JP2020150094A - Printed wiring board and manufacturing method thereof - Google Patents

Abstract

To improve connection reliability of a through-hole conductor of an electronic component built in an opening of a resin core substrate.SOLUTION: In a printed wiring board with an electronic component built into an opening of a resin core substrate, the electronic component includes a through-hole conductor that electrically connects conductor circuits on both sides of the electronic component and a through hole that penetrates the central portion of the through-hole conductor in the through-hole that penetrates the electronic component, and a resin having higher fluidity in a molten state than the resin constituting the core substrate is filled around the electronic component in the opening of the resin core substrate and in the through hole.SELECTED DRAWING: Figure 1

Description

The present invention relates to a printed wiring board in which electronic components such as an IC chip and a circuit board are embedded in an opening of a resin core substrate, and a method for manufacturing the printed wiring board.

In response to recent demands for higher density and lower profile of printed wiring boards, a design of a printed circuit board in which a glass substrate is coated with a resin has been proposed (see, for example, Patent Document 1).

In such a printed wiring board, an electronic component may be built in an opening of a resin core substrate, and such an electronic component is placed on both sides of the electronic component in a through hole penetrating the electronic component. It may have a through-hole conductor that electrically connects the conductor circuit of the above, and a through-hole that penetrates the central portion of the through-hole conductor.

When an electronic component is built in the opening of the resin core substrate in this way, the resin constituting the interlayer insulating material that is the material of the resin core substrate is heated and pressurized by a press to be melted, and the resin is melted. It is usual to fill the periphery of the electronic component in the opening of the resin core substrate with resin by pouring it around the electronic component in the opening of the core substrate, and fix the electronic component in the opening. ..

Japanese Patent No. 6148764

By the way, with the recent miniaturization of printed wiring boards, electronic components in which the through holes of through-hole conductors are previously filled with resin are built in the openings of the resin core substrate, but the through holes are filled with resin. In the process of manufacturing the printed wiring board, the electronic component built in the opening is also miniaturized, and the through hole of the through-hole conductor of the electronic component is also miniaturized, so that it can be used as a material for a resin core substrate. In the method in which the resin of the interlayer insulating material is heated and pressed by a press and poured around the electronic component in the opening of the resin core substrate, it is the filling volume that simultaneously fills the opening for the electronic component and the through hole provided in the electronic component. It becomes difficult from the ratio of. For this reason, the resin cannot be filled into the through hole of the through hole conductor, a cavity remains in the through hole, and the air in the cavity causes corrosion of the through hole conductor, so that both sides of the electronic component are both sides. It may reduce the reliability of the electrical connection of the upper conductor circuit.

The printed wiring board of the present invention is a printed wiring board in which an electronic component is built in an opening of a resin core substrate, and the electronic component is placed on both sides of the electronic component in a through hole penetrating the electronic component. It has a through-hole conductor that electrically connects the conductor circuit of the above, and a through hole that penetrates the central portion of the through-hole conductor, and has a through hole around the electronic component in the opening and in the through hole. It is filled with a resin having higher fluidity in a molten state than the resin constituting the core substrate.

In the method for manufacturing a printed wiring board of the present invention, when manufacturing a printed wiring board in which an electronic component is incorporated in an opening of a resin core substrate, the electronic component is placed in a through hole penetrating the electronic component. It has a through-hole conductor that electrically connects the conductor circuits on both sides of the component, and a through hole that penetrates the central portion of the through-hole conductor, and has a through hole around the electronic component in the opening and the through hole. The inside is filled with a molten resin having a higher fluidity than the resin constituting the core substrate.

According to the embodiment of the present invention, the periphery of the electronic component in the opening of the resin core substrate and the inside of the through hole are melted more than the resin constituting the core substrate due to, for example, low viscosity or inclusion of a small diameter filler. Since the fluidity in the state is increased and the resin is filled with a resin corresponding to a small diameter or a narrow cavity, no cavity remains in the through hole, so that electricity is generated by the through-hole conductor of the conductor circuit on both sides of the electronic component. The reliability of the target connection can be improved.

It is sectional drawing which shows the printed wiring board of one Embodiment of this invention. (A) to (g) are cross-sectional views illustrating each step of the manufacturing method of the printed wiring board of the embodiment shown in FIG.

