JP5263035B2 - Resin surface processing method and composite member, housing, and electronic device manufacturing method - Google Patents

Description

  The present invention relates to a processing method for roughening a resin surface, and a method for manufacturing a composite member, a casing, and an electronic device using this method.

  From the aesthetic point of view or in order to impart properties such as conductivity, a method of metal plating the resin surface is used. When the adhesion between the resin surface and the metal plating film is weak, the metal plating film is easily peeled off from the resin surface. It is known that when the resin surface is roughened, the adhesion of the metal plating film is improved by a so-called anchor effect.

  When the inorganic filler is contained in the resin member, fine irregularities can be formed by etching or detaching the inorganic filler exposed on the resin surface. Further, when the resin surface is an acrylonitrile-butadiene-styrene copolymer resin, when the resin surface is treated with a chromate-sulfuric acid mixed solution, the butadiene component is oxidatively decomposed and detached from the resin member. Thereby, irregularities can be formed on the resin surface.

  In recent years, printed wiring boards containing carbon fiber cloth have attracted attention. A printed wiring board containing a carbon fiber cloth has a lower coefficient of thermal expansion and a higher elastic modulus than a glass epoxy board. When a through hole is formed in a carbon fiber-containing printed wiring board, conductive carbon fiber is exposed on the side surface. In order to ensure insulation between the conductive member in the through hole and the carbon fiber, it is desirable to form an insulating resin film on the surface of the substrate and the side surface of the through hole.

JP 2007-103605 A JP 2008-41720 A

  In the method of roughening the resin surface by etching the inorganic filler, the resin surface not containing the inorganic filler cannot be roughened. In the method in which the butadiene component of the resin is oxidatively decomposed and desorbed from the resin member, the resin surface not containing the butadiene component cannot be roughened. Regardless of the type of resin, a method for roughening various resin surfaces is desired.

According to one aspect of the invention,
Forming a liquid film of monosubstituted trialkoxysilane or disubstituted dialkoxysilane by covering the resin surface of the exposed member with monosubstituted trialkoxysilane or disubstituted dialkoxysilane;
Forming a plurality of polysiloxane films interspersed on the resin surface by polymerizing the monosubstituted trialkoxysilane or disubstituted dialkoxysilane of the liquid film;
There is provided a method for processing a resin surface, which includes a step of roughening the resin surface by etching the resin surface using the polysiloxane film as an etching mask.

According to another aspect of the invention,
Forming a liquid film of monosubstituted trialkoxysilane or disubstituted dialkoxysilane by covering the resin surface of the exposed member with monosubstituted trialkoxysilane or disubstituted dialkoxysilane;
Forming a plurality of polysiloxane films interspersed on the resin surface by polymerizing the monosubstituted trialkoxysilane or disubstituted dialkoxysilane of the liquid film;
Roughening the resin surface by etching the resin surface using the polysiloxane film as an etching mask;
There is provided a method for producing a composite member including a step of forming a metal film by plating a metal on the roughened resin surface.

  Even when the resin surface does not contain an inorganic filler or when the resin surface does not contain a butadiene component, the resin surface can be roughened. By performing metal plating on the roughened resin surface, the adhesion strength of the plating film can be increased.

FIGS. 1A to 1D are cross-sectional views of a substrate in the middle of manufacturing for explaining a method for processing a resin surface according to Example 1. FIGS. (1E) to (1H) are cross-sectional views of the substrate in the course of manufacturing for explaining the resin surface processing method according to the first embodiment. (1I) to (1K) are cross-sectional views of the substrate in the course of production for explaining the resin surface processing method according to Example 1, and (1L) is the resin surface processing method according to Example 1. It is sectional drawing of the board | substrate which carried out. It is a graph which shows the measurement result of the surface roughness of the copper film on a resin substrate. (3A)-(3C) are sectional views of the substrate in the middle of the method for manufacturing a printed wiring board according to the second embodiment. (3D)-(3F) are sectional views of the substrate in the middle of the method for manufacturing a printed wiring board according to the second embodiment. (3G) is a cross-sectional view of the substrate in the middle of the method for manufacturing a printed wiring board according to Example 2, and (3H) is a cross-sectional view of the printed wiring board manufactured by the method for manufacturing a printed wiring board according to Example 2. It is.

