipation ceramic block is disposed and enters the reflow machine, and that can continuously ensure the heat conduction and dissipation effect of the circuit board embedded with the heat dissipation ceramic block.

Disclosure of Invention

In view of the above disadvantages in the prior art, according to an embodiment of the present invention, it is desirable to provide a high thermal conductive circuit board with embedded ceramic thermal conductive blocks and a hollowed-out copper-clad plate, which aims to achieve the following objectives: (1) The hollow part of the high-heat-conduction metal layer corresponds to the fixing part and part of the heat-dissipation ceramic block, so that the problem that gas is released to burst the board when the reflow soldering machine is baked at high temperature is solved, and the product yield is improved; (2) The bottom of each radiating ceramic block is ensured to be provided with a heat-conducting metal layer, the central position of each radiating ceramic block is ensured to be well connected with the copper-clad plate in a heat-conducting way, and the heat generated by the heating element can be quickly and really discharged so as to achieve a better radiating effect; (3) The copper-clad plates are completely connected except the hollow parts, so that the heat energy of the whole circuit board can be easily discharged by the rear radiating fins, and the problem of uneven heat dissipation of the heat island is solved.

According to an embodiment, the invention provides a high thermal conductive circuit board with embedded ceramic thermal conductive blocks and hollow copper-clad layers, comprising: the circuit board comprises a circuit board body and a circuit board assembly, wherein the circuit board body comprises a first upper board surface and a first lower board surface opposite to the first upper board surface, and at least one through hole penetrating through the first upper board surface and the first lower board surface is formed in the circuit board body; at least one heat dissipation ceramic block correspondingly embedded in the through hole, wherein the heat dissipation ceramic block comprises a second upper plate surface and a second lower plate surface, and the heat conductivity coefficient of the heat dissipation ceramic block is higher than that of the dielectric material layer; at least one fixing part for embedding and fixing the heat dissipation ceramic block in the through hole of the circuit substrate body, and making the second lower board surface correspond to the first lower board surface respectively, wherein the circuit substrate body has a through hole inner edge connecting the first upper board surface and the first lower board surface and surrounding the through hole, the heat dissipation ceramic block has an outer periphery connecting the second upper board surface and the second lower board surface, and the fixing part is a fixing material between the through hole inner edge and the outer periphery for fixing and connecting the two; a metal circuit layer plated on the first upper board surface and the second upper board surface for arranging a plurality of circuit elements, wherein the circuit elements at least comprise a high-power element, and the high-power element is arranged on the metal circuit layer on the second upper board surface; and a hollowed high thermal conductivity metal layer disposed below the first lower plate surface and the second lower plate surface, wherein the heat conductivity coefficient of the hollowed high thermal conductivity metal layer is higher than that of the heat dissipation ceramic block, and at least a plurality of hollowed portions corresponding to the fixing portions are formed on the hollowed high thermal conductivity metal layer, so that at least a portion of the fixing portions and the heat dissipation ceramic block are exposed through the hollowed portions.

Compared with the prior art, due to the special design of the hollow-out part, on one hand, the part of the fixing part is exposed, so that gas and water vapor possibly released in the part can find a channel to be released, the problem of plate explosion is thoroughly solved, the manufacturing yield is obviously improved, and meanwhile, the manufacturing cost is effectively reduced; particularly, the hollow hole avoids the center of the embedded ceramic heat conducting block, so that heat energy emitted by the heating element is effectively led out, and the working efficiency of a final circuit board product is ensured; and the copper-clad part is not cut into thermal islands, so that the heat energy transmitted by the circuit board can be completely carried out as long as a plurality of radiating fins additionally arranged behind contact the copper-clad plate with good heat conduction, the problem of uneven heat dissipation is avoided, and the high-temperature heating element can operate in an ideal temperature environment.

According to an embodiment of the invention, in the high thermal conductivity circuit board with the embedded ceramic thermal conductive block and the hollowed copper-clad layer, the fixing portion is formed by filling a resin adhesive into a mechanical buffer mixture material which is formed by curing and has a flexibility greater than that of the heat dissipation ceramic block.

According to an embodiment of the present invention, in the high thermal conductive circuit board with embedded ceramic thermal conductive blocks and hollowed copper-clad layers, the circuit substrate body is a multi-layer circuit board including multiple dielectric material layers and multiple metal conductive layers.

