JP4457833B2 - Wiring pattern forming method, wiring pattern, and electronic device - Google Patents

Description

  The present invention relates to a wiring pattern forming method, a wiring pattern, and an electronic apparatus.

  For example, a lithography method is used to form a wiring pattern constituting an electronic device. However, the lithography method requires not only a large equipment such as a vacuum apparatus and a complicated process, but also has a material use efficiency of about several percent, so that most of the material must be discarded, and the manufacturing cost is high. In addition, there is a limit to miniaturization of the wiring pattern.

Therefore, as a process replacing the lithography method, a method (droplet discharge method) in which a liquid containing a functional material is discharged onto a substrate and a wiring pattern is directly drawn and formed has been studied. In this method, first, a liquid material in which conductive fine particles are dispersed is discharged from a droplet discharge head onto a substrate to draw and form a liquid line. Next, the liquid line is baked by heat treatment or laser irradiation to form an electrical wiring pattern (see, for example, Patent Document 1). According to this droplet discharge method, the manufacturing process is simplified, the material use efficiency is increased, and the manufacturing cost can be reduced. In addition, the wiring pattern can be miniaturized.
US Pat. No. 5,132,248

  In order to reduce the size of electronic devices, it is important to increase the number of layers as well as the wiring pattern. In order to increase the number of wiring patterns, electrical wirings are stacked and disposed via an interlayer insulating film, and the upper and lower electrical wirings are electrically connected by conductive posts. Here, in order to form a multilayer wiring pattern using the droplet discharge method, first, a liquid line is drawn and formed at the position where the electrical wiring is formed by the droplet discharge method, and the liquid line is baked to form the electrical wiring. To do. Next, a liquid post is drawn and formed on the electrical wiring by a droplet discharge method, and the liquid post is baked to form a conductive post. Furthermore, a liquid interlayer film is drawn and formed in a region other than the conductive post formation position by a droplet discharge method, and the liquid interlayer film is cured to form an interlayer insulating film.

  However, when the liquid interlayer film is drawn and formed after the conductive post is baked, the liquid interlayer film may flow and come into contact with the conductive post, and may get wet to the upper end portion of the conductive post. If the liquid interlayer film is cured in this state, an interlayer insulating film is formed on the upper end portion of the conduction post, and there is a problem that electrical connection between the conduction post and the upper layer electric wiring becomes impossible.

  SUMMARY An advantage of some aspects of the invention is to provide a wiring pattern excellent in the reliability of electrical connection, a method for forming the wiring pattern, and an electronic apparatus.

  In order to achieve the above object, the wiring pattern forming method of the present invention is a wiring pattern forming method in which a plurality of electrical wirings arranged in layers via an interlayer insulating film are connected to each other by conductive posts. Discharging a first droplet including the constituent material of the conductive post to form a liquid post at a position where the conductive post is formed; and discharging a second droplet including the constituent material of the interlayer insulating film. Forming a liquid interlayer film in a region other than the position where the conductive posts are formed, and the first droplet and the second droplet are made of a material exhibiting phase separation between each other. It is characterized by being.

  According to this configuration, even if the liquid interlayer film flows and comes into contact with the liquid post, the liquid interlayer film wets the upper end of the liquid post due to the phase separation of the first droplet and the second droplet. Absent. As a result, it is possible to prevent the interlayer insulating film from being formed on the upper end portion of the conductive post, and to ensure electrical connection between the conductive post and the upper-layer electric wiring. Therefore, it is possible to provide a wiring pattern with excellent electrical connection reliability.

Moreover, it is desirable that either the first droplet or the second droplet is made of a hydrophilic material and the other is made of a lipophilic material.
According to this configuration, the first droplet and the second droplet exhibit phase separation properties, and it is possible to provide a wiring pattern with excellent electrical connection reliability as described above.

In addition, it is desirable to temporarily dry the surface of the liquid post before the step of forming the liquid interlayer film.
According to this configuration, even if the liquid interlayer film flows and contacts the liquid post, the liquid post does not move or deform. Even when the surface of the liquid post is temporarily dried, the phase separation from the liquid interlayer film can be maintained.

In addition, after the step of forming the liquid interlayer film, it is desirable to first cure the liquid interlayer film and then cure the liquid post.
According to this configuration, it becomes possible to cure the liquid interlayer film while maintaining the phase separation from the liquid post, and the liquid interlayer film wets the upper end of the liquid post in the process of curing the liquid interlayer film. There is no. Therefore, it is possible to prevent the interlayer insulating film from being formed on the upper end portion of the conductive post, and it is possible to provide a wiring pattern having excellent electrical connection reliability.

Moreover, it is desirable that either one of the first droplet and the second droplet is made of a thermosetting material and the other is made of an ultraviolet curable material.
According to this configuration, the process of first curing the liquid interlayer film and then curing the liquid post can be easily performed. Therefore, it is possible to provide a wiring pattern having excellent electrical connection reliability as described above.

On the other hand, the wiring pattern of the present invention is manufactured by using the wiring pattern forming method described above.
According to this configuration, it is possible to provide a wiring pattern with excellent electrical connection reliability. In addition, since the droplet discharge method is adopted, a miniaturized wiring pattern can be provided.