  Hereinafter, embodiments will be described with reference to the drawings.

  With reference to FIG. 1A-FIG. 1L, the manufacturing method of the composite member by Example 1 is demonstrated.

  A resin substrate 10 shown in FIG. 1A is prepared. For example, the thickness of the resin substrate 10 is 3 mm, and the planar shape is a square having a side length of 50 mm. For the resin substrate 10, for example, a phenol novolac resin is used. The resin substrate 10 is placed on a spin coater, and several drops of methyltrimethoxysilane are dropped on the resin surface with a dropper. After rotation at a rotation speed of 100 rpm for 5 seconds, rotation is performed at a rotation speed of 500 rpm for 30 seconds. Thereby, the liquid film 11 is formed on the surface of the resin substrate 10.

  Instead of methyltrimethoxysilane, monosubstituted trialkoxysilane may be used, or disubstituted dialkoxysilane may be used. Examples of monosubstituted trialkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, aminomethyltrimethoxysilane, and the like. These monosubstituted trialkoxysilanes are liquids having a viscosity of 10 mPa · s or less at room temperature. This viscosity is equal to or less than that of water or ethanol. For this reason, even when the fine uneven | corrugated pattern is formed in the surface of the resin substrate 10, generation | occurrence | production of application | coating leakage etc. can be suppressed.

  Instead of using a spin coater, the liquid film 11 may be formed by immersing the resin substrate 10 in a monosubstituted trialkoxysilane filled in a container.

As shown in FIG. 1B, the liquid film 11 is irradiated with ultraviolet rays 12. As an ultraviolet light source, for example, a low-pressure mercury lamp can be used. The exposure amount is, for example, 9.0 J / cm ² . The ultraviolet rays to be used may be those containing a wavelength component having a wavelength of 300 nm or less. The exposure amount is preferably 1 J / cm ² or more.

  FIG. 1C shows a state after ultraviolet irradiation. By irradiation with ultraviolet rays, methyltrimethoxysilane in the liquid film 11 is polymerized to form polysiloxane. When the average film thickness of the polysiloxane is 0.5 μm or less, the molecules of methyltrimethoxysilane are aggregated at the time of polymerization, thereby forming a plurality of polysiloxane films 15 scattered in an island shape on the surface of the resin substrate 10. The In the region where the polysiloxane film 15 is not formed, the resin substrate 10 is exposed.

  As shown in FIG. 1D, the liquid film 17 is formed by re-applying methyltrimethoxysilane on the surface of the resin substrate 10 on which the polysiloxane film 15 is scattered. The formation method of the liquid film 17 is the same as the formation method of the liquid film 11 shown in FIG. 1A.

  As shown in FIG. 1E, the liquid film 17 is irradiated with ultraviolet rays 20. The irradiation conditions are the same as the irradiation conditions of the ultraviolet rays 12 shown in FIG. 1B.

  As shown in FIG. 1F, methyltrimethoxysilane in the liquid film 17 is polymerized to form polysiloxane. Thereby, the distribution density of the polysiloxane film 15 is increased.

  The application of methyltrimethoxysilane and UV irradiation are repeated three times alternately. That is, the application of methyltrimethoxysilane and the ultraviolet irradiation are repeated five times.

  As shown in FIG. 1G, the distribution density of the polysiloxane film 15 is further increased. If the liquid film of methyltrimethoxysilane is too thick, the polysiloxane film is not scattered and covers almost the entire surface of the resin substrate 10. By sufficiently thinning the liquid film formed by one application of methyltrimethoxysilane, the polysiloxane film 15 can be scattered on the surface of the resin substrate 10. The liquid film formed by one-time application of methyltrimethoxysilane is preferably thin to the extent that a polysiloxane film covering the entire surface of the resin substrate 10 is not formed after polymerization. For example, the average thickness of the polysiloxane film formed by one-time application of methyltrimethoxysilane and ultraviolet irradiation is preferably 0.5 μm or less, and more preferably 0.2 μm or less. Here, the “average thickness” means a thickness when it is assumed that the entire surface of the substrate is covered with a uniform thickness of polysiloxane corresponding to the total volume of the polysiloxane film 15.

