WO2013000207A1

WO2013000207A1 - Metal-based circuit board and manufacturing method therefor

Info

Publication number: WO2013000207A1
Application number: PCT/CN2011/080077
Authority: WO
Inventors: 余怀鹏; 谷新; 彭勤卫; 孔令文
Original assignee: 深南电路有限公司
Priority date: 2011-06-30
Filing date: 2011-09-23
Publication date: 2013-01-03
Also published as: CN102300397A

Abstract

Disclosed are a metal-based circuit board and a manufacturing method therefor. The method comprises: arranging on a surface of a top layer circuit a laminated layer (110), arranging a groove on the laminated layer, the bottom of the groove reaching at least the top layer circuit (120), electroplating the groove, and a metal electroplated onto the groove forming a metal base (130). By embedding within the circuit board the metal base used for heat dissipation, the circuit board is suitable for various types of packages, and allows for highly efficient heat dissipation.

Description

Metal base circuit board and method of manufacturing same

The present application claims priority to Chinese Patent Application No. 201110181156.0, entitled "Metal-Based Circuit Board and Its Manufacturing Method", filed on June 30, 2011, the entire contents of in.

Technical field

The present invention relates to the field of electronic packaging technology, and in particular to a metal based circuit board and a method of manufacturing the same.

Background technique

Today's electronic products are moving in two directions: on the one hand, the integration of products is getting higher and higher, and the power consumption is increasing; on the other hand, the products are getting lighter, thinner and shorter. This makes the heat dissipation contradiction of the product more and more prominent. As one of the key pillars of the development of the electronic information industry, integrated circuit packaging is also moving toward high integration, high performance, high reliability, low power consumption and low cost. Circuit boards, particularly package substrates in which the main carrier of packaged integrated circuits is used, are required to have more excellent heat dissipation performance.

As shown in FIG. 1 , a commonly used method for improving the heat dissipation performance of a package substrate is to laminate a metal plate as a metal base ( b ) on the package substrate ( a ) for heat dissipation. For the purpose of efficient heat dissipation, a thicker metal base is laminated. However, this method can only conduct heat from the outermost surface of the board, and the heat inside the board cannot be derived in time, and the heat dissipation effect is not good. In particular, where the chip is packaged, heat is accumulated in the package substrate.

Summary of the invention

The embodiment of the invention provides a metal-based circuit board and a manufacturing method thereof. The metal-based circuit board manufactured by the method can timely heat the heat inside the circuit board to improve heat dissipation efficiency.

A method of manufacturing a metal-based circuit board, comprising:

Laminating a layer on the surface of the upper layer circuit;

A groove is formed in the pressing layer, and a bottom of the groove reaches at least the upper circuit; the groove is plated, and a metal plated in the groove forms a metal base.

A metal based circuit board comprising:

a substrate, a circuit layer on the surface of the substrate, and a pressing layer disposed on the surface of the circuit layer; the pressing layer is provided with a groove reaching the circuit layer, and the groove is provided with a metal base formed by electroplating. The embodiment of the invention adopts a technical solution of forming a groove on the pressing layer of the circuit board and plating the groove to form a metal base in the groove, so that the metal base for heat dissipation can be embedded in the circuit board, thereby being made. The metal-based circuit board can dissipate heat inside the circuit board through the metal base embedded in the circuit board, and if the component is mounted on the metal base, the component can be dissipated, and the method is The circuit board, because its metal base is located in the recess, does not completely occupy a surface of the circuit board. Therefore, it is optional to make circuit patterns on both sides of the circuit board, so that both sides of the circuit board are used for connecting electronic components. Can improve the surface utilization of the board.

DRAWINGS

Figure 1 is a schematic view of a conventional circuit board laminated with a metal base;

2 is a flow chart of a method of manufacturing a metal-based circuit board according to an embodiment of the present invention;

3a-3s are schematic views of a metal-based circuit board according to an embodiment of the present invention in a manufacturing process; and Figs. 4a-4j are schematic views of a metal-based circuit board according to an embodiment of the present invention in a manufacturing process. detailed description

The embodiment of the invention provides a method for manufacturing a metal-based circuit board, comprising: providing a pressing layer on a surface of the upper layer circuit; forming a groove on the pressing layer, the bottom of the groove reaching at least the a layer of circuitry; electroplating the trench, the metal plated in the trench forming a metal radical. Embodiments of the present invention also provide corresponding metal based circuit boards. The details are described below separately. Embodiment 1

Referring to FIG. 2, an embodiment of the present invention provides a method of fabricating a metal-based circuit board.

