JP2005244120A - Method of manufacturing wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a wiring board which can go without a process of removing a back resin overflown to the laminate formation face of a core substrate when employing a method of filling up vacant through-holes with the back resin in the wiring board wherein a laminate is to be formed. <P>SOLUTION: An insulating material is attached to the first principal plane of a core substrate whereon the laminate is to be formed to cover first principal planes of the through-holes. Then, a composite material containing a heat curing material is attached to the second principal plane of the core substrate, and at the same time, the through-holes formed in the core substrate are filled up with the composite material, preventing the composite material filling in the through-holes from overflowing to the first principal plane side. By simultaneously heat-treating the insulating material and the composite material attached to the second principal plane, a process can be simplified. Thereafter, the laminate is formed on the first principal plane side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to a method for manufacturing a wiring board.

  As a wiring board for fine arrangement, a build-up board has been developed in which a double-sided printed wiring board is used as a core layer, and thin insulating resin layers and conductor layers are alternately stacked thereon. This build-up method has become widespread for ease of design for fine patterning of conductor circuits and weight reduction.

  The printed wiring board is manufactured by forming a circuit on the surface of a metal foil-clad laminate. This laminated board is produced using a prepreg. A prepreg is generally obtained by impregnating a base material such as a glass cloth or an aramid fiber cloth with a synthetic resin such as an epoxy resin or a polyimide resin, followed by drying and semi-curing. The prepreg is a film body made of an organic resin and has a characteristic that when heated, the resin component becomes a viscous liquid and gradually cures with time. Therefore, this makes it possible to bond and integrate the substrate segments of the stacked layers.

  The multilayer wiring board is manufactured by laminating an outer layer metal foil such as a copper foil via a prepreg on an inner layer substrate on which an inner layer circuit is formed, and then heating and pressing the laminated body. It is often performed using.

  A multilayer printed wiring board manufactured by the build-up method has a higher degree of freedom in wiring design than a conventional multilayer printed wiring board, but it is used as a high-performance printed wiring board taking advantage of this feature. Therefore, it is required to further reduce the thickness of the interlayer insulating layer and improve the flatness of the circuit pattern. The build-up multilayer wiring board is a double-sided multilayer board in which resin insulation layers are laminated on both sides of a ceramic or resin core board, or a single-area multilayer wiring board in which a resin insulation layer is laminated on one side of the core board. (Patent Document 1).

  However, in a wiring board in which a buildup layer is formed only on one side, the warping of the board increases due to the lamination. Further, there is a problem that warpage occurs due to a difference in coefficient of thermal expansion between the buildup layer and the core substrate. Therefore, there is a method for preventing warping by attaching a back surface resin to the back surface of the wiring board. When the back surface resin is used and the method of preventing the warping of the wiring board is employed, there is a method of filling the hollow through hole with the back surface resin when temporarily bonding the pair of core substrates.

  FIG. 5 will be described with reference to the prior art. The plate-like core substrate 2 includes a plurality of through-hole conductors 4 penetrating between the front and back surfaces, and core wiring layers 10 and 11 formed on the front and back surfaces of the core substrate 2. A plurality of through holes 3 are formed in the core substrate 2, and through hole conductors 4 made of copper plating are formed in each through hole 3. A back insulating layer (back resin layer) 12 is formed at a predetermined position of the core wiring layer 11 on the back surface side of the core substrate 2 in order to suppress warping of the wiring substrate. The inside of each through-hole conductor 4 is filled with a filling resin 5 of the same type as the back surface resin.

  In order to simplify the process, when the same kind of prepreg is used for the formation of the back insulating layer 12 and the filling of the through holes, the prepreg after pressing protrudes to the surface as shown in FIG. The buildup layer and the back surface insulating layer are formed using different polymer materials in order to prevent warping of the wiring board. In this state, the first buildup layer 15 is made of a resin different from the protruding prepreg. When using this, the flatness of the first buildup layer 15 is lowered as shown in FIG. Furthermore, the adhesiveness between these resins is poor, causing delamination. Therefore, in order to prevent this, a process of removing the prepreg protruding from the through hole is required, which leads to an increase in cost.

JP 2001-36237 A

  As described above, when such a process is adopted, if the back surface resin flows out to the surface of the core substrate where the buildup layer is formed and the buildup layer is formed without removing this, the flatness of the substrate is poor. Or delamination is likely to occur at the interface. Therefore, before the buildup layer was formed, the back surface resin that flowed out of the through hole of the core substrate had to be removed.

