JP2018200975A - Metallic film formation product and method for manufacturing the same - Google Patents

Abstract

To provide a metallic film formation product having a conductive metallic film with excellent adhesion and conductivity provided on a surface of a base plate made of resin containing inorganic particles, and a method for manufacturing the metallic film formation product.SOLUTION: A metallic film formation product (10) of the present invention comprises: a base material (1) that includes a resin and inorganic particles dispersed in the resin; a surface modification film (2) that is formed on a surface of the base material (1); and a conductive metallic film (3) that is formed on a surface of the surface modification film (2) and made of conductive metal. The surface modification film (2) has a texture in which the inorganic particles included in the base material (1) constitutes a molten aggregate while including a void.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a metal film-formed product and a method for producing a metal film-formed product.

A multilayer surface mount type inductor in which a conductive circuit is formed on a magnetic ferrite core is used for a noise filter that removes high-frequency noise from a transmission signal of a digital electronic device such as a cellular phone. The ferrite core used in this surface-mount type inductor is a thermosetting resin (for example, iron oxide (Fe ₂ O ₃ ) particles (usually having a particle diameter of Φ1 to 5 μm) added with divalent metal oxide fine particles. Ferrite-containing thermosetting resin molded product dispersed and mixed in (epoxy resin). Such a ferrite-containing thermosetting resin molded product can be produced by injecting it into a molding die before curing the resin, and then heat curing the resin. An inductor can be formed by directly forming conductive wiring on the ferrite-containing thermosetting resin substrate. Also, by laminating the substrate on which the wiring is formed, a multilayer surface mount type inductor can also be manufactured.

  Currently, multilayer surface mount type inductors are mainly manufactured by a printing method of thick film conductive Cu (copper) paste. In this method, a Cu paste containing copper particles and an uncured epoxy resin is spirally printed on the surface of a ferrite-containing thermosetting resin substrate by a dispenser, screen printing or the like, and then heated at 150 ° C. for about 30 to 60 minutes. Is a method of curing. Also, as another method of manufacturing an inductor, a furnace firing green sheet in which ferrite particles are mixed with a binder is prepared, and furnace firing type conductive paste such as copper or silver is spirally printed on the surface of the green sheet, There is a method of firing at a temperature of 900 ° C. Both methods require a long heating process after printing the conductive paste.

  As another method, there is a method of forming a spiral wiring by a photolithography method after semi-additive copper plating is performed on the entire surface of the ferrite-containing thermosetting resin substrate. This method does not require a furnace for baking or thermosetting, but it requires complex processes such as photosensitive resist printing, exposure, development, chemical etching and resist stripping in addition to the semi-additive copper plating process. And In addition, there is a problem of chemical waste liquid treatment and cleaning water drainage treatment.

  This photolithography method has the feature that the wiring can be miniaturized and a smaller surface mount type inductor can be manufactured. However, the process is complicated, the manufacturing equipment is expensive, and the cost is increased. Not suitable for other than performance type applications. On the other hand, in the method using a conductive paste, a multilayer inductor can be manufactured by forming via holes in a substrate and filling the conductive paste before laminating. However, as with the photolithography method, the process is long and costly. It will be up.

Thus, the conventional method has a big problem that it is impossible to manufacture an inductor in one line because the process is complicated and long. Currently, global warming caused by CO ₂ discharged from the manufacturing process has become a problem, and there is a global demand for simplifying the manufacturing process to the ultimate. Specifically, for example, in the manufacture of an inductor, it is desirable that the three steps of via hole processing on the ferrite-containing thermosetting resin substrate, conductive paste printing, and conductive paste sintering be completed in one line.

  As a technique capable of performing via hole processing on a base material, conductive paste printing, and conductive paste sintering in one line, there is Patent Document 1. Patent Document 1 contains a copper microparticle, a volatile organic solvent, and a binder on a substrate in a method of manufacturing a wiring substrate in which conductive wiring is formed on an electrically insulating substrate. A coating film forming step for obtaining a coating film by applying a dispersion, a drying step for drying and removing the organic solvent by heating the coating film, and a coating film having a wavelength of 300 to 600 nm in the atmosphere after the drying step. A wiring board comprising: a laser light irradiation step for obtaining a copper microparticle sintered film by irradiating a laser beam to decompose the binder and sintering the copper microparticles to adhere to the substrate. A manufacturing method is disclosed.

  The method of manufacturing a wiring board described in Patent Document 1 uses HLP (High Speed Laser Placing: registered trademark), and uses laser light for via hole processing and conductive paste sintering. , Via hole processing on the substrate, conductive paste printing and conductive paste sintering can be carried out in one line.

Patent No. 5859075

  In the technique described in Patent Document 1, a glass epoxy substrate in which glass fiber is impregnated with a liquid epoxy resin and thermally cured is used as a substrate on which conductive wiring is formed. When such a substrate is used, the laser energy absorption rate of the glass fiber is low in the laser light irradiation process, so the temperature of the glass fiber does not rise, and the epoxy resin also has a low laser light absorption rate, so the substrate is ablated. It is never done. For this reason, when a glass epoxy substrate that does not contain inorganic particles (metal oxide particles, metal particles, quartz, etc.) is used, an electroconductive copper sintered film having adhesion can be obtained as in the example of Patent Document 1. It is done.

