JP2005101043A - Method for manufacturing multilayer printed-wiring board having recess for embedding electronic component and through hole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a multilayer printed-wiring board having a recess for embedding electronic components and a through hole that reduces costs, prevents deterioration in insulation performance, prevents the restriction of applicability, further, can suppress influence to a circuit portion, and enables high-density wiring and high-density packaging. <P>SOLUTION: At the upper side of a lower printed-wiring board having a circuit 9 for electronic components to be embedded, an upper printed-wiring board 16 on which a hole of desired size is punched is heated and crimped via a bonding sheet 11 at a place in which the electronic components are packaged. Additionally, the through hole 4 and external layer wiring 8 are formed, and then the bonding sheet 11 at the bottom of the recess 13 for embedding electronic components of the multilayer printed-wiring board is removed by laser machining or chemical treatment for exposing the circuit 9 for electronic components. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer printed wiring board having a recess for embedding an electronic component.

  As electronic devices become lighter, thinner, and more multifunctional, printed wiring boards used in electronic devices are also demanded to be faster and thinner. In addition, printed wiring boards are increasingly used for rewiring electronic components used in electronic devices. In that case, higher density and thinner plates are required.

  Therefore, there is a demand for a multilayer printed wiring board capable of suppressing the layer thickness or reducing the area by mounting or sandwiching relatively thick electronic components and semiconductor bare chips, etc. in the depression of the printed wiring board. Increasing year by year.

  For example, Japanese Patent Application Laid-Open No. 7-22536 discloses a multilayer printed wiring board in which a semiconductor is mounted in a recess formed by cutting out an inner layer circuit of the multilayer printed wiring board.

  Conventionally, when manufacturing a multilayer printed wiring board having a recess for embedding an electronic component, a method of cutting out an inner layer pattern after lamination has been used. When cutting the inner layer pattern with a blade, the inner layer copper thickness of 70 to 100 μm is required to absorb the vertical position accuracy of the cutting device and the thickness variation of the printed wiring board. Then, it is thin and difficult to form a pattern with a pitch of 120 μm or less corresponding to flip chip mounting which has been increasing in recent years. In addition, since the cutting process cannot be performed by overlapping the wiring boards, it is a process for each sheet, and there is a problem that the working efficiency is low and only the tip portion of the blade is used, resulting in high cost. .

  As a countermeasure, an upper printed wiring board provided with a hole for embedding an electronic component and a lower printed wiring board having a circuit for an electronic component embedded in the hole correspond to the hole of the upper printed wiring board. There is a multilayer printed wiring board provided with a depression for embedding an electronic component formed by bonding through an adhesive layer having a hole at a position. In the multilayer printed wiring board having the depressions for embedding electronic parts formed in this way, through holes are used to establish electrical connection between the upper printed wiring board and the lower printed wiring board.

  For example, in order to manufacture such a multilayer printed wiring board with a through hole, (1) an upper printed wiring board provided with holes for embedding electronic components and a lower printed wiring board having a circuit for electronic components Then, bonding is performed via an adhesive layer having a hole at a position corresponding to the hole for embedding the electronic component, thereby forming a recess opening. (2) Open through-holes for through-holes, and then form a protective film in the recessed openings, and provide an electroless copper plating layer on the entire surface to give conductivity to the inner surfaces of through-holes for through-holes. To do. (3) The protective film in the recess opening is removed and soft etching is performed to remove the electroless copper plating layer other than the wiring portion and the inner surface of the through hole. (4) A protective film is formed in the recessed opening, and electrolytic copper plating is performed on the wiring portion and the electroless copper plating layer of the through hole to complete the through hole. (5) Soft etching is performed to adjust the thickness of the wiring portion and to completely remove the remaining portion of the electroless plating layer. (6) The protective film of the hollow opening is removed.