On the other hand, an electronic apparatus of the present invention is characterized by including the above-described wiring pattern.
According to this configuration, since the electrical connection reliability is excellent and the miniaturized wiring pattern is provided, it is possible to provide a small electronic device excellent in electrical connection reliability.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

  FIG. 1 is an exploded perspective view of a liquid crystal module having a COF (Chip On Film) structure. In this embodiment, a method for forming a wiring pattern on a flexible printed circuit board (Flexible Printed Circuit; hereinafter referred to as “FPC”) 30 will be described as an example. The FPC 30 is obtained by forming electrical wiring patterns 39a and 39b on the surface of a flexible film substrate 31. As will be described in detail later, in the liquid crystal module 1 having the COF structure shown in FIG. 1, the FPC 30 is connected to the end of the liquid crystal panel 2, and the liquid crystal driving IC 100 is mounted on the surface of the FPC 30. An image is displayed on the liquid crystal panel 2 by outputting a drive signal from the liquid crystal drive IC 100 to the liquid crystal panel 2 via the FPC 30.

[Wiring pattern]
FIG. 2 is an explanatory diagram of a wiring pattern according to the embodiment, and is an enlarged view of a wiring formation portion of the FPC. 2A is a plan sectional view taken along line BB in FIG. 2B, and FIG. 2B is a side sectional view taken along line AA in FIG. As shown in FIG. 2B, in the wiring pattern of the present embodiment, the lower-layer electric wiring 32 and the upper-layer electric wiring 36 are stacked via the interlayer insulating film 54 and are electrically connected by the conductive posts 34. It has been configured. Note that the wiring patterns described below are merely examples, and the present invention can be applied to other wiring patterns.

  As shown in FIG. 2B, the FPC 30 includes a flexible film substrate 31 made of polyimide or the like. A base insulating film 51 is formed on the surface of the film substrate 31. The base insulating film 51 is made of an electrically insulating material whose main component is an ultraviolet curable resin such as acrylic.

  A plurality of electrical wirings 32 are formed on the surface of the base insulating film 51. The electrical wiring 32 is formed in a predetermined pattern using a conductive material such as Ag. An in-layer insulating film 52 is formed in a region where the electric wiring 32 is not formed on the surface of the base insulating film 51. Then, by adopting a droplet discharge method which will be described later, the line × space of the electric wiring 32 is made finer, for example, to about 30 μm × 30 μm.

  An interlayer insulating film 54 is formed so as to mainly cover the electrical wiring 32. This interlayer insulating film 54 is also made of the same resin material as that of the base insulating film 51. A conductive post 34 having a considerably high height is formed so as to penetrate the interlayer insulating film 54 upward from the end of the electric wiring 32. The conductive post 34 is formed in a cylindrical shape by the same conductive material such as Ag as the electric wiring 32. For example, the thickness of the electric wiring 32 is about 2 μm, and the height of the conductive post 34 is about 8 μm.

  An upper electrical wiring 36 is formed on the surface of the interlayer insulating film 54. Similarly to the lower-layer electrical wiring 32, the upper-layer electrical wiring 36 is also made of a conductive material such as Ag. As shown in FIG. 2A, the upper-layer electrical wiring 36 may be arranged so as to intersect with the lower-layer electrical wiring 32. The upper-layer electrical wiring 36 is connected to the upper end portion of the conduction post 34 to ensure electrical continuity with the lower-layer electrical wiring 32.

  Further, as shown in FIG. 2B, an in-layer insulating film 56 is formed in a region where the electrical wiring 36 is not formed on the surface of the interlayer insulating film 54. Further, a protective film 58 is formed so as to mainly cover the electrical wiring 36. The in-layer insulating film 56 and the protective film 58 are also made of the same resin material as that of the base insulating film 51.

  The wiring pattern provided with two layers of electrical wirings 32 and 36 has been described above as an example. However, a wiring pattern including three or more layers of electrical wiring may be used. In this case, similarly to the structure from the first-layer electrical wiring 32 to the second-layer electrical wiring 36, the n-th layer electrical wiring to the (n + 1) th-layer electrical wiring may be formed.

[Method of forming wiring pattern]
Next, a method for forming a wiring pattern according to the embodiment will be described.
FIG. 3 is a process chart of a wiring pattern forming method according to the embodiment. 4 and 5 are explanatory diagrams of a method for forming a wiring pattern according to the embodiment. Below, each process is demonstrated in order of the step number of the left end column of FIG.

  First, the surface of the film substrate 31 shown in FIG. 2B is cleaned (step 1). Specifically, the surface of the film substrate 31 is irradiated with excimer UV having a wavelength of 172 nm for about 300 seconds. The film substrate 31 may be washed with a solvent such as water, or may be washed using ultrasonic waves. Alternatively, the film substrate 31 may be cleaned by irradiating with plasma at normal pressure.

