JP2003264361A - Circuit board manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board manufacturing method in which a wiring conductor can be formed in a state that no step is formed on an insulating layer and a patterning process of etching, etc., for forming the wiring conductor can be omitted. <P>SOLUTION: A photosensitive resin film 2 is formed on a base body 1, the photosensitive resin film 2 is prebaked as an insulating layer 3, the prebaked insulator layer 3 is exposed and developed to form a negative pattern portion 8. A fluid 9 containing an organic metal and/or ultrafine particles of a metal is poured into the negative pattern portion 8, a postbaking process is performed, and thereby, the postbaked insulating layer 12 is attained, and the wiring conductor 13 is completed by sintering the metal-containing fluid 9. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a circuit board, and more particularly to a method for manufacturing a circuit board having an organic insulating layer.

The circuit board manufacturing method according to the present invention can be applied to, for example, manufacture of build-up multilayer circuit boards and multichip modules.

[0003]

2. Description of the Related Art As a circuit board having an organic insulating layer,
For example, there is a multilayer circuit board having an insulating layer made of polyimide. Such a multilayer circuit board is said to be formed by forming a patterned wiring conductor, then applying a polyimide precursor, or patterning a metal foil to be a wiring conductor on a polyimide film by etching and stacking it. Manufactured by the method.

According to the above method, a step such as etching is required for patterning the wiring conductor, which leads to an increase in the manufacturing cost of the multilayer circuit board.

Further, in the multilayer circuit board manufactured by such a method, since the insulating layer made of polyimide and the wiring conductor are not on the same plane, a step due to the thickness of the wiring conductor is neglected when multilayered. The quality of the multilayer circuit board is deteriorated.

In order to solve the above-mentioned problems, for example, as described in JP-A-6-310858, a photosensitive polyimide is exposed and developed to be patterned, and a negative pattern portion obtained by this patterning is formed. There has been proposed a method of forming a wiring conductor on the substrate. In this method, the polyimide is completely cured and then a metal film is formed on the negative pattern portion by plating.

[0007]

However, according to the above-mentioned publication, since plating is applied to form the wiring conductor in the negative pattern portion of the insulating layer made of polyimide, such plating is possible. It is necessary to perform processing for doing so in advance. For example, before forming an insulating layer made of polyimide, it is necessary to previously form a metal thin film to serve as an electric power absorbing film in plating and expose the metal thin film to the negative pattern portion. Therefore, the number of steps required to form the wiring conductor is increased by the step of forming the metal thin film, and thus the manufacturing cost of the multilayer circuit board is increased.

Therefore, an object of the present invention is to provide a method for manufacturing a circuit board, which is capable of reducing the manufacturing cost while making it difficult to form a step due to a wiring conductor while solving the above problems. Is to try.

[0009]

In order to solve the above-mentioned technical problems, a method of manufacturing a circuit board according to the present invention is provided with an insulating layer made of a photosensitive resin patterned by exposure and development. A step of producing a base body,
A step of introducing organic metal and / or ultrafine metal particles into the negative pattern portion of the insulating layer; and a step of sintering the organic metal and / or ultrafine metal particles in the negative pattern portion to form a wiring conductor Is characterized by.

In the step of producing the above-mentioned substrate, preferably, a step of forming an uncured photosensitive resin film made of a precursor of a photosensitive resin on the substrate, and heating and curing the uncured photosensitive resin film. To form an insulating layer, and a step of patterning the insulating layer by performing exposure and development processing are performed.

Further, in the step of manufacturing the substrate, the above-mentioned patterned insulating layer may be at a stage where the photosensitive resin is prebaked. In this case, a step of post-baking the photosensitive resin is further included. The step of sintering the organic metal and / or the ultrafine metal particles is preferably performed at the same time as the step of post-baking the photosensitive resin.

When the organic metal and / or the ultrafine metal particles are charged, a fluid containing the organic metal and / or ultrafine metal particles is prepared, and the fluid is poured into the negative pattern portion of the insulating layer. preferable.

The above-mentioned step of pouring the fluid is carried out, for example, by injecting the fluid into the negative pattern portion of the insulating layer by using a dispenser, or by flowing the negative pattern portion of the insulating layer by using a scraper. It is carried out so that the overflowing part is scraped off while pouring the body.

In the step of introducing the organometallic and / or ultrafine metal particles, the organometallic and / or ultrafine metal particles are preferably introduced only into the negative pattern portion of the insulating layer.

As the photosensitive resin, those containing photosensitive polyimide are preferably used.

The ultrafine metal particles preferably have an average particle size of 100 nm or less.

The organic metal and / or ultrafine metal particles are
It preferably contains at least one selected from silver, platinum, gold, palladium, copper and nickel.

When the method for manufacturing a circuit board according to the present invention is directed to a method for manufacturing a multilayer circuit board, after the above-mentioned step of introducing the organic metal and / or the ultrafine metal particles, the insulating layer is further exposed. And a step of performing a development treatment to form a second insulating layer made of a patterned photosensitive resin, and a step of introducing organic metal and / or ultrafine metal particles into the negative pattern portion of the second insulating layer. Performed and these steps are repeated as needed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view sequentially showing schematically typical steps included in a method for manufacturing a circuit board according to an embodiment of the present invention.