The manufacture of the board begins with the processing of the substrate. The substrate is the basic material for manufacturing circuit boards. As shown in FIG. 3a, the substrate includes an inner layer of an insulating dielectric layer 210 and a metal conductive layer 220 overlying the insulating medium. The insulating dielectric layer 210 may be an epoxy resin, a glass cloth, or the like. 220 can be a copper foil. Typically, the substrate can be a copper clad laminate.

The circuit pattern can be formed by performing the steps of filming, exposing, developing, etching, removing the film on the metal conductive layer of the substrate, and the metal conductive layer which has been formed into a circuit can be referred to as a circuit layer. The film may be a dry film. The dry film is a high molecular compound which, after being irradiated by ultraviolet rays, can produce a polymerization reaction to form a stable substance attached to the surface of the substrate, thereby achieving the function of blocking plating and etching. Apply a dry film to the surface of the metal conductive layer, and dry the part where the circuit is not required. The film is blocked by a light blocking material, and then the dry film is exposed by ultraviolet rays, and then developed by a developing solution, wherein the unblocked dry film is exposed to the surface of the metal conductive layer after exposure, and is blocked by the dry film which is not exposed to be exposed. In the developer. Then, etching is performed, and the portion of the metal conductive layer that is not protected by the dry film is etched away by the etching liquid, and the protected portion remains to form a circuit pattern. Finally, the dry film is removed, and the step of fabricating the circuit to form the circuit layer ends.

It is possible to fabricate a circuit on only one side of the substrate to form a single panel. It is also possible to fabricate a circuit on both the upper and lower sides of the substrate to form a double panel. It is also possible to use a Clearance Hole, a Build Up method, or a plating method. Multilayer boards are produced by methods such as general method (PTH). The method of the embodiments of the present invention is directed to a multilayer board.

Referring to FIG. 2, a method for manufacturing a metal-based circuit board according to an embodiment of the present invention includes:

110. A pressing layer is disposed on a surface of the upper layer circuit.

The above-mentioned circuit can refer to the circuit fabricated on the surface of the substrate. However, as the number of layers increases, the upper layer circuit may also refer to circuits of other layers. The press layer can be set in two ways. In one embodiment, the pressing layer comprises: an insulating dielectric layer disposed on a surface of the upper layer of the circuit and a metal conductive layer disposed on a surface of the insulating dielectric layer. As shown in Fig. 3g, the bonding layer provided in this manner comprises: an insulating dielectric layer 240 disposed on the surface of the circuit layer 231 and a metal conductive layer 250 disposed on the surface of the insulating dielectric layer. In another aspect, the pressing layer comprises: a prepreg disposed on a surface of the upper layer of the circuit; and a next substrate disposed on the surface of the prepreg, at least one side of the next substrate contacting the prepreg A circuit has been made. In the above two methods, the settings may be set by pressing.

120. A groove is formed on the pressing layer, and a bottom of the groove reaches at least the circuit layer. As shown in Fig. 3h, a groove 304 is formed in the embossed layer to subsequently make a metal base embedded in the groove. The groove 304 has a certain depth, and the bottom portion can reach the upper layer circuit, that is, the circuit layer 231. Of course, it can be deeper. For example, the groove 304 can even be a through groove penetrating through the substrate. Generally, the bottom of the recess 304 is brought to the upper layer circuit, such as the circuit layer 231.

130. Electroplating the recess, and the metal plated in the recess forms a metal base.

The recess is electroplated and the metal plated in the recess forms a metal base for heat dissipation. This step may specifically include:

131. A dry film is disposed on a portion of the pressing layer where the groove is not formed. As shown in Fig. 3i, in this step, a dry film 260 is provided on other portions of the press-fit layer where no grooves are formed, in order to prevent portions other than the grooves from being plated. The steps of setting the dry film specifically include filming, exposure and development, and the following are not described in detail.