  However, although the technology described in Patent Document 1 can form a wiring film having adhesion to a resin substrate, a base material is a thermosetting resin in which inorganic particles are dispersed in a resin used as a base material for an inductor. In such a case, sufficient adhesion cannot be obtained. The reason is that the inorganic particles have a high laser energy absorption rate, plasma is generated on the surface of these particles, the resin in the vicinity of the particles is ablated, and decomposition gas is generated at the interface. On the other hand, the melting point of inorganic particles such as ferrite is usually as high as 1000 ° C. or higher, and the inorganic particles under the copper microparticle paste coating film do not reach melting. For this reason, high adhesion between the base material and the conductive metal film cannot be obtained.

  In view of the above circumstances, an object of the present invention is to provide a metal film-formed product having high adhesion between a base material and a conductive metal film and excellent in conductivity, and a method for producing the metal film-formed product.

  In order to achieve the above object, the present invention is formed on a surface of a base material containing a resin and inorganic particles dispersed in the resin, a surface modification film formed on the surface of the base material, and the surface modification film, A conductive metal film made of a conductive metal, and the surface-modified film has a structure in which inorganic particles contained in the base material constitute a molten aggregate while containing voids. A metal film forming product is provided.

  The present invention also provides a structure in which a resin and a surface of a base material including inorganic particles dispersed in the resin are irradiated with laser light, and the inorganic particles included in the base material constitute a melt aggregate while including voids. Forming a surface modification film, applying a conductive paste containing a conductive metal to the surface of the surface modification film, forming a coating film, drying the coating film, and dry coating And a step of irradiating the film with a laser beam to sinter conductive metal contained in the dried coating film to form a metal film.

  More specific configurations of the present invention are described in the claims.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness of a base material and an electroconductive metal film is high, and the manufacturing method of the metal film formation product and metal film formation product excellent in electroconductivity can be provided.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

It is sectional drawing which shows typically an example of the metal film formation goods of this invention. It is sectional drawing which shows typically the 1st example (laminated type surface mount type inductor) of the components of the electronic device using the metal film formation goods of this invention. It is a schematic diagram of the laminated body of the base material of FIG. 2A. It is a perspective view which shows typically the 2nd example (antenna) of the components of the electronic device using the metal film formation goods of this invention. It is a perspective view which shows typically the 3rd example (connector) of the components of the electronic device using the metal film formation goods of this invention. It is a figure which shows the 1st example of the manufacturing method flow of the metal film formation goods of this invention. It is a schematic diagram which shows an example of the system which manufactures the metal film formation goods of this invention. It is a schematic diagram which shows the 2nd example of the manufacturing process of the metal film formation goods of this invention. It is a schematic diagram which shows the 3rd example of the manufacturing process of the metal film formation goods of this invention. 2 is a SEM observation photograph of the surface of the base material of Example 1. 2 is a SEM observation photograph of the surface modified film of Example 1. It is the reflection and absorption spectrum of the base material of Example 1. 6 is a graph showing the results of EDX analysis of the surface of the surface modified film of Example 1. 2 is a SEM observation photograph of copper microparticles in the conductive paste of Example 1. It is a cross-sectional SEM observation photograph of the base material after the coating film drying of Example 1. FIG. It is the reflection, absorption, and transmission spectrum of the coating film after drying of Example 1. It is an optical microscope observation photograph of the surface of the base material after the metal film formation process of Example 1 (after copper microparticle sintering). It is a cross-sectional SEM observation photograph of the base material after the metal film formation process of Example 1 (after copper microparticle sintering). 4 is an optical microscope observation photograph of the surface of the base material after the conductive metal film forming step of Example 2. 4 is an optical microscope observation photograph of the surface of a base material of Example 3. 6 is an optical microscope observation photograph of the surface of a base material after the surface modified film forming step of Example 3.

[Basic idea of the present invention]
As described above, the base material used for components constituting electronic devices such as inductors is made of a thermosetting resin containing inorganic particles (metal particles, oxide particles, quartz, etc.). Conducted extensive studies on a method for forming a conductive metal film having excellent adhesion on the surface of such a substrate. As a result, before forming the conductive metal film on the surface of the base material, as a surface modification treatment process of the base material, the surface of the base material is irradiated with laser light under a predetermined condition to ablate the surface of the base material in advance. It discovered that the adhesiveness of a base material and an electroconductive metal film improves markedly by processing.

  More specifically, when the surface of the base material is irradiated with laser light under a predetermined condition, the resin at the portion irradiated with the laser light is removed by laser ablation. At this time, the inorganic particles at the location irradiated with the laser melt. Therefore, a structure in which the inorganic particles constituting the base material form a molten aggregate while including voids generated by ablation of the resin is formed in the laser light irradiation portion. When a conductive paste containing conductive metal particles is applied to the surface having this structure, the conductive metal film and the substrate are mechanically strengthened by the penetration of the conductive paste into the voids generated by ablation of the resin. Join (mechanical locking). That is, the layer (surface modified film) having a structure constituting the melt aggregate while containing the voids serves as a bonding layer for bonding the base material and the conductive metal film. The present invention is based on this finding.

