JP2006093493A - Printed wiring board with built-in part and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that soldering paste is liable to fly off or bleed out when parts are installed inside a printed wiring board so as to provide a built-in part mounted printed wiring board which is excellent in interlayer adhesion when the parts installed inside are sealed up with an insulating material. <P>SOLUTION: A protective film equipped with an opening through which, at least, a part of a part mounting pad appears is formed between the insulating board of the printed wiring board with the built-in parts and the insulating material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  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 technology related to printed wiring boards of molds. 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 space saving and high 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 the printed wiring board is important.

  On the other hand, as a conventional component built-in type printed wiring board, for example, a structure shown in FIG. 4 has already been reported (see Patent Document 1). That is, as shown in FIG. 4A, the component 5 is mounted on the copper clad laminate 1 corresponding to the inner layer portion of the printed wiring board, and then the copper clad laminate 1 having the component 5 is arranged in the inner layer direction. A component built-in type printed wiring board (FIG. 4B) obtained by laminating the copper-clad laminate 1 after mounting the component 5 from the upper and lower surfaces of the insulating base 6 later.

  However, if the component is mounted in advance on a copper-clad laminate, etc., and the printed circuit board with built-in component is introduced into the printed wiring board through the lamination process, the component mounting process and the printed wiring after lamination There are many technical issues in the field of reliability as plates. That is, there are the following problems.

  First, as a problem at the time of component mounting, for example, when mounting a component on an inner printed wiring board as shown in FIG. 1C, the component is placed in a predetermined place by using a solder paste or the like. Although it is mounted, solder paste splattering or blurring often occur during the reflow process during the mounting process. This fault state occurred even when the surface mounting of the component which is a conventional technique, but when the solder paste splatters or blurring occurs, it becomes a problem that it adheres between the mounting pads, Cause electrical short. Therefore, when forming a high-quality component-embedded substrate, it is necessary to form a protective film that can suppress an electrical short circuit.

  In addition, when the component is mounted, it is necessary to provide the protective film in addition to the component mounting pad in order to perform nickel / gold plating processing in order to promote soldering.

Furthermore, interlayer adhesiveness is mentioned as a problem in the reliability field as a printed wiring board after lamination. In other words, as described above, since the component is mounted on the inner layer portion of the printed wiring board by soldering or the like, it is necessary to protect the circuit surface to be mounted by forming a protective film on the circuit surface to be mounted at the time of mounting. , By forming a protective film on the circuit surface to be mounted, when a multilayer board is produced by stacking and pressing the insulating base material, sufficient adhesion strength cannot be obtained at the interface between the protective film and the insulating resin. . In addition, since sufficient adhesion strength cannot be obtained at the interface between the protective film and the insulating resin, the delamination failure occurs at the interface between the protective film and the insulating resin in the heat resistance test as a reliability test of the printed wiring board. There is a point.
JP 2001-119147 A

  The problem to be solved by the present invention based on the background as described above is to eliminate the problem of solder paste scattering and blurring that occurs when components are installed in the inner layer when creating a component built-in type printed wiring board. In addition, another object is to obtain a component-embedded printed wiring board whose interlayer adhesion when sealing a component mounted on an inner layer portion with an insulating base material can withstand a reliability test such as a heat resistance test.

  The present inventors have made various studies in order to solve the above problems. As a result, when installing components on the inner layer of printed wiring boards, it is effective to form a protective film in advance and to roughen the surface to withstand reliability tests such as heat resistance tests. As a result, the present invention was completed.

  That is, the present invention mounts a chip component on the component mounting pad of the insulating substrate provided with the component mounting pad and the wiring circuit on at least one surface, and laminates the insulating base material on the chip component mounting surface of the insulating substrate. A component built-in type printed wiring board, wherein a protective film having an opening exposing at least a part of a component mounting pad is provided between the insulating substrate and the insulating base. The above-mentioned problem is solved by a mold printed wiring board.

  In the component-embedded printed wiring board, the component mounting pad is nickel / gold plated.

  Further, the present invention is characterized in that the protective film is roughened in the component built-in printed wiring board.