132. Electroplating the groove to achieve a predetermined thickness of the metal plated in the groove.

Once the dry film is set, the groove can be plated to control the thickness of the coating and stop plating when the preset thickness is reached. As shown in Fig. 3j, after plating, the metal in the recess, i.e., the metal base 305, may be slightly higher than the metal conductive layer 250 included in the press-fit layer.

133. Remove the dry film and smooth the surface.

As shown in Fig. 3k and Fig. 31, the dry film is finally removed, and the metal base 305 and the metal conductive layer 250 are aligned.

At this point, the metal base is completed.

After the metal substrate is fabricated, the outermost circuit pattern is formed by laminating, exposing, developing, etching, and removing the film on the outermost one or two metal conductive layers to form the outermost circuit layer, and then setting Good solder mask and pad, metal-based board is completed. In order to better conduct the heat inside the circuit board to the metal base of the surface layer of the circuit board, the present invention also provides two preferred embodiments:

In one embodiment, in order to transfer the heat of the circuit on one side of the substrate and the heat inside the substrate to the metal substrate on the other side, before step 110, a thermal via may be formed on the substrate. The specific steps include:

101. A through hole is formed in the substrate, and the through hole is metallized.

As shown in Fig. 3b, a through hole 301 is preliminarily formed on the substrate. The via 301 is then metallized to achieve heat transfer between the upper and lower sides. As shown in Fig. 3c, metallization means depositing a layer of metal 302, such as copper, on the walls of the vias 301. The through hole 301 is a through hole for heat conduction. In the actual process, other through holes for conducting electricity may be opened according to the needs of the circuit to realize electrical connection between the two layers of circuits.

102. The through hole is filled with a heat conductive material, and the heat conductive material is a cured resin or a metal paste. In order to increase the cross-sectional area of the through-hole heat transfer and improve the heat transfer efficiency, the through hole after metallization can be used. The thermally conductive material 303 is filled, as shown in Figure 3d. The filled thermally conductive material 303 may be a cured resin or a metal paste.

103. Perform chemical copper plating or electroplating on the substrate subjected to steps 101 and 102 to form a metal conductive layer covering the surface of the substrate.

As shown in Fig. 3e, the substrate subjected to steps 101 and 102 can be subjected to electroless copper plating or electroplating to form a new metal conductive layer 230 covering the surface of the substrate on the original metal conductive layer. If the filled heat conductive material is an insulating cured resin, the metal conductive layer 230 is formed by a method of chemically sinking copper; if the filled heat conductive material is a conductive metal paste, the metal conductive layer 230 is formed by electroplating. The purpose of providing the metal conductive layer 230 is to prepare for subsequent metallization to form a metal base. If the heat conductive material is an insulating cured resin, the metal base cannot be subsequently plated without first performing chemical copper immersion; if the heat conductive material is electrically conductive In the case of the metal paste, it is difficult to electroplate a metal base of a sufficient thickness without first performing electroplating. Forming a metallic conductive layer means that the thermal via is completed. Of course, it is also possible to laminate a thermal conductive insulating layer over the copper plating hole and then deposit the copper plating. In this way, the copper plating hole can be connected to the interlayer circuit in addition to the heat conducting hole.

104. Making a circuit on the metal conductive layer.

As shown in Fig. 3f, after the thermal via is completed, a circuit pattern can be formed on the metal conductive layer 230 by lamination, exposure, development, etching, film removal, etc., to form the circuit layer 231.

Then, steps 110-130 are performed to provide a pressing layer on the surface of the upper layer circuit, that is, the circuit layer 231, a groove is formed on the pressing layer, and the groove is plated to form a metal base. Wherein, the position of the groove formed may be a position corresponding to the through hole 301 on the pressing layer.

The metal base prepared in this embodiment is located in the opened recess, the top of which is flush with the metal conductive layer 250 of the outer layer, and the bottom is in contact with the circuit layer 231 of the inner layer, so that heat can be conducted with high efficiency. Moreover, since the groove is opened at the position where the through hole is located, the metal base in the groove and the filled heat conductive material in the through hole may be connected through the circuit layer 231, and the groove is provided on both sides of the circuit board with the metal base In this case, the metal base on both sides can transmit heat well through the heat conductive material in the through hole.

In another embodiment, in order to better transfer the heat inside the circuit board to the metal base of the surface layer of the circuit board, the following preferred solution can be adopted:

101, as shown in FIG. 3p, a through groove 307 is formed in the substrate. The through slot 307 extends through the entire substrate. The position of the through groove 307 corresponds to the position of the groove 304. The size of the channel 307 can also be chosen to be comparable to the size of the recess 304.