Hereinafter, embodiments of the printed wiring board according to the present invention will be described with reference to the drawings. In the description of the drawings, similar elements are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a cross-sectional view showing a printed wiring board according to an embodiment of the present invention, and FIGS. 2 (a) to 2 (g) show a method for manufacturing a printed wiring board according to the embodiment shown in FIG. It is sectional drawing which shows each process. The printed wiring board 10 of this embodiment includes a core board 12 and a build-up layer 14.

The core substrate 12 is made of an insulating resin composition such as an epoxy resin containing an inorganic filler such as silica or alumina or a BT (bismaleimide triazine) resin, and contains a reinforcing material such as glass cloth. A conductor circuit layer 22 is formed on each of the F surface 12F, which is the front surface of the core substrate 12, and the B surface 12B, which is the back surface of the core substrate 12. The conductor circuit layer 22 is made of a conductive metal such as copper. A plurality of through-hole conductors 24 are formed on the core substrate 12. Each of the through-hole conductors 24 is made of a conductive metal such as copper, and electrically connects the conductor circuit layers 22 on the F surface 12F, which is the front surface of the core substrate 12, and the B surface 12B, which is the back surface. are doing.

The core substrate 12 has a component accommodating portion 26 defining a rectangular opening in the central portion, and the component accommodating portion 26 includes a through hole penetrating the core substrate 12 in the thickness direction thereof. The component accommodating portion 26 accommodates electronic components 28 such as an IC chip and a glass substrate constituting a circuit board. A conductor circuit layer 30 is formed on each of the F surface 28F, which is the front surface of the electronic component 28, and the B surface 28B, which is the back surface of the electronic component 28. The conductor circuit layer 30 is made of a conductive metal such as copper. The electronic component 28 has, for example, a plurality of through holes that penetrate the electronic component 28 in the thickness direction thereof, and a cylindrical through-hole conductor 32 is formed on the inner peripheral surface of each through hole. Each of the through-hole conductors 32 is made of a conductive metal such as copper, and electrically connects the conductor circuit layers 30 on the F surface 28F and the B surface 28B of the electronic component 28. A fine through hole 34 is formed in the center of each through-hole conductor 32.

The build-up layer 14 is formed on the F surface 12F and the B surface 12B of the core substrate 12, respectively. The build-up layer 14 is formed by alternately laminating the interlayer insulating layer 36 and the conductor circuit layer 38. The interlayer insulating layer 36 is made of a resin composition such as an epoxy resin containing an inorganic filler such as silica or alumina or a BT (bismaleimide triazine) resin. The interlayer insulating layer 36 preferably contains a reinforcing material such as a glass cloth. The conductor circuit layer 38 is made of a conductive metal such as copper.

An interlayer insulating layer 36 having a composition different from that of the insulating resin composition constituting the core substrate 12 is formed in the gap around the electronic component 28 in the component accommodating portion 26 and in the through hole 34 of the through-hole conductor 32. An insulating resin 40 having the same composition as the insulating resin composition is filled and solidified, and the insulating resin 40 fixes the electronic component 28 at a predetermined position in the component accommodating portion 26 and the through-hole conductor 32. The through-hole conductor 32 is prevented from corroding by blocking the contact between the conductor and the air. The insulating resin 40 preferably contains an inorganic filler such as silica or alumina.

The conductor circuit layer 38 of the build-up layer 14 on the F surface 12F and the B surface 12B of the core substrate 12 is formed on the conductor circuit layer 22 on the F surface 12F and the B surface 12B of the core substrate 12. They are electrically connected to each other via a via hole conductor 42 penetrating the interlayer insulating layer 36 of the above. The conductor circuit layer 38 of the build-up layer 14 on the F surface 12F also has a via hole of the build-up layer 14 in the conductor circuit layer 30 on the F surface 28F of the electronic component 28 in the component accommodating portion 26 of the core substrate 12. It is electrically connected via a conductor 42. The via hole conductor 42 can be formed of the same conductive metal as the conductor circuit layer 22, the conductor circuit layer 30, and the conductor circuit layer 38, for example, copper.

