JP4452878B2 - Method for forming a thin film circuit - Google Patents

Description

  The present invention can be applied to electronic devices such as personal computers and related devices, audio and video devices, inkjet printers, mobile phones, household electrical products, industrial pots, control devices for automatic production lines, various measuring devices, etc. The present invention relates to a method for forming a thin film circuit suitable for a printed wiring board to be used.

  Conventionally, a typical three-layer copper-clad laminate as a flexible printed wiring board is generally manufactured according to the procedure shown in FIGS. That is, (A) a copper foil 13 whose surface to be coated 13a is chemically or physically roughened in advance is attached to the surface of the polyimide film 11 on which the adhesive 12 is applied, and laminated and integrated. A photoresist 14 is applied to the surface of the laminated body 10 on the copper foil 13 side, (C) the photoresist 14 is exposed through a circuit pattern mask 15, and (D) an uncured resist in an unexposed portion by development. (E) The exposed portion of the copper foil 13 is removed by etching, and (F) the copper layer 13b constituting the circuit is exposed by removing the cured resist. In recent years, instead of using the mask 15 in the exposure step (C), laser exposure is also performed in which laser light is irradiated along a circuit pattern.

  However, in the above-mentioned conventional flexible printed wiring board, the copper foil 13 used as a circuit constituent material has a thickness of several tens to hundreds of μm in order to ensure the strength to withstand handling such as a sticking operation to the polyimide film 11. Since the side erosion occurs at the time of etching, the wiring width of the circuit is at least about 100 μm, which limits the density of the circuit pattern, and is the earliest advancement in the performance and miniaturization of electronic devices in the future. It is no longer available.

  In addition, the manufacturing method described above is very complicated in process and consumes chemicals such as an adhesive, a photoresist solution, a developing solution, a resist stripping solution, and an etching solution, so that the manufacturing cost is extremely high. In addition, it is not suitable for low-volume, multi-product production, and after use, developing solution, resist stripping solution, etching solution, etc. become a burden on the environment and cost for waste liquid processing, and generally used as copper foil 13 About 80% of the copper that has been removed is removed by etching. However, the cost of collecting the copper is usually discarded because of high costs, and there are many problems from the viewpoint of saving resources.

  In view of the above-described circumstances, the present invention can set the conductor thickness of a circuit such as a printed wiring board to be extremely thin, thereby enabling a circuit pattern to be remarkably densified as compared with the prior art, and as in the prior art. High-performance thin-film circuits with high adhesion strength of conductive metal to the substrate by a very simple process without the need for an adhesive, photoresist solution, developing solution, resist stripping solution, etching solution, etc. The purpose is to provide a method that can be formed and that is environmentally friendly and can contribute to resource saving.

  In order to achieve the above object, in the present invention, by irradiating the surface of a specific polymer substrate with a laser beam, the chemical bond part of the polymer is selectively dissociated so that the substrate surface part in the irradiation region is formed. The film is modified to be hydrophilic and a thin film circuit is formed by depositing a metal thin film on the irradiated area by electroless plating.

（ｍは２以上の整数）
で示す構造のポリイミドからなる高分子基材の表面に、その高分子基材よりもアブレーションしきい値が高い材料の微粒子を散布したのち、レーザ光を照射することにより、イミド環のＣ−Ｎ結合を選択的に解離させて照射域の基材表面部を親水性に改質すると同時に照射域に微細凹凸を形成し、次いで無電解メッキによって前記照射域に金属薄膜を被着させることを特徴としている。 That is, the method for forming a thin film circuit according to the invention of claim 1 includes the following formula (I):

(M is an integer of 2 or more)
After spraying fine particles of a material having an ablation threshold higher than that of the polymer base material on the surface of the polymer base material made of polyimide having the structure shown in FIG. The bond is selectively dissociated to modify the surface of the substrate in the irradiated area to be hydrophilic, and at the same time, fine irregularities are formed in the irradiated area, and then a metal thin film is deposited on the irradiated area by electroless plating. It is said.