Next, as a premise for forming the base insulating film 51 on the surface of the film substrate 31, a bank (peripheral portion) of the base insulating film 51 is drawn and formed (step 2). This drawing is performed by a droplet discharge method (inkjet method). That is, a resin material before curing, which is a material for forming the base insulating film 51, is discharged along the peripheral edge of the region where the base insulating film 51 is formed using a droplet discharge device described later.
Next, the discharged resin material is cured (step 3). Specifically, UV with a wavelength of 365 nm is irradiated for about 4 seconds to cure the UV curable resin that is the material for forming the base insulating film 51. Thereby, a bank is formed at the peripheral edge of the formation region of the base insulating film 51.

Next, the base insulating film 51 is drawn and formed inside the formed bank (step 4). This drawing is also performed by a droplet discharge method. Specifically, a resin material before curing, which is a material for forming the base insulating film 51, is discharged from the droplet discharge head while scanning a droplet discharge head of a droplet discharge device, which will be described later, over the entire bank. Here, even if the discharged resin material flows, the resin material is dammed by the bank of the peripheral portion, so that it does not spread beyond the formation region of the base insulating film 51.
Next, the discharged resin material is cured (step 5). Specifically, UV with a wavelength of 365 nm is irradiated for about 60 seconds to cure the UV curable resin that is the material for forming the base insulating film 51. As a result, a base insulating film 51 is formed on the surface of the film substrate 31 as shown in FIG.

  Next, as a premise for forming an electrical wiring on the surface of the base insulating film 51, the contact angle of the surface of the base insulating film 51 is adjusted (step 6). As will be described below, when a droplet containing a material for forming an electrical wiring is ejected, if the contact angle with the surface of the base insulating film 51 is too large, the ejected droplet becomes a ball and is placed in a predetermined position. It becomes difficult to form electrical wiring of a predetermined shape. On the other hand, if the contact angle with the surface of the base insulating film 51 is too small, the discharged droplets spread out and it is difficult to make the electrical wiring finer. Since the surface of the cured base insulating film 51 exhibits liquid repellency, the contact angle of the surface of the base insulating film 51 is adjusted by irradiating the surface with excimer UV having a wavelength of 172 nm for about 15 seconds. The degree of relaxation of liquid repellency can be adjusted by the irradiation time of ultraviolet light, but can also be adjusted by a combination with the intensity of ultraviolet light, wavelength, heat treatment (heating), and the like. Note that other methods of lyophilic treatment include plasma treatment using oxygen as a reactive gas, treatment of exposing a substrate to an ozone atmosphere, and the like.

  Next, as shown in FIG. 4B, a liquid line 32p, which will later become electrical wiring, is drawn and formed on the surface of the base insulating film 51 (step 7). This drawing is performed by a droplet discharge method using a droplet discharge device described later. What is discharged here is a dispersion liquid in which conductive fine particles, which are materials for forming electrical wiring, are dispersed in a dispersion medium. Silver is preferably used as the conductive fine particles. In addition, fine particles of conductive polymer or superconductor can be used in addition to metal fine particles containing any of gold, copper, palladium, and nickel.

  The conductive fine particles can be used by coating the surface with an organic substance to improve dispersibility. Examples of the coating material that coats the surface of the conductive fine particles include polymers that induce steric hindrance and electrostatic repulsion. The particle diameter of the conductive fine particles is preferably 5 nm or more and 0.1 μm or less. If it is larger than 0.1 μm, nozzle clogging is likely to occur and ejection by the droplet ejection head becomes difficult. On the other hand, if the thickness is smaller than 5 nm, the volume ratio of the coating agent to the conductive fine particles is increased, and the ratio of organic substances in the obtained conductor is excessive.

  The dispersion medium to be used is not particularly limited as long as it can disperse the above-mentioned conductive fine particles and does not cause aggregation. In addition to water, alcohols such as methanol, ethanol, propanol and butanol, n- Hydrocarbon compounds such as heptane, n-octane, decane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydronaphthalene, cyclohexylbenzene, or ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl Ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether Le, p- ether compounds such as dioxane, propylene carbonate, .gamma.-butyrolactone, N- methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, may be mentioned polar compounds such as cyclohexanone. Among these, water, alcohols, hydrocarbon compounds, and ether compounds are preferable and particularly preferable from the viewpoints of fine particle dispersibility, dispersion stability, and ease of application to the droplet discharge method. Examples of the dispersion medium include water and hydrocarbon compounds. These dispersion media can be used alone or as a mixture of two or more.

  The liquid dispersion medium containing conductive fine particles preferably has a vapor pressure at room temperature of 0.001 mmHg or more and 200 mmHg or less (about 0.133 Pa or more and 26600 Pa or less). This is because when the vapor pressure is higher than 200 mmHg, the dispersion medium rapidly evaporates after ejection, and it becomes difficult to form a good conductor. The vapor pressure of the dispersion medium is more preferably 0.001 mmHg or more and 50 mmHg or less (about 0.133 Pa or more and 6650 Pa or less). This is because when the vapor pressure is higher than 50 mmHg, nozzle clogging due to drying tends to occur when droplets are ejected by the droplet ejection method, and stable ejection becomes difficult. On the other hand, in the case of a dispersion medium having a vapor pressure lower than 0.001 mmHg at room temperature, drying becomes slow and the dispersion medium tends to remain in the conductor, and a high-quality conductor can be obtained after heat and / or light treatment in the subsequent process. It's hard to be done.