  Accordingly, an object of the present invention is to eliminate the step of removing the backside resin that has flowed out to the laminate-forming surface of the core substrate when a method of filling a hollow through hole with a backside resin in a wiring board having a laminate is provided. It is to provide a method for manufacturing a substrate.

Means for Solving the Problems and Effects of the Invention

The manufacturing method of the wiring board of the present invention for solving the above problems is as follows.
A method of manufacturing a wiring board having a laminate in which insulating layers and wiring layers made of a thermosetting material are alternately laminated on a core substrate,
After adhering an insulating material to the first main surface forming the laminate of the core substrate, a composite material containing a thermosetting material is attached to the second main surface and filled into a through hole formed in the core substrate,
Thereafter, a laminate is formed on the first main surface side.

  By adhering an insulating material to the first main surface of the core substrate, a composite material containing a thermosetting material that forms the back insulating layer is attached to the second main surface, and when the through hole is filled, the composite It is possible to prevent the material from flowing out from the through hole to the first main surface side. Thereby, it is possible to prevent the flatness of the surface of the wiring board from being deteriorated and the delamination from being easily generated at the interface. That is, the adhesion reliability between the core substrate and the first buildup layer can be improved.

The manufacturing method of the second wiring board of the present invention is as follows:
A method of manufacturing a wiring board having a laminate in which insulating layers and wiring layers made of a thermosetting material are alternately laminated on a core substrate,
After adhering an insulating material to the first main surface forming the laminate of the core substrate, a composite material containing a thermosetting material is attached to the second main surface, and a through hole formed in the core substrate is filled. ,
Furthermore, a release sheet is attached thereon, the second main surface sides of the two core substrates are opposed to each other, and the core substrates are bonded to each other.
Thereafter, a laminate is formed on the first main surface side.

  By adhering the insulating material to the first main surface, the filling resin can be prevented from flowing out from the through hole to the first main surface side as described above. An insulating material is attached to the first main surface of each of the two core substrates, a thermosetting material is attached to the second main surface, and the inside of the through hole is filled with the thermosetting material. By laminating the second main surface sides of each other to form a laminate, the laminate can be formed efficiently. In addition, when the 2nd main surface sides of two core substrates are made to oppose and core substrates are adhere | attached, 2nd main surfaces will be bonded together on both sides of a release sheet.

  When an insulating material is used, workability is good. As the insulating material, a thermosetting polymer such as a thermosetting resin can be used. By using a thermosetting resin as an insulating material covering the first main surface, heat treatment can be performed and cured, and this can be used as the first buildup layer. In particular, by using a film-like insulating material made of an epoxy resin containing a silica filler, adhesion can be made with good adhesion, and handling can be simple.

  In the manufacturing process of the present invention, the composite material for forming the back surface insulating layer attached to the second main surface of the core substrate and the insulating material attached to the first main surface of the core substrate are simultaneously thermoset. be able to.

  By simultaneously thermosetting the insulating material attached to the main surface of the core substrate and the composite material attached to the second main surface, the process can be simplified. Thereby, cost can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to examples shown in the drawings. FIG. 1 shows a cross-sectional view of a wiring board 1 of the present invention. A plate-like core substrate 2 composed of a heat-resistant resin plate (for example, bismaleimide-triazine resin plate) or a fiber reinforced resin plate (for example, glass fiber reinforced epoxy resin), and the front and back surfaces of the core substrate 2 A plurality of through-hole conductors 4 penetrating therethrough, and core wiring layers 10 and 11 formed on the front and back surfaces of the core substrate 2 are provided. The surface of the core substrate 2, that is, the wiring layer 10 side is defined as a first main surface, and the back surface of the core substrate 2, that is, the wiring layer 11 side is defined as a second main surface.

  A plurality of through holes 3 are formed in the core substrate 2, and through hole conductors 4 made of copper plating are formed in each through hole 3. Further, the inside of each through-hole conductor 4 is filled with a filling resin 5 of the same type as the back surface resin.