  As described above, the structure of a metal film-forming product having a surface-modified film having a structure composed of a molten aggregate of inorganic particles and voids between a base material and a conductive metal film is conventionally used. It was a breakthrough that was not there. Moreover, the manufacturing method which can manufacture the metal film formation product which has such a structure is also novel.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail using drawing.

[Metal film forming products]
FIG. 1 is a cross-sectional view schematically showing an example of a metal film-formed product of the present invention. As shown in FIG. 1, a metal film-formed product 10 of the present invention includes a base material 1 containing a resin and inorganic particles dispersed in the resin, a surface modified film 2 formed on the surface of the base material 1, a surface A conductive metal film 3 formed of a conductive metal is formed on the surface of the modified film 2.

As the base material 1, as described above, a material used for a part constituting an electronic device such as an inductor is used. Specifically, a material obtained by adding (dispersing and mixing) a metal oxide (for example, Fe ₂ O ₃ particles) or a metal (for example, Fe particles) to a thermosetting resin (for example, an epoxy resin) can be used. . Furthermore, a thermosetting resin obtained by adding a filler (for example, a spherical or short fiber quartz glass filler) to a thermosetting resin can also be used. Metals, metal oxides, fillers, and the like (hereinafter referred to as “inorganic particles”) contained in the base material 1 are melt-aggregated by laser (single pulse laser) light irradiation that is irradiated in a surface modification treatment step described later. Anything to do. A mixture of a plurality of the above-described inorganic particles may be used.

  More specifically, a thermosetting resin pellet containing 60 to 90 mass% of inorganic particles having an average particle diameter of several μm is prepared, and injection molded into a predetermined shape using the pellet, and then 1 h at 150 to 160 ° C. A molded product of inorganic particle-containing thermosetting resin that has been heat-treated to a certain degree can be used as the substrate 1. The molded product can usually be obtained as a commercial product produced by a resin molding manufacturer.

  As for the average particle diameter of the inorganic particle disperse | distributed to the base material 1, 0.5-30 micrometers is preferable. If the thickness is less than 0.5 μm, it is difficult to sufficiently coarsen the particles in the surface-modified film forming step described later, and it becomes difficult to form a three-dimensional melt aggregate having many voids. On the other hand, if it is larger than 30 μm, the three-dimensional melt aggregate becomes too rough, the contact area with the metal film decreases, and high adhesion cannot be obtained. When the average particle size of the inorganic particles dispersed in the substrate is 0.5 to 30 μm, the average particle size of the melt aggregate after the surface modified film forming step is approximately 10 to 50 μm.

  The shape of the molded product is formed into a plate shape having a thickness of about 0.5 to 2.0 mm when a surface mount type inductor is used. When a multilayer multilayer wiring inductor is used, it is formed to a thickness of about 0.2 to 0.5 mm. Further, in the case of a package type inductor, an irregular shape having a concave cavity at the center is formed. An inductor package having a sealed structure can be manufactured by forming a conductive wiring in the center and potting and sealing the recess with a liquid thermosetting resin.

  As described above, the surface-modified film 2 forms a molten aggregate (complex structure three-dimensional molten aggregate layer) while the inorganic particles constituting the substrate 1 include voids generated by ablation of the resin. Have an organization. The conductive metal film 3 is composed of a laser sintered film of a conductive metal such as Cu or silver (Ag).

[Electronic parts]
FIG. 2A is a cross-sectional view schematically showing a first example (layered surface mount type inductor) of an electronic device using the metal film-formed product of the present invention. FIG. 2B is a schematic view of a laminate of the base material of FIG. 2A. As shown in FIG. 2A, the inductor 200 is provided with a metal film-formed laminate 20 on the surface of a housing 27. As shown in FIG. 2B, the laminate 20 is configured by laminating a base material (metal film-formed product) 21 on which a metal film (internal electrode) 23 is formed. Each base material 21 is provided with a via hole 24, and each base material 21 is electrically connected to each other at the via hole 24 portion. An external electrode 25 is provided at the end of the base material 21 and is joined to the housing 27 by solder 26. As described above, the inductor 200 of the present invention has high adhesion between the base material 21 and the metal film 23 and is excellent in conductivity.

  FIG. 3 is a perspective view schematically showing a second example (antenna) of a part of an electronic device using the metal film-formed product of the present invention. The antenna shown in FIG. 3 is mounted on an RFID (Radio Frequency Identifier) or the like. As shown in FIG. 3, the antenna 30 includes a base material 31 and a conductive metal film (wiring) 33.

  FIG. 4 is a perspective view schematically showing a third example (connector) of an electronic device component using the metal film-formed product of the present invention. The connector is used for connecting wiring in an electronic circuit or the like, and has various shapes. FIG. 4 shows a box-shaped female terminal. As shown in FIG. 4, the connector 40 includes a base material 41 and a conductive metal film 43. The base material 41 has a male terminal insertion hole 42. As shown in FIGS. 2A to 4, the metal film-formed product of the present invention can be applied to parts constituting various electronic devices. Furthermore, the metal film-formed product of the present invention can be used for motors, vibrators, etc. by using thermosetting resin molded products containing magnetic particles such as ferrite and diamagnetic particles such as copper and silver. Applicable.

