JPH1065312A - Formation of conductor pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow formation of a conductor of a prescribed shape with high accuracy and stability by forming a thick-film conductor on a substrate in a prescribed pattern and directing a laser beam to a terminal edge of the thick film conductor, so as to sublime and remove the same part. SOLUTION: A conductor film 2 in a prescribed form is formed on a board 1, consisting of a material with high reflectance, for instance, of alumina by a screen printing method followed by drying. Then, while moving at least either of the board 1 or an optical system at a certain speed, a laser beam L is directed to a terminal edge part 2a of the conductor film 2 after drying, so as to sublime and remove the same part. Next, the board 1 with the remaining conductor film 2 is put into a heating furnace for firing a conductor film 2. Thereby, a conductor with a fine terminal edge line and a uniform thickness can be formed with high accuracy and stability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor pattern forming method for forming a conductor such as a land on a substrate.

[0002]

2. Description of the Related Art A screen printing technique and a photolithography technique are generally used for forming such a conductive pattern.

In a method for forming a conductor pattern using a screen printing technique, a conductor paste is printed on a substrate through a screen in a predetermined pattern, which is dried and fired to form a desired conductor pattern on the substrate. .

On the other hand, in a conductor pattern forming method using a photolithography technique, after a conductor film is formed on a substrate, a photoresist is applied to the surface of the conductor film to expose and expose.
A desired conductor pattern is formed on the substrate by developing, dissolving and removing an unnecessary portion to which the resist is not applied using a dissolving agent, and then removing the resist.

[0005] In addition, as shown in FIG.
01, a photosensitive conductor film 102 is formed thereon, and after drying, an ultra-high pressure mercury lamp is used as a light source to emit ultraviolet rays 103 having a wavelength of 365 to 436 nm.
Is exposed through a mask 104 and exposed (see FIG. 3A), unnecessary portions of the unexposed conductor film 102 are dissolved and removed using an alkali developing solution, and then the unnecessary portions are removed. In some cases, a desired conductor pattern is formed on the substrate by baking the conductor film 102a on the substrate 101 (see FIG. 2B).

[0006]

However, the conventional method of forming a conductor pattern using a screen printing technique requires a low cost, but it is difficult to control the viscosity of the conductor paste. Difficult to form. Also, the thickness of the conductor is easily changed due to the difference in the conductor width, and the edge line of the conductor is easily disturbed. Is unstable.

On the other hand, the conventional conductor pattern forming method using the photolithography technique has a disadvantage that the cost is considerably higher than the screen printing method due to the complicated process, and the exposure and exposure of the conductor film near the substrate are difficult. It is difficult to sufficiently perform exposure, and as a result, a portion of the conductor film near the substrate is depressed during dissolution and removal, so that the edge line of the conductor is disturbed and the formed conductor is likely to fall off the substrate.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a conductor pattern forming method capable of forming a conductor having a desired shape with high accuracy and stability.

[0009]

According to a first aspect of the present invention, there is provided a method for forming a conductor pattern, comprising the steps of: forming a thick film conductor on a substrate in a predetermined pattern; The edge is irradiated with laser light to sublimate the same,
And a removing step. According to this conductor pattern forming method, a conductor having a clean edge line and a uniform thickness can be formed by irradiating a laser beam to the edge portion of the thick film conductor and sublimating and removing the portion.

According to a second aspect of the present invention, there is provided a method of forming a conductor pattern, comprising: forming a thick film conductor on a substrate in a predetermined pattern; irradiating a part of the thick film conductor with laser light to sublimate unnecessary portions; Removing and forming a component mounting portion. According to this method of forming a conductor pattern, by irradiating a part of the thick film conductor with a laser beam to sublimate and remove unnecessary portions to form a component mounting portion, a component having a clean edge line and a uniform thickness is formed. A conductor having a mounting portion can be formed.

According to a fifth aspect of the present invention, there is provided a method of forming a conductive pattern, comprising: forming a photosensitive thick film conductor on a substrate; and irradiating a required portion of the thick film conductor with a laser beam to cause a photosensitive reaction. And a step of dissolving and removing an unnecessary portion of the thick film conductor which does not cause a photosensitive reaction using a dissolving agent. According to this method of forming a conductor pattern, a necessary portion of the thick film conductor is irradiated with laser light to cause a photosensitive reaction, and an unnecessary portion of the thick film conductor that does not cause the photosensitive reaction is dissolved and removed using a dissolving agent. Thus, a conductor having a clean edge line and a uniform thickness can be formed.