  The average thickness of the polysiloxane film depends on the thickness of the liquid film formed by one application. The thickness of the liquid film can be adjusted by changing spin coating conditions and immersion conditions.

As shown in FIG. 1H, the surface layer portion of the resin substrate 10 is etched by exposing the surface of the resin substrate 10 on which the polysiloxane film 15 is distributed to Ar plasma 22. At this time, the polysiloxane film 15 acts as an etching mask. Etching with Ar plasma is performed using, for example, a parallel plate type plasma etching apparatus under conditions of high frequency power for plasma generation of 300 mW / cm ² , pressure of 133 Pa (1 Torr), Ar gas flow rate of 100 sccm, and etching time of 5 minutes to 30 minutes. Under this condition, the etching rate of the resin substrate is 0.05 μm / min to 0.15 μm / min.

  Gas plasma other than Ar plasma may be used. For example, oxygen plasma, nitrogen plasma, or the like may be used.

  FIG. 1I shows a cross-sectional view of the resin substrate 10 after etching. The surface layer portion of the resin substrate 10 in a region not covered with the polysiloxane film 15 is etched to form a recess 23. Thereby, the surface of the resin substrate 10 is roughened. The polysiloxane film 15 is also etched and thinned, but is not completely removed.

  As shown in FIG. 1J, the polysiloxane film 15 (FIG. 1I) remaining on the surface of the resin substrate 10 is removed. The removal of the polysiloxane film 15 can be performed, for example, by attaching and then peeling off an adhesive tape. In addition, it is also possible to remove the polysiloxane film 15 by chemical etching. When the polysiloxane film 15 is completely removed by the etching process shown in FIGS. 1H and 1I, it is not necessary to remove the polysiloxane film 15 with an adhesive tape or the like.

  As shown in FIG. 1K, a copper base film 25 is formed on the surface of the resin substrate 10 by electroless plating of copper. The thickness of the base film 25 is, for example, 0.2 μm to 0.5 μm.

  As shown in FIG. 1L, a copper film 26 is formed on the base film 25 by electroplating copper. The thickness of the copper film 26 is, for example, 30 μm. As shown in FIG. 1J, since the surface layer portion of the resin substrate 10 is roughened, the adhesion strength between the base film 25 and the copper film 26 can be increased by a so-called anchor effect.

In FIG. 2, the measurement result of the flatness of the surface before and after roughening the surface of the resin substrate 10 is shown. The flatness was measured with a stylus thickness meter. The horizontal axis in FIG. 2 corresponds to the position within the surface, and the vertical axis corresponds to the height of the surface. A solid line S ₀ indicates a measurement result of the surface flatness of the resin substrate 10 before roughening (before forming the liquid film 11 in FIG. 1A). A solid line S ₁ shows the measurement result of the surface flatness of the resin substrate 10 (corresponding to FIG. 1J) after the surface is roughened by the method of the above embodiment and the polysiloxane film 15 is removed. For reference, the measurement results of the surface flatness of the resin substrate 10 after exposure to Ar plasma without forming a polysiloxane film 15, indicated by a solid line S _2. The Ar plasma treatment time for the samples of the solid lines S ₁ and S ₂ was 5 minutes.

When the solid lines S ₀ and S ₁ are compared, it can be seen that the surface is roughened by etching the surface layer portion of the resin substrate 10 using the polysiloxane film 15 as an etching mask. The height difference between the peaks and valleys on the surface of the resin substrate 10 after etching was about 1 μm.

Surface roughness indicated by the solid line S ₁ is found to be rougher than the surface roughness indicated by the solid line S _2. In other words, it was confirmed that the surface after etching can be made rougher by allowing the polysiloxane film 15 to be scattered on the surface of the resin substrate 10 before etching with Ar plasma.