  In the component-embedded printed wiring board, the protective film is an epoxy acrylate resin that is exposed and developed.

  The present invention also includes a step of forming a component mounting pad and a wiring circuit on at least one surface of the insulating substrate, and a step of forming a protective film having an opening that exposes at least a part of the component mounting pad on the insulating substrate. A component built-in type printed wiring comprising: mounting a chip component on the component mounting pad; and laminating an insulating base material on the insulating substrate, and sealing the chip component with the insulating base material. It is a manufacturing method of a board.

  Further, the present invention is characterized in that the method for manufacturing a component built-in printed wiring board further includes a step of performing nickel / gold plating on a component mounting pad.

  Moreover, the present invention is characterized in that the method for manufacturing a component built-in type printed wiring board further includes a step of roughening the protective film.

  In addition, the present invention is characterized in that the protective film is roughened using wet blasting or buffing.

  According to the present invention, it is possible to solve the problem of solder paste splattering and blurring that occurs when components are installed in the inner layer portion. Thus, it is possible to obtain a component built-in type printed wiring board that has excellent interlayer adhesion when sealing a component mounted on the inner layer portion and can withstand a reliability test such as a heat resistance test.

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): Advantages of protective film when mounting components Point 2): Adhesion reliability between layers Point 3): Roughening method of protective film

  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. 1 (a), after processing the copper foil roughening of the copper-clad laminate 1 using the copper-clad laminate 1 on both sides, as shown in FIG. 1 (b), After the wiring circuit 8 including the component mounting pad 2 is formed and then the protective film 3 is formed, the surface of the protective film 3 is roughened by wet blasting, buffing or the like as shown in FIG. Then, 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 with a mounter on the predetermined component mounting pad portion 2 of the printed wiring board obtained above via the solder paste 4, and the structure shown in FIG. Get.

  Next, the component-embedded substrate is formed by stacking the structure (FIG. 1D) on which the chip component 5 is mounted, using the prepreg as the insulating base 6. That is, as shown in FIG. 2A, the surface side on which the chip component 5 is mounted is directed to the center side (insulating base material 6 side), and the insulating base material (prepreg) 6 is the substrate after mounting the component. It installs so that it may pinch | interpose and performs lamination | stacking pressurization and obtains the structure shown in FIG.2 (b). Hereinafter, in the structure of the required printed wiring board, the circuit formation of the copper foil portion of the outermost layer is performed to obtain the structure shown in FIG. 2 (c), and then according to the required structure of the printed wiring board, Insulating base materials and conductor base materials are alternately laminated under the above-mentioned lamination conditions.

Point 1): Advantages of protective film when mounting components In FIGS. 1 (c) to 1 (d), when mounting the chip component 5, the solder paste 4 is used to mount the component at a predetermined location. In the mounting process, the solder paste 4 is often scattered or smeared during reflow. When such solder paste 4 splatters or blurs, it becomes a problem that it adheres between the component mounting pads 2 and causes an electrical short circuit. Therefore, when forming a high-quality component-embedded substrate, this is a problem to be solved. In such a background, the protective film 3 of the present invention is composed of an epoxy acrylate resin that is exposed and developed, so that the component mounting pad 2 is formed with high accuracy, and there is no need to perform nickel / gold plating processing on an extra portion. Have The protective film 3 may be either a film type or a liquid type, but the film type is preferred from the viewpoint that the film thickness is uniform.

  In the present invention, the protective film 3 to be used can be arranged as shown in FIG. 3, for example, according to the required structure of the printed wiring board. 3A shows a structure in which the protective film 3 is not covered between the component mounting pad 2 and the component mounting pad 2, and FIG. 3B shows a structure in which the protective film 3 is not covered on the component mounting pad 2. 3 is a structure in which the protective film 3 is partially covered, FIG. 3C is a structure in which the protective film 3 is partially covered between the component mounting pad 2 and the component mounting pad 2, and FIG. The structure in which the protective film 3 is partially covered on the component mounting pads 2 and the protective film 3 is also covered between the component mounting pads 2 is shown.