（ｘ及びｙは２以上の整数）
で示す構造の耐熱性液晶ポリマーからなる高分子基材の表面に、その高分子基材よりもアブレーションしきい値が高い材料の微粒子を散布したのち、レーザ光を照射することにより、エステル結合のＣ−Ｏ結合部を選択的に解離させて照射域の基材表面部を親水性に改質すると同時に照射域に微細凹凸を形成し、次いで無電解メッキによって前記照射域に金属薄膜を被着させることを特徴としている。 In addition, a method for forming a thin film circuit according to the invention of claim 2 includes the following formula (II):

(X and y are integers of 2 or more)
After spraying fine particles of a material having a higher ablation threshold than that of the polymer substrate on the surface of the polymer substrate composed of the heat-resistant liquid crystal polymer having the structure shown in FIG. By selectively dissociating the C—O bond part, the surface of the substrate in the irradiated area is modified to be hydrophilic, and at the same time fine irregularities are formed in the irradiated area, and then a metal thin film is deposited on the irradiated area by electroless plating. It is characterized by letting.

As a means for dispersing fine particles of a material having a higher ablation threshold than the polymer base as described above, the surface of the polymer base is irradiated with laser light as a pretreatment, as in the invention of claim 3, There is a method in which carbon fine particles scattered by ablation at the time of irradiation are naturally dropped onto the surface of the polymer substrate. In order to set the irradiation pattern of the laser beam as the circuit pattern, a method of drawing a circuit pattern on the surface of the polymer substrate by the laser beam as in the invention of claim 4 or as in the invention of claim 5 A method of irradiating a laser beam through a mask having a light transmission pattern corresponding to the circuit pattern may be employed.

According to the method for forming a thin film circuit according to claim 1 and claim 2, by irradiating the surface of a specific polymer base material, which is originally hydrophobic, with laser light, the surface portion of the base material in the irradiation region is made hydrophilic. Since the metal deposits and adheres to the irradiated area by the next electroless plating to form a metal thin film, by setting the irradiation pattern of the laser beam on the surface of the polymer substrate as a circuit pattern A circuit pattern made of a very thin conductor metal with a wiring width of several μm to several tens of μm can be directly formed on the surface of the polymer substrate, and the circuit pattern can be greatly densified compared to the conventional case. possible and that Do not. In addition , since thin film circuits can be formed only by laser light irradiation and electroless plating, printed wiring boards can be manufactured very efficiently and at low cost. to consume, Rutotomoni can contribute to resource conservation without waste, the burden of waste liquid treatment can be significantly reduced as compared with the conventional, the burden on the environment is extremely slight throughout the process. Moreover, in this thin film circuit forming method, fine particles of a material having an ablation threshold higher than that of the polymer base material are dispersed on the surface of the polymer base material, and then irradiated with the laser light. At the same time as the selective dissociation of the bond portion, fine irregularities are formed in the irradiation region, so that by adjusting the energy density of the laser beam so as to suppress the evaporation of the fine particles and to cause the evaporation of the surface portion of the polymer substrate The surface of the polymer substrate in the irradiated area is formed with fine irregularities with convex portions where the laser light is blocked by each fine particle and concave portions due to evaporation where the unobstructed portions are evaporated. An anchor effect is produced in the conductive metal layer of the thin film circuit formed by plating.

According to the invention of claim 3, in forming fine irregularities simultaneously with the above surface modification , the surface of the polymer base material is irradiated with laser light as a pre-treatment, so that the scattered carbon fine particles are Since it naturally drops on the surface of the base material, it is not necessary to separately prepare fine particles for spraying, and no separate device for the spraying is required, thereby reducing material costs and equipment costs, There is an advantage that it is only necessary to irradiate the laser beam a plurality of times in the surface modification step.

According to the fourth aspect of the present invention, in the method for forming a thin film circuit described above , a wiring pattern is directly drawn with a laser beam on the surface of the polymer substrate, so that the metal thin film is covered in accordance with the pattern through electroless plating. Therefore, even complex and precise thin film circuits can be formed very easily. On the other hand, according to the invention of claim 5, in the method of forming a thin film circuit described above, since the laser beam is irradiated through a mask having a light transmission pattern corresponding to the circuit pattern, a part of the required circuit pattern Alternatively, the entire surface can be modified at once, and the surface modification operation can be performed efficiently.

  Hereinafter, embodiments of a method for forming a thin film circuit according to the present invention will be specifically described with reference to the drawings.

  In the thin film circuit forming method shown in FIG. 1, the ablation threshold is first higher on the surface of the polymer substrate 1 shown in FIG. The fine particles 2 made of material are dispersed. Thereafter, as shown in FIG. 3C, a laser beam L focused by, for example, a focusing lens S on the surface of the polymer base material 1 on which the fine particles 2 are dispersed is passed through a scanning head H for a predetermined time. Irradiate along the circuit pattern. Next, the polymer thin film 1 after the laser irradiation is subjected to an electroless plating treatment, whereby the metal thin film 3 is deposited only on the laser light L irradiation region on the surface of the polymer base 1, and thus the thin film A circuit 30 is formed.