  Furthermore, a plurality of buildup insulating layers 15 and 23, a solder resist layer 29, and a plurality of buildup wiring layers 21 and 27 made of a polymer material are formed on the surface side of the core substrate 2, that is, the first main surface side. ing. The build-up insulating layers 15 and 23 and the solder resist layer 29 and the build-up wiring layers 21 and 27 are alternately laminated to form a laminate (build-up layer). In order to connect the core wiring layer 10 and the buildup wiring layers 21 and 27, filled via conductors 16 and 24 made of copper plating are formed on the buildup insulating layers 15 and 23, respectively.

  The build-up insulating layer 15 is formed by heat-curing a film-like insulating material. As the insulating material, a thermosetting resin may be used, and for example, an epoxy resin is used. In particular, in this example, a film-like thermosetting resin made of an epoxy resin containing an inorganic filler was used. This is cured by heat treatment, and adhesion to the first main surface of the core substrate can be ensured. The film-like resin is cured to form the buildup layer 15.

  Solder connection for mounting electronic components on the printed wiring board at a predetermined position on the uppermost buildup wiring layer 27 so as to penetrate the solder resist layer 29 and protrude the first main surface 30 of the wiring board. A portion (solder bump) 31 is formed. The solder bump 31 is made of a low melting point alloy such as Sn—Ag.

  Further, at a predetermined position of the core wiring layer 11 on the back surface side of the core substrate 2, that is, on the second main surface side, a back insulating layer (back resin layer) 12 is formed by a composite material of inorganic fibers and thermosetting polymer material. Is formed. Examples of the composite material include resins containing glass fiber or carbon fiber. That is, a prepreg can be used. Further, as the resin, a two-dimensional polymerization type (network polymer) resin, for example, a BT (bismaleimide-triazine) resin may be used. Alternatively, a one-dimensional polymerization type (linear polymer) resin such as an epoxy resin may be used. At a predetermined position of the back surface insulating layer 12, an opening 14 that opens to the second main surface 32 is formed, and a part of the core wiring layer 11 is exposed. The core wiring layer 11 is coated with Ni and Au plating on its surface, and serves as a connection terminal to a printed board such as a mother board.

  The back surface insulating layer 12 is formed of a composite material (resin containing inorganic fibers) of inorganic fibers and a thermosetting polymer material, and maintains a balance with heat shrinkage due to the buildup layer formed on the surface of the core substrate 2. Accordingly, warping of the wiring board 1 can be suppressed. From the viewpoint of preventing warping due to the build-up layer, it is particularly desirable to use a two-dimensional polymerization type (network polymer) resin.

  The composite material filling the through-hole 5 is formed of the same resin as the composite material forming the back insulating layer 12. Since the back surface insulating layer 12 and the through hole 5 are formed of the same kind of composite material, the process can be simplified. Furthermore, the 2nd buildup layer 23 can acquire the curvature suppression effect of the wiring board by back surface resin by using a different composite material from the 1st buildup layer 15 and the back surface insulating layer 12. FIG.

  In FIG. 2 to FIG. 4, steps until the back surface resin layer of the present invention is formed are shown. First, as shown to Fig.2 (a), the copper foils 10 and 11 are affixed on the surface and back surface of the plate-shaped core board | substrate 2 comprised with the heat resistant resin board, the fiber reinforced resin board, etc. FIG. Next, as shown in FIG.2 (b), the predetermined position of this core board | substrate 2 is pierced with a laser irradiation or a drill. Thus, a plurality of through holes 3 are formed.

  Next, electroless copper plating and electrolytic copper plating are performed on the entire surface of the core substrate 2. As a result, as shown in FIG. 2C, the through-hole conductor 4 is formed on the surface of the inner wall of each through-hole 3. Next, a wiring layer is formed by a known photolithography technique and etching technique. First, after forming an etching resist layer on the copper plating layer, the copper plating layer and the copper foil not covered with the etching resist layer are removed by etching. As a result, as shown in FIG. 2D, wiring layers 10 and 11 having a predetermined pattern are formed.

  Further, as shown in FIG. 3A, a film-like thermosetting polymer material 15 is stuck on the first main surface of the core substrate 2 so as to close the opening on the first main surface side of each through hole 3. . This thermosetting polymer material is, for example, an epoxy resin containing an inorganic filler. This film-like thermosetting polymer material needs to be attached so as to ensure adhesion with the core substrate 2. In the case where the adhesive is not adhered and adhered, when the through-hole 5 is filled with a thermosetting resin later, it may cause the protrusion or the core substrate 2 and the buildup layer 15 may be peeled off. The epoxy resin containing the film-like inorganic filler is later heat-treated to adhere to the core substrate 2 to form the first buildup layer 15.