According to the printed wiring board 10 of this embodiment, the pitch of a plurality of IC chips mounted on the printed wiring board 10 of this embodiment by using the electronic component 28 built in the component accommodating portion 26 as an interposer, for example. It can be used for electrical connection between different electrodes or between the electrodes of those IC chips and the electrode pads of the conductor circuit layer 38 of the build-up layer 14. Further, what is the insulating resin composition constituting the core substrate 12 filled in the periphery of the electronic component 28 built in the component accommodating portion 26 and in the through hole 34 of the through-hole conductor 32 of the electronic component 28? Since the same insulating resin 40 as the insulating resin composition constituting the interlayer insulating layer 36 having a different composition is solidified, the electronic component 28 can be accurately positioned and fixed in the component accommodating portion 26, and the electronic component 28 can be positioned and fixed. The reliability of the electrical connection by the through-hole conductor 32 of the conductor circuit layer 30 on both sides can be improved.

Next, an embodiment of the method for manufacturing a printed wiring board of the present invention will be described with reference to FIGS. 2 (a) and 2 (g). Elements similar to those described in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted as appropriate.

(1) First, as the material of the core substrate 12 as shown in FIG. 2A, both the front and back surfaces of an insulating base material made of an epoxy resin or BT (bismaleimide triazine) resin and a reinforcing material such as glass cloth are used. Those laminated with copper foil are prepared.

(2) Next, irradiation with a carbon dioxide gas laser or hole processing with a mechanical drill is applied from the surface side of the insulating base material to drill holes for forming through holes for through-hole conductors. Further, on the back surface side of the insulating base material, holes are drilled by applying, for example, carbon dioxide laser irradiation or hole processing with a mechanical drill to the positions directly behind the holes on the front surface, and the holes on the front surface and the back surface thereof. By connecting them to each other, a core substrate 12 having a through hole for the through-hole conductor 24 is formed. Further, in the central portion of the core substrate 12, a component accommodating portion 26 as a through hole having a rectangular opening is formed by, for example, irradiation with a carbon dioxide gas laser or hole processing with a mechanical drill.

(3) Next, electroless plating is performed on the copper foil of the F surface 12F, which is the front surface of the core substrate 12, and the B surface 12B, which is the back surface, and the inner peripheral surface of the through hole. A film is formed. Then, a plating resist having a predetermined pattern is formed on the electroless plating film on the copper foil, and the plating resist covers the component accommodating portion 26, but the through holes for the through-hole conductor are exposed.

(4) Next, an electrolytic plating process is performed, the electrolytic plating is filled in the through holes for the through-hole conductor to form the through-hole conductor 24, and then the electroplating film on the copper foil is exposed from the plating resist. An electroplating film is formed on the part where it is formed. After that, the plating resist is peeled off, the electroless plating film and the copper foil below the plating resist are removed, and the remaining electrolytic plating film, the electroless plating film, and the copper foil form the F surface 12F of the core substrate 12 and the copper foil. The conductor circuit layer 22 is formed on the B surface 12B, respectively. The conductor circuit layers 22 on the F surface 12F and the B surface 12B of the core substrate 12 are electrically connected to each other by the through-hole conductor 24.

(5) After that, as shown in FIG. 2A, for example, the tape 44 made of an adhesive film is the conductor circuit layer on the B side 12B side of the core substrate 12 which is downward in the drawing. It is attached on the 22 so as to close the component accommodating portion 26. Next, an electronic component 28 to be incorporated in the component accommodating portion 26 of the printed wiring board 10 is prepared, and the electronic component 28 is arranged at a predetermined position of the component accommodating portion 26 by a mounter (not shown).

(6) In the electronic component 28 as well, for example, similarly to the core substrate 12, a conductor layer to be a conductor circuit layer 30 is formed on the F surface 28F which is the front side surface and the B surface 28B which is the back side surface, respectively. .. The conductor layers on the F surface 28F and the B surface 28B of the electronic component 28 are electrically connected to each other by the through-hole conductor 32. Further, a fine through hole 34 penetrating from the F surface 28F side to the B surface 28B side of the electronic component 28 is formed in the central portion of each through hole conductor 32.

(7) Next, the core substrate 12 on the tape 44 and the electronic component 28 arranged in the component accommodating portion 26 are covered with a printing plate (not shown) that exposes only the component accommodating portion 26, and the core substrate. The F surface 12F of 12 is totally covered, and in that state, the composition is the same as that of the insulating resin composition constituting the interlayer insulating layer 36, which is different from the insulating resin composition constituting the core substrate 12. The insulated resin material in the molten state is selectively supplied into the component housing 26 by, for example, printing and coating, and through holes around the electronic component 28 in the component housing 26 and in the center of the through-hole conductor 32 due to reduced pressure. It is densely filled in 34. The reduced pressure level at the time of filling is -5 Pa to -10000 Pa, and the viscosity of the molten resin is 100 Pa · s to 1,000 Pa, which is higher in fluidity than the molten state of the insulating resin composition of the core substrate 12. When s is set, the molten resin is surely filled in the through hole 34. Further, when the filler contained in the molten resin has a smaller diameter than the filler contained in the insulating resin composition of the core substrate 12 and a central particle size of 0.1 μm to 15 μm, the molten resin into the through hole 34 Filling is done more reliably.

