TWI837847B - Circuit board and method of fabricating the same - Google Patents

Abstract

A circuit board and a method of fabricating the same are provided in the present invention. The circuit board includes a first substrate, a second substrate, a dielectric layer disposed between the first substrate and the second substrate, and a bending metal plate disposed within the dielectric layer. The bending metal plate includes a first U-shaped plate and a second U-shaped plate. The first U-shaped plate includes a lower base plate, a first outer lateral plate and a second outer lateral plate, and the second U-shaped plate includes an upper base plate, a first inner lateral plate and a second inner lateral plate. A cavity is between the first U-shaped plate and the second U-shaped plate. The circuit board further includes a phase change material (PCM) filled in the cavity of the bending metal plate and an electronic element disposed on the upper base plate and between the first inner lateral plate and the second inner lateral plate. The present invention uses the bending metal plate filled with phase change material to achieve heat dissipation and electromagnetic screen.

Description

Circuit board and manufacturing method thereof

The present invention relates to a circuit board and a manufacturing method thereof, and in particular to a circuit board and a manufacturing method thereof having both heat dissipation and electromagnetic shielding.

In recent years, electronic equipment has developed rapidly, with multifunctionality, high circuit density and miniaturization being the main research directions. However, as the density of electronic components in the equipment increases, the heat generated by the electronic equipment also increases, so the heat dissipation effect of the electronic equipment must be improved. In addition, various products with RF components such as smart phones will have electromagnetic interference and affect the circuit function, so the electromagnetic shielding problem of electronic equipment must also be dealt with.

One aspect of the present invention is to provide a circuit board comprising a bent metal plate filled with a phase change material to achieve the effects of heat dissipation and electromagnetic shielding.

Another aspect of the present invention is to provide a method for manufacturing a circuit board.

According to one aspect of the present invention, a circuit board is provided, which includes a first substrate, a second substrate disposed on the first substrate, a dielectric layer disposed between the first substrate and the second substrate, and a bent metal plate disposed in the dielectric layer. The first substrate includes a first circuit layer, and the second substrate includes a second circuit layer. The bent metal plate includes a first U-shaped plate and a second U-shaped plate, the first U-shaped plate includes a lower base plate, a first outer side plate and a second outer side plate, and the second U-shaped plate includes an upper base plate, a first inner side plate and a second inner side plate. The first inner side plate is connected to the first outer side plate, and the second inner side plate is connected to the second outer side plate. There is a cavity between the first U-shaped plate and the second U-shaped plate. The circuit board also includes a phase change material filled in the cavity and an electronic component disposed on the upper base plate and between the first inner side plate and the second inner side plate.

According to an embodiment of the present invention, the circuit board further includes a first thermally conductive adhesive layer disposed between the first circuit layer of the first substrate and the bent metal plate.

According to an embodiment of the present invention, the circuit board further comprises a second thermally conductive adhesive layer disposed between the bent metal plate and the electronic component.

According to an embodiment of the present invention, the circuit board further includes a plurality of conductive blind vias extending from the second circuit layer to the electronic components.

According to an embodiment of the present invention, the circuit board further includes at least one conductive via extending from the second circuit layer to the first circuit layer.

According to an embodiment of the present invention, a gap is formed between the electronic component and the first inner plate and the second inner plate of the bent metal plate, and a dielectric layer is filled in the gap.

According to an embodiment of the present invention, the electronic component directly contacts the first inner plate and the second inner plate of the bent metal plate.

According to another aspect of the present invention, a method for manufacturing a circuit board is provided, the method comprising providing a lower substrate, wherein the lower substrate comprises a first substrate layer and a first metal layer below the first substrate layer; removing a portion of the first substrate layer to form a groove exposing a portion of the first metal layer; forming a bent metal plate on the groove, wherein the bent metal plate comprises a first U-shaped plate and a second U-shaped plate, the first U-shaped plate comprises a lower bottom plate, a first outer side plate and a second outer side plate, the second U-shaped plate comprises an upper bottom plate, a first inner side plate and a second inner side plate. The first inner side plate is connected to the first outer side plate, and the second inner side plate is connected to the second outer side plate. There is a cavity between the first U-shaped plate and the second U-shaped plate, and a phase change material is filled in the cavity of the bent metal plate; an electronic component is placed on the upper base plate of the bent metal plate and between the first inner plate and the second inner plate; an upper substrate is formed above the electronic component, wherein the upper substrate includes a second substrate layer and a second metal layer above the second substrate layer; and the first metal layer and the second metal layer are patterned to form multiple circuit layers respectively.

