JP2006059952A - Manufacturing method of printed wiring board with built-in component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board with built-in components which are not affected by a voluminal protruding part of a component and superior in smoothness of an inner layer core of the printed wiring board and also in electrical connection stability of it. <P>SOLUTION: At least one layer of insulating base material and conductor base material are alternately laminated on both surfaces of the inner layer substrate, where a component is mounted on a component mounting pad, with the component sealed up with the insulating base material, at the same time, when laminating. A through hole of a size substantially the same as that of a mounting component is provided, in advance, on both the insulating base materials laminated on both surfaces of the inner layer substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a component built-in type printed wiring board in which components are provided in an inner layer portion of the printed wiring board.

  In recent years, there is a need for miniaturization, weight reduction, and high density of printed wiring boards. Built-in components obtained by introducing chip parts mounted on the surface of printed wiring boards into the printed wiring board. There is a technique related to a printed wiring board of a mold (see, for example, Patent Document 1). Since this component built-in type printed wiring board can structurally enable chip components to be introduced into the printed wiring board, it can cope with a reduction in space and density of the surface mounting portion. It will be possible to greatly contribute to the further development of the board.

  In addition, the component built-in type printed wiring board has an electrical wiring structure that uses the inner layer portion of the printed wiring board from the conventional planar surface mounting portion, for example, to place passive components directly under the LSI. The structure and the like can be arranged in three dimensions, and as a result, there is an advantage that it is effective in optimizing the signal wiring in order to cope with the high-speed operation of the LSI. In such a technical background, elemental technology for introducing chip parts and the like into printed wiring boards is important, and research on some existing problems and problems in conventional printed wiring board manufacturing methods Development is urgently needed.

  One of the technical problems in the method for manufacturing a component built-in type printed wiring board is that the smoothness of the inner core part of the printed wiring board is impaired. This is caused by a state in which the core portion of the inner layer is gently curved at the position where the component is introduced by introducing the component into the printed wiring board.

  Problems of such a conventional method of manufacturing a component-embedded printed wiring board will be described with reference to FIG. FIG. 3A shows a copper-clad laminate 1 serving as an inner layer portion of a printed wiring board. After component mounting pads 2 on which chip components 5 are mounted are formed by circuit formation, the component mounting pads 2 and the chips are formed. For the purpose of electrically connecting the component 5, the chip component 5 is mounted on the component mounting pad 2 by a solder paste connecting method using a screen printing method or a connecting method using a conductive adhesive or the like. .

  Next, the chip component 5 is located in the inner layer portion of the printed wiring board, and for the purpose of protecting the component, a through-hole 7 is provided in the insulating base material 6 in the B stage state, and from the upper surface of the chip component 5 Stacked (FIG. 3B), the chip component 5 is formed so as to be positioned inside the insulating base 6, and then a circuit is formed based on the desired printed wiring board structure, and the component built-in type printed wiring Get a board.

  However, in such a method for manufacturing a component built-in type printed wiring board in the laminating method, since the through hole 7 exists only in one insulating substrate on the side where the component is mounted, the insulating substrate When 6 melts, the inner layer core portion existing in the molten resin generates a pressure difference from the front and back due to the presence or absence of drilling of the insulating base 6, and as a result, the inner layer core portion is bent and formed as it is. End up. That is, non-uniformity in the stacking pressure occurs in the vicinity of the component mounting portion, resulting in a problem that the inner layer core portion is gently curved as shown in FIG.

  Further, the bending problem of the structural core member causes stress at the joint between the chip component 5 and the component mounting pad portion 2, and increases the conduction resistance value between the chip component 5 and the component mounting pad portion 2 or breaks the wire. Cause a defect.

  Further, the chip component 5 incorporated in the printed wiring board is required to use a small size called 0603 and has a thin structure, so that the flatness of the inner core portion is obtained. When the stacking pressure is further increased, the chip component 5 is easily damaged and broken under a strong physical pressure. That is, there is a problem that the chip is damaged by the laminating press pressure when manufacturing the chip component built-in substrate.

Therefore, as a manufacturing method of a component built-in type printed wiring board in the required insulating base material laminating method, the insulating base material 6 seals the chip part 5 without being affected by the volumetric convex structure of the part. A structure that is easy to stop is required, and this technology greatly contributes to the improvement of the stability of the electrical connection of the chip component 5 and the quality of the printed wiring board with a built-in component.
JP 2001-119147 A

  The problem to be solved by the present invention based on the background as described above is influenced by the volumetric convex structure of the component when the component installed on the inner layer portion of the printed wiring board is laminated with the insulating base material. An object is to obtain a printed wiring board with a built-in component that is excellent in smoothness of the inner core portion and excellent in electrical connection stability between the component and the printed wiring board.