Point 2): Interlayer Adhesion Reliability In the present invention, as a means for improving the adhesion between the protective film 3 and the insulating base material (prepreg) 6, the surface of the coated protective film 3 is wet-blasted or buffed. It is roughened by etc.

  As an explanation of the technical background, since a built-in component is mounted on the inner layer by solder bonding, it is necessary to protect the circuit surface to be mounted by forming the protective film 3 on the circuit surface to be mounted at the time of mounting. . However, when the protective film 3 is formed on the circuit surface to be mounted, the surface of the protective film 3 formed on the inner layer is smooth and repellent when a multilayer board is manufactured by laminating and pressing the insulating base 6. There is water or the like, and sufficient adhesion strength cannot be obtained at the interface between the protective film 3 and the insulating substrate 6. In addition, since sufficient adhesion strength cannot be obtained at the interface between the protective film 3 and the insulating base material 6, an interlayer is formed at the interface between the protective film 3 and the insulating base material 6 in a heat resistance test as a reliability test of the printed wiring board. A peeling defect occurs. In addition, delamination occurs at the interface in the same way during the heat flow of reflow applied when various components are mounted on the outermost layer of the multilayer printed wiring board with built-in components, ensuring sufficient heat resistance of the printed wiring board. It will not be possible.

  On the other hand, roughening the surface of the protective film 3 improves the adhesion with the insulating substrate 6 formed on the contact surface. The surface roughening method of the protective film 3 was examined for buffing, wet blasting, plasma treatment, and chemical polishing as desmearing as physical polishing, judging from production efficiency, running cost, adhesion effectiveness, etc. A roughening method by wet blasting or buffing is effective, and it is possible to roughen the surface for the purpose of removing the surface water repellency of the protective film 3, and adhesion to the insulating substrate 6. The heat resistance of the component built-in substrate can be improved.

Point 3): Roughening method of protective film As described above, wet blasting or buffing is used as a roughening method of the protective film 3 in the present invention. Among these, surface roughening by wet blasting is particularly preferable because the roughened state has no directionality and unevenness in the roughened state cannot be produced. A feature of wet blasting is a method of thoroughly mixing an abrasive (# 800-2000), water and air, and then spraying it onto a printed circuit board like a shower at an air pressure of 0.1-0.3 MPa from a jet port called a blast gun. It is. At this time, the abrasive is struck against the surface of the protective film 3, and as a result, the surface of the protective film 3 can be uniformly and finely roughened. In addition, since the printed wiring board is transported by a conveyor and the wet blasting abrasive hits the vertical direction against the printed wiring board, for example, even on a printed wiring board where a slight warp has occurred, the abrasive is sufficiently hit and roughened well. The

The wet blasting uses, for example, “Physical Fine Etcher: FR-663, Wet Blasting System” manufactured by Macau Corporation as a horizontal device that is sprayed in a vertical direction with respect to a printed wiring board, and processing speed: 0.3-2 It is preferable to carry out under the standard conditions of 0.7 M / min, air consumption: 8.0 to 12.0 m ³ / min, air pressure of 0.1 to 0.3 MPa, and abrasive: # 800 to 2000. In this case, a method in which water, an abrasive (slurry liquid), and compressed air are mixed and projected onto a workpiece from an injection port called a blast gun is particularly desirable. The surface roughened state of the printed wiring board roughened under these conditions has a surface roughness average (Ra) value of 0.3 to 0.8 μm, and this roughened state is like a prepreg in the laminating process. Adhesion with the insulating base 6 is improved.

  In addition, when polishing by buffing, it is preferable to use a buff having a # 800 count condition.

  The following examples further illustrate the present invention.

