KR101125317B1 - Circuit board and method of manufacturing the same - Google Patents

Abstract

An object of this invention is to provide the wiring board which refine | miniaturizes the arrangement pitch of the through-holes formed in a wiring board, and satisfy | fills the characteristics, such as intensity | strength and a low thermal expansion coefficient requested | required by a wiring board.

The prepreg 10a formed by impregnating the carbon fiber 5a so that the position through which the conducting through hole 19 passes can be made into the air gap 6, and impregnating the resin 11 with the carbon fiber 5a. The process of forming the core part 10 by thermocompression bonding 10b and 10c, and the through hole 13 which passes the inside of the pore 6 in the position which becomes the said pore 6 of this core part 10. Forming a conductive layer 14 on the inner surface of the through hole 13 and forming a conductive through hole 19 in an arrangement that does not interfere with the carbon fiber 5a. It includes the process made into.

Description

CIRCUIT BOARD AND METHOD OF MANUFACTURING THE SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board and a manufacturing method thereof, and more particularly, to a wiring board having a core substrate, a method of manufacturing the wiring board, and a prepreg used for a semiconductor device and wiring board using the wiring board. It is about.

There is a product in which a core substrate is provided with carbon fiber reinforced plastic (CFRP) in a wiring board on which a semiconductor element is mounted. The core substrate provided with the carbon fiber reinforced plastic has a lower coefficient of thermal expansion compared to a core substrate composed of a conventional glass epoxy substrate, and the wiring substrate using the core substrate allows the thermal expansion coefficient to match the thermal expansion coefficient of the semiconductor element. This is useful for preventing thermal stresses generated between semiconductor devices and wiring boards.

The wiring board is formed by stacking wiring layers on both surfaces of the core substrate, and through-holes (PTH (Plated through hole)) for electrical conduction are formed in the core substrate for the electrical connection with the wiring layers stacked on both surfaces thereof. This conducting through hole is formed by forming a through hole in the substrate and forming a conducting portion (plating layer) on the inner wall surface of the through hole by plating.

By the way, in the case of the core substrate provided with the core part which has electroconductivity like carbon fiber reinforced plastics, when through-hole is simply formed in a board | substrate and plating on the inner wall surface of a through-hole, a through-hole and a core part are electrically shorted. Throw it away. For this reason, when forming a through-hole in the core board | substrate provided with the electroconductive core part, after forming a hole with a larger diameter than a through-hole in a core board | substrate, and filling a base hole with resin which has insulation, Through-holes are formed in the holes so that the through-holes and the core portion are not electrically shorted (see Patent Documents 1 and 2).

Patent Document 1: Japanese Patent Laid-Open No. 2003-218287

Patent Document 2: Japanese Patent Publication No. 2004/064467

However, in the arrangement in which the base hole is formed in the core substrate and the through hole is penetrated in the base hole, since the base hole is larger in diameter than the through hole, it is compared with the case where the through hole is simply arranged in the core substrate. The space | interval of the conduction through-hole becomes large, and there exists a restriction | limiting in arrange | positioning a conduction through-hole at high density.

In addition, when the insulating resin is filled into the base hole, the thermal expansion coefficient of the core substrate acts to increase, and in the case of the wiring substrate having carbon fiber in the core portion, the advantage of the core substrate formed by the low thermal expansion coefficient is reduced. Is inhibited.

DISCLOSURE OF THE INVENTION The present invention has been made to solve these problems, and a wiring board capable of miniaturizing the arrangement pitch of the through-holes formed in the wiring board and satisfying characteristics such as strength, thermal expansion coefficient, etc. required for the core substrate, and its It is an object to provide a manufacturing method, a prepreg used for a semiconductor device and a wiring board.

This invention is equipped with the following structures in order to achieve the said objective.

That is, as a manufacturing method of a wiring board, the process of arrange | positioning a fiber so that the position through which a through-hole may pass through is made into an air gap, thermocompressing the prepreg formed by impregnating resin, and forming the core part, Forming a through hole passing through the inner side of the cavity at a position to be formed, and forming a conductive layer on the inner surface of the through hole to form a through hole in an arrangement that does not interfere with the fiber to form a core substrate. Characterized in that it comprises a.