  When such a manufacturing method is adopted, the manufacturing process is complicated and the cost is increased, and in the electroless copper plating process for forming the through hole, a palladium catalyst is required, and when applying the catalyst, There was a problem that the liquid permeated between the protective film and the lower printed wiring board, palladium was deposited, and the insulating performance was deteriorated. Further, there is a limit to the size of the recessed opening where the protective film can be applied, and there is a problem that the range in which such a method can be applied is limited.

In addition, since the soft etching process is added twice to remove the electroless copper plating on the circuit part for the electronic component, there is a problem that the circuit width is narrowed and it is difficult to mount the electronic component.
Japanese Patent Laid-Open No. 7-22536

  The object of the present invention is low-cost, does not degrade insulation performance, is not subject to application scope restrictions, and can control high-density wiring and high-density mounting while suppressing the influence on the circuit part. An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board having a recess for embedding an electronic component and a through hole.

  The method of manufacturing a multilayer printed wiring board having a recess for embedding an electronic component and a through hole according to the present invention includes (1) a lower printed wiring board having a circuit for the electronic component, and a hole for embedding the electronic component. Bonding the upper printed wiring board provided with a through an adhesive layer to form a multilayer printed wiring board; (2) providing a through hole for a through hole in the multilayer printed wiring board; (3 ) Step of forming electroless plating and electrolytic plating on the electroless plating and etching to form an outermost layer circuit on the multilayer printed wiring board; (4) Group consisting of laser irradiation, chemical treatment and plasma desmear treatment The recess for embedding the electronic component of the multilayer printed wiring board formed by the hole of the upper printed wiring board is at least one method selected from Step to remove some or all of the adhesive layer exposed to the part, characterized in that it consists of.

  In the prior art, since the through-hole plating and etching are performed while protecting the circuit for the electronic component at the bottom of the depression with the protective film, the cost is increased, the insulation performance is lowered, and the width of the circuit is reduced. These problems can be solved by the present invention. As a result, according to the manufacturing method of the present invention, high-density wiring and high-density mounting can be realized for a multilayer printed wiring board provided with various electronic component embedding depressions at low cost and easily.

  In the method of manufacturing a multilayer printed wiring board having a recess for embedding an electronic component and a through hole according to the present invention, first, a lower printed wiring board having a circuit for an electronic component embedded in the recess of the multilayer printed wiring board; Then, an upper printed wiring board provided with a hole in which the electronic component is embedded is prepared, and these printed wiring boards are joined by thermocompression bonding through an adhesive layer to form a multilayer printed wiring board. As the adhesive layer, a thin adhesive sheet having a low content of inorganic fillers, short fibers and the like and excellent in laser processability, for example, an epoxy adhesive film manufactured by Hitachi Chemical or Yodogawa Paper Mill is used. In addition, it is not necessary to provide the hole corresponding to the hole provided in the said upper side printed wiring board in the adhesive bond layer. In the case of the present invention, the adhesive layer is not provided with conductivity, and the adhesive layer is not provided with holes corresponding to the depressions, so that the upper and lower printed wiring boards are electrically connected. It is completely shut off.

  Next, a through hole for a through hole for electrically connecting the upper and lower printed wiring boards is provided in the formed multilayer printed wiring board.

  Thereafter, for example, after palladium is deposited as an electroless plating catalyst by dipping or the like, an electroless copper plating layer is provided on the entire surface of the multilayer printed wiring board to impart conductivity to the inner surface of the through hole for the through hole. . Then, soft etching is performed to remove the electroless plating layer other than the wiring part and the inner surface of the through hole, and the plating part of the wiring part and the through hole is grown to a required thickness by electrolytic copper plating, so that the through hole is formed. The outermost layer circuit is formed on the multilayer printed wiring board.

  In the present invention, the hole corresponding to the depression is not provided in the adhesive layer, and the circuit for the electronic component in the lower printed wiring board is protected by the adhesive layer. There is no need to provide a membrane.