  The present inventor has made various studies in order to solve the above problems. As a result, the inventors have focused on the fact that the lamination pressure in the vicinity of the component mounting portion can be made uniform by laminating an insulating base material such as a prepreg having a through hole in advance at the upper and lower positions of the place where the chip component is mounted. Specifically, a through hole is provided in each of the insulating base material located above and below the component installed in the inner layer of the printed wiring board, and both the upper and lower through holes are formed perpendicular to the chip component. It has been found that if it is arranged in the direction and laminated, it is effective for making the lamination pressure uniform, and the present invention has been completed.

  That is, according to the present invention, at least one insulating base material and a conductive base material are alternately laminated on both surfaces of an inner layer substrate in which a component is mounted on a component mounting pad, and the component is sealed with the insulating base material simultaneously with the lamination. In the method for manufacturing a component built-in type printed wiring board, a through hole having a size substantially the same as that of a mounted component is provided in advance on both of the insulating base materials laminated on both surfaces of the inner substrate. The above-mentioned problem is solved by this manufacturing method.

  By adopting such a configuration, since the resin of the insulating base material is filled around the built-in component, the insulating property is improved.

  As the insulating substrate, a glass woven fabric, an aramid woven fabric, a glass nonwoven fabric or an aramid nonwoven fabric impregnated with a resin is preferably used. In other words, warping can be prevented and strength can be increased by adding a reinforcing material made of woven or non-woven fabric to the insulating base.

  In the present invention, the through hole is sealed when the insulating base material is laminated.

  According to the present invention, a component built-in type that is not affected by the volumetric convex portion of the component, has excellent smoothness of the inner core portion of the printed wiring board, and has excellent electrical connection stability between the component and the printed wiring board. A printed wiring board can be provided.

Embodiments of the present invention will be described below with reference to the drawings.
In addition, particularly important points in the present invention are shown below, and their advantages are described in order.
Point 1): Smoothness of inner layer core part Point 2): Connection reliability of built-in parts Point 3): Sealing of through hole Point 4): Explanation of structure

  An overall method for manufacturing a component built-in type printed wiring board according to the present invention will be described with reference to FIGS. First, as shown in FIG. 1A, a double-sided copper-clad laminate 1 is used, and after copper foil roughening of the copper-clad laminate 1 is processed, circuit formation including component mounting pads 2 is performed ( FIG. 1 (b)). Next, a gold-resistant plating resist is attached to the circuit-formed substrate, electroless gold plating is performed, and nickel / gold plating is performed on the surface of the component mounting pad 2. Next, the target chip component 5 is mounted on a predetermined portion of the printed wiring board obtained above via the solder paste 4 with a mounter to obtain the structure shown in FIG.

  Next, the prepreg provided with the through holes 7a and 7b is used as the insulating bases 6a and 6b on the structure (FIG. 2A) on which the chip component 5 is mounted to form a component-embedded substrate by stacking. I do. That is, as shown in FIG. 2 (b), the structure is placed in the center as a core portion of a printed wiring board, and insulating bases (prepregs) 6a and 6b having through holes 7a and 7b from the upper and lower surfaces thereof are attached to the structure. The through-holes 7a and 7b are placed so as to be positioned at the chip component 5, and the copper foil 3 is placed outside the insulating base material (prepreg) 6 to perform lamination and pressurization, as shown in FIG. Obtain a component built-in printed wiring board. In the following, the circuit formation of the copper foil portion 3 is performed in the required printed wiring board structure, and then the insulating base material and the conductive base material are alternately laminated under the above-mentioned lamination conditions according to the required structure of the printed wiring board. Thus, a component built-in type multilayer printed wiring board is obtained.

Point 1): Smoothness of inner layer core portion Insulating base material (prepreg) 6a having a through hole 7a stacked on the component mounting side and component mounting with respect to the core portion after chip component 5 mounting in FIG. The method of the present invention using the insulating base material (prepreg) 6b having the through hole 7b laminated on the opposite side of the substrate exhibits a functional role excellent in the surface smoothness of the inner layer core portion. This will be described below.