102, as shown in FIG. 3q, the through trench 307 is plated and filled. After plating, the vias 307 are completely filled with the plating material, and the plating material located in the vias 307 forms the inner metal base 308 located within the substrate. Of course, before electroplating, it is necessary to perform a copper immersion treatment on the through-groove 307 to form a conductive layer on the surface of the substrate and the inner wall of the via 307 for subsequent plating.

Then, in step 104, a circuit layer 231 is formed on the surface of the substrate.

Then, steps 110-130 are performed, a pressing layer is disposed on the surface of the circuit layer 231, a groove 304 is formed on the pressing layer, and the groove 304 is plated to form a metal base 305. The position of the groove 304 may be the position of the pressing layer corresponding to the groove 307. The formed metal base 305 and the inner metal base 308 are joined together to form a monolithic metal base throughout the entire circuit board.

Since the metal base formed in this embodiment is a monolithic metal base penetrating the entire circuit board. Thus, the heat of one surface of the board can be better transferred to the other surface, and the heat inside the board can be better transmitted on the metal base of the surface of the board. Compared with the method for filling heat in the through hole formed in the substrate used in the previous embodiment to transfer heat, the present embodiment can have higher heat transfer by using a whole metal base extending through the entire circuit board to transfer heat. Efficiency for more efficient heat dissipation. Further, if the circuit board needs to be provided with more layers of circuits, it is necessary to provide a plurality of pressing layers, and at least one circuit forming circuit layer is formed on each of the pressing layers. In this application scenario, the metal-based board can be fabricated in the following two ways:

Method 1: After the metal base is formed in step 130, a layer of circuit is formed on the set pressing layer, and then steps 110-130 are repeatedly performed, that is, the pressing layer is repeatedly set, the groove is opened, and the groove is plated. A step of. For details, please refer to FIG. 3m. After step 130, it may include:

Forming a layer of circuitry on the current bonding layer to form a new circuit layer 251;

A new bonding layer is disposed on the surface of the new circuit layer 251;

Opening a new groove on the new pressing layer, the bottom of the new groove reaching the new circuit layer 251; plating the new groove, and plating a metal in the new groove to form a new metal Base 306. In this way, each time the lap layer is added, the metal base is made once, and finally, A plurality of metal bases formed in multiple times are joined together to form a final metal base.

Wherein, if the inner layer metal base 308 has been previously prepared in the substrate, the cross-sectional structure of the circuit board after the layer is formed by the present method and the metal base is formed on the build-up layer is as shown in Fig. 3r.

Manner 2: Step 110 is repeated before step 120 to set a plurality of bonding layers until the required number of circuit layers is reached, wherein a circuit is formed on the previous bonding layer before each of the next bonding layers is disposed. Then, step 120 is performed, a groove is formed on the plurality of pressing layers, and the bottom of the groove reaches the innermost circuit layer, and then step 130 is performed to plate the bottom of the groove reaching the innermost circuit layer. Forming a metal base. Referring to Figure 3n, the metal base formed in this manner is a monolithic metal base 305.

Wherein, if the inner metal base 308 has been previously prepared in the substrate, the cross-sectional structure of the metal-based circuit board produced by the present method is as shown in Fig. 3s. The method for manufacturing the metal-based circuit board according to the embodiment of the present invention has been described in detail above with reference to FIGS. 3a-3s. Wherein, the pressing layer is provided in the method of 110-130, the groove is formed, and the step of plating the groove can be performed on both sides of the substrate at the same time, and the finished circuit board is provided with embedded metal on both sides thereof. base.

However, the method provided by the embodiment of the present invention is also applicable to other scenarios. For example, as shown in Figures 4a-4j,

The step of providing a pressing layer as described in 110-140, opening a groove, and plating the groove may be performed only on one surface of the substrate, that is, forming an embedded metal base 305 on only one side, and then An outer layer circuit is formed on one side of the metal substrate; a metal plate 300 for heat dissipation may be disposed on the other side of the substrate as a metal heat conduction layer, and specifically, may be formed on the other side, that is, the opposite surface of the circuit layer. The insulating bonding layer 400 is bonded to the bonding layer 400 with a thermally conductive metal layer.