An embodiment of the present invention will be described with reference to FIGS.
First, as a double-sided copper-clad laminate 1 shown in FIG. 1 (a), a copper-clad laminate (product number: MCL-E-679F, substrate thickness 0.1 mm, copper foil thickness 12 μm) manufactured by Hitachi Chemical Co., Ltd. is used. After the copper foil roughening of the copper clad laminate 1 is processed, a dry film etching resist (thickness: 65 μm) is laminated on the copper foil surface (sticking temperature: 100 ° C.), and then one side surface of the copper clad laminate 1 Only with exposure to ultraviolet light (condition: 45 mJ / cm ² ) and development (condition: 1.0 wt% sodium carbonate aqueous solution, 30 ° C., spray pressure 0.2 MPa), ferric chloride solution (condition: 40 Etching is performed using a spray pressure of 0.2 MPa, and the dry film etching resist is peeled off (conditions: 2.2 wt% sodium hydroxide aqueous solution, 40 ° C., spray pressure of 0.18 MPa). And wiring times The path 8 was formed (FIG. 1 (b)).

After the copper part on the surface of the double-sided copper-clad laminate 1 on which the component mounting pad 2 and the wiring circuit 8 are formed is treated with a copper foil surface roughening material (product number: CZ-8100 / CL) manufactured by MEC, protection is performed. As the film 3, a film type solder resist (product number: PFR800AUS402, thickness 30 μm) manufactured by Taiyo Ink Co., Ltd. was attached. As this formation method, after thermocompression bonding (conditions: 60 ° C., 60 seconds) using a vacuum applicator, hot pressing (conditions: hot plate 80 ° C., pressure 4 MPa, pressing time 75 seconds) is performed, and the solder resist is removed. Flowed to smooth the surface. Then, exposure (condition: 430 mJ / cm ² ) with an exposure machine having a metal halide lamp as a light source, preheating after exposure (condition: 80 ° C., 5 minutes) and development (condition: 1 wt% sodium carbonate aqueous solution, 30 ° C., spray A pressure of 0.2 MPa and a development time of 120 seconds were sequentially performed, and after the development, post-baking (conditions: 150 ° C., 70 minutes) was performed in a drying furnace (FIG. 1B).

Next, a wet blast polishing method was used as a method for roughening the surface of the protective film 3. The usage conditions are as follows: a horizontal device that is sprayed in the direction perpendicular to the printed circuit board is used, processing speed: 1.5 M / min, air consumption: 10.0 m ³ / min, air pressure 0.2 MPa, polishing agent : # 800 was a standard condition. Moreover, the method of mixing water, an abrasive | polishing agent (slurry liquid), and compressed air (abrasive grain concentration 20%), and projecting on a to-be-processed object from the injection port called a blast gun was used. The roughened state in the figure is shown by the difference in the surface state of the protective film 3 shown in FIG. 1C from FIG.

Next, a gold-resistant plating resist “H-8050” for electroless nickel / partial gold plating manufactured by Hitachi Chemical Co., Ltd. is laminated on both surfaces of the structure shown in FIG. 1B (sticking temperature: 120 ° C., roll pressure 0. 5MPa), and then exposure (condition: 140mJ / cm ² ) and development (condition: 1wt% sodium carbonate aqueous solution, 30 ° C, spray pressure 0.2MPa) using an exposure machine with a high-pressure mercury lamp as the light source. A portion other than the pad 2 where electroless gold plating treatment is not desired and a copper exposed portion not covered with the solder resist were coated with a gold-resistant plating resist. Further, the entire surface of the solid copper portion on the back side where no parts are mounted was similarly coated with a gold-resistant plating resist.

  Next, an electroless gold plating process is performed, and after nickel (thickness: 5 μm) / gold plating (0.05 μm) is applied to the surface of the component mounting pad 2, the gold-resistant plating resist is peeled off (conditions: 3. 0 ± 0.5 wt% sodium hydroxide aqueous solution, 50 ° C., spray pressure 0.2 MPa).

  Next, in order to mount the target chip component 5 on a predetermined portion of the printed wiring board obtained as described above, first, as shown in FIG. 1C, lead-free solder paste 4 (Sn-3 0.0Ag-0.5Cu) as a mounting material, and applied to the component mounting pad portion 2 by a screen printing method using a metal mask. The opening diameter of the metal mask at this time was the same as the shape of the chip component mounting pad portion 2.

  Next, the chip component 5 was mounted on the component mounting pad portion 2 with a mounter. The chip component 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.