  The dispersoid concentration when the conductive fine particles are dispersed in the dispersion medium is 1% by mass or more and 80% by mass or less, and can be adjusted according to the desired thickness of the conductor. If it exceeds 80% by mass, aggregation tends to occur and it is difficult to obtain a uniform conductor.

The surface tension of the conductive fine particle dispersion is preferably in the range of 0.02 N / m to 0.07 N / m. When the liquid is discharged by the droplet discharge method, if the surface tension is less than 0.02 N / m, the wettability of the ink composition with respect to the nozzle surface increases, and thus flight bending easily occurs, resulting in 0.07 N / m. This is because the shape of the meniscus at the tip of the nozzle is not stable, and it becomes difficult to control the discharge amount and the discharge timing.
In order to adjust the surface tension, a trace amount of a surface tension regulator such as fluorine, silicon, or nonion can be added to the dispersion liquid in a range that does not unduly reduce the contact angle with the base insulating film 51. . The nonionic surface tension adjusting agent improves the wettability to the base insulating film 51, improves the leveling property of the film, and helps to prevent the occurrence of coating crushing and the generation of distorted skin. The dispersion liquid may contain an organic compound such as alcohol, ether, ester, or ketone as necessary.

  The viscosity of the dispersion is preferably 1 mPa · s or more and 50 mPa · s or less. When discharging by the droplet discharge method, if the viscosity is less than 1 mPa · s, the nozzle periphery is easily contaminated by the outflow of the ink, and if the viscosity is more than 50 mPa · s, the nozzle hole has eyes. This is because the clogging frequency increases and it becomes difficult to smoothly discharge droplets.

In the present embodiment, the dispersion liquid droplets (first droplets) are ejected from a droplet ejection head and dropped onto a location where an electrical wiring is to be formed. At this time, it is desirable to adjust the overlapping degree of the liquid droplets to be continuously discharged so that the liquid pool (bulge) does not occur. In particular, it is desirable to employ a discharge method in which a plurality of liquid droplets are discharged separately so as not to contact each other in the first discharge, and the gap is filled by the second and subsequent discharges.
As a result, the liquid line 32 p is formed on the surface of the base insulating film 51.

  Next, the liquid line 32p is fired (step 8). Specifically, the film substrate 31 on which the liquid line 32p is formed is heated by a hot plate at 150 ° C. for about 30 minutes. This firing treatment is usually performed in the air, but can also be performed in an inert gas atmosphere such as nitrogen, argon, helium, etc., if necessary. Although the firing temperature was set to 150 ° C., the boiling point (vapor pressure) of the dispersion medium contained in the liquid line 32p, the type and pressure of the atmospheric gas, the thermal behavior such as the dispersibility and oxidation of fine particles, the coating It is desirable to set appropriately in consideration of the presence / absence and amount of the material, the heat-resistant temperature of the substrate, and the like.

  Such a baking process can be performed by lamp annealing in addition to a process using a normal hot plate, an electric furnace, or the like. The light source used for lamp annealing is not particularly limited, but excimer laser such as infrared lamp, xenon lamp, YAG laser, argon laser, carbon dioxide laser, XeF, XeCl, XeBr, KrF, KrCl, ArF, ArCl, etc. Can be used as a light source. These light sources generally have a power output in the range of 10 W or more and 5000 W or less, but in this embodiment, a range of 100 W or more and 1000 W or less is sufficient.

  By the baking treatment as described above, the dispersion medium contained in the liquid line 32p is volatilized, and electrical contact between the conductive fine particles is ensured. Thereby, the electrical wiring 32 is formed.

Next, as shown in FIG. 4C, a liquid post 34p, which will later become a conductive post, is drawn and formed at the end of the fired electrical wiring 32 (step 9). This drawing is also performed by a droplet discharge method using a droplet discharge device, which will be described later, in the same manner as the liquid line drawing in step 7. What is discharged here is a droplet (first droplet) of a dispersion liquid in which conductive fine particles, which are conductive post forming materials, are dispersed in a dispersion medium. Specifically, the droplet is used for drawing a liquid line. Is the same. That is, after drawing the liquid line, the same droplet discharge head may be used to discharge the droplet to the formation position of the conductive post.
As described above, the conductive post needs to be formed at a considerable height. Therefore, a large number of droplets are ejected and deposited by the droplet ejection method to form a liquid post 34p having a considerably high height.

  Next, the liquid post 34p is temporarily dried (step 10). This temporary drying is performed so that at least the surface of the liquid post 34p is dried. Specifically, dry air such as low humidity air or inert gas is blown toward the liquid post 34p. The temperature of the dry air may be normal temperature (about 25 ° C.) or high temperature. Further, instead of blowing dry air, the liquid post 34p may be irradiated with infrared rays using an infrared lamp or the like. As described above, by employing dry air blowing or infrared irradiation, temporary drying can be performed with a simple manufacturing facility and manufacturing process, so that an increase in facility cost and manufacturing cost can be suppressed. Moreover, even if the temperature rises temporarily due to temporary drying, it can be immediately returned to room temperature, so that the manufacturing time can be shortened.