[Method for producing metal film-formed product]
FIG. 5 is a diagram showing a first example of a flow of a method for producing a metal film-formed product of the present invention. FIG. 5 shows a manufacturing flow together with a cross-sectional view of the metal film-formed product. The same applies to FIGS. 7 and 8 described later. Hereafter, the manufacturing method of the metal film formation product of this invention is demonstrated along FIG.

(A) Base material preparation process First, the base material 51 is prepared. The specific configuration of the substrate 51 is as described above, and a material in which inorganic particles are dispersed in a resin is used.

(B) Surface modified film forming step (laser ablation and melt aggregate forming step)
Next, the surface of the substrate 51 is irradiated with a laser beam (pulse laser) 50 in the direction of the arrow in the figure. The laser beam 50 is applied to the entire surface of the substrate 51 or a portion where a conductive metal film (conductive wiring) is formed in a conductive metal film formation process described later, and laser ablation of resin on the surface of the substrate 51 and inorganic The formation of a molten aggregate of particles is performed at the same time to form a surface modified film 52. When the entire surface of the base material 51 is irradiated with a pulse laser, conductive wiring can be formed on the entire surface of the base material 51. When selectively irradiating a part of the surface of the substrate 51 with a pulse laser, conductive wiring is formed in the part irradiated with the pulse laser. As the conditions for the pulse laser, an optimum condition for simultaneously removing the ablation of the thermosetting resin and melting and aggregating the inorganic particles is selected. Specifically, the laser conditions include laser wavelength, frequency, beam diameter, power (or energy), scanning speed, laser beam focal position, irradiation atmosphere, and the like. The irradiation atmosphere may be an atmosphere in which the ablation removal of the thermosetting resin and the melt-aggregation of the inorganic additive particles can be performed, and may be an inert atmosphere or the air.

  For example, when a thermosetting resin substrate containing ferrite is used as the substrate 51, laser wavelength: 400 to 600 nm, frequency: 10 to 50 kHz, beam diameter: 10 to 50 μm, laser power: 1 to 6 W, scanning speed: 50 to 1000 mm / s, laser beam focal position (defocus): None, and the irradiation atmosphere is preferably in the air.

(C) Via hole formation process When forming a laminated body (multilayer conductive wiring) as shown in FIGS. 2A and 2B, it is necessary to form via holes 23 for electrically connecting the upper and lower wirings. For the opening of the via hole, the laser device (pulse laser oscillation device) used in the surface modified film forming step (b) described above and the conductive metal film forming step (f) described later can be shared. The laser irradiation conditions for forming the via holes are the same as the conditions (ablation conditions) in the above-described (b) surface modified film forming step. The pulse laser 50 is scanned in the direction of the arrow in the figure to form a via hole 54 in the substrate 51.

(D) Conductive paste coating film forming step Next, a conductive paste containing metal particles as a raw material for the conductive metal film is printed on a portion (surface modified film 52) irradiated with a pulse laser using a coating apparatus 58. Then, the coating film 55 is formed. In the conductive paste containing metal particles, for example, highly conductive metal microparticles such as copper having an average particle diameter of 1 to 3 μm are uniformly dispersed in a viscous material in which an organic solvent, a binder, a viscosity modifier and the like are mixed. Things can be used.

  As a method for printing the conductive paste, pattern printing such as screen mask printing and dispenser printing can be used. Alternatively, the entire surface printing using a squeegee may be performed, and the conductive paste in a portion other than the portion irradiated with the pulse laser may be removed with a solvent after the conductive metal film forming step described later.

  The viscosity of the conductive paste is preferably 2500 to 3500 mPa · s. When the viscosity is less than 2500 mPa · s, the content of the metal particles is reduced and the solvent component is increased, so that the drying time in the drying step described later is increased. On the other hand, if it exceeds 3500 mPa · s, the viscosity becomes too high, and the printability deteriorates. More specifically, it is difficult for the conductive paste to penetrate into the voids of the surface modified film 2, and voids are likely to appear in the metal film after the paste is sintered.

  The film thickness of the coating film 55 (printing thickness of the conductive paste) is applied to be thicker than the final required film thickness obtained in the conductive metal film forming step described later. Depending on the volume ratio of the metal particles in the conductive paste, when the volume ratio is 30%, a thickness of about three times the thickness of the target sintered film is applied.

  As the coating device 56, a high-speed jet dispenser (Musashi Engineering Co., Ltd., model: MEET-H) can be used. This dispenser has a nozzle that can discharge the space at high speed, and can also be used to print the molten aggregates and voids of the inorganic particles constituting the surface modified film 52 and to fill the via holes 54 with conductive paste. It is. The difference between the surface modified layer and the surface modified groove can be distinguished by the depth of the surface modified layer. For example, when the thickness of the conductive wiring layer made of a copper microparticle sintered film is set to about 7 μm, a groove-shaped pattern having a depth of about 21 μm, which is three times that, is formed completely from the surface of the molded product. A buried conductive wiring layer can be formed. When it is desired to make the conductive wiring layer higher than the surface of the molded product, the groove depth of the surface modification layer is processed to be shallow.