  A prepreg was used as the insulating base material 6 on the structure (FIG. 1D) on which the chip component 5 was mounted, and a component-embedded substrate was formed by lamination. The manufacturing method will be described with reference to FIG.

  The chip component 5 was mounted on the copper-clad laminate 1 corresponding to the inner layer portion of the printed wiring board as described above to obtain the structure shown in FIG. In this example, since the chip component 5 having a height of 0.26 mm was used, the insulating base material 6 for sealing the chip component 5 by lamination was a prepreg manufactured by Hitachi Chemical (product number: GEA679F, thickness 0.15 mm). 2 layers).

  Next, as shown in FIG. 2A, the surface side on which the chip component 5 is mounted is directed toward the insulating base material (prepreg) 6 and the two substrates on which the chip component 5 is mounted are used for insulation. The base material (prepreg) 6 was installed so as to be sandwiched from both sides, and pin lamination lamination pressure was performed. The conditions for stacking pressurization are as follows: in a laminator with a high degree of vacuum, the peak temperature is 190 ° C., the maximum pressure during stacking is 3 MPa, and the structure shown in FIG. Obtained.

  Thereafter, in the required printed wiring board structure, circuit formation of the outermost copper foil portion was performed under the same conditions as in the above-described circuit formation method, and the structure shown in FIG. 2C was obtained. Next, in accordance with the required structure of the printed wiring board, the insulating base material and the conductor base material were further alternately laminated under the above-mentioned lamination conditions to obtain a component built-in type multilayer printed wiring board (not shown).

Test Example The roughening of the surface of the protective film 3 in the present invention makes the adhesiveness with the insulating substrate 6 good in the laminating process, and as a result, the reliability particularly when testing the heat resistance is improved. Therefore, in order to specifically show the effect of the roughening, the following heat resistance test was performed.

  As a reliability test method, a heat resistance test using reflow used for component mounting and the like, and as a reflow temperature condition, a top peak temperature was set to 260 ° C. Further, as the test substrate, the component built-in substrate prepared in the above example was used. As a result, when the surface of the protective film 3 was roughened, it was confirmed that problems such as peeling did not occur even when the reflow was performed four times.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 2 is a schematic cross-sectional process explanatory diagram showing the method for manufacturing the component built-in type printed wiring board of the present invention, following FIG. Plane explanatory drawing which shows the example of formation of a protective film. Schematic cross-sectional process explanatory drawing which shows the manufacturing method of the conventional component built-in type printed wiring board.

Explanation of symbols

1: Copper-clad laminate 2: Component mounting pad 3: Protective film 4: Solder paste 5: Chip component 6: Insulating substrate 7: Opening of protective film 8: Wiring circuit

Claims (8)

  A component built-in printed wiring in which a chip component is mounted on the component mounting pad of the insulating substrate provided with a component mounting pad and a wiring circuit on at least one surface, and an insulating substrate is laminated on the chip component mounting surface of the insulating substrate. A component built-in type printed wiring board, wherein a protective film having an opening exposing at least a part of a component mounting pad is provided between the insulating substrate and the insulating base.   2. The component built-in printed wiring board according to claim 1, wherein the component mounting pad is nickel / gold plated.   The component built-in type printed wiring board according to claim 1, wherein the protective film is roughened.   The component built-in type printed wiring board according to claim 1, wherein the protective film is an epoxy acrylate resin that performs exposure and development.   Forming a component mounting pad and a wiring circuit on at least one surface of the insulating substrate; forming a protective film having an opening exposing at least a part of the component mounting pad on the insulating substrate; and A method of manufacturing a component-embedded printed wiring board, comprising: mounting a chip component; and laminating an insulating base material on the insulating substrate, and sealing the chip component with the insulating base material.   6. The method of manufacturing a component built-in printed wiring board according to claim 5, further comprising a step of performing nickel / gold plating on the component mounting pad.   The method of manufacturing a component built-in printed wiring board according to claim 5 or 6, further comprising a step of roughening the protective film.   The method of manufacturing a component built-in type printed wiring board according to claim 7, wherein the roughening of the protective film is performed using wet blasting or buffing.

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