[0012]

FIG. 1 shows a conductive pattern forming method according to a first embodiment of the present invention. First, FIG.
As shown in (a), a conductor film 2 having a predetermined shape is formed on a substrate 1 made of a material having a high reflectivity, for example, alumina by a screen printing method, and this is dried. Drying conditions are about 120 to 150 ° C. for about 15 minutes. The shape of the conductor film 2 formed here depends on the conductor (FIG. 1) to be finally obtained.
(Refer to 2 'of (e)) and is similar to FIG.

In the above screen printing, Ag, Ag-
A conductor paste prepared by mixing a solvent, a binder and a glass frit with a metal powder selected from Pd, Au, Cu, Ni or the like is used. The glass frit mixed into the conductive paste is for enhancing the adhesion between the conductive film 2 and the substrate 1, and preferably has a softening point of 400 to 700 ° C. in an amount of 5 to 20 vol% based on the metal powder. You.

Next, as shown in FIGS. 1B and 1C,
While moving at least one of the substrate 1 and the optical system (not shown) at a constant speed, the edge portion 2 of the dried conductive film 2
a, in other words, an unnecessary portion (the hatched portion in FIG. 1B) of the conductive film 2 is irradiated with the laser beam L to sublimate and remove the portion.

The laser light L has a continuous pulse wave having a wavelength of 1064.1 nm, an output of 0.4 to 1.0 W, and a frequency of 3
ＡＧ7 KHz YAG laser light is used. When the width of the portion to be removed is larger than the spot diameter of the irradiation laser light L, the above-described partial removal is performed by scanning the laser light L a plurality of times.

As shown in FIGS. 1D and 1E, an unnecessary portion of the initially formed conductor film 2 is removed by irradiating a laser beam, whereby a conductor film 2 'having a desired shape is formed.
Created above.

Next, the substrate 1 on which the conductor film 2 'is left is put into a heating furnace (not shown), and the conductor film 2' is fired. The firing conditions are about 600 to 850 ° C. for about 10 minutes. When the metal powder contained in the conductor paste is Cu or Ni, the firing is performed in a nitrogen atmosphere or an argon atmosphere.

Thus, the formation of the conductor pattern is completed. Incidentally, a semiconductor element P as shown in FIG. 1E is mounted face-down on the conductor obtained in this embodiment.

According to the conductor pattern forming method according to this embodiment, the edge 2a of the conductor film 2 is irradiated with the laser beam L to sublimate and remove the edge, so that the edge line is clean and the thickness is small. Can be formed stably with high accuracy. In addition, since a conductor having a flat surface can be obtained, there is an advantage that a contact area between the conductor and an electrode of the mounted component can be secured and the mounted component can be stably supported. Furthermore, since the conductor film 2 before firing, that is, the conductor film 2 in a state where the solvent is left is irradiated with the laser beam L to perform partial removal, the absorptance of the conductor film 2 for the laser beam is reduced. It is possible to increase the processing accuracy.

FIG. 2 shows a method for forming a conductor pattern according to a second embodiment of the present invention. First, as shown in FIG. 2A, a conductor film 3 having a predetermined shape is formed on a substrate 1 made of a material having a high reflectance, for example, alumina by a screen printing method, and this is dried. Drying conditions are 120 ~
150 ° C. for about 15 minutes. The shape of the conductor film 3 formed here is such that the component mounting portion of the conductor finally obtained (see 3 ′ in FIG. 2E) is continuous and the portion is large.

In the above screen printing, Ag, Ag-
A conductor paste prepared by mixing a solvent, a binder and a glass frit with a metal powder selected from Pd, Au, Cu, Ni or the like is used. The glass frit mixed in the conductive paste is for enhancing the adhesion between the conductive film 3 and the substrate 1, and preferably has a softening point of 400 to 700 ° C. in an amount of 5 to 20 vol% based on the metal powder. You.

Next, as shown in FIGS. 2B and 2C,
While moving at least one of the substrate 1 and an optical system (not shown) at a constant speed, a part 3a of the component mounting portion of the dried conductor film 3, in other words, an unnecessary portion of the conductor film 3 (FIG. 2)
The hatched portion (b) is irradiated with the laser beam L to sublimate and remove the portion.

The laser light L has a continuous pulse wave having a wavelength of 1064.1 nm, an output of 0.4 to 1.0 W, and a frequency of 3
ＡＧ7 KHz YAG laser light is used. When the width of the portion to be removed is larger than the spot diameter of the irradiation laser light L, the above-described partial removal is performed by scanning the laser light L a plurality of times.