In the step of forming the core part, the fiber is formed as a carbon fiber woven fabric, and in the step of forming the core part, the fiber is formed by using a prepreg having an air gap through which the through-hole is passed. By using a prepreg formed of a woven fabric composed of a carbon fiber and a non-conductive fiber, the prepreg having a hole through which the through-holes pass through the woven fabric prevents electrical short-circuit between the conductive core portion and the conductor through-hole and prevents the wiring board. It can manufacture.

Moreover, as a structure of a wiring board, the core which comprises the core board | substrate, the wiring layer laminated | stacked on both surfaces of the core board | substrate, and the through-hole provided in the said core board | substrate by electrically connecting this wiring layer, and comprising the core which comprises the said core board | substrate The part is formed by thermocompressing a prepreg formed by impregnating a fiber in a resin, and the conductive through hole is provided so as not to interfere with the fiber of the core part. It is also possible to use a wiring board as an interposer.

The said fiber is formed as a carbon fiber woven fabric, and the thing in which the air gap which the said through-hole passes through is formed in this carbon fiber woven fabric is used suitably.

In addition, the fiber is formed as a woven fabric of a carbon fiber and a non-conductive fiber, and an air gap in which the through-holes pass through the woven fabric is effectively used.

Moreover, a semiconductor device can be provided by mounting a semiconductor element on the said wiring board.

The prepreg constituting the core portion constituting the core substrate of the wiring board contains fibers having a coefficient of thermal expansion lower than that of copper, and the fibers are provided in an arrangement which does not interfere with the through-holes formed in the core substrate. Is used effectively.

In addition, when the fiber is formed as a carbon fiber woven fabric and an air gap through which the conductive through hole passes is formed in the carbon fiber woven fabric, an electrical short circuit with the conductive through hole is prevented and the core substrate is configured as a core substrate having a low coefficient of thermal expansion. There is an advantage that it becomes. In addition, it is suitably used that the fiber is formed as a woven fabric of a carbon fiber and a non-conductive fiber, and an air gap through which the through-holes pass is formed in the woven fabric.

In the wiring board and the manufacturing method thereof according to the present invention, the fibers in the prepreg are disposed so that the fibers contained in the prepreg forming the core portion of the core substrate are disposed so as not to interfere with the position where the through-holes of the core substrate pass. Through-holes can be formed irrespective of the arrangement of the through holes, and through-holes can be arranged at a fine pitch. Furthermore, by appropriately selecting the fibers contained in the prepreg, it is possible to provide a core substrate having characteristics such as required strength.

(Manufacturing method of wiring board)

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of the manufacturing method of the wiring board which concerns on this invention is described.

In the manufacturing method of the wiring board of this embodiment, the core board provided with the core part which consists of carbon fiber reinforced plastics is used.

1A to 1F show the steps up to forming the core substrate 20 with the core portion 10 made of carbon fiber reinforced plastic.

FIG. 1A shows a prepreg 12 containing carbon fibers and a prepreg 12 containing fillers such as alumina, silica, and the like, for thermally compressing, in order to adjust the coefficient of thermal expansion. The state which arrange | positioned is shown.

In the present embodiment, the core part 10 is formed by overlapping three prepregs 10a, 10b, and 10c. However, the number of prepregs constituting the core part 10 is the thickness of the wiring board or the core board. Can be appropriately selected from the requirements for the strength and the like.

The most characteristic structure in the manufacturing method of the wiring board of this embodiment is the structure of the prepreg 10a, 10b, 10c which comprises the core part and contains carbon fiber. That is, the prepreg 10a, 10b, 10c is comprised as a woven fabric using carbon fiber of long fiber, impregnates resin, such as an epoxy resin, to the woven fabric of carbon fiber, and is formed as a semi-hardened state which has adhesiveness.

The structure characteristic in the prepreg 10a, 10b, 10c is the weaving method. That is, in a normal woven fabric, the fibers are woven uniformly into cotton, but the carbon fiber woven fabric used for the prepregs 10a, 10b, and 10c used in the present embodiment is a conductive through-hole and carbon fiber formed in the core substrate. In order not to interfere 5a, the position through which the through-holes pass through is woven so as to be an empty portion.