Further, in the case where the heat conduction through hole 301 is formed in the substrate, the embedded metal base transfers heat to more efficiently dissipate heat.

Further, the circuit board is packaged with components, such as a chip, above the recess, and the metal base can also dissipate heat for the component. Of course, it is also possible to form a circuit layer on both sides of the substrate, to provide a pressing layer on the circuit layer, to form a groove on the pressing layer and to plate the groove, and then, the pressing layer on one of the sides A thermally conductive insulating layer is laminated on the circuit layer, and the metal plate is disposed on the insulating layer. In summary, this embodiment introduces a method for manufacturing a metal-based circuit board, which adopts a technical solution of forming a groove on a press-bonding layer of a circuit board and plating the groove to form a metal base located in the groove. The metal base for heat dissipation is embedded inside the circuit board, so that the heat inside the circuit board can be dissipated through the metal base embedded in the groove, and optionally in the two outermost layers (ie: It is suitable for various types of package forms, and can reduce the thickness of the metal-based heat-dissipating circuit board when only the metal base is provided in the groove of the press-bonding layer; on the other hand, the metal The base and the board are integrated to reduce the thermal resistance between them for efficient heat dissipation. The technical solution is particularly suitable for the fabrication of a package substrate of a packaged integrated circuit, and of course, can also be used for the fabrication of other various types of circuit boards. In addition, in the method of the embodiment of the present invention, the metal base is formed by the electroplating method, and the metal base having a small area can be fabricated on the package substrate having a size of only several millimeters, or the metal base having a large area can be fabricated on the large circuit board. Therefore, the scope of application is quite extensive, and it is suitable for mass production and industrialization. Embodiment 2

Referring to FIG. 3a-3n, an embodiment of the present invention provides a metal-based circuit board, including:

a substrate 210, a circuit layer 231 on the surface of the substrate, and a bonding layer disposed on the surface of the circuit layer 231;

A recess 304 is formed in the press layer to reach the circuit layer, and a metal base 305 formed by electroplating is disposed in the recess.

The pressing layer may include: an insulating dielectric layer disposed on a surface of the upper layer of the circuit and a metal conductive layer disposed on a surface of the insulating dielectric layer; or the pressing layer may further include: The prepreg of the surface of the upper layer of the circuit and the next layer of the substrate disposed on the surface of the prepreg, and at least one side of the substrate of the lower layer contacting the prepreg has been fabricated.

In one embodiment, a metallized through hole 301 is defined in the substrate 210 corresponding to the recess 304. The through hole 301 is filled with a heat conductive material 303, and the heat conductive material 303 is a cured resin or a metal. Slurry.

In another embodiment, the circuit layer 231 includes an upper circuit layer and a lower circuit layer on an upper surface of the substrate 210, the pressing layer includes an upper bonding layer disposed on a surface of the upper circuit layer and disposed in the The lower press layer on the surface of the lower circuit layer. In still another embodiment, the pressing layer includes two or more sub-pressing layers disposed in sequence, and the groove 304 and the metal base 305 disposed in the groove 304 penetrate the two or more layers. Press layer.

In another embodiment, the circuit board further includes an adhesive layer and a metal heat conductive layer, wherein the circuit layer is located on a surface of the substrate, and a surface of the adhesive layer is bonded to the substrate opposite to the circuit layer. The surface, the other surface of the bonding layer is provided with the metal heat conducting layer. The metal-based circuit board provided in this embodiment may specifically be a metal-based package substrate for packaging of an integrated circuit; or other various types of circuit boards, such as a system circuit board, a radio frequency circuit board, a power circuit board, and the like. .

The metal-based circuit board provided in this embodiment, on the one hand, realizes that the metal base for heat dissipation is embedded inside the circuit board, so that the two outermost layers of the circuit board can be wired, which is suitable for various types of package forms. Moreover, the thickness of the metal-based heat dissipation circuit board can be reduced; on the other hand, the metal base and the circuit board are integrated to reduce the thermal resistance between them to achieve efficient heat dissipation.

The above is only a preferred embodiment of the present invention, and is only used to help understand the method of the present invention and its core idea, but the scope of the present invention is not limited thereto, and any person skilled in the art may disclose the present invention. Variations or substitutions that are conceivable within the scope of the invention are intended to be included within the scope of the invention. The scope of protection of the invention should be determined by the scope of the claims.