(8) After that, the molten resin filled around the electronic component 28 in the component accommodating portion 26 and in the through hole 34 at the center of the through-hole conductor 32 is cured, and as shown in FIG. 2B, The cured insulating resin accurately positions and fixes the electronic component 28 at a predetermined position in the component accommodating portion 26, and blocks contact between the inner peripheral surface of the through hole 34 at the center of the through-hole conductor 32 and air. To do.

(9) Next, as shown in FIG. 2C, the tape 44 is peeled off from the core substrate 12 and the electronic component 28 arranged in the component accommodating portion 26 thereof.

(10) Next, as shown in FIG. 2D, the conductor circuit layer 22 on the F surface 12F and the B surface 12B of the core substrate 12 and the electronic component 28 on the F surface 28F and the B surface 28B. The conductor layer is removed by, for example, etching. Further, the resin protruding from the F surface 12F and the B surface 12B of the core substrate 12 and the resin protruding from the F surface 28F and the B surface 28B of the electronic component 28 are removed by, for example, cutting or grinding, and the F surface 12F of the core substrate 12 is removed. The F surface 28F of the electronic component 28 is also flat and flush, and the B surface 12B of the core substrate 12 and the B surface 28B of the electronic component 28 are also flat and flush.

(11) Next, as shown in FIG. 2E, the core substrate 12 is electroplated on the F surface 12F and the B surface 12B, and on the F surface 28F and the B surface 28B of the electronic component 28. The electroless plating film 46 serving as a seed layer for forming the conductor circuit layer is formed.

(12) Next, as shown in FIG. 2 (f), by the semi-additive method, on the F surface 12F and the B surface 12B of the core substrate 12, and on the F surface 28F and the B surface 28B of the electronic component 28. A predetermined pattern of plating resist is formed on each of the electroless plating films 46, and then an electrolytic plating process is performed to form an electrolytic plating film on a portion of the electroless plating film 46 exposed from the plating resist. To. After that, the plating resist is peeled off and the electroless plating film below the plating resist is removed, and the remaining electrolytic plating film and the electroless plating film form a conductor on the F surface 12F and the B surface 12B of the core substrate 12. The circuit layer 22 is formed, and the conductor circuit layer 30 is also formed on the F surface 28F and the B surface 28B of the electronic component 28, respectively.

(13) Next, as shown in FIG. 2 (g), the conductor circuit layer on the F surface 12F side conductor circuit layer 22 of the core substrate 12 and the F surface 28F side of the electronic component 28, which are upward in the figure. A B-stage prepreg 48 in which an insulating resin such as epoxy resin or BT resin is impregnated with a reinforcing material such as glass cloth for forming an interlayer insulating layer 36 is laminated on the prepreg 48, and a copper foil is placed on the prepreg 48. (Not shown) are laminated, after which the prepreg 48 and the copper foil on it are heat pressed.

(14) Next, in the same manner as described above, on the conductor circuit layer 22 on the B surface 12B side of the core substrate 12 and on the conductor circuit layer 30 on the B surface 28B side of the electronic component 28, which are oriented downward in the drawing. A B-stage prepreg 48 impregnated with an insulating resin such as epoxy resin or BT resin is laminated on a reinforcing material such as glass cloth for forming the interlayer insulating layer 36, and a copper foil (not shown) is laminated on the prepreg 48. ) Are laminated, and then the prepreg 48 and the copper foil on it are heat-pressed. It is also possible to apply an insulating resin material without a reinforcing material such as glass cloth instead of at least one prepreg 48 on the F surface 12F side and the B surface 12B side of the core substrate 12.