2, the state which looked at the carbon fiber woven fabric 5 used for the prepreg 10a, 10b, 10c from the planar direction is shown. Although the carbon fiber woven fabric 5 is formed by weaving the carbon fibers 5a in a flat weave, the hollow portions (herein referred to herein as voids) are formed at predetermined intervals so that the plain weave portions are positioned at regular intervals. When forming the core substrate, a through hole passes through this cavity 6. That is, the carbon fiber woven fabric 5 is woven so as to form the void 6 in advance in accordance with the arrangement of the through-holes formed in the core substrate.

Although the planar arrangement of the through-holes formed in the core substrate differs depending on the product, the through-holes provided in the core substrate are usually arranged in a vertically and horizontally aligned interval. In this way, when the through-holes are arranged at predetermined intervals, it is possible to form the carbon fiber woven fabric 5 so that the voids 6 are formed in accordance with the planar arrangement of the through-holes.

In the case of forming the carbon fiber woven fabric 5, the position of the air gap can be adjusted according to the arrangement of the through-holes, and the longitudinal and horizontal dimensions of the air gap 6 through which the through-holes pass can be adjusted.

The diameter of the disconnection of carbon fiber is about several micrometers. Therefore, it is also possible to weave the disconnection of carbon fiber and to form the carbon fiber woven fabric 5 as shown in FIG. 2, and to form the carbon fiber woven fabric 5 using the braided thread which combined the multiple disconnection of the carbon fiber. You may. In the case of the twisted yarn of the carbon fiber, the diameter is about several tens of m.

Although the arrangement pitch of the through-holes formed in the core substrate is different depending on the product, for example, when the through-holes are arranged at an arrangement pitch of about 400 μm used in a general semiconductor element mounting substrate, the twisted yarn having a diameter of about several tens of micrometers is used. It is easy to form the carbon fiber woven fabric 5 in an arrangement in which the voids 6 are formed at appropriate positions by using a.

Although the carbon fiber woven fabric 5 shown in FIG. 2 is woven so that the carbon fibers 5a cross at right angles to each other, the carbon fiber 5a is obliquely crossed such that the crossing angles of the carbon fibers 5a cross at an angle other than the right angle, for example, 120 °. It is also possible to form the carbon fiber woven fabric 5 in which the voids 6 are formed by a method of intersecting. It is also possible to weave the planar shape of the blank 6 formed in the carbon fiber woven fabric 5 into a rectangle, a lozenge, a hexagon, an octagon, etc. in addition to the square.

In addition, although an example of the carbon fiber woven fabric 5 in which the voids 6 are aligned at regular intervals in the longitudinal and horizontal directions is shown in FIG. 2, the through-holes formed in the core substrate are not evenly arranged, but in a plane. When arranged unevenly, it is also conceivable to form the carbon fiber woven fabric 5 so as to form the voids 6 in accordance with the planar arrangement of these conductive through holes. This invention is not limited to the wiring board in which the through-holes are uniformly arranged, and can be applied also when the through-holes are unevenly arranged.

Prepreg can be obtained by impregnating the carbon fiber woven fabric 5 into a resin. This prepreg is obtained by impregnating the resin in the carbon fiber 5a portion of the carbon fiber woven fabric 5 and filling the voids 6 with the resin 11. In addition, when the void 6 is formed large, the void 6 may not be filled with resin in some cases.

1A is a state in which the prepregs 10a, 10b, and 10c thus obtained are aligned. In the case where a plurality of prepregs are stacked and aligned in this manner, the prepregs are aligned so that the planar positions of the voids 6 of the carbon fiber woven fabric 5 coincide with each other.

During the manufacturing process, the large-size carbon fiber woven fabric 5 is prepared, and the carbon fiber woven fabric 5 is impregnated with a resin such as an epoxy resin to form large prepregs 10a, 10b, and 10c, and the large-size prepreg 10a. , 10b, 10c) are used to form the core substrate. 1A to 1F show enlarged portions of large prepregs 10a, 10b, and 10c that can be divided into a plurality.