Claims

Rights request

A method of manufacturing a metal-based circuit board, comprising:

Laminating a layer on the surface of the upper layer circuit;

The method according to claim 1, wherein before the setting of the pressing layer on the surface of the upper layer circuit, the method further comprises:

Opening a through hole in the substrate and metallizing the through hole;

Filling the through hole with a heat conductive material, the heat conductive material being a cured resin or a metal paste; plating the substrate subjected to the above treatment to form a metal conductive layer covering the surface of the substrate; and fabricating a circuit on the metal conductive layer .

The method according to claim 2, wherein the forming the groove on the pressing layer comprises:

A groove is formed in the press-bonding layer at a position corresponding to the through hole.

Opening a through groove on the substrate, the position of the through groove corresponding to the position of the groove;

Plating the through trenches;

An electrical circuit is fabricated on the surface of the substrate.

The method according to claim 1, wherein the plating the groove comprises: providing a dry film at a portion of the pressing layer where the groove is not formed;

Electroplating the trench to bring the metal plated in the trench to a predetermined thickness;

The dry film is removed and the surface is leveled.

6. The method of claim 1 wherein:

The pressing layer includes: an insulating dielectric layer disposed on a surface of the upper layer of the circuit; and a metal conductive layer disposed on a surface of the insulating dielectric layer; or

The pressing layer includes: a prepreg disposed on a surface of the upper layer of the circuit; and a next substrate disposed on a surface of the prepreg, wherein at least one side of the underlying substrate contacting the prepreg has Make a good circuit.

The method according to any one of claims 1 to 6, wherein after the plating is performed on the groove, the method further comprises:

Forming a layer of circuitry on the laminated layer;

Repeating the steps of providing a pressing layer, opening a groove, and plating the groove.

8. A method according to any one of claims 1 to 6, characterized in that:

The providing a pressing layer on the surface of the upper layer circuit includes: providing at least two pressing layers on the surface of the upper layer circuit, wherein each of the pressing layers is formed on the previous pressing layer before each of the lower pressing layers is disposed The opening of the groove on the embossing layer comprises: starting a groove on the at least two pressing layers, the bottom portion of the groove reaching the upper layer circuit.

The method according to claim 1 or 2, wherein the plating is performed on the recess, and after plating the metal in the recess to form a metal base, the method further comprises:

An adhesive layer is formed on the opposite side of the upper layer of the circuit, and a thermally conductive metal layer is bonded to the adhesive layer.

10. A metal-based circuit board, comprising:

a substrate, a circuit layer on the surface of the substrate, and a pressing layer disposed on the surface of the circuit layer; the pressing layer is provided with a groove reaching the circuit layer, and the groove is provided with a metal base formed by electroplating.

11. The metal base circuit board according to claim 10, wherein:

The pressing layer includes: a prepreg disposed on a surface of the upper layer of the circuit; and a next substrate disposed on a surface of the prepreg, wherein at least one side of the underlying substrate contacting the prepreg has been fabricated.

12. The metal base circuit board according to claim 10, wherein:

A metallized through hole is formed in the substrate corresponding to the position of the groove, and the through hole is filled with a heat conductive material, and the heat conductive material is a cured resin or a metal paste.

13. The metal base circuit board according to claim 10, wherein:

A through groove is formed on the substrate corresponding to the position of the groove, and the through groove is filled with plating.

14. The metal base circuit board according to claim 10, wherein:

The circuit layer includes an upper circuit layer on an upper surface of the substrate and a lower circuit layer on a lower surface of the substrate, the pressing layer including an upper bonding layer on a surface of the upper circuit layer and a surface disposed on the lower circuit layer Press down the layer.

15. The metal base circuit board according to claim 10, wherein:

The press-fit layer includes two or more sub-nip layers disposed in sequence, and the groove and the metal base disposed in the groove penetrate the two or more sub-nip layers.

The metal base circuit board according to claim 10 or 15, wherein the circuit board further comprises an adhesive layer and a metal heat conductive layer, wherein the circuit layer is located on a surface of the substrate, and the adhesive layer is The surface is bonded to a surface of the substrate opposite to the circuit layer, and the other surface of the bonding layer is provided with the metal heat conducting layer.