According to an embodiment of the present invention, the step of forming the bent metal plate on the groove further includes forming a first thermally conductive adhesive layer in the groove; and laminating the bent metal plate on the first thermally conductive adhesive layer.

According to one embodiment of the present invention, the step of placing the electronic component further includes forming a second thermally conductive adhesive layer on the upper base plate of the bent metal plate; and placing the electronic component on the second thermally conductive adhesive layer.

According to an embodiment of the present invention, the step of forming the upper substrate above the electronic element further includes forming a dielectric layer between the lower substrate and the upper substrate.

According to an embodiment of the present invention, before forming the circuit layer, the method further comprises forming a plurality of conductive blind vias, wherein the conductive blind vias extend from the upper substrate to the electronic element.

According to an embodiment of the present invention, before forming the circuit layer, the method further comprises forming at least one conductive via, wherein the conductive via extends from the upper substrate to the lower substrate.

According to one embodiment of the present invention, the step of forming the bent metal plate includes bending the first metal plate into the first U-shaped plate, wherein the first U-shaped plate has a recessed area; filling the phase change material into the recessed area; connecting the second metal plate and the first U-shaped plate, wherein the second metal plate covers the phase change material; and bending the second metal plate into the second U-shaped plate so that the phase change material is sealed between the first U-shaped plate and the second U-shaped plate.

By applying the circuit board and the manufacturing method thereof of the present invention, the cavity in the bent metal plate is filled with phase change material, and the electronic components are arranged on the upper base plate of the bent metal plate and between the first inner plate and the second inner plate, so as to achieve the effects of heat dissipation and electromagnetic shielding at the same time.

The present invention provides many different embodiments or examples to implement different features of the invention. The specific examples of components and configurations described below are intended to simplify the present invention. These are of course only examples and are not intended to be limiting. For example, a description of a first feature formed on or above a second feature includes embodiments in which the first feature and the second feature are in direct contact, and also includes embodiments in which other features are formed between the first feature and the second feature, so that the first feature and the second feature are not in direct contact. In addition, the present invention repeats component symbols and/or letters in various specific examples. The purpose of this repetition is to simplify and clarify the description and does not represent a relationship between the various discussed embodiments and/or configurations.

Furthermore, spatially relative terms, such as "beneath," "below," "lower," "above," "upper," etc., are used to facilitate description of the relationship of a part or feature to other parts or features depicted in the drawings. Spatially relative terms include different orientations of the component when in use or operation in addition to the orientation depicted in the drawings. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used in the present invention can be interpreted in this manner.

In conventional circuit boards, electromagnetic shielding and heat dissipation functions must be achieved by separately setting different components, but they usually have problems such as high manufacturing cost, poor product yield or poor electromagnetic shielding effect. Therefore, the present invention provides a circuit board and a manufacturing method thereof, which utilizes phase change material (PCM) to fill the cavity in the bent metal plate, and sets the electronic components on the upper base plate of the bent metal plate and between the first inner plate and the second inner plate to achieve the effects of heat dissipation and electromagnetic shielding at the same time.

Please refer to FIG. 1, which shows a cross-sectional view of a circuit board 100 according to some embodiments of the present invention. The circuit board 100 includes a first substrate 110 and a second substrate 120 on the first substrate 110. In some embodiments, the first substrate 110 includes a first base material layer 102 and a first circuit layer 104, and the second substrate 120 includes a second base material layer 112 and a second circuit layer 114. The circuit board 100 further includes a dielectric layer 130 disposed between the first substrate 110 and the second substrate 120.