FIG. 1B shows a state in which the prepregs 10a, 10b, 10c, and 12 are thermally compressed to form a flat plate. The core part 10 formed integrally with the prepreg 10a, 10b, 10c is arrange | positioned inside the insulating layer 12a which consists of the prepreg 12. As shown in FIG. The core portion 10 includes a region including the carbon fiber 5a and a region serving as the void 6 of the carbon fiber woven fabric 5. The region containing the carbon fiber 5a is an electrically conductive region, and the region of the void 6 is an region filled with the resin 11 and is electrically insulating. When the resin 11 is not filled in the air gap 6 of the carbon fiber woven fabric 5 in the prepreg state, the resin is released from the prepreg 12 into the air gap 6 by thermocompressing the prepreg 12. Is charged.

After the core portion 10 is integrally formed, the through-holes are formed in accordance with the portion of the core portion 10 filled with the resin [11 (12)], in other words, the portion to be the cavity 6 of the carbon fiber woven fabric 5. 13) (FIG. 1C). The through hole 13 is formed in a smaller diameter than the cavity 6 formed in the carbon fiber woven fabric 5. As a result, the resin 11 is exposed to the inner surface of the through hole 13. The through hole 13 is formed by, for example, drilling.

FIG. 1D shows electroless copper plating and electrolytic copper plating on the core portion 10 to form conductive through holes, and the conductor layer (on the inner surface of the through hole 13 and the surface of the core portion 10). 14) is formed. Since the inner surface of the through hole 13 is covered with the resin 11 and the insulating layer 12a, even if the conductor layer 14 is deposited on the inner surface of the through hole 13, the conductor layer 14 and The area of the core portion 10 containing the conductive carbon fiber 5a is not electrically shorted.

FIG. 1E shows a state in which the conductor layer 16 is formed on both surfaces of the core portion 10 after filling the through hole 13 with the resin 15. The conductor layer 16 may be formed by plating.

In FIG. 1F, the conductor layers 16 and 14 are etched in a predetermined pattern to form a wiring pattern 18 on the surface of the substrate, thereby forming the core substrate 20. The conductor layer 14 formed on the inner side surface of the through hole 13 becomes a conductive through hole 19 for electrically connecting wiring patterns formed on both surfaces of the core substrate 20.

The through hole 19 is disposed through the through hole 13 formed in the core portion 10, and the through surface 13 is covered with the electrically insulating resin 11, so that the through hole 19 is formed. The hole 19 is prevented from being electrically shorted to the conductor portion of the core portion 10, that is, the region in which the carbon fiber 5a is contained.

Thus, in the manufacturing method of the core board | substrate of this embodiment, the core board | substrate 20 is provided in the carbon fiber woven fabric 5 which comprises the core part 10 by providing the air gap 6 through which the through-hole 19 passes. At the time of forming the through-hole 19 in (), the through-hole 19 is prevented from conducting with the carbon fiber woven fabric 5, and the through-hole 19 is electrically shorted to the core portion 10. Is prevented.

In addition, the core portion 10 of the core substrate 20 only needs to provide a through hole 13 for forming a through hole 19, and the base hole through which the through hole passes, as in the conventional core substrate, is formed. There is no need to form. Thereby, the arrangement pitch of the through-holes 19 formed in the core substrate 20 can be narrowed compared with the conventional core substrate, and the through-holes 19 can be formed more densely.

In addition, since the through hole 13 formed in the core part 10 is smaller in diameter than before, even when the resin 15 is filled in the through hole 13, the resin is filled in the base hole as in the prior art. In comparison with this, the filling amount of the resin can be suppressed, and the increase in the coefficient of thermal expansion of the core substrate can be effectively suppressed.

(Wiring board)

3 shows a state in which the wiring layer 30 is formed by laminating the wiring layer 22 on both surfaces of the core substrate 20. The wiring layer 22 is formed such that the wiring pattern 26 is electrically connected between the insulating layers 25 through the via holes 24. The wiring pattern 26 formed in the wiring layer 22 on both surfaces of the wiring board 30 is electrically connected through the through-holes 19 formed in the core substrate 20.

The wiring layer 22 can be formed by, for example, a buildup method. On one surface of the wiring board 30 on which the semiconductor element is mounted, a pad 27 to which the semiconductor element is connected is formed. On the other side of the wiring board 30, lands 29 to which external connection terminals are joined, such as solder balls, are formed.