  By the way, in Step 9 described above, a large number of droplets are ejected and deposited by the droplet ejection method to form a liquid post 34p having a considerably high height. However, it is difficult to secure the height of the liquid post 34p even if a large number of droplets are ejected at one time, and conversely, the diameter of the liquid post 34p becomes large and short-circuits with an adjacent electric wiring or conduction post. There is a risk. Therefore, the droplet discharge may be divided into a plurality of times and a small number of droplet discharges and temporary drying may be repeated. As described above, if a new droplet is ejected after the previously ejected droplet is temporarily dried, the new droplet does not spread on the surface of the base insulating film 51, so that the liquid post 34p is formed at a considerable height. can do.

  Next, as shown in FIG. 5A, the contact angle of the surface of the base insulating film 51 is adjusted as a premise for forming the in-layer insulating film 52 in the formation layer of the electrical wiring 32 (step 11). Since the surface of the hardened base insulating film 51 exhibits liquid repellency, excimer UV having a wavelength of 172 nm is irradiated for about 60 seconds in order to impart lyophilicity to the surface.

  Next, the in-layer insulating film 52 is drawn and formed around the electrical wiring 32 (step 12). This drawing is also performed using a droplet discharge device in the same manner as the drawing of the base insulating film 51. Here, first, a gap is formed around the liquid post 34p and the electric wiring 32, and the resin material is discharged to the outside.

  Next, an excimer UV having a wavelength of 172 nm is applied to the gap between the liquid post 34p and the electric wiring 32 for about 10 seconds to perform a lyophilic process (step 13). Thereby, since the lyophilic property is imparted to the gap around the liquid post 34p and the electric wiring 32, the resin material flows into the gap and comes into contact with the liquid post 34p and the electric wiring 32. In this case, the resin material wets the surface of the electric wiring 32 but does not wet the liquid post 34p as described below.

  Then, the discharged resin material is cured (step 14). Specifically, UV with a wavelength of 365 nm is irradiated for about 4 seconds to cure the UV curable resin that is the material for forming the in-layer insulating film 52. Thereby, the in-layer insulating film 52 is formed.

  Next, the liquid interlayer film 54p is drawn and formed mainly on the surface of the electric wiring 32 in a region other than the position where the conductive post is formed (step 15). Similar to the drawing of the base insulating film 51, this drawing is also performed by a droplet discharge method using a droplet discharge device. Here, the liquid droplets (second droplets) of the resin material, which is the material for forming the interlayer insulating film, are discharged. Specifically, the liquid material used for drawing the base insulating film 51 and the in-layer insulating film 52 is discharged. It is the same as a droplet. That is, after drawing the base insulating film 51 and the in-layer insulating film 52, the liquid material may be discharged to the formation position of the interlayer insulating film using the same droplet discharge head.

  In the present embodiment, the resin material of the liquid interlayer film 54p is discharged in a state where the liquid post 34p is temporarily dried without firing. The discharged resin material flows on the surfaces of the electric wiring 32 and the in-layer insulating film 52 and comes into contact with the liquid post 34p. Since the liquid post 34p is temporarily dried, it does not move or deform even when the liquid interlayer film 54p contacts.

  Here, the forming material of the liquid post 34p is obtained by dispersing conductive fine particles in a dispersion medium such as water or alcohol, and has hydrophilicity. On the other hand, the resin material which is a material for forming the liquid interlayer film 54p has lipophilicity. That is, the forming material (first droplet) of the liquid post 34p and the forming material (second droplet) of the liquid interlayer film 54p are mutually phase-separable or incompatible. The phase separation property is a property that is not familiar and has a low chemical affinity. Therefore, even if the liquid interlayer film 54p flows and abuts on the liquid post 34p, the contact angle becomes large as shown in FIG. 5A due to the phase separation of the first droplet and the second droplet. Thus, the liquid interlayer film 54p does not wet the upper end portion of the liquid post 34p.

  In the present embodiment, a hydrophilic material is used as the material for forming the liquid post 34p, and an oleophilic material is used as the material for forming the liquid interlayer film 54p. On the contrary, an oleophilic material is used as the material for forming the liquid post 34p. A material may be employed, and a hydrophilic material may be employed as a material for forming the liquid interlayer film 54p. In this case as well, the liquid interlayer film 54p can be prevented from getting wet to the upper end of the liquid post 34p.

  By the way, when the dispersion medium of the liquid post 34p is volatilized and the conductive post is baked, the hydrophilicity is lost. Along with this, the phase separation property with the liquid interlayer film 54p disappears, so that the liquid interlayer film 54p in contact with the conductive post wets the upper end portion of the conductive post. When the liquid interlayer film 54p is cured in this state, an interlayer insulating film is formed on the upper end portion of the conduction post.

  Therefore, as shown in FIG. 5B, UV 72 is irradiated to cure the liquid interlayer film 54p prior to the liquid post 34p (step 16). Specifically, UV 72 having a wavelength of 365 nm is irradiated for about 60 seconds to cure the UV curable resin that is a material for forming the liquid interlayer film 54p. Thereby, the interlayer insulating film 54 is formed. In addition, since the heating action by UV irradiation is small, the liquid post is maintained in a temporarily dried state without being fired. Therefore, it is possible to cure the liquid interlayer film 54p while maintaining phase separation from the liquid post, and the liquid interlayer film 54p wets the upper end of the liquid post 34p in the process of curing the liquid interlayer film 54p. There is no.