As shown in FIGS. 2D and 2E, an unnecessary portion of the first formed conductive film 3 is removed by irradiating a laser beam, thereby forming a conductive film having a desired shape having a component mounting portion 3b. 3 'is created on the substrate 1.

Next, the substrate 1 on which the conductor film 3 'is left is put into a heating furnace (not shown), and the conductor film 3' is fired. The firing conditions are about 600 to 850 ° C. for about 10 minutes. When the metal powder contained in the conductor paste is Cu or Ni, the firing is performed in a nitrogen atmosphere or an argon atmosphere.

Thus, the formation of the conductor pattern is completed. Incidentally, a semiconductor element P as shown in FIG. 2E is mounted face-down on the conductor obtained in the present embodiment. Also, a wiring conductor film 4 is formed on the substrate 1 in a predetermined pattern before the components are mounted, so that the end overlaps the conductor film 3 ′,
It is fired together with the conductor film 3 '.

According to the method for forming a conductor pattern according to the present embodiment, the part 3a is sublimated and removed by irradiating a part of the conductor film 3 with the laser beam L to form the component mounting part 3b. Compared with the method shown in the first embodiment, the time required for partial removal can be shortened and the number of steps can be simplified.
Other effects are the same as those of the first embodiment.

In the first and second embodiments, the residue S generated at the time of partially removing the conductor films 2 'and 3' before firing is reduced as shown in FIG. In the case where it adheres to the surfaces of the conductor films 2 and 3 ', a processing jig 5 having a flat surface is pressed against the surfaces of the conductor films 2' and 3 'before firing as shown in FIG. S may be pushed in to flatten the surface, or a laser beam may be applied again to the residue adhering portion to remove it. Further, in order to further improve the processing accuracy by laser beam irradiation, the conductive film 2
In order to enhance the laser light absorbing property of No. 3, carbon, an organic dye, a low melting point metal powder, etc. may be added to the conductor paste in advance.

In the first and second embodiments, the conductor film before firing is irradiated with laser light. Partial removal may be performed. In this case,
Processing accuracy can be improved by avoiding the effect of contraction of the conductor film that may occur when the conductor film before firing is irradiated with laser light.

In order to further improve the processing accuracy when irradiating the fired conductor film with laser light, it is preferable to add cobalt powder to the conductor paste in advance in order to increase the laser light absorption of the conductor film. . In the case where the properties of the conductor are changed by the addition of the cobalt powder, the continuous pulse wave has a wavelength of 355 nm (third high frequency) or 266 nm.
It is preferable to use (fourth high frequency) YAG laser light, and the shorter the wavelength of the metal material, the better the laser light absorbency, and hence the higher the processing accuracy.

When the characteristics of the conductor are changed by irradiating the sintered conductor film with the YAG laser beam, unnecessary portions may be removed by excimer laser beam. And the characteristic change can be suppressed.

Further, in a case where the residue S generated during the partial removal of the baked conductor film adheres to the surface of the conductor film 6 as shown in FIG. Irradiation may be performed to remove this. If the re-irradiation causes an adverse effect on the conductor (such as damage to an edge portion), the conductor may be polished by sandblasting.

Incidentally, when the surface of the conductor film 6 after partial removal is slightly curved as shown in FIG. 4 and residue S adheres to the end of the surface, it is not always necessary to remove the residue S. Instead, the contact area between the conductor and the electrode of the mounted component is increased by using the residue S attached to the surface end, and the mounted component can be stably supported.

FIG. 5 shows a method for forming a conductor pattern according to a third embodiment of the present invention. First, as shown in FIG. 5A, a conductor film 7 having a predetermined thickness, a so-called solid pattern, is formed on a substrate 1 made of alumina or the like by a screen printing method and dried. Drying conditions are 120-15
0 ° C., about 15 minutes.

In the above screen printing, Ag, Ag-
A photosensitive conductive paste prepared by mixing a photosensitive polymer, a photopolymerization initiator, and a glass frit with a metal powder selected from Pd, Au, Cu, or the like is used. The glass frit is used to increase the adhesion between the conductive film 7 and the substrate 1, and preferably has a softening point of 400 to 700 ° C. in an amount of 5 to 20 vol% based on the metal powder.

Next, as shown in FIG. 5B, while the substrate 1 or at least one of the optical systems (not shown) is moved at a constant speed, the dried conductor film 7 is irradiated with a laser beam L, Required portion 7a of conductor film 7 (portion to be left as conductor)
To cause a photosensitive reaction.