  The line width of the coating film 55 of the conductive paste is set to a value that satisfies the required performance of the target electronic component. For example, in the case of a power inductor or the like, it is about 0.5 to 1.0 mm. In addition, since a high-frequency signal transmission noise filter of a portable electronic device needs to be reduced in size and weight, the line width is set to 0.1 to 0.2 mm.

(E) Coating film drying step After printing the conductive paste, heat drying is performed for the purpose of removing excess organic solvent contained in the printed conductive paste. The drying temperature and time are preferably set to a temperature of 100 to 120 ° C. and a time of 1 to 15 minutes in order to suppress oxidation of metal particles during drying in the air. If the drying process is performed under a weak reduced pressure of about 1/2 of atmospheric pressure (0.05 MPa), the time can be shortened. Further, when drying is performed in an atmosphere of an inert gas such as a nitrogen stream where metal particles do not oxidize, the drying temperature can be raised to the heat resistance temperature (about 230 ° C.) of the base material 51 mainly composed of a thermosetting resin. Yes, the drying time can be shortened within 1 minute.

(F) Conductive metal film forming process (conductive paste sintering process)
Next, the surface of the coating film 56 that has been subjected to the drying treatment is irradiated with a pulse laser 50 to sinter the metal particles contained in the conductive paste, thereby forming the conductive metal film 53. The pulse laser used here may be the pulse laser device used in the above-described base surface modification film forming step (b) and via hole forming step (c). Laser irradiation conditions for sintering the metal particles contained in the dried coating film 56 include frequency, beam diameter, power (or energy), scanning speed, laser beam focal position, and the like, and thermosetting resin containing inorganic particles. Adhesiveness of the conductive film is obtained, and the value is set so that the conductive metal particles are sintered.

  For example, when a thermosetting resin substrate containing ferrite is used as the base material 51 and copper microparticles are used as the conductive metal, the laser wavelength is 400 to 600 nm, the frequency is 10 to 50 kHz, the beam diameter is 10 to 300 μm, Laser power (or energy): 1 to 6 W, scanning speed: 0.5 to 200 mm / s, laser beam focal position: 0 to 8 mm (defocus) in the downward direction of the substrate are preferable. The irradiation atmosphere may be an air or an inert gas atmosphere.

  FIG. 6 is a schematic diagram showing an example of a production system for a metal film-formed product of the present invention. FIG. 6 shows a configuration in which the steps (a) to (f) are made into one line. As shown in FIG. 6, when the laser beam irradiation device is shared by three devices of the via hole forming device, the surface modified film forming device, and the conductive metal film forming device, the laser beam irradiation device 62 is fixed and arranged at the center. By doing so, all the steps (a) to (f) can be roughly divided into three configurations. The base material set chamber 61 can be shared for carrying in the base material and carrying out the metal film-formed product. By performing the conductive paste applying device and the conductive paste drying device on the hot plate 63 set at a temperature, it becomes possible to perform two steps in one stage, and the molded product can be easily transported.

  FIG. 7 is a schematic view showing a second example of the production process of the metal film-formed product of the present invention. FIG. 7 is a process diagram in the case of manufacturing a conductive wiring board or an electronic component having a multilayer wiring. A thermosetting adhesive film 77 is affixed to the surface of the base material 71a (the back surface, that is, the surface opposite to the surface on which the conductive metal film is provided). For the thermosetting adhesive film 77, for example, a thermosetting adhesive film for bonding a wiring board laminated by Yodogawa Paper Co., Ltd. can be used. This adhesive film is a B-stage epoxy resin, and can be laminated and bonded to each other by heating and curing at 160 ° C. for about 1 h. In addition, since it is once liquefied before heat curing, it is excellent in wettability and filling property between the wiring boards and can be applied with a low pressure, and voids between the base materials 71a and 71b (between the wiring boards) Does not occur. After applying the adhesive film 70, the conductive paste is printed to form the coating film 75 (step (7d)), dried (not shown), and irradiated with laser light to form the conductive metal film 73. (Step (7f)), the base materials 71a and 71b can be electrically connected through the via holes 74.

  FIG. 8 is a schematic view showing a third example of the production process of the metal film-formed product of the present invention. As shown in FIG. 8, when the substrate 81b is a double-sided wiring board, three layers of wiring can be formed.

  The present invention has the following many effects.

(1) Making One Line of Conductive Wiring Formation Process As shown in FIG. 6, the process can be made one line as compared with the conventional method (thick film conductive paste method or photolithography method). Specifically, (i) surface modification film formation (laser ablation of resin and melt aggregate formation of inorganic particles), (ii) in the formation of a conductive circuit by laser irradiation to a thermosetting resin molded product containing inorganic particles, Four processes of copper conductive paste application, (iii) conductive paste drying (solvent removal), and (iv) conductive metal film formation (laser sintering) can be made into one line. The conventional conductive paste thermosetting method requires a thermosetting treatment in a heating furnace for 30 to 60 minutes, and the entire process stagnates in this step, so one line cannot be formed. Here, the line formation means that the substrate moves on the conveyance path, and apparatuses used for each process are connected and arranged on the conveyance path, so that the product is completed without the substrate stagnating. In the present invention, since the processing times (i) to (iv) are completed within 15 minutes, one line is possible.