  Next, part or all of the adhesive sheet exposed at the bottom of the recess for embedding the electronic component in the multilayer printed wiring board is removed by laser processing, and the electronic component for the electronic component provided on the lower printed wiring board Expose the circuit.

  In the above embodiment, an adhesive sheet having good laser processability is used as the adhesive layer, and laser processing is performed at the time of removal. However, in the thermocompression bonding of the lower printed wiring board and the upper wiring board, it is chemically easy. A thin adhesive sheet that can be etched, such as a heat-sealable polyimide film or a thermoplastic polyimide film, may be used, in which case, after through-hole plating and etching of the outermost layer circuit, the bottom of the recess for embedding the electronic component A part or all of the exposed adhesive sheet is removed by chemical solution processing or plasma desmear processing to expose a circuit for electronic components provided on the lower printed wiring board.

  The chemical solution treatment means treatment by spraying an etching solution, immersion in an etching solution, or the like. As the plasma desmear treatment, oxygen plasma, carbon tetrafluoride plasma, or the like can be used.

  In the process according to the present invention, the circuit for the electronic component of the lower printed wiring board located in the recess for embedding the electronic component is placed on the adhesive layer until the electrolytic copper plating process is completed and the adhesive layer is removed. When the palladium catalyst is applied in the electroless copper plating process, the solution does not penetrate and there is no problem that the insulation performance of the circuit is deteriorated. Similarly, the protection of the adhesive layer does not affect the circuit portion for the electronic component of the lower printed wiring board due to the soft etching, and there is no problem that the circuit width becomes narrow. Furthermore, laser processing, chemical treatment, or plasma desmear treatment for removing the adhesive layer exposed at the bottom of the recess for embedding electronic components is not limited by the size of the opening of the recess, so a wide range of multilayer printed wiring Applicable to plates.

  In the method of the present invention, known techniques can be employed for the thermocompression bonding process, drilling process, electroless copper plating process, electrolytic copper plating process, etching process and laser processing.

(Example 1)
FIG. 1 is a series of cross-sectional views showing the manufacturing process of the lower printed wiring board.

First, (A) a copper foil (2) is provided on both the front and back sides or one side (both sides in the figure) of the insulator substrate (1) to form a laminate,
(B) An opening (3) is provided in a desired portion of the laminate,
(C) The inner surface of the opening is plated (4) to complete the through hole,
(D) The copper foil of the laminated board is selectively etched to form an inner wiring layer (5), thereby forming a first inner wiring board in which the inner wiring layer (5) is formed on both the front and back surfaces.

  Next, (E) the first inner layer wiring board is coated with the copper foil (2) on both sides through an adhesive sheet (6), a prepreg (a glass fiber cloth impregnated with an insulating resin and semi-cured), etc. Adhesion with heating and pressure.

And (F) Etching is performed on a desired portion of the copper foil (2) to remove the adhesive sheet and prepreg exposed in the opening formed in the copper foil,
(G) The opening (7) is plated to form a micro via connection, and the copper foil (2) is selectively etched to form a wiring layer (5).

  When this wiring layer (5) is formed, an electrode pattern (9) for mounting an electronic component is provided at a location corresponding to the recess for embedding the electronic component. Through the above steps, the lower printed wiring board (14) is formed.

  As the insulator substrate (1), in addition to the glass epoxy laminate, a substrate using various functional fibers as a core agent, an organic film substrate combining long and short organic molecules, and the like can also be used. For example, glass substrate-epoxy resin laminate (the glass epoxy laminate), glass substrate-polyimide resin laminate, glass substrate-Teflon (registered trademark) resin laminate, aramid substrate-epoxy resin laminate, ethylene A fluorine base material-epoxy resin laminate, a polyphenylene ether resin laminate, a polyester ester / polyetherimide copolymer substrate (sheet), an acrylic copolymer substrate (sheet), a polyimide sheet, or the like can be used.