  Laser beam scanning may be performed by a method of moving an XY table on which a polymer substrate is placed, instead of using a scanning head, or movement in the optical axis direction by the scanning head and movement of the XY table. It is also possible to do this by combining the two.

  In the thin film circuit forming method of the present invention, a mask having a light transmission pattern corresponding to the circuit pattern is used instead of the method of drawing the circuit pattern by scanning the laser beam as described above, and the mask is passed through this mask. A method of collectively irradiating the surface of the polymer substrate with laser light may be employed. That is, in the method using this mask, part or all of the required circuit patterns can be surface-modified at once.

  Here, the surface of the polymer substrate 1 is inherently hydrophobic because the metal thin film 3 is deposited only on the surface of the polymer substrate 1 irradiated with the laser light L by the electroless plating process. Although it is repellent (water-repellent) and repels the plating solution, in the region irradiated with the laser beam L, the polymer chemical bond portion of the base material is selectively dissociated by the energy of the laser beam L and is modified to be hydrophilic. In order to show the affinity for the plating solution, the metal is selectively deposited on the irradiated region by the reducing action of the plating bath.

  Therefore, the polymer base material 1 needs to have a hydrophobic (water-repellent) surface without containing a hydrophilic group in the polymer structure. In addition to this, surface modification by laser light irradiation is performed. Therefore, high heat resistance and compatibility as a substrate for a thin film circuit such as a printed wiring board are also required. Therefore, in the present invention, as the polymer substrate 1 that can satisfy these requirements, polyimide having a chemical structure represented by the following formula (I) or heat resistance having a chemical structure represented by the following formula (II): A liquid crystal polymer is used.

（ｍは２以上の整数）

(M is an integer of 2 or more)

（ｘ及びｙは２以上の整数）

(X and y are integers of 2 or more)

  That is, by irradiating a laser beam having an appropriate intensity, the CN bond of the imide ring is selectively dissociated in the polyimide of the above formula (I), and the ester bond in the heat resistant liquid crystal polymer of the above formula (II). Since the C—O bond portion of these is selectively dissociated, a strong hydrophilicity can be exhibited by adding a hydrophilic group such as an OH group to these dissociation portions. In addition, in order to add a hydrophilic group in this way, it is not necessary to perform a separate process. In the irradiation with laser light in the atmosphere, OH groups are naturally derived from moisture in the air at the stage of irradiation. To the dissociation part. In laser light irradiation in an artificial atmosphere such as an inert gas, a gas component that can generate a hydrophilic group such as water vapor may be mixed in the atmosphere.

  On the other hand, before the irradiation with the laser beam L, the base of the metal thin film 3 deposited and deposited in the electroless plating is preliminarily dispersed on the surface of the polymer substrate 1 as described above. The adhesion strength and adhesion to the surface of the material 1 are improved. This will be explained with reference to FIG. 2. When the laser beam L is irradiated with the fine particles 2 scattered on the surface of the polymer substrate 1 as shown in FIG. 2A, the energy density of the fine particles 2 is evaporated. In the irradiation region L of the laser beam L, the portion which becomes the shadow of each particle of the fine particles 2 on the surface of the base material 1 is controlled by adjusting so as to suppress and evaporate the surface portion of the polymer base material 1. While the light does not evaporate, the evaporation does not proceed. On the other hand, as a result of the evaporation of the part where the fine particles 2 do not exist, the shadowed part of the fine particles 2 is projected on the surface after irradiation as shown in FIG. This produces fine irregularities G in which other portions and other portions become concave portions. Thus, the irradiation zone Z having the fine unevenness G has been converted to hydrophilic as described above, and the metal thin film 3 is formed on the portion having the fine unevenness G as shown in FIG. Since the metal film 3 is deposited and deposited, the metal thin film 3 exhibits excellent adhesion strength and adhesion to the surface of the substrate 1 due to the anchor effect by the fine unevenness G.