According to an embodiment of the invention, in the high thermal conductivity circuit board having the embedded ceramic heat conducting block and the hollowed copper-clad layer, the hollowed portion includes a plurality of hollowed holes corresponding to the heat dissipation ceramic block and surrounding the fixing portion, and the plurality of hollowed holes are radially and symmetrically distributed.

According to an embodiment of the present invention, in the high thermal conductivity circuit board having the embedded ceramic thermal conductive block and the hollowed copper-clad layer, the circuit board body is formed with a plurality of through holes, the heat dissipation ceramic block and the corresponding fixing portion are respectively embedded in the plurality of through holes, and the hollowed portion is disposed by a dotted line penetrating at least a part of the plurality of heat dissipation ceramic blocks and the fixing portion.

Drawings

FIG. 1 is a schematic diagram of a copper plate mesh structure in Taiwan patent I670998 of the invention.

FIG. 2 is a schematic view of the structure of the copper plate slot in Taiwan patent I690246.

FIG. 3 is a schematic cross-sectional view of the high thermal conductivity circuit board of the present invention.

FIG. 4 is a perspective exploded view of the high thermal conductivity circuit board of the present invention.

FIG. 5 is a schematic view of another high thermal conductivity circuit board according to the present invention.

FIG. 6 is a schematic diagram of a structure in which a plurality of through holes are arranged in a dotted line according to the present invention.

Wherein: 1 is a copper plate; 10 is a hole; 12 is a slot; 2 is a heat dissipation ceramic block; 3 is a heat dissipation independent area; 4. 4', 4' are circuit substrate bodies; 40 is a dielectric material layer; 41. 41 'and 41' are heat dissipation ceramic blocks; 42. 42', 42' are fixing parts; 43 is a metal conductive layer; 44. 44' is a hollow high heat-conducting metal; 400. 400' is a through hole; 401 is a first upper plate surface; 402 is a first lower plate surface; 404 is the inner edge of the through hole; 410 is a second upper plate surface; 412 is a second lower deck; 414 is an outer periphery; 440. 440', 440 "are hollowed-out parts; and 5 is a high-power element.

Detailed Description

The invention is further illustrated with reference to the following figures and specific examples. These examples are to be construed as merely illustrative and not limitative of the remainder of the disclosure in any way whatsoever. After reading the description of the present invention, one skilled in the art can make various changes and modifications to the invention, and these equivalent changes and modifications also fall into the scope of the invention defined by the claims.

As shown in fig. 3-4, in the high thermal conductivity circuit board with embedded ceramic thermal conductive blocks and hollowed copper-clad layers according to the preferred embodiment of the present invention, the dielectric material layer 40 of the circuit board body 4 in each figure is based on FR-4 in a multi-layer form, a through hole 400 is pre-cut in the dielectric material layer 40 by, for example, a laser, and then a corresponding heat dissipation ceramic block 41 (square column) made of, for example, aluminum nitride (AIN) material is embedded in the through hole 400. However, as those skilled in the art can readily appreciate, the FR-4 substrate size in this embodiment can range from greater than 10cm ² To less than 3600cm ² Simply substituted within the scope of (1). The aforementioned circuit substrate body 4 mainly takes the form of a multilayer circuit board having a plurality of dielectric material layers 40 and a plurality of metal conductive layers 43.

For convenience of illustration, the surface of the dielectric material layer 40 above the drawing is referred to as a first upper board 401, the opposite lower surface is referred to as a first lower board 402, the upper and lower surfaces of the heat dissipation ceramic block 41 are referred to as a second upper board 410 and a second lower board 412, respectively, and the thickness of the dielectric material layer 40 is similar to the thickness of the heat dissipation ceramic block 41. Of course, this is well knownThose skilled in the art will readily understand that the dielectric material layer 40 may be formed by epoxy resin or glass fiber prepreg substrates such as FR-1 (common name: bakelite board), FR-3, FR-6, G-10, etc.; the cutting method can also be mechanical cutting, etc., and the heat dissipation ceramic block 41 can be silicon nitride (Si) ₃ N ₄ ) Alumina (Al) ₂ O ₃ ) Silicon carbide (SiC), beryllium oxide (BeO), and the like, all of which do not prevent the practice of the invention.