The circuit board 100 includes a bent metal plate 140 in a dielectric layer 130. The bent metal plate 140 includes a first U-shaped plate 210 and a second U-shaped plate 235. The first U-shaped plate 210 includes a lower base plate 202, a first outer plate 204, and a second outer plate 206, and the second U-shaped plate 235 includes an upper base plate 232, a first inner plate 234, and a second inner plate 236. The first inner plate 234 is connected to the first outer plate 204, and the second inner plate 236 is connected to the second outer plate 206. The first U-shaped plate 210 is mainly used to support the structure of the bent metal plate 140, and the second U-shaped plate 235 is used to carry the electronic components 160 (described below). In some embodiments, the bent metal plate 140 includes a material having mechanical strength, plasticity and high thermal conductivity, such as a copper plate, an aluminum plate, an iron plate or an alloy. The bent metal plate 140 has a cavity between the first U-shaped plate 210 and the second U-shaped plate 235, and the phase change material 150 is filled in the cavity. In some embodiments, the phase change material 150 is a solid-liquid conversion phase change material. In some specific examples, the phase change material 150 can be wax ( _{CnH2n +2} , where n is 20 to 40), an inorganic salt hydrate (such as sodium phosphate dodecahydrate, calcium nitrate tetrahydrate and sodium acetate trihydrate) and a fatty acid (such as lauric acid and myristic acid), etc.

In some embodiments, the first thermally conductive adhesive layer 135 can be selectively disposed in a groove (not shown) of the first substrate 110 so that the bent metal plate 140 is disposed on the first thermally conductive adhesive layer 135. In other words, the first thermally conductive adhesive layer 135 is between the first circuit layer 104 and the lower base plate 202 of the bent metal plate 140. In some embodiments, the first thermally conductive adhesive layer 135 can be a highly thermally conductive silicone, epoxy resin, or acrylic resin.

The circuit board 100 further includes an electronic component 160 disposed on the upper base plate 232 of the bent metal plate 140 and between the first inner plate 234 and the second inner plate 236. Therefore, the distance between the first inner plate 234 and the second inner plate 236 must be adjusted according to the size of the electronic component 160 to be placed. The electronic component 160 can be surrounded by the bent metal plate 140 to prevent the electronic component 160 from being disturbed by electromagnetic waves, so as to achieve the effect of electromagnetic shielding. Furthermore, due to the phase change material 150 filled in the bent metal plate 140, the heat generated by the electronic component 160 during operation can be effectively transferred out. In some embodiments, there are gaps 10 filled with dielectric layer 130 between the electronic component 160 and the first inner plate 234 and the second inner plate 236 of the bent metal plate 140, as shown in FIG. 1 , that is, the electronic component 160 does not contact the first inner plate 234 and/or the second inner plate 236 of the bent metal plate 140. In other embodiments, the side of the electronic component 160 may directly contact the first inner plate 234 and/or the second inner plate 236 of the bent metal plate 140.

In some embodiments, the second thermally conductive adhesive layer 165 can be selectively disposed on the upper base plate 232 of the bent metal plate 140 so that the electronic component 160 is placed on the second thermally conductive adhesive layer 165, and the second thermally conductive adhesive layer 165 can adhere the electronic component 160 to the upper base plate 232. In some embodiments, the second thermally conductive adhesive layer 165 can be a highly thermally conductive silicone, epoxy resin, or acrylic resin. The first thermally conductive adhesive layer 135 and the second thermally conductive adhesive layer 165 are both helpful for heat dissipation of the circuit board 100.

In some embodiments, the circuit board 100 may selectively include a plurality of conductive blind vias 170 and/or at least one conductive through hole 180. The conductive blind via 170 may extend from the second circuit layer 114 to the electronic element 160. The conductive through hole 180 may extend from the second circuit layer 114 to the first circuit layer 104. The provision of the conductive blind vias 170 and the conductive through hole 180 may also help the circuit board 100 to dissipate heat.