  As means for dispersing the fine particles 2 on the surface of the polymer substrate 1, there are a method of spontaneously dropping carbon particles generated and scattered by ablation at the time of laser irradiation, and a method of flying carbon nanoparticles from an electrode in arc discharge. Various methods such as flying spraying by electrical discharge, mechanical spraying, spraying from a nozzle, and sputtering can be employed. In addition, the method by laser irradiation is different from laser beam irradiation for modifying the surface of the base material 1 described above by performing laser beam irradiation once or a plurality of times on the surface of the base material 1 as a pretreatment. The carbon particles generated by the ablation of the polymer of the base material 1 are used for the natural fall by gravity on the surface of the base material 1 after flying, and the laser beam for this purpose is a laser for modification. What is necessary is just to irradiate the same place (pattern) as light irradiation.

  The fine particles 2 can be used without particular limitation as long as they have a higher ablation threshold than the polymer substrate 1 including the carbon particles. However, in the case of mechanical spraying or spraying from a nozzle, In order to avoid a short circuit due to the remaining fine particles, fine powder of an inorganic non-conductive material such as ceramic, glass, rock, or iron is preferable. However, a fine powder of a conductive material can also be used if the adhered fine particles can be reliably removed by surface cleaning or the like before electroless plating.

  As a laser beam irradiation source used for modifying the surface of a polymer substrate, one having a photon energy intensity corresponding to the type of chemical bond to be selectively dissociated from the polymer may be used. A light (wavelength 400 μm or less) laser is preferred. Further, the intensity of the laser beam should be set so that its power density is equal to or higher than the threshold value of the polymer substrate. Thus, the atmosphere at the time of laser light irradiation is not particularly limited, and may be either air or inert gas.

Incidentally, FIG. 3 represents the relationship between the laser wavelength and the photon energy as a curve P, and the main chemical bonds (CN, C—C, C = C, C≡C) of the polymer on this curve P. , C≡N). The C—C bond excludes a constituent part of an aromatic ring such as a benzene ring. From this figure, in order to selectively dissociate a specific chemical bond, a laser having a wavelength having a photon energy higher than the bond energy is required. For example, in the surface modification of a polymer substrate made of polyimide, C- It can be seen that an ultraviolet laser is useful in performing selective dissociation of N bonds. However, even in the case of a visible light laser, a recently developed femto (10 ^-15 ) second laser has a multiphoton dissociation (dissociation by two or more photons) even if the energy of one photon is smaller than the chemical bond energy. Thus, surface modification can be performed in the same manner.

  Electroless plating follows general methods used for plating conductive metals on plastics, metal salts supplying metal ions, reducing agents, chelating agents for forming metal chelates, and pH adjusting agents such as NaOH. A plating solution containing an optional auxiliary component such as a stabilizer is prepared, and the polymer substrate 1 that has been subjected to laser irradiation along the circuit pattern described above may be immersed in the plating bath for a required time. As a result of the reduction reaction, the metal ions are selectively deposited only in the laser light irradiation zone Z of the polymer substrate 1 to form a thin film circuit.

  The metal forming the thin film circuit may be any metal that can be electrolessly plated and has high conductivity, and usually copper or a copper alloy is employed. When copper or a copper alloy is used, for example, copper sulfate is generally used as a metal salt, formaldehyde is used as a reducing agent, and Rochelle salt is used as a chelating agent, for example, for thinning with a plating thickness of 1 μm or less. . For thickening up to a plating thickness of 10 μm or less, for example, copper sulfate is generally used as a metal salt, formaldehyde is used as a reducing agent, and EDTA is used as a chelating agent.

  The electroless plating process in the present invention does not require setting different conditions, and may be performed according to a normal electroless plating process. It is possible to use a commercially available electroless plating bath corresponding to the kind of the material. For example, in electroless copper plating, a commercially available electroless copper plating bath for thinning or thickening can be used without hindrance.

  In electroless plating, if the bath liquid is vibrated by ultrasonic waves or the like, the contact probability of the liquid with respect to the surface modification portion of the polymer base material is increased, so that the formation efficiency of the metal thin film is improved. There is an advantage.

  According to such a method of forming a thin film circuit, a conductor circuit can be formed in only three steps of fine particle dispersion, laser light irradiation, and electroless plating, so that a printed wiring board can be manufactured extremely efficiently and at low cost. Suitable for high-mix low-volume production. In addition, since the circuit pattern has an irradiation area of the laser beam as it is, the metal thin film is deposited, the wiring width can be set from several μm to several tens of μm, and the metal layer deposited by electroless plating can be used. Since the thickness can be set to be extremely thin corresponding to the wiring width, it is possible to dramatically increase the density as compared with the conventional case. In addition, this method consumes only the amount of conductor metal necessary for circuit formation, so there is no waste as in conventional circuit formation by etching, contributing to resource savings, and the electroless plating bath has no consumption components. Since it can be replenished and used repeatedly, the burden of waste liquid treatment is remarkably reduced as compared with the prior art, and the burden on the environment is extremely small throughout the entire process.