Then, a fixing material such as epoxy resin glue is filled into the gap between the outer periphery 414 of the aluminum nitride heat dissipation ceramic block 41 and the inner edge 404 of the through hole of the FR-4 dielectric material layer 40, after the glue material is cured, the outer periphery 414 and the inner edge 404 of the through hole of the heat dissipation ceramic block 41 can be firmly combined, and the fixing part 42 formed by curing the glue material has flexibility larger than that of the heat dissipation ceramic block 41, so that the material is a good mechanical buffer mixed material, so that even if the thermal expansion coefficients of the two different materials are different, the buffer protection can be provided, and no problem is generated in the subsequent heating treatment and operation process. It is understood that although the embodiment is described with epoxy resin adhesive, the silicon substrate and other flexible adhesive materials can be easily changed without affecting the practice of the present invention.

After the heat dissipation ceramic block 41 is embedded in the through hole 400 of the dielectric material layer 40 by the fixing portion 42, polishing may be performed to make the first upper board surface 401 and the second upper board surface 410 flush with each other, so that in this embodiment, a metal seed layer of titanium and a layer of copper is sequentially formed on the first upper board surface 401 and the second upper board surface 410 in a sputtering manner, and then the metal seed layer is thickened in an electroplating manner to form an electroplated copper layer. Of course, those skilled in the art can readily understand that the above-mentioned copper layer protecting material can be replaced by Organic Solderability Preservatives (OSP), silver, tin, etc., without hindering the practice of the present invention. The metal layer is processed by a series of subsequent conventional processing procedures such as layout (Pattern) to form the metal circuit layer 43 in this embodiment. Of course, those skilled in the art can also use conventional evaporation or other feasible methods and use other suitable metals to form the metal circuit layer 43 of the multi-layer structure.

Since the first lower plate 402 and the second lower plate 412 are also flush with each other, copper has a better thermal conductivity (380 Wm) ^-1 K ^-1 ) Therefore, in the present embodiment, a copper metal layer is also formed under the first bottom plate 402 and the second bottom plate 412, so as to form a hollow high thermal conductivity metal 44 with a thermal conductivity higher than that of the dielectric material layer 40. Since the hollow-out metal 44 with high thermal conductivity connects the dielectric material layer 40 and the heat dissipation ceramic block 41 with good thermal conductivity, but the thermal conductivity of the heat dissipation ceramic block 41 and the hollow-out metal 44 with high thermal conductivity is much higher than that of the dielectric material layer 40, the hollow-out metal 44 with high thermal conductivity mainly guides the heat energy from the heat dissipation ceramic block 41 out from the horizontal direction of the drawing, and relatively, the general circuit components disposed above the dielectric material layer 40 will not be easily interfered by the heat energy from the heat dissipation ceramic block 41, thereby isolating the high heat emitted from the high power component 5 from other peripheral general circuit components.

After the dielectric material layer 40 is completely disposed, the circuit component further includes at least one high-power component 5, in this case, the high-power component 5 is, for example, an IGBT, and is soldered and fixed to the metal circuit layer 43 at a position corresponding to the pad above the heat-dissipating ceramic block 41 by Surface-mount technology (SMT), and each electrode of the IGBT is connected to the corresponding pad through a metal lead. Because the IGBT has the advantages of high efficiency, fast switching speed, etc., it is often applied to electronic devices with large workload, such as: the IGBT will generate a large amount of heat energy when the electronic equipment is running, the heat energy will directly pass through the heat dissipation ceramic block 41 of alumina, and is conducted downwards to the hollow high heat conduction metal 44, and is conducted away from the position of the heat dissipation ceramic block 41, the heat energy will be further dissipated in a large area by the whole piece of the hollow high heat conduction metal 44, even if the lower heat dissipation fin is only screwed with the circuit board by a plurality of bolts, good heat conduction can be achieved at the screwed pressurized part, the heat energy emitted on the whole circuit board can be carried out by the rear heat dissipation fin, and the effect of increasing the heat dissipation efficiency is achieved.

The hollow portion 440 formed by the hollow high thermal conductivity metal 44 corresponds to the fixing portion 42 and a part of the heat dissipation ceramic block 41, so that the fixing portion 42 and a part of the heat dissipation ceramic block 41 are exposed through the hollow portion 440, so long as the part of the heat dissipation ceramic block 41 does not pass through the whole heat dissipation ceramic block 41 at the periphery of the heat dissipation ceramic block 41, so that the gas and water generated when the reflow soldering machine is subjected to high temperature baking are discharged through the hollow portion 440 without causing the problem of board explosion due to expansion, and meanwhile, the hollow high thermal conductivity metal 44 attached to the central position of the heat dissipation ceramic block 41 can dissipate heat in a large area, thereby achieving the effect of increasing the heat dissipation efficiency.