(2) Reduction of manufacturing time Since each process is completed in a short time as described above, the time to complete the entire process can be reduced.

(3) Low cost No expensive manufacturing equipment costs are required, the manufacturing time can be shortened, and a metal film-formed product can be manufactured at low cost.

(4) Sharing of laser beam irradiation device Normally, via hole formation processing of a multilayer wiring board uses a carbon dioxide laser or a YAG laser, but in the present invention, it can be shared with a surface modification laser and a conductive paste sintering laser. . Therefore, it is possible to construct a manufacturing facility that can share one laser beam irradiation apparatus in three processes.

(5) Environmental response Since the generation of carbon dioxide can be suppressed to the utmost limit, global warming can be suppressed and it can contribute to global environmental conservation.

  For example, Japanese Patent Application Laid-Open No. 5-283235, Japanese Patent Application Laid-Open No. 5-304019, and Japanese Patent Application Laid-Open No. 6-84648 are disclosed as techniques relating to inductor manufacturing. This is different from the present invention in which a conductive metal film is formed by bonding.

There are also the following references on laser ablation:
Okada, Sugioka Current status and future development of laser ablation applications Plasma Fusion Res. Vol. 79, no. 12 (2003) 1278-1286
According to this technical document, the current main application fields of laser ablation are as follows.

(A) Functional thin film formation on a substrate Thin film production by laser ablation is generally called Pulsed-Laser Deposition (PLD). Ablation is performed by irradiating a target with a pulsed laser and facing the ablation particles. This is a method of forming a film on a substrate. This method is applied to formation of a DLC (Diamond Like Carbon) wear-resistant film on a metal workpiece using a super hard material.

(B) Creation of nanostructures As this application is known to produce carbon nanofibers by laser ablation to graphite, some of the emissions directly emitted from the target by ablation include atoms and molecules. There are also various sizes of clusters and nanoparticles, and by collecting them, nanostructures can be created.

(C) Material processing In laser ablation, high energy neutral particles, radicals, and ions are emitted from solid materials to form plasma, and the solid surface is etched by the emitted plasma. Heating and evaporation of materials with infrared lasers are also broadly defined by laser ablation, and drilling and cutting of metal (steel) plates using a high-power carbon dioxide laser (wavelength 10.6 μm) are the most popular materials One of the applications of processing. On the other hand, in the electronics field, punching of printed circuit boards for mobile phones has become a large market. In addition, laser ablation is widely used for marking of Si wafers and IC packages, correction of photomasks and IC circuits, resistance trimming of hybrid ICs, and drilling of inkjet printer nozzles.

Many of the above use infrared Nd: YAG lasers (wavelength 1.06 μm). When trying to process a material more precisely and finely, it is necessary to minimize the thermal influence around the processed part. For this purpose, it is desirable to use a laser having a short wavelength and a short pulse width. As the wavelength becomes shorter, the absorption coefficient for the material increases, and the energy can be efficiently injected into the processing region. On the other hand, when the absorption coefficient is small, the laser light penetrates deep inside the material and the energy is absorbed even in the unprocessed region, which affects the periphery of the processed part. In addition, since the photon energy increases as the wavelength becomes shorter, the photodissociation phenomenon of atoms and molecules in the solid can be induced, and non-thermal processing can be realized. On the other hand, the thermal diffusion length D when the laser is irradiated can be expressed by the equation D = 2 (k · t) ^1/2 . Therefore, when the pulse width is shortened, D is also shortened, and the thermal influence on the periphery of the processed portion is reduced. Where κ is the thermal diffusion coefficient of the material and t is the pulse width. For these reasons, excimer lasers, which are ultraviolet nanosecond pulse lasers, are mainly used today for fine processing.

The present invention applies laser light to surface modification of an inorganic particle-containing thermosetting resin substrate. When an infrared Nd: YAG laser (wavelength: 1.06 μm) or carbon dioxide laser (wavelength: 10.6 μm) for drilling a material is used as the laser, smear (heat Decomposition residue) and ablation which is complete evaporation scattering cannot be obtained. For complete ablation purposes, a single pulse laser is preferred because of the relationship D = 2 (k · t) ^1/2 . However, in the present invention, the resin of the thermosetting resin substrate containing inorganic particles is ablated and removed, and the inorganic particles are melted to form a three-dimensional aggregate. For such a purpose, the laser beam is preferably a green laser (wavelength 532 nm) pulse laser for laser marking, for example.

  In the above-mentioned document, as in the present invention, a technique is disclosed for simultaneously performing resin ablation removal and inorganic particle three-dimensional melt aggregation of a target inorganic particle-containing resin substrate by one laser irradiation. There is no.

  Hereinafter, based on an Example, this invention is demonstrated more concretely.

  In this example, a ferrite-containing thermosetting epoxy resin molding (thickness: 2 mm, a square shape with a side of 11 mm) was used as a base material, and a power inductor wiring (copper microparticle sintered film) formation experiment was conducted. It was. FIG. 9 is an SEM (Scanning Electron Microscope) observation photograph of the surface of the base material of Example 1. As shown in FIG. 9, the base material has a configuration in which ferrite particles 91 having an average particle diameter of about 5 μm are dispersed in a thermosetting resin 90.