  As shown in FIG. 3B, the back insulating layer 12 is formed on the back surface of the core substrate 2. For example, the back insulating layer 12 is made of BT resin containing glass fibers. A release sheet 13 is attached on the back resin layer 12. Further, the inside of the through hole 5 is also filled with a resin for forming the back surface resin layer 12. Since a film-like insulating material is attached to the first main surface side of the core substrate of the through hole 5, the resin in the through hole 5 does not protrude to the first main surface side. As shown above, two core substrates 2 on which a film-like thermosetting resin is pasted and the back surface resin layer 12 is formed are prepared, and the release sheet 13 is sandwiched as shown in FIG. Bond two core substrates. Here, heat treatment of the back surface resin, the filling resin in the through hole, and the resin of the first buildup layer is performed by vacuum hot pressing. By the heat treatment, the back surface resin, the filling resin, and the film-like thermosetting resin forming the first buildup layer are cured.

  Thereafter, as shown in FIG. 4A, the filled via conductor 16 is formed in the buildup insulating layer 15, and the buildup wiring layer 21 is further formed on the buildup insulating layer 15. Thereafter, the build-up insulating layer 23, the via conductor 24, the build-up wiring layer 27, and the insulating layer (solder resist layer) 29 are formed. The second or higher buildup insulating layer is made of a material different from that of the first buildup insulating layer 15. Finally, solder bumps 31 for connecting the IC chip are formed. After forming the buildup layer in this way, the core substrate 2 is separated from the release sheet 13 as shown in FIG.

  The wiring substrate 1 in which the opening 14 is formed in the back surface insulating layer 12 and the wiring layer 11 is exposed is manufactured as shown in FIG. Thereby, conduction can be established on the back side. Further, on the upper surface of the printed wiring board 1 on which the build-up layer is formed, solder bumps 31 and the like are formed for mounting IC chips and the like, and a solder resist layer 29 is provided so that the solder bumps 31 are not fused to each other. Yes. The solder resist is made of an insulating resin, which is to prevent the IC chip and the wiring layer to be mounted from being short-circuited except at a predetermined connection position.

  After the IC chip is bonded to the wiring layer of the wiring board using solder, an underfill is filled between the IC chip and the printed wiring board. This underfill is filled between the IC chip and the printed wiring board in a fluid state and then cured by heat treatment. After mounting the IC chip, the wiring substrate 1 is heat-treated to complete the bonding of the IC chip.

Sectional drawing of the wiring board by the manufacturing process of this invention. The figure explaining the manufacturing process of this invention. The figure explaining the manufacturing process of this invention following FIG. The figure explaining the manufacturing process of this invention following FIG. The figure explaining the conventional manufacturing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wiring board 13 Release sheet 12 Back surface resin layer 15 Thermosetting film (1st buildup layer)

Claims (4)

A method of manufacturing a wiring board having a laminate in which insulating layers and wiring layers made of a thermosetting material are alternately laminated on a core substrate,
After adhering an insulating material to the first main surface forming the laminate of the core substrate, a composite material including a thermosetting material is attached to the second main surface and filled in the through-hole formed in the core substrate. And
Then, the said laminated body is formed in said 1st main surface side, The manufacturing method of the wiring board characterized by the above-mentioned. A method of manufacturing a wiring board having a laminate in which insulating layers and wiring layers made of a thermosetting material are alternately laminated on a core substrate,
After adhering an insulating material to the first main surface forming the laminate of the core substrate, a composite material including a thermosetting material is attached to the second main surface, and in the through hole formed in the core substrate. Filling,
Furthermore, a release sheet is attached thereon, the second main surface sides of the two core substrates are opposed to each other, and the core substrates are bonded to each other,
Then, the said laminated body is formed in said 1st main surface side, The manufacturing method of the wiring board characterized by the above-mentioned.   The method for manufacturing a wiring board according to claim 1, wherein the insulating material includes an epoxy resin and a silica filler. The composite material for forming the back surface insulating layer attached to the second main surface of the core substrate and the insulating material attached to the first main surface of the core substrate are simultaneously thermoset. Item 4. The method for manufacturing a wiring board according to any one of Items 1 to 3.

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