  In the above-described embodiment, in order to increase the adhesion strength and adhesion of the metal thin film formed by electroless plating to the polymer base material, fine particles are dispersed on the surface of the base material before laser irradiation. Although unevenness is formed, in the method of the present invention, sufficient adhesion strength and adhesion can be obtained even if there is no anchor effect due to fine unevenness depending on the film thickness of the metal thin film and the form of the circuit pattern. In such a case, the dispersion of fine particles may be omitted. Therefore, in this case, the formation of the thin film circuit can be performed in two steps of laser light irradiation and electroless plating, and the production efficiency of printed wiring boards and the like can be further improved and the cost can be reduced.

Using a short pulse FGH (fourth harmonic) laser (Meister 1000DF manufactured by MHI, pulse width 3.5 × 10 ⁻⁹ seconds, wavelength 266 μm), a polyimide film of 50 μm thickness [Upilex film manufactured by Ube Industries, Ltd. On the surface (upper surface) of the base material made of the polyimide having the structure represented by formula (I), as a pretreatment, a laser beam whose power density on the irradiated surface is set to be equal to or higher than the ablation threshold of polyimide is irradiated with an irradiation spot diameter of 20 μm. Irradiated by scanning in a straight line, carbon particles generated and scattered by ablation were dispersed on the surface of the substrate by natural fall. Next, the surface of the base material on which the carbon particles were dispersed was irradiated with the laser by scanning the laser beam linearly again under the same conditions to modify the irradiation area to be hydrophilic and to form fine irregularities. In this example, a straight line pattern was used as a simulated wiring pattern in order to examine the formation state of the metal thin film to be a thin film circuit.

  Next, for the polyimide film that has been surface-modified and formed with fine irregularities by irradiation with the laser beam described above, using an ultrasonic cleaning tank, an electroless copper plating bath for thinning (Okuno Pharmaceutical Co., Ltd .... In the same manner, electroless copper plating was performed according to the following procedure in accordance with a conventional method, and a copper thin film was deposited on the surface modified portion. In the following, ultrasonic vibrations were applied to the polyimide film bath.

In an ultrasonic cleaning tank, the polyimide film described above is first degreased by immersing it in a degreasing chemical solution (A screen A220) at a liquid temperature of 65 ° C. After washing with spray water, 35% HCl solution and palladium are used as a catalyst treatment. Immerse in a 3: 1 mixture with the catalyst solution (Catalyst C) at room temperature for 4 minutes, spray water wash, and then as an accelerator treatment, soak in a 98% H ₂ SO ₄ solution at a liquid temperature of 40 ° C. for 4 minutes, and then rinse with water. Later, copper plating was performed by dipping for 20 minutes at room temperature in an electroless plating bath (a 1: 1 mixture of solution OPC-700A and OPC-700B).

  A pretreatment was performed in the same manner as in Example 1 except that a heat-resistant liquid crystal polymer film having a thickness of 50 μm was used as the polymer substrate (a Bexter film manufactured by Kuraray Co., Ltd., a liquid crystal polymer having a structure represented by the formula (II)). Surface modification by sequentially applying carbon particles by laser irradiation, reforming to hydrophilicity by laser irradiation, forming fine irregularities, and electroless copper plating using a thin electroless copper plating bath A copper thin film was formed on the part.

  About the film which gave the electroless copper plating of the said Example 1 and 2, when the surface containing the said surface modification part was expanded and examined by the microscope (100 time), the adhesion part of the copper thin film was both films. It was confirmed that the laser beam continued as a white line reflecting light from the light source over the entire length scanned with a width of 20 μm, which coincided with the irradiation width of the laser beam. Moreover, when the identification pattern by low-vacuum SEM-EDX (energy dispersive X-ray spectrometer) was investigated about both films, as for both films, the presence of copper in the film surface was only a laser beam irradiation area with a width of 20 μm, It was confirmed that copper was selectively deposited on the irradiated area by electroless copper plating.

  It should be noted that the laser beam irradiation area has been modified to be hydrophilic by the selective formation of a copper thin film on the irradiation area by the electroless plating. To further confirm this, Example 1 And about the film before and behind the irradiation of the laser beam in Example 2, Cis spectrum distribution measurement was performed by an X-ray photoelectron spectrometer (XPS). 4A shows the polyimide film of Example 1 before laser light irradiation, FIG. 4B shows the same laser light irradiation, and FIG. 5A shows the heat resistant liquid crystal polymer film of Example 2 before laser light irradiation. FIG. 5B shows a Cis spectrum distribution diagram after the laser light irradiation.