  The lower printed wiring board (14) can be used alone, but after chemically treating the surface of the conductor layer, a plurality of insulator substrates and copper foil are combined through an adhesive sheet, and the same procedure as described above is performed. Thus, it can be multi-layered.

  FIG. 2 is a series of cross-sectional views showing the manufacturing process of the upper printed wiring board.

  (A) Similarly to the lower printed wiring board (14), an upper printed wiring board laminate is formed.

  (B) In the laminated body for the upper printed wiring board, a hole (12) having a desired size is provided by punching processing, router processing, drilling processing, or the like at the place where the electronic component is embedded, and the upper printed wiring board (16). Form. The upper printed wiring board (16) can also be subjected to chemical treatment on the surface of the conductor layer in order to improve the adhesion with the adhesive sheet.

  FIG. 3 is a series of sectional views showing a manufacturing process for forming a multilayer printed wiring board using the lower printed wiring board and the upper printed wiring board.

  (A) After overlapping the lower printed wiring board (14) and the upper printed wiring board (16) through the adhesive sheet (11) while aligning the positions of the electrodes and the windows, The multilayer printed wiring board (17) provided with the depression for embedding electronic components is formed by thermocompression bonding. As the adhesive sheet (11), an insulator having a low content of inorganic fillers, short fibers and the like and having good laser processability, for example, an epoxy adhesive film manufactured by Hitachi Chemical or Yodogawa Paper Mill is selected.

In this state, the upper printed wiring board (16) and the lower printed wiring board (14) are not electrically connected.
(B) Open the through hole (3) by drilling,
(C) For electrical connection between the lower printed wiring board (14) and the upper printed wiring board (16), the inner surface of the through hole (3) is subjected to electroless plating, followed by electrolytic plating, (4) is formed.

  Next, (D) the copper foil on the upper and lower surfaces of the wiring board (17) is selectively etched to form the outer layer wiring (8) to obtain the multilayer printed wiring board (18). At this time, the copper at the bottom of the electronic component embedding recess (13) is also removed at the same time.

  Further, (E) the bottom of the recess (13) for embedding the electronic component is spotted by laser processing to expose the electrode pattern (9) for mounting the electronic component, thereby obtaining the multilayer printed wiring board (19).

  The multilayer printed wiring board (19) provided with the hollow (13) which embeds an electronic component is manufactured by the above process, as shown in a sectional view in FIG.

  When semiconductor elements were mounted in the depressions of the multilayer printed wiring board thus obtained, 200 semiconductor devices were manufactured, and a continuity test was performed on these 200 devices. As a result, no defective product was detected.

Moreover, as a result of applying a voltage of DC 10V over a period of 1000 hours between the patterns of 100 μm pitch at the bottom of the recesses in an environment of 85 ° C. and 85% relative humidity with respect to 10 multilayer printed wiring boards, 1 × 10 ¹¹ Ω The above insulation resistance was maintained.

(Example 2)
Examples according to other aspects of the invention will now be described. The manufacturing process is the same as that of the first embodiment, and FIGS. 1 to 4 can be referred to.

  First, similarly to Example 1, a lower printed wiring board (14) and an upper printed wiring board (16) are manufactured and heat-pressed through an adhesive sheet (11). As the adhesive sheet (11), an insulator that can be easily etched by chemicals such as polyimide and alkali-solubilized epoxy resin, for example, a heat-fusible polyimide film or a thermoplastic polyimide film is used without any pores.

  Next, the through hole (3) is opened, and the inner surface of the through hole (3) is plated for electrical connection between the lower printed wiring board (14) and the upper printed wiring board (16). A hole (4) is formed.

  Further, the copper foil on the upper surface and the lower surface is selectively etched to form the outer layer wiring (8), thereby obtaining the multilayer wiring layer (18). At this time, the copper at the bottom of the electronic component embedding recess (13) is also removed at the same time.