  As the ferrite particles 91, FeSiCr ferrite was used. First, a surface modification film was formed on the entire surface of the molded body. For the formation of the surface modified film, a green laser marker (manufactured by Keyence Corporation, model: MD-S9900A, wavelength: 532 nm, maximum output: 6 W, scanning speed range: 1-1000 m / s, beam spot diameter: 25 μm) is used. It was. The surface-modified film was formed under conditions in which ablation of the epoxy resin and melt aggregation of the ferrite particles occur simultaneously in the atmosphere (output 3.7 W, frequency 30 kHz, scanning speed 800 mm / s, and no defocus).

  FIG. 10 is a SEM observation photograph of the surface modified film of Example 1. As shown in FIG. 10, the epoxy resin is removed by laser ablation to form a gap 102. Further, the ferrite particles are melt-agglomerated to form a melt aggregate 101 having a three-dimensional structure having a diameter of about 10 to 50 μm. The gap 102 has a maximum of about 10 μm, and has a configuration in which it enters the back (in the thickness direction of the base material) from the surface of the surface modification layer.

  FIG. 11 is a reflection and absorption spectrum of the base material of Example 1. As shown in FIG. 11, the absorptance of the green laser marker of the base material at a wavelength of 532 nm is 85%, and the base material has a high absorption rate. FIG. 12 is a graph showing the results of EDX (Energy Dispersive X-ray Spectroscopy) analysis of the surface of the surface modified film of Example 1. An SEM apparatus (manufactured by Hitachi High-Technologies Corporation, model: S-4300) was used for EDX analysis. In addition, Table 1 below shows the composition of elements obtained from the graph of FIG.

  From the results of FIG. 12 and Table 1, after the surface modification film is formed, C due to the epoxy resin decreases and Fe, Cr, Si components, which are ferrite components, increase, and epoxy resin ablation and ferrite melting It can be seen that the aggregation is performed effectively.

  After the surface modified film was formed, a copper microparticle paste having the composition shown in Table 2 below was printed on the entire surface of the substrate by the squeegee method. The paste had a viscosity of 3000 mPa · s. The thickness of the coating film was 50 μm. HXR-Cu (average particle diameter: 1 μm) manufactured by Nippon Atomizing Co., Ltd. was used for the copper microparticles. FIG. 13 is a SEM observation photograph of copper microparticles in the conductive paste of Example 1.

  After printing the conductive paste, the solvent was dried in air at 110 ° C. for 15 minutes. FIG. 14 is a cross-sectional SEM observation photograph of the substrate after drying of the coating film of Example 1. As shown in FIG. 14, it can be seen that the copper microparticle coating film 146 is formed by deep penetration of the copper microparticles into the voids of the melt aggregate 141 ′ in which the ferrite particles are melted and aggregated.

  FIG. 15 shows reflection, absorption, and transmission spectra after drying the coating film in Example 1. As shown in FIG. 13, the coating film from which the solvent has been removed by drying has an absorptance of 90% or more at a wavelength of 532 nm, and it is understood that the copper microparticles are effectively sintered by the green laser having this wavelength. .

  Next, the coating film was irradiated with a green laser. Sintering with a green laser was performed in the air under the conditions of an output of 2.7 W, a frequency of 40 kHz, a scanning speed of 1 mm / s, and a defocus amount: 6 mm in the substrate downward direction. A wiring with a line width of about 0.6 mm and a thickness of about 27 μm could be formed by a single laser irradiation at a scanning speed of 1 mm / s. The reason why a wiring having a line width of 0.6 mm with respect to the focal beam diameter of 0.025 mm is obtained by defocusing.

  16 is an optical microscope observation photograph of the upper surface of the base material after the metal film formation step of Example 1 (after copper microparticle sintering), and FIG. 17 is a cross-sectional SEM photograph of FIG. As shown in FIG. 16, the portion not irradiated with the laser becomes an unsintered portion (state after drying the conductive paste) 166, and this portion can be easily removed with a solvent such as ethyl alcohol. The adhesion of the sintered film 163 was affixed with an adhesive tape and peeled off (adhesive strength: 2 N / cm). As a result, no peeling occurred. Moreover, as a result of measuring the specific resistance value of the wiring by the four-terminal method, a value of 15.6 μΩcm was obtained. This value is about 1/2 to 1/3 as compared with a conductive metal paste in which copper or silver particles are mixed with an uncured epoxy resin and cured.

  In this embodiment, the surface modification film is formed not in the entire surface of the substrate but in a line shape (line width: 300 μm, depth: 50 μm), and other conditions are the same as in Example 1. It was. The line width of 300 μm is 100 μm larger than the beam width of 200 μm in laser sintering, and the depth is such that the laser sintered film wiring having a thickness of 27 μm is completely buried. After the laser beam irradiation in the surface modification film forming step was performed with a line width of 300 μm, the conductive paste was filled in the groove with a squeegee, and the green laser was irradiated after the solvent was dried. 18 shows an optical microscope observation photograph of the surface of the base material after the conductive metal film forming step of Example 2. FIG. As shown in FIG. 18, the wiring buried in the groove subjected to the surface modification treatment could be formed.