  As the best structure of the component built-in type printed wiring board, as shown in FIG. 2 (c), the insulating part which is the B stage is melted at the time of lamination and melted to obtain fluidity. A structure in which the entire periphery of the chip component 5 is covered and sealed is desirable. However, when only the insulating base material 6 having the through holes 7 stacked on the component mounting side is used for the core portion after chip component mounting as in the conventional method shown in FIG. ), The inner layer core portion is curved, and surface smoothness and connection reliability between the component mounting pad 2 and the chip component 5 become problems.

  The inconvenience such as the bending of the inner layer core part is caused by the pressure in the vicinity of the parts caused by the lamination particularly in the lamination process of the insulation base 6 because the through hole 7 of the insulation base 6 exists in FIG. Can be caused by imbalance. In addition, when the lamination pressure is changed to a low pressure, the basic interlayer adhesion of the printed wiring board is affected. When the pressure is high, the chip component 5 built in the printed wiring board is damaged. Cause problems.

  On the other hand, in the present invention, since the insulating bases 6a and 6b provided with the through holes 7a and 7b are laminated on both the upper and lower surfaces of the core portion after mounting the components, the vicinity of the components at the time of stacking In this case, there is no problem that the inner layer core portion is curved, and the electrical connection reliability between the chip component 5 and the component pad 2 of the printed wiring board is improved. It greatly contributes to the improvement of the quality of the entire component built-in printed wiring board. Moreover, since the method for manufacturing a component built-in type printed wiring board according to the present invention can be used as it is from the past, it is possible to efficiently obtain a high quality component built-in type printed wiring board. Is possible.

Point 2): Connection reliability of built-in components The curved state of the inner core portion in the conventional method occurs in the laminating process, and thus becomes a defect that occurs after the completion of the substrate incorporating the components. Accordingly, the stress generated from the curved state affects the interface between the chip component 5 and the component mounting pad 2 of the printed wiring board, resulting in problems such as cracks or peeling at the interface, and the high level of the printed wiring board. In the context of increasing density and downsizing of chip parts, not only will this be a major technical issue, but in particular, printed wiring boards for high frequency applications will develop electrical problems such as increased resistance.

  On the other hand, in the present invention, since the inner layer core portion is excellent in smoothness, the electrical connection reliability between the chip component 5 and the component mounting pad 2 of the printed wiring board is improved, and the density of the printed wiring board is increased. It can cope with downsizing of chip parts.

Point 3): Sealing of through-holes In the present invention, the through-holes 7a and 7b provided in the insulating bases 6a and 6b are sealed and filled by lamination. That is, when the insulating base materials 6a and 6b are laminated from the upper surface and the lower surface as the next process with respect to the structure after mounting the chip parts shown in FIG. The resin component 6b works with good fluidity, fills the through holes 7a and 7b, and forms a structure in which the through holes are sealed as shown in FIG. Therefore, the through holes 7a and 7b themselves do not become a void portion in the printed wiring board.

Point 4): Explanation of the structure of the object In the present invention, the component mounting pads 2 are provided in the circuit formation on the copper clad laminate 1 of the inner core, and the insulating bases 6a and 6b that are stacked one after the other are mounted on the insulating bases 6a and 6b in advance. Through holes 7a and 7b having substantially the same size as the mounted parts are provided. If the through holes 7a and 7b are too small relative to the component, the chip component 5 and the insulating bases 6a and 6b come into contact with each other, and a sealing structure that takes into account the component and the convex structure cannot be obtained. On the other hand, if the size is too large for the part, the resin component in the insulating bases 6a and 6b cannot sufficiently seal the opening during lamination heating, which causes new problems such as voids. Accordingly, in the present invention, the through holes 7a and 7b having substantially the same size as the parts mounted in advance on the insulating bases 6a and 6b are provided.

  Further, in the present invention, the structure shown in FIG. 2C obtained by laminating the insulating bases 6a and 6b has a glass of the insulating bases 6a and 6b around the built-in chip component 5. The resin component impregnated in the woven fabric or the like is melted at the time of laminating and heating, and the chip component 5 is sealed. Thereby, since the resin component which does not contain glass etc. is mainly filled in the circumference | surroundings of the chip component 5, it has the effect of improving insulation.

  Furthermore, by using a glass woven fabric and an aramid woven fabric, and a glass nonwoven fabric and an aramid nonwoven fabric, a reinforcing element is introduced into the material itself, which helps to prevent warping as intended.

  The following examples further illustrate the present invention.