2A to 2D illustrate cross-sectional views of intermediate stages of the manufacturing process of the bent metal plate 140 filled with phase change material 150 according to some embodiments. First, referring to FIG. 2A , the first metal plate is bent into a first U-shaped plate 210, so that the first U-shaped plate 210 includes a bottom plate 202, a first outer plate 204, and a second outer plate 206. The bottom plate 202 is connected between the first outer plate 204 and the second outer plate 206 to form a recessed area R1.

Next, as shown in FIG. 2B , the phase change material 150 is filled into the recessed area R1, and the phase change material 150 is solid at this time to prevent the phase change material 150 from being lost during the manufacturing process of the bending metal plate 140. Then, please refer to FIG. 2C , solder 220 is added to the top of the first outer plate 204 and the second outer plate 206 of the first U-shaped plate 210, and then the second metal plate 230 is connected to the first U-shaped plate 210 by solder 220. Therefore, the second metal plate 230 will cover the phase change material 150.

Next, referring to FIG. 2D , the second metal plate 230 is bent into a second U-shaped plate 235, and the shape of the phase change material 150 is changed into a U-shape, and is sealed between the first U-shaped plate 210 and the second U-shaped plate 235. Similar to the first U-shaped plate 210, the second U-shaped plate 235 also includes an upper bottom plate 232, a first inner plate 234, and a second inner plate 236, and the upper bottom plate 232 is connected between the first inner plate 234 and the second inner plate 236. Furthermore, the first inner plate 234 is connected to the first outer plate 204, and the second inner plate 236 is connected to the second outer plate 206. In other words, the phase change material 150 is distributed between the lower bottom plate 202 and the upper bottom plate 232, between the first outer plate 204 and the first inner plate 234, and between the second outer plate 206 and the second inner plate 236. The first U-shaped plate 210 and the second U-shaped plate 235 in FIG. 2D together form the bent metal plate 140 in FIG. 1.

Please refer to FIG. 3A to FIG. 3G, which are cross-sectional views of the intermediate stages of the manufacturing method of the circuit board 100 according to some embodiments of the present invention. First, please refer to FIG. 3A, and provide a lower substrate 310. The lower substrate 310 includes a first substrate layer 102 and a first metal layer 304, wherein the first metal layer 304 is below the first substrate layer 102. In some embodiments, the lower substrate 310 is a single-sided copper-clad substrate. Then, please refer to FIG. 3B, remove part of the first substrate layer 102 to form a groove R2, wherein the groove R2 will expose part of the first metal layer 304.

Referring to FIG. 3C , the bent metal plate 140 filled with the phase change material 150 prepared in FIG. 2D is placed on the groove R2 (refer to FIG. 3B ). In some embodiments, a first thermally conductive adhesive layer 135 may be formed on the groove R2 (refer to FIG. 3B ), and then the bent metal plate 140 of FIG. 2D is attached to the first thermally conductive adhesive layer 135 to help the heat dissipation of the circuit board 100. In some embodiments, the first thermally conductive adhesive layer 135 may be a highly thermally conductive silicone, epoxy resin, or acrylic resin. The upper base plate 232, the first inner plate 234, and the second inner plate 236 of the bent metal plate 140 may form a groove R3.

Please refer to FIG. 3D , the electronic component 160 is placed in the groove R3 (refer to FIG. 3C ), that is, on the upper bottom plate 232 of the bent metal plate 140 and between the first inner plate 234 and the second inner plate 236 , so that the electronic component 160 is surrounded on three sides, thereby achieving the effect of electromagnetic shielding. In some embodiments, a second thermally conductive adhesive layer 165 may be formed on the upper bottom plate 232 of the groove R3 (refer to FIG. 3C ), and then the electronic component 160 is placed on the second thermally conductive adhesive layer 165 to help the electronic component 160 dissipate heat. In some embodiments, the second thermally conductive adhesive layer 165 may be a highly thermally conductive silicone, epoxy resin, or acrylic resin.