(15) In this way, the resin component of the prepreg 48 is solidified by a heating press to form an interlayer insulating layer 36 on the F surface 12F of the core substrate 12 and the F surface 28F of the electronic component 28, and the core substrate 12 is formed. After the interlayer insulating layer 36 is also formed on the B surface 12B and the B surface 28B of the electronic component 28, for example, a carbon dioxide gas laser is irradiated to a predetermined position from above the copper foil on the interlayer insulating layer 36 to copper. Via holes are formed through the foil and the interlayer insulating layer 36. The via hole partially exposes the conductor circuit layer 22 and the conductor circuit layer 30.

(16) Next, an opening is opened on the copper foil on the interlayer insulating layer 36 at a position where the conductor circuit layer 22 and the conductor circuit layer 30 are formed in addition to the position of the via hole by, for example, a photolithography method. The plating resist to have is formed.

(17) Next, a metal film (not shown) is formed on the inner surface of the opening and the via hole of the plating resist by, for example, electroless plating. The metal film may be formed by sputtering or vacuum deposition. By the electrolytic plating treatment using this metal film as a seed layer, a plating film on the via hole conductor 42 and the copper foil is formed. The electrolytic plating treatment is preferably an electrolytic copper plating treatment. After that, the plating resist is removed by peeling.

(18) Next, the portion of the copper foil on which the plating film is not formed on the surface is removed by etching. As a result, a conductor circuit layer 38 made of a copper foil and a plating film is formed on the interlayer insulating layer 36 on the F surface 12F and the B surface 12B of the core substrate 12 and on the F surface 28F and the B surface 28B of the electronic component 28. .. As shown in FIG. 1, the conductor circuit layer 38 on the interlayer insulating layer 36 is electrically connected to the conductor circuit layer 22 on the F surface 12F and the B surface 12B of the core substrate 12 by the via hole conductor 42. , It is also electrically connected to the conductor circuit layer 30 on the F surface 28F of the electronic component 28 in the component accommodating portion 26.

The present invention is not limited to the above embodiment, and various modifications and modifications can be made without departing from the description of the claims. For example, in the method for manufacturing the printed wiring board of the embodiment shown in FIG. 1 and the printed wiring board of the embodiment shown in FIGS. 2 (a) to 2 (g), an interlayer insulating layer is provided on the front surface and the back surface of the core substrate. Although it has one build-up layer, the method for manufacturing the printed wiring board of the present invention and the printed wiring board of the present invention is not limited to this, and each layer is placed on at least one of the front surface and the back surface of the core substrate. It may include two or more build-up layers having an insulating layer.

10 Printed circuit board 12 Core board 12F Front side (F side)
12B back side (B side)
14 Build-up layer 22 Conductor circuit layer 24 Through-hole conductor 26 Parts housing 28 Electronic components 28F Front side surface (F surface)
28B back side (B side)
30 Conductor circuit layer 32 Through-hole conductor 34 Through hole 36 Interlayer insulation layer 38 Conductor circuit layer 40 Insulation resin 42 Viahole conductor 44 Tape 46 Electrolytic plating film 48 Prepreg

Claims (6)

A printed wiring board with electronic components built into the openings of a resin core board.
The electronic component has a through-hole conductor that electrically connects conductor circuits on both sides of the electronic component and a through-hole that penetrates the center of the through-hole conductor in the through-hole that penetrates the electronic component. Have and
The periphery of the electronic component and the inside of the through hole in the opening are filled with a resin having a higher fluidity in a molten state than the resin constituting the core substrate. In the method of manufacturing a printed wiring board in which a glass substrate is built in an opening of a resin core substrate,
The glass substrate has a through-hole conductor that electrically connects conductor circuits on both sides of the glass substrate and a through-hole that penetrates the center of the through-hole conductor in a through-hole that penetrates the glass substrate. Have and
The periphery of the glass substrate and the inside of the through hole in the opening are filled with a molten resin having a higher fluidity than the molten state of the resin constituting the core substrate. The method for manufacturing a printed wiring board according to claim 2.
The molten resin has a composition different from that of the resin constituting the core substrate, and has the same composition as the resin constituting the interlayer insulating layer laminated on the core substrate. The method for manufacturing a printed wiring board according to claim 2 or 3.
The viscosity of the molten resin is 100 Pa · s to 1,000 Pa · s. The method for manufacturing a printed wiring board according to any one of claims 2 to 4.
The molten resin is filled in the opening by a printing method or a film laminate. The method for manufacturing a printed wiring board according to any one of claims 2 to 5.
The molten resin contains a filler having a center particle size of 0.1 μm to 15 μm.

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