  Then, an etching process is performed with a strong alkaline solution such as hydrazine to remove the resin at the bottom of the recess (13) for embedding the electronic component, and the electrode pattern (9) for mounting the electronic component is exposed.

  In this step, in addition to the etching process using a chemical solution, a thin adhesive sheet (11) is used, and further, the resin near the electrode pattern for mounting the electronic component is reduced by the resin flow at the time of thermocompression bonding. Removal by processing is also possible.

  As described above, as shown in the cross-sectional view of FIG. 4, a multilayer printed wiring board having a recess (13) for embedding electronic components is manufactured.

  When semiconductor elements were mounted in the depressions of the multilayer printed wiring board thus obtained, 200 semiconductor devices were manufactured, and a continuity test was performed on these 200 devices. As a result, no defective product was detected.

Moreover, as a result of applying a voltage of DC 10V over a period of 1000 hours between the patterns of 100 μm pitch at the bottom of the recesses in an environment of 85 ° C. and 85% relative humidity with respect to 10 multilayer printed wiring boards, 1 × 10 ¹¹ Ω The above insulation resistance was maintained.

(Comparative Example 1)
For comparison, a lower printed wiring board and an upper printed wiring board are manufactured by a conventional manufacturing method, and an adhesive sheet having holes at positions corresponding to the holes provided in the upper printed wiring board, such as GEA- manufactured by Hitachi Chemical Co., Ltd. The upper and lower printed wiring boards are joined via 679N to form a multilayer printed wiring board having a recess for embedding electronic components, and then a through hole for a through hole is opened, and then a protective film is formed in the recess An electroless copper plating layer is provided on the entire surface to impart conductivity to the inner surface of the through hole, and then the protective film is removed and soft etching is performed, so that there is nothing other than the wiring portion and the inner surface of the through hole. After removing the electrolytic copper plating layer, a protective film was formed in the recess, and a through hole was completed by electrolytic copper plating. Further, after performing soft etching for adjusting the thickness of the wiring portion and completely removing the remaining portion of the electroless plating layer, the protective film was removed.

With respect to 10 multilayer printed wiring boards obtained in this way, a voltage of 10 V DC was applied over a period of 1000 hours between 100 μm pitch patterns at the bottom of the depressions in an environment of 85 ° C. and 85% relative humidity. The insulation resistance value decreased to 1 × 10 ⁸ or less in the / 10 sample.

It is a series of sectional views showing a manufacturing method of a lower side printed wiring board in the present invention. It is a series of sectional views showing the manufacturing method of the upper side printed wiring board in the present invention. It is a series of sectional views showing a manufacturing method of a multilayer printed wiring board in the present invention. It is sectional drawing which shows one Example of the multilayer printed wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulator board | substrate 2 Copper foil 3 Through-hole 4 Through hole 5 Inner layer wiring 6 Adhesive sheet 7 Micro via 8 Outer layer wiring 9 Circuit for electronic component mounting 11 Adhesive sheet 12 Hole for embedding electronic component 13 Depression for embedding electronic component 14 Lower printed wiring board 16 Upper printed wiring board 17, 18, 19 Multilayer printed wiring board

Claims (1)

  (1) A lower side printed wiring board having a circuit for an electronic component and an upper side printed wiring board provided with a hole for embedding the electronic component are joined together via an adhesive layer to obtain a multilayer printed wiring board. (2) providing a through hole for a through hole in the multilayer printed wiring board; (3) performing electroplating on the electroless plating and the electroless plating, etching the multilayer printed wiring; A step of forming an outermost layer circuit on the board; (4) the multilayer printed wiring board formed by the holes of the upper printed wiring board by at least one method selected from the group consisting of laser irradiation, chemical treatment and plasma desmear treatment; Removing a part or all of the adhesive layer exposed at the bottom of the electronic component embedding recess of the electronic component embedding Method of manufacturing a multilayer printed wiring board having a through-hole with.

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