Next, as shown in FIG. 5C, the liquid post 34p is fired by heating with the hot plate 74 (step 17). Specifically, the film substrate 31 on which the liquid post 34p is formed is heated by a hot plate at 150 ° C. for about 30 minutes. Then, the dispersion medium contained in the liquid post 34p is volatilized from the upper end portion thereof, electrical contact between the conductive fine particles is ensured, and the conductive post 34 is fired.
As described above, it is possible to prevent the interlayer insulating film from being formed on the upper end portion of the conductive post 34.

  In this embodiment, a thermosetting material in a broad sense that the dispersion medium is volatilized by heating to disperse the dispersoid is used as the formation material (first droplet) of the liquid post 34p, and the formation material (formation of the liquid interlayer film 54p ( The UV curable material is adopted as the second droplet), but conversely, the UV curable material is adopted as the liquid post 34p forming material (first droplet) and the liquid interlayer film 54p forming material ( A thermosetting material may be adopted as the second droplet). In this case, first, the liquid interlayer film 54p may be cured by heating with a hot plate or the like, and then the liquid post 34p may be cured by irradiation with UV.

  Thus, if one of the first droplet and the second droplet is made of a thermosetting material and the other is made of a UV curable material, the liquid interlayer film is first cured, The process of curing the liquid post can be easily performed. As a result, the liquid interlayer film 54p can be cured while maintaining phase separation from the liquid post 34p, and the liquid interlayer film 54p wets the upper end of the liquid post 34p in the process of curing the liquid interlayer film 54p. It will not go up. Therefore, it is possible to prevent the interlayer insulating film from being formed on the upper end portion of the conductive post 34.

Next, as shown in FIG. 2B, an upper electrical wiring 36 is formed on the surface of the interlayer insulating film 54. The specific method is the same as Step 6 to Step 10 for forming the lower-layer electric wiring 32.
Next, an in-layer insulating film 56 is formed on the formation layer of the electrical wiring 36. The specific method is the same as Step 11 to Step 14 for forming the in-layer insulating film 52 in the formation layer of the electric wiring 32. Furthermore, if Step 15 and Step 16 are performed, an interlayer insulating film can be formed on the surface of the upper electrical wiring 36.

Thus, by repeating Step 6 to Step 16, the electrical wiring can be arranged in a stacked manner. A protective film 58 may be formed on the surface of the uppermost electrical wiring by the same method as in Step 15 and Step 16.
As described above, the wiring pattern of this embodiment shown in FIG. 2 is formed.

As described above, in the wiring pattern forming method of this embodiment, the step of discharging the first droplet by the droplet discharge method to draw and form the liquid post at the formation position of the conductive post (step 9), the droplet And a step of drawing and forming a liquid interlayer film in a region other than the formation position of the conductive post by discharging the second droplet by a discharging method (step 15), and the first droplet and the second droplet are mutually It was set as the structure comprised with the material which shows phase-separation property.
According to this configuration, even if the liquid interlayer film flows and comes into contact with the liquid post, the liquid interlayer film wets the upper end of the liquid post due to the phase separation of the first droplet and the second droplet. Absent. As a result, it is possible to prevent the interlayer insulating film from being formed on the upper end portion of the conductive post, and to ensure electrical connection between the conductive post and the upper-layer electric wiring. Therefore, it is possible to provide a wiring pattern with excellent electrical connection reliability.

In the wiring pattern forming method of this embodiment, after the step of drawing and forming the liquid interlayer film (step 15), the liquid interlayer film is first cured (step 16), and then the liquid post is cured (step 17). ) Configuration.
According to this configuration, it becomes possible to cure the liquid interlayer film while maintaining the phase separation from the liquid post, and the liquid interlayer film wets the upper end of the liquid post in the process of curing the liquid interlayer film. There is no. Therefore, it is possible to prevent the interlayer insulating film from being formed on the upper end portion of the conduction post.

  In addition, since the method for forming a wiring pattern according to the present embodiment employs a droplet discharge method for forming electric wiring, conductive posts, and various insulating films, it is possible to improve material use efficiency and reduce manufacturing costs. can do. Furthermore, the electrical wiring can be multilayered and miniaturized. For example, the line × space width of a plurality of electrical wirings can be reduced from the conventional 50 μm × 50 μm to about 30 μm × 30 μm. As a result, the FPC can be miniaturized, and the electro-optical device and electronic apparatus that employ the FPC can be miniaturized.

  In the present embodiment, the wiring pattern forming method in the FPC has been described as an example, but the present invention can also be applied as a wiring pattern forming method in a hard substrate. Moreover, although this embodiment demonstrated the case where a conduction post was formed in the edge part of electrical wiring, the case where a conduction post is formed on the electrode land of electrical wiring is also contained in the technical scope of this invention.