Example 1
An embodiment of the present invention will be described with reference to FIGS.
As a double-sided copper-clad laminate 1 shown in FIG. 1 (a), a copper-clad laminate (product number: MCL-E-679F, base material thickness 0.4 mm, copper foil thickness 12 μm) manufactured by Hitachi Chemical Co., Ltd. is used. After the copper foil roughening of the tension laminate 1 is processed, a dry film etching resist (thickness: 65 μm) is laminated on the surface of the copper foil (sticking temperature: 100 ° C.), and then exposed to ultraviolet rays (conditions: 45 mJ / cm ² ) and development (conditions: 1.0 wt% sodium carbonate aqueous solution, 30 ° C., spray pressure 0.2 MPa), using ferric chloride solution (conditions: 40 ° C., spray pressure 0.2 MPa). After etching, the dry film etching resist was peeled off (conditions: 2.2 wt% sodium hydroxide aqueous solution, 40 ° C., spray pressure 0.18 MPa), and circuit formation including component mounting pads 2 was performed (FIG. 1 (b ).

Next, a nickel / gold plating resist film “H-8050” manufactured by Hitachi Chemical Co., Ltd. is laminated on the substrate after the circuit is formed (applying temperature: 120 ° C.), and then exposed to ultraviolet rays (conditions: 140 mJ / cm ² ) and development (conditions: 1 wt% sodium carbonate aqueous solution, 30 ° C., spray pressure 0.2 MPa), and a gold-resistant plating resist was applied.

  Next, electroless gold plating treatment was performed, and nickel (thickness: 5 μm) / gold plating (0.05 μm) was applied to the surface of the component mounting pad 2.

  Next, the target chip component 5 was mounted on a predetermined portion of the printed wiring board obtained above. That is, as shown in FIG. 1 (c), lead-free solder paste 4 (Sn-3.0Ag-0.5Cu) is used as the mounting material, and the component mounting pad 2 is obtained by screen printing using a metal mask. Applied to. The opening diameter of the metal mask at this time was the same as the shape of the component mounting pad 2.

  Next, the chip component 5 was mounted on the component mounting pad 2 with a mounter. The chip component 5 used here was a 0603 size resistor component. Then, reflow heating was performed using a temperature profile with a first temperature rise temperature of 150 to 160 ° C. (100 seconds) and a second temperature rise temperature of 260 ° C. to obtain the structure shown in FIG.

Incidentally, when mounting the chip component 5, a solder resist is provided around the component mounting pad 2 (not shown) in order to cause difficulty in mounting due to a particularly small component of 0603 size. As a method for forming the solder resist, a film solder resist (product number: PFR800AUS402, thickness 30 μm) manufactured by Taiyo Ink Co., Ltd. was subjected to thermocompression bonding (conditions: 60 ° C., 60 seconds) using a vacuum applicator, Hot pressing (conditions: hot plate 85 ° C., pressure 1 MPa, pressing time 60 seconds) was performed to flow the solder resist and smooth the surface. Thereafter, ultraviolet exposure (condition: 430 mJ / cm ² ) and development (condition: 1 wt% sodium carbonate aqueous solution, 30 ° C., spray pressure 0.2 MPa) are performed with an exposure machine, and post-baking in a drying furnace after the development (condition: 150 ° C., 70 minutes).

  Next, prepregs were used as the insulating bases 6a and 6b on the structure shown in FIG. 2A obtained by mounting the chip component 5, and a component-embedded substrate was formed by stacking. The formation method will be described with reference to FIG.

  In this embodiment, a chip component 5 having a height of 0.26 mm is used, and the insulating bases 6a and 6b for sealing the chip component 5 by lamination are prepregs (product number: GEA679F, thickness made by Hitachi Chemical). 0.3 mm) was used.

  First, as shown in FIG.2 (b), the through-holes 7a and 7b were formed in the component mounting position of the insulation base materials (prepreg) 6a and 6b. As a method for forming the through holes 7a and 7b, in consideration of the shape and dimensions of the parts, a router process was used in order to provide appropriate through holes.

  As the conditions for drilling the router, processing using 30,000 rpm and a drill bit diameter of 1.5 mm was performed.

  Next, as shown in FIG. 2 (b), the structure of FIG. 2 (a) is placed in the center as the core of the printed wiring board, and an insulating base material (prepreg having pierced holes 7a and 7b from its upper and lower surfaces is provided. ) 6a and 6b were placed so that the through holes 7a and 7b were positioned at the chip component 5, and the copper foil 3 was placed outside the insulating bases (prepreg) 6a and 6b, and the lamination pressure was applied. . The conditions for stacking pressurization are as follows: the peak temperature is set to 190 ° C. and the maximum pressure during stacking is set to 3 MPa in the stacking machine with a high degree of vacuum, and the stacking of the present invention shown in FIG. A printed wiring board with built-in components was obtained.