4 shows a state in which the semiconductor device 50 having the semiconductor element 40 mounted on the wiring board 30 is mounted on the mounting board 60. The semiconductor element 40 is mounted on the wiring board 30 by flip chip connection. The semiconductor device 50 is mounted on the mounting substrate 60 by joining the solder balls 62 to the lands 29.

The semiconductor element 40 and the mounting substrate 60 are formed through the through-holes 19 formed in the wiring board 30, the wiring patterns 18 and 26 formed in the wiring layer 22, the via holes 24, and the like. Electrically connected.

As described above, the through-holes 13 are drilled to form the through-holes 19 in the core substrate 20, so that the through-throughs 19 formed in the wiring board 30 are formed. It is possible to arrange the holes 19 at a fine pitch of 400 mu m pitch, for example, which is suitable for mounting a semiconductor element in which electrodes are arranged at a fine pitch.

In addition, the wiring substrate 30 and the semiconductor device 50 of the present embodiment use the carbon fiber woven fabric 5 having a low thermal expansion coefficient as the core substrate 20, whereby the thermal expansion coefficient of the semiconductor element 40 is thermally expanded. It is possible to match the coefficients. The thermal expansion coefficient of the carbon fiber is about 1 ppm / 占 폚, and the thermal expansion coefficient of silicon constituting the semiconductor element 40 is about 3 ppm / 占 폚. Therefore, the wiring board (by adjusting the thermal expansion coefficient of the insulating layer 25 used for the wiring layer 22 or mixing filler into the prepreg containing the carbon fiber constituting the core portion 10). The total thermal expansion coefficient of 30 may be matched to the thermal expansion coefficient of the semiconductor device 40.

Thus, by matching the thermal expansion coefficient of the wiring board 30 with the thermal expansion coefficient of the semiconductor element 40, the semiconductor element 40 and the wiring board 30 during the heat treatment process or during the mounting operation in the manufacturing process. It is possible to alleviate the thermal stress generated in the circuit, and to provide a highly reliable wiring board 30 and semiconductor device 50.

Moreover, in the said embodiment, although the core part 10 of the core board | substrate 20 was formed using the carbon fiber woven fabric 5, the woven fabric which comprises the core part 10 is made of the fiber different from the carbon fiber 5a. It may also be formed as a composite fabric.

In addition, in the said embodiment, although the example in which the semiconductor device 50 which mounted the semiconductor element 40 in the wiring board 30 was mounted on the mounting board 60 is shown, the wiring board 30 is used as an interposer. It can also be set as the structure which mounts the semiconductor device which mounts the semiconductor element 40 on the circuit board through the wiring board 30 on the circuit board.

FIG. 5 shows a plan view of the composite woven fabric 8 produced by weaving the carbon fiber 5a and the arimid fiber 7 in the carbon fiber woven fabric 5 shown in FIG. Also in the case of this woven fabric 8, it is woven so that the air gap 6 may be formed in accordance with the arrangement of the through-holes 19 formed in the core substrate 20. The aramid fiber 7 has a coefficient of thermal expansion of 2 to 3 ppm / 占 폚 lower than that of silicon and is suitably used as a fiber constituting the woven fabric 8. Of course, it is also possible to use non-conductive fibers, such as resin fibers other than aramid fibers, ceramic fibers, or conductive fibers.

Even when using this woven fabric 8, the woven fabric 8 is immersed in resin, such as an epoxy resin, and the woven fabric 8 is impregnated with resin, and a prepreg is formed. The method of forming a core substrate using the prepreg formed using the woven fabric 8 is the same as that of the method mentioned above.

According to the method of using the woven fabric 8 made of a composite fabric of fibers such as aramid fibers 7 and carbon fibers 5a, the core portion 10 is controlled by adjusting the composition ratio of the carbon fibers 5a and aramid fibers 7. There is an advantage in that the coefficient of thermal expansion of.

In addition, after forming a wiring board, when cutting a large wiring board with the member isolate | separated individually, as shown in FIG. 5, the position where the aramid fiber 7 is arrange | positioned is cut position (for example, in the figure By cutting along the line AA), the aramid fibers 7 are exposed on the cut end surface of the wiring board, the range in which the carbon fibers 5a are exposed is suppressed, and the outer surface of the wiring board separated separately. The problem that the carbon fiber 5a is peeled from the carbon fiber 5a or the carbon fiber 5a exposed to the side surface of the wiring board is in contact with other electronic components and electrically shorted can be prevented.