(Droplet discharge device)
Next, a droplet discharge apparatus used for the droplet discharge method will be described with reference to FIGS.
FIG. 6 is a perspective view of the droplet discharge device. In FIG. 6, the X direction is the left-right direction of the base 12, the Y direction is the front-rear direction, and the Z direction is the up-down direction. The droplet discharge device 10 mainly includes a droplet discharge head (hereinafter simply referred to as a head) 20 and a table 46 on which a substrate 31 is placed. The operation of the droplet discharge device 10 is controlled by the control device 23.

  The table 46 on which the substrate 31 is placed can be moved and positioned in the Y direction by the first moving means 14, and can be swung and positioned in the θz direction by the motor 44. On the other hand, the head 20 can be moved and positioned in the X direction by the second moving means, and can be moved and positioned in the Z direction by the linear motor 62. The head 20 can be swung and positioned in the α, β, and γ directions by motors 64, 66, and 68, respectively. Accordingly, the droplet discharge device 10 can accurately control the relative position and posture between the ink discharge surface 20P of the head 20 and the substrate 31 on the table 46.

  Here, a structural example of the head 20 will be described with reference to FIG. FIG. 7 is a side sectional view of the droplet discharge head. The head 20 discharges the ink 21 from the nozzle 91 by a droplet discharge method. Various known technologies such as a piezo method in which ink is ejected using a piezoelectric element as a piezoelectric element, and a method in which ink is ejected by bubbles generated by heating the ink are applied as a droplet ejection method. can do. Of these, the piezo method has the advantage that it does not affect the composition of the material because it does not apply heat to the ink. Therefore, the above-described piezo method is adopted for the head 20 of FIG.

  A head body 90 of the head 20 is formed with a reservoir 95 and a plurality of ink chambers 93 branched from the reservoir 95. The reservoir 95 is a flow path for supplying ink to each ink chamber 93. A nozzle plate that constitutes an ink ejection surface is attached to the lower end surface of the head main body 90. In the nozzle plate, a plurality of nozzles 91 for discharging ink are opened corresponding to the respective ink chambers 93. An ink flow path is formed from each ink chamber 93 toward the corresponding nozzle 91. On the other hand, a diaphragm 94 is attached to the upper end surface of the head main body 90. The diaphragm 94 constitutes a wall surface of each ink chamber 93. Piezo elements 92 are provided outside the diaphragm 94 so as to correspond to the ink chambers 93. The piezo element 92 is obtained by holding a piezoelectric material such as crystal between a pair of electrodes (not shown). The pair of electrodes is connected to the drive circuit 99.

  When an electric signal is input from the drive circuit 99 to the piezo element 92, the piezo element 92 is expanded or contracted. When the piezo element 92 contracts and deforms, the pressure in the ink chamber 93 decreases, and the ink 21 flows from the reservoir 95 into the ink chamber 93. When the piezo element 92 expands and deforms, the pressure in the ink chamber 93 increases and the ink 21 is ejected from the nozzle 91. Note that the amount of deformation of the piezo element 92 can be controlled by changing the applied voltage. Further, the deformation speed of the piezo element 92 can be controlled by changing the frequency of the applied voltage. That is, by controlling the voltage applied to the piezo element 92, the ejection conditions of the ink 21 can be controlled.

  The capping unit 22 shown in FIG. 6 is for capping the ink ejection surface 20P when the droplet ejection apparatus 10 is on standby to prevent the ink ejection surface 20P of the head 20 from drying. The cleaning unit 24 sucks the inside of the nozzles in order to remove clogging of the nozzles in the head 20. The cleaning unit 24 can also wipe the ink discharge surface 20P in order to remove dirt on the ink discharge surface 20P in the head 20.

[Electro-optical device]
In the present embodiment, the wiring pattern formed on the FPC has been described as an example. Returning to FIG. 1, a liquid crystal module as an example of an electro-optical device employing the FPC will be described.
FIG. 1 is an exploded perspective view of a liquid crystal module having a COF (Chip On Film) structure. The liquid crystal module 1 roughly includes a color display liquid crystal panel 2, an FPC 30 connected to the liquid crystal panel 2, and a liquid crystal driving IC 100 mounted on the FPC 30. Note that an illumination device such as a backlight and other auxiliary devices are attached to the liquid crystal panel 2 as necessary.

  The liquid crystal panel 2 has a pair of substrates 5a and 5b bonded by a sealing material 4, and liquid crystal is sealed in a so-called cell gap formed between the substrates 5b and 5b. In other words, the liquid crystal is sandwiched between the substrate 5a and the substrate 5b. These substrates 5a and 5b are generally formed of a translucent material such as glass or synthetic resin. A polarizing plate 6a is attached to the outer surfaces of the substrate 5a and the substrate 5b.

  An electrode 7a is formed on the inner surface of the substrate 5a, and an electrode 7b is formed on the inner surface of the substrate 5b. These electrodes 7a and 7b are formed of a light-transmitting material such as ITO (Indium Tin Oxide). The substrate 5a has a projecting portion that projects from the substrate 5b, and a plurality of terminals 8 are formed on the projecting portion. These terminals 8 are formed simultaneously with the electrodes 7a when the electrodes 7a are formed on the substrate 5a. Accordingly, these terminals 8 are made of, for example, ITO. These terminals 8 include one that extends integrally from the electrode 7a and one that is connected to the electrode 7b via a conductive material (not shown).