  4A and 4B, the peak (about 288.2 eV) of the imide ring (O = C—N—C═O) in the molecular structure of the polyimide represented by the formula (I) before the laser beam irradiation is obtained. It is decreased after laser light irradiation, and it can be seen that the imide ring was selectively cleaved by laser light irradiation, and an OH group was added to this dissociation part. 5A and 5B, the peak of the ester bond (O—C═O) in the liquid crystal polymer represented by the formula (II) before laser light irradiation is not observed after laser light irradiation, and C It can be seen that the peak of —O bond is lowered after laser light irradiation, and the C—O bond part in the ester bond is selectively dissociated by the laser light irradiation, and an OH group is added to this dissociated part.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic cross section which shows the formation method of the thin film circuit which concerns on one Embodiment of this invention in order of a process, (A) is a polymer base material, (B) is a polymer base material which disperse | distributed microparticles | fine-particles on the surface, (C) Is the laser beam irradiation state on the substrate surface, and (D) is the state where a thin film circuit is formed on the substrate surface. 2A and 2B are schematic cross-sectional views for explaining the action of dispersed fine particles in the formation of the thin film circuit, wherein FIG. 3A is an irradiation state of a laser beam on the surface of a polymer substrate on which fine particles are dispersed, and FIG. A base material and (C) each show a state in which a conductive metal layer is formed on the surface of the base material. It is explanatory drawing which added the wavelength of various lasers, and the binding energy of a chemical bond to the correlation diagram of a laser wavelength and photon energy. The Cis spectrum distribution by the X-ray photoelectron spectrometer of the polyimide film before and after laser beam irradiation in Example 2 is shown, (A) is a Cis spectrum distribution diagram before laser beam irradiation, and (B) is the Cis spectrum distribution after laser beam irradiation. FIG. The Cis spectrum distribution by the X-ray photoelectron spectrometer of the heat-resistant liquid crystal polymer film before and after laser light irradiation in Example 1 is shown, (A) is the Cis spectrum distribution before laser light irradiation, and (B) is after laser light irradiation. It is a Cis spectrum distribution map. It is a schematic cross section which shows the manufacturing method of the conventional 3-layer copper-clad printed wiring board in order of a process, (A) is a sticking state of a polyimide film and copper foil, (B) is a photo on the copper foil surface after sticking. (C) is an exposed state, (D) is a state where an ineffective resist is removed, (E) is a state after etching, and (E) is a state after circuit formation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymer base material 2 Fine particle 3 Metal thin film 30 Thin film circuit L Laser beam Z Irradiation area G Fine unevenness

Claims (5)

The following formula (I);

(M is an integer of 2 or more)
After spraying fine particles of a material having an ablation threshold higher than that of the polymer base material on the surface of the polymer base material made of polyimide having the structure shown in FIG. The bond is selectively dissociated to modify the surface of the substrate in the irradiated area to be hydrophilic, and at the same time, fine irregularities are formed in the irradiated area, and then a metal thin film is deposited on the irradiated area by electroless plating. A method for forming a thin film circuit.









Following formula (II);

(X and y are integers of 2 or more)
After spraying fine particles of a material having a higher ablation threshold than that of the polymer substrate on the surface of the polymer substrate composed of the heat-resistant liquid crystal polymer having the structure shown in FIG. By selectively dissociating the C—O bond part, the surface of the substrate in the irradiated area is modified to be hydrophilic, and at the same time fine irregularities are formed in the irradiated area, and then a metal thin film is deposited on the irradiated area by electroless plating. A method for forming a thin film circuit, comprising: Claims: The surface of the polymer base material is irradiated with laser light as a pretreatment, and the carbon fine particles scattered by the ablation at the time of irradiation are naturally dropped onto the surface of the polymer base material, thereby dispersing the fine particles. 3. A method for forming a thin film circuit according to 1 or 2. The method for forming a thin film circuit according to claim 1, wherein a circuit pattern is drawn on the surface of the polymer substrate by the laser beam . 4. The method of forming a thin film circuit according to claim 1, wherein the surface of the polymer substrate is irradiated with the laser beam through a mask having a light transmission pattern corresponding to the circuit pattern .

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