  The adhesion strength of the copper film 26 produced by the method according to the above example was measured. Hereinafter, the measurement method (JIS C6481) will be briefly described. First, the copper film 26 is patterned into a strip shape having a width of 10 mm. One end of the strip-shaped copper film 26 is peeled off, and the tip of the peeled portion is grasped with a gripping tool. The copper foil 26 is pulled so that the pulling direction is perpendicular to the surface of the resin substrate 10, and the copper film 26 is peeled off at a speed of 50 mm per minute. The minimum value of the tensile force during the peeling period is defined as the peeling strength.

  The peel strength of the copper film 26 produced by the method according to the example was about 60 gw / cm. The peel strength of the copper film formed on the resin substrate 10 whose surface is not etched is 0 gw / cm, and the copper film on the resin substrate 10 on which Ar plasma treatment has been performed without masking with the polysiloxane film 15 is performed. The peel strength was 40 gw / cm. From this result, it is understood that the adhesion strength of the copper film 26 is increased by performing the roughening by the method according to the embodiment.

  In the above embodiment, the roughened resin substrate 10 is electrolessly plated with copper and further electroplated with copper. However, when other metals are plated, the adhesion strength can be improved by the anchor effect. it can.

  In addition, a resin having an etching characteristic that has an etching rate faster than that of polysiloxane can be used for the resin substrate 10 under the processing conditions applied in the plasma processing shown in FIG. 1H. For example, an epoxy resin, a polyimide resin, a bismaleimide triazine resin, or the like can be used for the resin substrate 10 in addition to the phenol resin.

  In the state shown in FIG. 1G, if the average thickness of the polysiloxane film 15 is too thin, the ratio of the region where the substrate is exposed is too high, and sufficient roughening cannot be performed. When the average thickness of the polysiloxane film 15 is 0.3 μm, almost half of the substrate surface can be covered with the polysiloxane film 15. In order to sufficiently roughen the surface, it is preferable that the average thickness of the polysiloxane film 15 is 0.3 μm or more.

  Further, in order to obtain a sufficient anchor effect, the surface roughness of the resin substrate 10 is preferably 0.15 μm or more, expressed by Ra defined in JIS B0601-1994.

  In the first embodiment, metal plating is performed on the resin substrate. However, it is also possible to perform metal plating on other resin members, for example, housings having various shapes.

  With reference to FIGS. 3A to 3H, a method of manufacturing a composite substrate according to the second embodiment will be described.

  As shown in FIG. 3A, a through hole 53 is formed in the printed wiring board 50. For the printed wiring board 50, for example, a composite board in which a cloth 51 made of carbon fiber is impregnated with an epoxy resin is used. The thickness of the printed wiring board 50 is, for example, 300 μm to 1 cm, and the diameter of the through hole 53 is, for example, 50 μm to 500 μm. The carbon fiber cloth 51 is exposed on the side surface of the through hole 53.

  As shown in FIG. 3B, an insulating resin layer 55 is formed on the surface of the printed wiring board 50 and the side surface of the through hole 53. For the resin layer 55, phenol resin, epoxy resin, polyimide resin, bismaleimide triazine resin, or the like is used.

  As shown in FIG. 3C, the surface of the resin layer 55 is roughened. The steps from FIG. 1A to FIG. 1J of Example 1 are applied to the roughening treatment.

  As shown in FIG. 3D, a copper film 56 is formed on the surface of the roughened resin layer 55 by electrolessly plating copper and further electroplating copper.

  As shown in FIG. 3E, a conductive member 58 is filled in the through hole 53. The conductive member 58 is formed by, for example, filling a through paste 53 with a conductive paste and then curing it.

  As shown in FIG. 3F, resist patterns 60 corresponding to the wiring pattern to be formed are formed on both surfaces of the printed wiring board 50.

  As shown in FIG. 3G, the copper wiring 56A is left by etching the copper film 56 (FIG. 3F) using the resist pattern 60 as an etching mask.

  As shown in FIG. 3H, the resist pattern 60 (FIG. 3G) is removed. The copper wiring 56 </ b> A remains on both sides of the printed wiring board 50. The conductive member 58 remains in the through hole 53.