  On the other hand, wiring patterns 39a and 39b are formed on the surface of the FPC 30 by the wiring pattern forming method according to the present embodiment. That is, the input wiring pattern 39a is formed from one short side to the center of the FPC 30, and the output wiring pattern 39b is formed from the other short side to the center. Electrode pads (not shown) are formed at the ends on the center side of the input wiring pattern 39a and the output wiring pattern 39b.

  A liquid crystal driving IC 100 is mounted on the surface of the FPC 30. Specifically, a plurality of bump electrodes formed on the active surface of the liquid crystal driving IC 100 with respect to a plurality of electrode pads formed on the surface of the FPC 30 are ACF (Anisotropic Conductive Film) 160. Connected through. The ACF 160 is formed by dispersing a large number of conductive particles in a thermoplastic or thermosetting adhesive resin. As described above, the so-called COF structure is realized by mounting the liquid crystal driving IC 100 on the surface of the FPC 30.

  The FPC 30 including the liquid crystal driving IC 100 is connected to the substrate 5 a of the liquid crystal panel 2. Specifically, the output wiring pattern 39b of the FPC 30 is electrically connected to the terminal 8 of the substrate 5a via the ACF 140. Since the FPC 30 has flexibility, it can be space-saving by freely folding it.

  In the liquid crystal module 1 configured as described above, a signal is input to the liquid crystal driving IC 100 via the input wiring pattern 39 a of the FPC 30. Then, a driving signal is output from the liquid crystal driving IC 100 to the liquid crystal panel 2 via the output wiring pattern 39b of the FPC 30. As a result, an image is displayed on the liquid crystal panel 2.

  Note that the electro-optical device of the present invention includes a device having an electro-optic effect that changes the light transmittance by changing the refractive index of a substance by an electric field, and a device that converts electric energy into optical energy. ing. That is, the present invention is not limited to a liquid crystal display device, but an organic EL (Electro-Luminescence) device, an inorganic EL device, a plasma display device, an electrophoretic display device, and a display device using an electron-emitting device (Field Emission Display and Surface- It can also be widely applied to light emitting devices such as Conduction Electron-Emitter Display. For example, an organic EL module can be configured by connecting an FPC having the wiring pattern of the present invention to an organic EL panel.

[Electronics]
Next, an electronic apparatus manufactured using the film forming method of this embodiment will be described with reference to FIG. FIG. 8 is a perspective view of the mobile phone. In FIG. 8, reference numeral 1000 indicates a mobile phone, and reference numeral 1001 indicates a display unit. The display unit 1001 of the cellular phone 1000 employs an electro-optical device having the wiring pattern of the present embodiment. Therefore, it is possible to provide a small mobile phone 1000 with excellent electrical connection reliability.
The present invention is not limited to the above mobile phone, but is an electronic book, personal computer, digital still camera, liquid crystal television, viewfinder type or monitor direct-view type video tape recorder, car navigation device, pager, electronic notebook, calculator, word processor, work It can be suitably used as an image display means for electronic devices such as stations, videophones, POS terminals, touch panels, etc. In any case, a small electronic device with excellent electrical connection reliability can be provided.

  The technical scope of the present invention is not limited to the above-described embodiments, and includes various modifications made to the above-described embodiments without departing from the spirit of the present invention. That is, the specific materials and configurations described in the embodiments are merely examples, and can be changed as appropriate.

It is a disassembled perspective view of the liquid crystal module of a COF structure. It is explanatory drawing of the wiring pattern which concerns on embodiment. It is a process chart of the formation method of the wiring pattern concerning an embodiment. It is explanatory drawing of the formation method of the wiring pattern which concerns on embodiment. It is explanatory drawing of the formation method of the wiring pattern which concerns on embodiment. It is a perspective view of a droplet discharge device. It is side surface sectional drawing of a droplet discharge head. It is a perspective view of a mobile phone.

Explanation of symbols

  32 ... Electric wiring 34 ... Conduction post 34p ... Liquid post 36 ... Electric wiring 54 ... Interlayer insulation film 54p ... Liquid interlayer film

Claims (4)

A method of forming a wiring pattern in which a plurality of electrical wirings arranged in layers via an interlayer insulating film are connected to each other by conductive posts,
Discharging a first droplet containing a constituent material of the conductive post to form a liquid post at a position where the conductive post is formed;
Discharging a second droplet containing the constituent material of the interlayer insulating film to form a liquid interlayer film in a region other than the formation position of the conduction post,
The first droplet and the second droplet are made of a material exhibiting phase separation from each other,
Either one of the first droplet and the second droplet is made of a hydrophilic material, and the other is made of a lipophilic material.
Either one of the first droplet and the second droplet is made of a thermosetting material, and the other is made of an ultraviolet curable material,
A method of forming a wiring pattern, wherein after the step of forming the liquid interlayer film, the liquid interlayer film is first cured and then the liquid post is cured. Wherein before the step of forming a liquid interlayer film, the wiring pattern forming method according to claim 1, characterized in that to provisionally drying the surface of the liquid post. A wiring pattern manufactured using the method for forming a wiring pattern according to claim 1 . An electronic apparatus comprising the wiring pattern according to claim 3 .

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