In addition, when using the woven fabric which combined carbon fiber and another fiber, the fiber used in combination with a carbon fiber is not limited to one type of fiber. It is also possible to form a woven fabric by combining a carbon fiber and two or more different fibers, or it is also possible to use other conductive fibers instead of the carbon fibers.

In addition, in the said embodiment, although the carbon fiber woven fabric 5 was used for the core part 10, it is not limited to a woven fabric, It is also possible to use a nonwoven fabric.

In addition, the present invention can also be applied to the case of using non-conductive fibers such as ceramic fibers or ceramic fillers having conductivity other than carbon fibers as the core portion constituting the core substrate 20. In other words, the core substrate is a fiber having a lower thermal expansion coefficient than that of copper or a semiconductor element as a fiber having a constant strength required as a holder of the wiring board and a thermal expansion coefficient not significantly different from the semiconductor element mounted on the wiring board. Therefore, in the case where these materials (fibers) are used, the fibers are arranged in an arrangement which does not interfere with the passage position of the through-hole and serves the purpose of adjusting the strength or the coefficient of thermal expansion of the core substrate in the same manner as in the above-described embodiment. A core board | substrate or a wiring board can be formed.

1A to 1F are cross-sectional views illustrating steps of manufacturing the core substrate.

2 is a plan view showing the arrangement of the carbon fiber woven fabric and the through-holes;

3 is a cross-sectional view of a wiring board.

4 is a cross-sectional view of a state in which a semiconductor device is mounted.

5 is a plan view illustrating an example of a woven fabric forming a core portion.

Claims (15)

A process of arranging fibers so that a position through which a through-hole passes through is made empty, and forming a core by thermocompressing a prepreg formed by impregnating resin, wherein the fibers are formed as a woven fabric of a carbon fiber and a non-conductive fiber. And a prepreg in which a pore through which the through-hole passes through the woven fabric is used as the prepreg, and Forming a through hole passing through the inside of the cavity at a position at which the core portion becomes the cavity; Forming a conductive layer on an inner surface of the through hole to form a through hole in an arrangement which does not interfere with the fiber to form a core substrate; Cutting the wiring board at the position where the non-conductive fibers are disposed, and exposing the non-conductive fibers to the cut end surface Method for producing a wiring board comprising a. The manufacturing method of the wiring board of Claim 1 including the process of laminating | stacking a wiring layer on both surfaces of the said core board | substrate. The method of manufacturing a wiring board according to claim 1 or 2, wherein in the step of forming the core portion, a plurality of prepregs are thermocompressed by aligning the positions of the voids with each other. delete delete The core substrate, A wiring layer laminated on both sides of the core substrate, Through-holes electrically connected to the wiring layer and provided in the core substrate. Including, The core part constituting the core substrate is formed by thermocompressing a prepreg formed by impregnating a fiber into a resin, The conductive through hole is provided so as not to interfere with the fiber of the core portion, The fiber is formed as a woven fabric of a carbon fiber and a non-conductive fiber, and a space through which the conductive through hole passes is formed in the woven fabric. The wiring board is cut | disconnected in the position where the said nonelectroconductive fiber is arrange | positioned, and the said nonelectroconductive fiber was exposed to the cut end surface, The wiring board characterized by the above-mentioned. 7. The wiring board of claim 6, wherein the fiber has a lower coefficient of thermal expansion than a semiconductor device. delete delete The wiring board according to claim 6, wherein the non-conductive fibers are aramid fibers. The core substrate, A wiring layer laminated on both sides of the core substrate, Through-holes electrically connected to the wiring layer and provided in the core substrate. Including, The core part constituting the core substrate is formed by thermocompressing a prepreg formed by impregnating a fiber into a resin, The semiconductor element is mounted on the wiring board provided with the said through-hole so that it may not interfere with the fiber of the core part, or the semiconductor element is mounted using the wiring board as an interposer, The fiber is formed as a woven fabric of a carbon fiber and a non-conductive fiber, and a space through which the conductive through hole passes is formed in the woven fabric. The wiring board is cut at a position where the non-conductive fibers are disposed, and the non-conductive fibers are exposed at the cut end surface. delete delete delete delete

Images