Fig. 5 is a schematic structural diagram of another high thermal conductivity circuit board according to the present invention. As can be seen from the figure, the plurality of the hollow portions 440' formed on the circuit substrate body 4' are mainly disposed around the fixing portion 42' and partially correspond to four corners of the heat dissipation ceramic block 41', that is, the positions of the periphery of the part of the heat dissipation ceramic block 41' and the whole fixing portion 42' are exposed to the outside, in addition, the hollow portions 440' may be radially and symmetrically distributed on the hollow high thermal conductivity metal 44', except for the periphery of the part of the heat dissipation ceramic block 41' and the whole fixing portion 42', the remaining hollow portions 440' are disposed in a radial shape, so as to increase the efficiency of exhausting the gas and the moisture without affecting the heat dissipation effect.

FIG. 6 is a schematic view of a structure in which a plurality of through holes are arranged in a dotted line according to the present invention. In the circuit substrate body 4", for example, a plurality of through holes 400" are formed, each through hole 400 "is provided with a heat-dissipating ceramic block 41" and a corresponding fixing portion 42", and the hollow portions 440" are connected in series with the heat-dissipating ceramic blocks 41 "in a dotted line manner in a cross manner, and more importantly, the hollow portions 440" corresponding to the heat-dissipating ceramic blocks 41 "are only located at the periphery of the heat-dissipating ceramic blocks 41" and are not exposed at the central position, and the positions covered by the fixing portions 42 "are completely exposed, so that the efficiency of exhausting the gas and the moisture can be increased by connecting the heat-dissipating ceramic blocks 41" in series in a dotted line manner in a cross manner, and the heat-dissipating effect is not affected.

Claims (5)

1. The utility model provides a high heat conduction circuit board with embedded ceramic heat conduction piece and fretwork cover copper layer, characterized by includes:

the circuit board comprises a circuit board body and a circuit board assembly, wherein the circuit board body comprises a first upper board surface and a first lower board surface opposite to the first upper board surface, and at least one through hole penetrating through the first upper board surface and the first lower board surface is formed in the circuit board body;

at least one heat dissipation ceramic block correspondingly embedded in the through hole, wherein the heat dissipation ceramic block comprises a second upper plate surface and a second lower plate surface, and the heat conductivity coefficient of the heat dissipation ceramic block is higher than that of the dielectric material layer;

at least one fixing part for embedding and fixing the heat dissipation ceramic block in the through hole of the circuit substrate body, and making the second lower board surface correspond to the first lower board surface respectively, wherein the circuit substrate body is provided with a through hole inner edge which connects the first upper board surface and the first lower board surface and surrounds the through hole, the heat dissipation ceramic block is provided with an outer peripheral edge which connects the second upper board surface and the second lower board surface, and the fixing part is a fixing material which is arranged between the through hole inner edge and the outer peripheral edge and is used for fixing and connecting the two;

a metal circuit layer plated on the first upper board surface and the second upper board surface for disposing a plurality of circuit components, wherein the circuit components at least comprise a high-power component, and the high-power component is disposed on the metal circuit layer on the second upper board surface; and

and a hollow high thermal conductivity metal layer disposed below the first lower plate surface and the second lower plate surface, wherein the heat conductivity coefficient of the hollow high thermal conductivity metal layer is higher than that of the heat dissipation ceramic block, and at least a plurality of hollow parts corresponding to the fixing parts are formed on the hollow high thermal conductivity metal layer, so that at least part of the fixing parts and the heat dissipation ceramic block are exposed through the hollow parts.

2. The high thermal conductivity circuit board according to claim 1, wherein said fixing portion is formed by filling and curing a resin paste into a mechanically buffering mixture having a flexibility greater than that of said heat-dissipating ceramic block.

3. The high thermal conductivity circuit board according to claim 1, wherein said circuit substrate body is a multilayer circuit board including a plurality of dielectric material layers and a plurality of metal conductive layers.

4. The PCB of claim 1, 2 or 3, wherein the hollowed-out portion comprises a plurality of hollowed-out holes corresponding to at least the heat-dissipating ceramic block and surrounding the fixing portion, and the plurality of hollowed-out holes are radially and symmetrically distributed.

5. The highly thermally conductive circuit board according to claim 1, 2 or 3, wherein the circuit board body is formed with a plurality of through holes, the heat-dissipating ceramic blocks and the corresponding fixing portions are respectively embedded in the plurality of through holes, and the hollow portions are disposed by dotted lines penetrating at least a part of the plurality of heat-dissipating ceramic blocks and the fixing portions.

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