  In the following, the circuit formation of the copper foil portion 3 is performed in the required printed wiring board structure, and then the insulating base material and the conductive base material are alternately laminated under the above-mentioned lamination conditions according to the required structure of the printed wiring board. Thus, a component built-in type multilayer printed wiring board was obtained.

Test Example The present invention has the effect of suppressing the curvature of the core member and improving the surface smoothness. Therefore, in order to specifically show that such an effect of the present invention is superior to the conventional method, a through hole is provided only in the insulating base material (6a in FIG. 4) on the chip component 5 side. Comparison is made between the printed wiring board obtained by the conventional method and the printed wiring board obtained by the method of the present invention in which through holes are provided in the insulating bases (6a and 6b in FIG. 4) on both the upper and lower sides. It was.

  First, in FIG. 4, the thickness of the insulating base material of the printed wiring board obtained by the conventional method in which the through hole is provided only in the insulating base material 6a, and through holes are provided in both 6a and 6b in FIG. The thickness of the insulating substrate of the printed wiring board obtained by the method of the present invention was measured at the component mounting surface side A1 portion shown in FIG. 4 and the opposite surface side A2 portion. The results are shown in Table 1.

  From Table 1, the thickness of the insulating base material is 300 μm for both the A1 part and the A2 part in both the conventional method and the method of the present invention, and there is no difference with respect to the target insulating base material thickness. confirmed. This is because the parts used are small parts of 0603 size and the through holes have the same shape as the parts size, so the through holes are supplied from the insulating base material sealed in the lamination process This is because the resin content is small, so that the thickness of the insulating substrate due to the presence or absence of through holes on the front and back of the parts does not have a great influence.

  Next, the printed wiring board obtained by the conventional method in which through holes are provided only in the insulating substrate 6a in FIG. 4 and the method of the present invention in which through holes are provided in both 6a and 6b in FIG. In order to compare the degree of curvature of the core member with the printed wiring board, particularly in the vicinity of the chip component 5 mounting, the bulging portion is measured at the component mounting surface side B1 portion and the opposite surface side B2 portion shown in FIG. did. The results are shown in Table 2.

  From Table 2, the swell (B1 part) on the component mounting side of the printed wiring board obtained by the conventional method is 45 μm, and the swell (B2 part) on the opposite side of the component mounting is 44 μm. In FIG. 4, it was confirmed that the conventional method in which through holes were provided only at 6a) was affected by the stacking pressure, and the core member was bent particularly near the mounted component.

  On the other hand, the swell (B1 part) on the component mounting side of the printed wiring board obtained by the method of the present invention is 0 μm, and the swell (B2 part) on the opposite side of the component mounting is also 0 μm. In the method of the present invention in which through holes are provided in the insulating bases on both the upper and lower sides (6a and 6b in FIG. 4), a core portion excellent in smoothness can be obtained particularly near the mounted component without being affected by the lamination pressure. Was confirmed.

The schematic cross-sectional process explanatory drawing which shows the manufacture example of the component built-in type printed wiring board by this invention method. The schematic cross-sectional process explanatory drawing which shows the manufacture example of the component built-in type printed wiring board by the method of this invention following FIG. The schematic cross-sectional process explanatory drawing which shows the manufacture example of the component built-in type printed wiring board by the conventional method. Explanatory drawing of the measurement location in a test example.

Explanation of symbols

1: Copper-clad laminate 2: Component mounting pads 3, 3a, 3b: Copper foil 4: Solder paste 5: Chip components 6, 6a, 6b: Insulating base material 7, 7a, 7b: Through hole 8: Curved core portion

Claims (4)

  Component-embedded printed wiring in which at least one insulating base material and conductor base material are alternately laminated on both sides of the inner layer substrate on which the component is mounted on the component mounting pad, and the component is sealed with the insulating base material simultaneously with the lamination. A method for producing a printed wiring board with built-in components, wherein a through hole having a size substantially the same as that of a mounted component is provided in advance on both insulating base materials laminated on both surfaces of the inner layer substrate.   The method of manufacturing a component built-in type printed wiring board according to claim 1, wherein the through hole is sealed when the insulating base material is laminated.   The method for manufacturing a component built-in printed wiring board according to claim 1 or 2, wherein the insulating base material is a glass woven fabric or an aramid woven fabric impregnated with a resin.   The method for producing a component built-in type printed wiring board according to claim 1 or 2, wherein the insulating base material is a glass nonwoven fabric or an aramid nonwoven fabric impregnated with a resin.

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