Referring to FIG. 3E , a dielectric layer 130 is formed on the lower substrate 310 and the electronic element 160, and then an upper substrate 320 is pressed on the dielectric layer 130 and the electronic element 160. In other words, the dielectric layer 130 is disposed between the upper substrate 320 and the lower substrate 310. The upper substrate 320 includes a second base material layer 112 and a second metal layer 314. In some embodiments, the upper substrate 320 is a single-sided copper-clad plate. Thus, the electronic element 160 is buried in the dielectric layer 130 without the need for an additional groove step.

Referring to FIG. 3F , a drilling operation is performed to form an opening O1 extending from the upper substrate 320 to expose the electronic element 160, and to form a through hole V1 extending from the upper substrate 320 to the lower substrate 310. FIG. 3F only shows the formation of two openings O1 and one through hole V1, but the present invention does not limit the number of openings O1 and through holes V1, so different numbers of openings O1 and through holes V1 can be formed according to subsequent applications.

Please refer to FIG. 3G , and fill the opening O1 and the through hole V1 (see FIG. 3F ) with conductive material to form a conductive blind via 170 and a conductive through hole 180, respectively. In some embodiments, the conductive blind via 170 and the conductive through hole 180 can be formed by electroplating or chemical plating. As described above, the number of the conductive blind via 170 and the conductive through hole 180 can be adjusted according to subsequent applications. The conductive blind via 170 extends from the second metal layer 314 to the electronic element 160 so that the heat generated by the electronic element 160 can be quickly dissipated. Then, the first metal layer 304 and the second metal layer 314 are patterned to form the first circuit layer 104 and the second circuit layer 114, respectively. In this way, the circuit board 100 shown in FIG. 1 can be manufactured.

By applying the circuit board and the manufacturing method thereof provided by the present invention, the phase change material is filled in the cavity in the bent metal plate, and the electronic components are arranged on the upper bottom plate of the bent metal plate and between the first inner plate and the second inner plate, not only the slotting step can be omitted, but also the heat dissipation and electromagnetic shielding effects can be achieved at the same time even if the electronic components are buried in the circuit board. Furthermore, the manufacturing process of the bent metal plate filled with phase change material is simple, and materials can be saved to reduce costs.

Although the present invention has been disclosed as above with several embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the scope of the attached patent application.

10: gap 100: circuit board 102: first substrate layer 104: first circuit layer 110: first substrate 112: second substrate layer 114: second circuit layer 120: second substrate 130: dielectric layer 135: first thermal conductive adhesive layer 140: bent metal plate 150: phase change material 160: electronic component 165: second thermal conductive adhesive layer 170: conductive blind hole 180: conductive through hole 202: lower base plate 204: first outer plate 206: second outer plate 210: first U-shaped plate 220: solder 230: second metal plate 232: upper base plate 234: first inner plate 235: Second U-shaped plate 236: Second inner plate 304: First metal layer 310: Lower substrate 314: Second metal layer 320: Upper substrate O1: Opening R1: Recessed area R2: Groove R3: Groove V1: Through hole

The present invention is best understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, as is standard practice in the industry, many features are not drawn to scale. In fact, for the sake of clarity of discussion, the dimensions of many features may be arbitrarily scaled. [FIG. 1] shows a cross-sectional view of a circuit board according to some embodiments of the present invention. [FIG. 2A] to [FIG. 2D] show cross-sectional views of intermediate stages in the manufacturing process of a bent metal plate filled with a phase change material according to some embodiments of the present invention. [FIG. 3A] to [FIG. 3G] show cross-sectional views of intermediate stages in the manufacturing method of a circuit board according to some embodiments of the present invention.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

10: gap 100: circuit board 102: first base material layer 104: first circuit layer 110: first substrate 112: second base material layer 114: second circuit layer 120: second substrate 130: dielectric layer 135: first thermal conductive adhesive layer 140: bent metal plate 150: phase change material 160: electronic component 165: second thermal conductive adhesive layer 170: conductive blind hole 180: conductive through hole 202: lower base plate 204: first outer side plate 206: second outer side plate 210: first U-shaped plate 232: upper base plate 234: first inner side plate 235: second U-shaped plate 236: Second medial plate

Claims (14)