  Since the surface of the resin layer 55 is roughened, the adhesion strength of the copper wiring 56A can be increased. Further, since the side surface of the through hole 53 is covered with the insulating resin layer 55, the copper wiring 56A and the conductive member 58 in the through hole 53 do not contact the cloth 51 made of carbon fiber. For this reason, the occurrence of an unexpected short circuit failure can be suppressed.

  In the plasma processing step when the surface of the resin layer 55 is roughened, the surface of the resin layer 55 in the through hole 53 is less exposed to plasma than the resin layer 55 on the flat surface. For this reason, sufficient roughening may not be performed. However, since the conductive member 58 is filled in the through hole 53, the copper wiring 56A covering the side surface of the through hole 53 is hardly peeled off. For this reason, even if the surface roughness of the side surface of the through hole 53 is lower than the surface roughness of the flat surface, the problem of peeling hardly occurs.

  This printed wiring board is applied to various electronic devices.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Resin board | substrate 11 Liquid film 12 Ultraviolet ray 15 Polysiloxane film 17 Liquid film 20 Ultraviolet ray 22 Ar plasma 23 Recess 25 Underlayer 26 Copper film 50 Printed wiring board 51 Carbon fiber cloth 53 Through hole 55 Resin layer 56 Copper film 56A Copper wiring 58 conductive member 60 resist pattern

Claims (7)

Forming a liquid film of monosubstituted trialkoxysilane or disubstituted dialkoxysilane by covering the resin surface of the exposed member with monosubstituted trialkoxysilane or disubstituted dialkoxysilane;
Forming a plurality of polysiloxane films interspersed on the resin surface by polymerizing the monosubstituted trialkoxysilane or disubstituted dialkoxysilane of the liquid film;
And a step of roughening the resin surface by etching the resin surface using the polysiloxane film as an etching mask.   The method for processing a resin surface according to claim 1, wherein, in the roughening step, the resin surface is etched by exposing the resin surface and the polysiloxane film to plasma. Forming a liquid film of monosubstituted trialkoxysilane or disubstituted dialkoxysilane by covering the resin surface of the exposed member with monosubstituted trialkoxysilane or disubstituted dialkoxysilane;
Forming a plurality of polysiloxane films interspersed on the resin surface by polymerizing the monosubstituted trialkoxysilane or disubstituted dialkoxysilane of the liquid film;
Roughening the resin surface by etching the resin surface using the polysiloxane film as an etching mask;
And forming a metal film by plating a metal on the roughened resin surface.   The method for producing a composite member according to claim 3, wherein after the surface of the resin is roughened and before the metal film is formed, the polysiloxane film is removed. The member where the resin is exposed is a resin substrate in which a carbon fiber is contained therein and a through hole penetrating from one surface to the other surface is formed;
The method of manufacturing a composite member according to claim 3 or 4, wherein the liquid film is formed on a surface of the resin substrate and on a side surface of the through hole. Forming a liquid film of monosubstituted trialkoxysilane or disubstituted dialkoxysilane by covering the resin surface of the exposed member with monosubstituted trialkoxysilane or disubstituted dialkoxysilane;
Forming a plurality of polysiloxane films interspersed on the resin surface by polymerizing the monosubstituted trialkoxysilane or disubstituted dialkoxysilane of the liquid film;
Roughening the resin surface by etching the resin surface using the polysiloxane film as an etching mask;
Forming a metal film by plating a metal on the roughened resin surface. Forming a liquid film of monosubstituted trialkoxysilane or disubstituted dialkoxysilane by covering the resin surface of the exposed member with monosubstituted trialkoxysilane or disubstituted dialkoxysilane;
Forming a plurality of polysiloxane films interspersed on the resin surface by polymerizing the monosubstituted trialkoxysilane or disubstituted dialkoxysilane of the liquid film;
Roughening the resin surface by etching the resin surface using the polysiloxane film as an etching mask;
Forming a metal film by plating a metal on the roughened resin surface.

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