  In this example, a semiconductor package sealing resin (manufactured by Sumitomo Bakelite Co., Ltd., product name: G600) in which a spherical quartz filler was contained in a black thermosetting epoxy resin was used as the base material. The purpose of the black sealing resin used in the semiconductor package is to suppress charging of the sealing resin and prevent electrostatic breakdown of the semiconductor chip by adding a small amount of carbon powder. The G600 has flame retardancy of V0 level in the US flame retardant standard UL-94 and has a heat resistant temperature up to 260 ° C.

  FIG. 19 is an optical micrograph of the surface of the substrate of Example 3. As shown in FIG. 19, the filler of this sealing resin has a spherical filler distribution with a particle diameter of about 10 to 50 μm.

  FIG. 20 is an optical micrograph after the surface modified film forming step of Example 3. The surface modification treatment step was performed with a green laser under conditions of an output of 0.9 W, a frequency of 20 kHz, a scanning speed of 100 mm / s, and no defocus. As shown in FIG. 20, the fine particles of the filler disappear and become a molten aggregate of coarse particles of about 50 μm. When a copper microparticle paste is applied to the surface modified film to a thickness of 50 μm using a squeegee and irradiated with a green laser, a metal film having excellent adhesion and conductivity can be formed on the substrate. did it. From the result of the present Example, it was demonstrated that not only the ferrite-containing thermosetting epoxy resin molding but also a thermosetting epoxy resin containing a spherical quartz filler can be used as a substrate.

  As described above, according to the present invention, a metal film-formed product having a conductive metal film excellent in adhesion and conductivity, an electronic component using the same, and a method for producing a metal film-formed product are provided. It was shown that

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  1, 21, 31, 41, 51, 71a, 71b, 81, 81b ... base material, 2, 52, 72, 82, ... surface modified film, 3, 23, 33, 43, 53, 73, 83, 163 , 173, 183 ... conductive metal film, 10, 30, 40 ... metal film-formed product, 20 ... laminate of metal film-formed product, 24, 54, 74, 84 ... via hole, 25 ... external electrode, 27 ... housing Body, 28 ... solder, 200 ... electronic component (inductor), 30 ... antenna, 40 ... connector, 43 ... male terminal insertion hole, 50,70,80 antenna, 55,75,85 ... conductive paste coating film, 56 ... Conductive paste coating device, 56, 146, 166, 186 ... dried film of coating film, 58 ... coating device, 61 ... substrate set chamber, 62 ... laser light irradiation device, 63 ... hot plate, 77, 87 ... bonding Film, 90,1 0, 170 ... resin, 91,141, ... inorganic particles, 101,141', melting aggregates 171' ... inorganic particles, 102 ... gap,

Claims (10)

A substrate containing a resin and inorganic particles dispersed in the resin;
A surface modification film formed on the surface of the substrate;
A conductive metal film formed on the surface of the surface modification film and made of a conductive metal;
The surface-modified film has a structure in which the inorganic particles contained in the base material constitute a melt aggregate while containing voids.   The average particle size of the inorganic particles contained in the base material is 0.5 to 30 μm, and the average particle size of the inorganic particles constituting the melt aggregate of the surface modified film is 10 to 50 μm. The metal film-formed product according to claim 1, wherein   The metal film-formed product according to claim 1 or 2, wherein the resin is a thermosetting epoxy resin, and the inorganic particles are metal, metal oxide, quartz, or a mixture thereof.   The metal film-formed product according to any one of claims 1 to 3, wherein the metal film-formed product is a component constituting an electronic device.   The metal film-formed product according to claim 4, wherein the component is an inductor, an antenna, or a connector. The surface of the base material containing a resin and inorganic particles dispersed in the resin is irradiated with laser light, and the surface modification has a structure in which the inorganic particles contained in the base material constitute a melt aggregate while containing voids. Forming a membrane;
Applying a conductive paste containing a conductive metal to the surface of the surface modification film, and forming a coating film;
Drying the coating film;
Irradiating the dried coating film with a laser beam, and sintering the conductive metal contained in the dried coating film to form a metal film. .   The base material is obtained by mixing the resin, the inorganic particles, and a curing agent before the step of forming the surface modification film, placing the base material in a mold, and thermosetting the resin. The method for producing a metal film-formed product according to claim 6, wherein the product is a processed product.   8. The metal film-formed product according to claim 6 or 7, wherein the step of forming the surface-modified film is performed by selecting an entire surface of the base material or a portion on which the metal film is to be formed. Method. Preparing the base material provided with an adhesive film on the surface and the metal film-formed product, and joining the base material and the metal film-formed product with the adhesive film to produce a laminate;
Forming the surface modification film on the surface of the substrate opposite to the surface on which the adhesive film is provided;
Forming a via hole in a part of the surface modification film;
Applying a conductive paste to the via hole and the surface modification film to form a coating film;
Drying the coating film;
And a step of irradiating the dried coating film with laser light to sinter the conductive metal contained in the dried coating film to form a metal film. 2. A method for producing a metal film-formed product according to claim 1.   The method for producing a metal film-formed product according to any one of claims 6 to 9, wherein the laser beam in the step of forming the metal film is a pulsed laser beam having a wavelength of 532 nm.

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