A circuit board comprises: A first substrate comprising a first circuit layer; A second substrate disposed on the first substrate and comprising a second circuit layer; A dielectric layer disposed between the first substrate and the second substrate; A bent metal plate disposed in the dielectric layer, wherein the bent metal plate comprises a first U-shaped plate and a second U-shaped plate, the first U-shaped plate comprises a lower bottom plate, a first outer plate and a second outer plate, the second U-shaped plate comprises an upper bottom plate, a first inner plate and a second inner plate, the first inner plate is connected to the first outer plate, the second inner plate is connected to the second outer plate, and there is a cavity between the first U-shaped plate and the second U-shaped plate; A phase change material is filled in the cavity; and An electronic component is disposed on the upper base plate and between the first inner plate and the second inner plate. The circuit board as described in claim 1 further comprises: A first thermally conductive adhesive layer disposed between the first circuit layer of the first substrate and the bent metal plate. The circuit board as described in claim 1 further comprises: A second thermally conductive adhesive layer disposed between the bent metal plate and the electronic component. The circuit board as described in claim 1 further comprises: A plurality of conductive blind vias extending from the second circuit layer to the electronic component. The circuit board as described in claim 1 further comprises: At least one conductive via extending from the second circuit layer to the first circuit layer. A circuit board as described in claim 1, wherein a gap is formed between the electronic component and the first inner plate and the second inner plate of the bent metal plate, and the dielectric layer is filled in the gap. A circuit board as described in claim 1, wherein the electronic component directly contacts the first inner plate and the second inner plate of the bent metal plate. A method for manufacturing a circuit board, comprising: Providing a lower substrate, wherein the lower substrate comprises a first substrate layer and a first metal layer below the first substrate layer; Removing a portion of the first substrate layer to form a groove exposing a portion of the first metal layer; Forming a bent metal plate on the groove, wherein the bent metal plate comprises a first U-shaped plate and a second U-shaped plate, the first U-shaped plate comprises a lower bottom plate, a first outer plate and a second outer plate, the second U-shaped plate comprises an upper bottom plate, a first inner plate and a second inner plate, the first inner plate is connected to the first outer plate, the second inner plate is connected to the second outer plate, and there is a cavity between the first U-shaped plate and the second U-shaped plate, and a phase change material is filled in the cavity of the bent metal plate; Placing an electronic component on the upper base plate of the bent metal plate and between the first inner plate and the second inner plate; Forming an upper substrate above the electronic component, wherein the upper substrate includes a second substrate layer and a second metal layer above the second substrate layer; and Patterning the first metal layer and the second metal layer to form a plurality of circuit layers respectively. The method for manufacturing a circuit board as described in claim 8, wherein the step of forming the bent metal plate on the groove further includes: forming a first thermally conductive adhesive layer in the groove; and laminating the bent metal plate on the first thermally conductive adhesive layer. The method for manufacturing a circuit board as described in claim 8, wherein the step of placing the electronic component further comprises: forming a second thermally conductive adhesive layer on the upper base plate of the bent metal plate; and placing the electronic component on the second thermally conductive adhesive layer. The method for manufacturing a circuit board as described in claim 8, wherein the step of forming the upper substrate above the electronic element further includes: forming a dielectric layer between the lower substrate and the upper substrate. The method for manufacturing a circuit board as described in claim 8, wherein before forming the circuit layer, it further comprises: Forming a plurality of conductive blind vias, wherein the conductive blind vias extend from the upper substrate to the electronic component. The method for manufacturing a circuit board as described in claim 8, wherein before forming the circuit layer, it further comprises: forming at least one conductive via, wherein the conductive via extends from the upper substrate to the lower substrate. The manufacturing method of the circuit board as described in claim 8, wherein the step of forming the bent metal plate comprises: Bending a first metal plate into the first U-shaped plate, wherein the first U-shaped plate has a recessed area; Filling the phase change material into the recessed area; Connecting a second metal plate to the first U-shaped plate, wherein the second metal plate covers the phase change material; and Bending the second metal plate into the second U-shaped plate, so that the phase change material is sealed between the first U-shaped plate and the second U-shaped plate.

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