As the irradiation laser light L, a YAG laser light having a continuous pulse wave and a wavelength of 355 nm (third high frequency) is used. The laser beam irradiation conditions (output, frequency and moving speed) are set so that the irradiated portion is sufficiently exposed and does not sublime.

Next, as shown in FIG.
Unnecessary portions (non-photosensitive portions not irradiated with laser light) are dissolved and removed with an alkali developing solution. As the alkali developer, an inorganic developer or an organic developer is selectively used depending on the type of the photosensitive polymer.

Next, the substrate 1 on which the plurality of photosensitive portions 7a are left is put into a heating furnace (not shown), and the photosensitive portions 7a are baked. The firing conditions are about 600 to 850 ° C. for about 10 minutes. When the metal powder contained in the conductor paste is Cu or Ni, the firing is performed in a nitrogen atmosphere or an argon atmosphere. Thus, the formation of the conductor pattern is completed.

According to the conductor pattern forming method according to the present embodiment, the necessary portion 7a of the conductor film 7 is irradiated with the laser beam.
Can be performed instantaneously and sufficiently, so that when unnecessary portions of the conductive film 7 (non-photosensitive portions not irradiated with the laser beam) are dissolved and removed with an alkali developing solution, the portions 7a near the substrate are depressed. As a result, a conductor having a clean edge line and a uniform thickness can be formed with high accuracy and stability.

In the third embodiment, an example in which a plurality of band-shaped conductors are formed on a substrate is described. However, if the irradiation locus and position of the laser beam are changed, a conductor of an arbitrary shape is formed on the substrate. be able to.

As the irradiation laser light, an excimer laser light of XeFe (wavelength: 351 nm) may be used instead of the YAG laser light. In this case, the photosensitive reaction is promoted as compared with the case of irradiating the YAG laser light. Can be done.

As shown in FIG. 6, when the conductor film is irradiated with laser light at a time through a mask M that matches the pattern, the photosensitive reaction of all the portions to be left as conductors is performed at the same time to improve the productivity. Can be further improved.

[0044]

As described in detail above, according to the present invention,
A conductor having a desired shape with a clean edge line and a uniform thickness can be formed with high accuracy and stability.

[Brief description of the drawings]

FIG. 1 is a view showing a conductive pattern forming method according to a first embodiment of the present invention;

FIG. 2 is a view showing a conductive pattern forming method according to a second embodiment of the present invention;

FIG. 3 is a diagram showing a modification of the method for forming a conductor pattern shown in the first and second embodiments;

FIG. 4 is a diagram showing a modification of the method for forming a conductor pattern shown in the first and second embodiments;

FIG. 5 is a view showing a conductive pattern forming method according to a third embodiment of the present invention.

FIG. 6 is a view showing a modification of the conductor pattern forming method shown in the third embodiment.

FIG. 7 is a diagram showing a conventional conductor pattern forming method using a photolithography technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... substrate, 2 ... conductor film, 2a ... unnecessary part, 2 '... conductor film after partial removal, L ... laser beam, 3 ... conductor film, 3a ... unnecessary part, 3' ... conductor film after partial removal, 3b ... Component mounting portion, S. Residue, 5: Processing jig, 6: Conductive film after partial removal, 7: Conductive film, 7a: Photosensitive portion, M: Mask.

Claims (5)

[Claims] A step of forming a thick-film conductor on a substrate in a predetermined pattern; and a step of irradiating a laser beam to an edge portion of the thick-film conductor to sublimate and remove the portion. A method for forming a conductive pattern, which is characterized by 2. A step of forming a thick-film conductor on a substrate in a predetermined pattern, and a step of irradiating a part of the thick-film conductor with laser light to sublimate and remove unnecessary portions to form a component mounting portion. A method for forming a conductor pattern, comprising: 3. The method for forming a conductor pattern according to claim 1, wherein partial removal of the thick film conductor by laser light irradiation is performed on the thick film conductor before firing. 4. The method for forming a conductor pattern according to claim 1, wherein partial removal of the thick film conductor by laser beam irradiation is performed on the thick film conductor after firing. 5. A step of forming a photosensitive thick-film conductor on a substrate, a step of irradiating a required portion of the thick-film conductor with a laser beam to cause a photosensitive reaction, and a step of forming a photosensitive conductor without a photosensitive reaction. A step of dissolving and removing unnecessary portions using a dissolving agent.