First, as shown in FIG. 1A, a plate-shaped substrate 1 is prepared. The substrate 1 is made of, for example, alumina or glass, which is made of a material that is electrically insulating and can withstand the temperature in the heating step performed later.

Next, as also shown in FIG. 1 (1), a precursor of a photosensitive resin such as photosensitive polyimide is applied in a solution state onto the substrate 1 and then dried to form an unreacted solution. The cured photosensitive resin film 2 is formed. The photosensitive resin precursor that forms the photosensitive resin film 2 includes
If necessary, an inorganic material filler such as a dielectric ceramic powder or an organic metal may be dispersed to adjust the dielectric constant and the like.

Next, the uncured photosensitive resin film 2 is heat-cured, so that the uncured photosensitive resin film 2 becomes the insulating layer 3 as shown in FIG. 1 (2). In the case of photosensitive polyimide, for example, first, 100 to 200 ° C.
Pre-baked at a temperature of about 300 ° C., then exposed and developed, and then post-baked at a temperature of about 300 to 400 ° C., and after the post-baking, an insulating layer provided on a circuit board as a product is obtained. . Therefore,
In this case, it should be understood that the insulating layer 3 shown in FIG. 1 (2) has been prebaked.

Next, as shown in FIG. 1C, an exposure process is performed. More specifically, the insulating layer 3 after prebaking
On the other hand, a light beam 5 such as ultraviolet rays is emitted. As a result, exposed portions 6 and unexposed portions 7 are formed in the insulating layer 3 after prebaking, corresponding to the pattern given by the photomask 4.

Next, as shown in FIG. 1 (4), a developing process is performed. More specifically, the unexposed portion 7 is dissolved in the developing solution and removed, leaving only the exposed portion 6 on the substrate 1, and as a result, the portion corresponding to the unexposed portion 7 of the insulating layer 3 after prebaking. The negative pattern portion 8 is formed on the.

As described above, the base 1 on which the patterned insulating layer 3 is formed is manufactured.

In the illustrated embodiment, the photosensitive resin used to form the insulating layer 3 is a negative type, but by changing the pattern of the photomask 4, a positive type photosensitive resin is used. Resins can also be used.

Next, as shown in FIG. 1 (5), for introducing the organic metal and / or the ultrafine metal particles 9 into the negative pattern portion 8 of the insulating layer 3 after prebaking, for example, the organic metal and / or A fluid 9 containing ultrafine metal particles (hereinafter, simply referred to as “metal-containing fluid”) 9 is poured into the negative pattern portion 8.

In pouring the metal-containing fluid 9, for example, a dispenser 10 of which a part is shown in FIG. 1 (5) is used. That is, the metal-containing fluid 9 is poured toward the negative pattern portion 8 from the nozzle portion at the tip of the dispenser 10.

Instead of the method using the dispenser 10 described above, a scraper 11 as shown by a broken line in FIG. 1 (5) is used, whereby the metal-containing fluid 9 is poured into the negative pattern portion 9 and the overflow portion is removed. It may be scraped.

As described above, when the metal-containing fluid 9 is poured into the negative pattern portion 8 by using the dispenser 10 or the scraper 11, the organic metal and / or the ultrafine metal particles are introduced into the negative pattern portion 8 only. Easy to do.

When, for example, a metal resinate is used as the organic metal, the resinate itself is a liquid, so that the metal-containing fluid 9 can be used as it is. In addition, in order to adjust the viscosity of the metal-containing fluid 9, a binder or the like may be added here.

On the other hand, when ultrafine metal particles are used, the metal-containing fluid 9 can be usually prepared by dispersing the ultrafine metal particles in a suitable liquid. Even in this case, an appropriate binder may be added in order to adjust the viscosity of the metal-containing fluid 9, and when such a binder is added, the liquid for dispersing the ultrafine metal particles may be: A solvent that can dissolve the binder is used.

In order to introduce the ultrafine metal particles into the negative pattern portion 8, the above-described metal-containing fluid 9 is used. For example, the ultrafine metal particles are introduced as they are.
Other methods may be applied.

As the metal contained in the organic metal or the metal contained in the ultrafine metal particles, for example, silver, platinum,
At least one selected from gold, palladium, copper and nickel is preferably used.

The metal used in the form of ultrafine particles is
This is because it is possible to sinter the metal at a temperature about the same as the curing temperature of the resin. From this viewpoint, the ultrafine metal particles used preferably have an average particle size of 100 nm or less.

Next, as shown in FIG. 1 (5), the photosensitive resin forming the insulating layer 3 is post-baked and the organic metal and / or ultrafine metal particles contained in the metal-containing fluid 9 are sintered. The structure is, for example, 300-4
Heat treatment is performed at a temperature of about 00 ° C. As a result, FIG.
As shown in (6), the post-baked insulating layer 12 is obtained on the substrate 1, and the negative pattern portion 8 is formed.
At, the wiring conductor 13 is obtained.

As shown in FIG. 1 (6), the wiring conductor 13
Is preferably formed in a state where no step is formed on the insulating layer 12 after post-baking. In order to obtain such a state, the following consideration is given.

Both the pre-baked insulating layer 3 and the metal-containing fluid 9 shown in FIG. 1 (5) are shrunk by heat treatment, and the post-baked insulating layer 12 shown in FIG. 1 (6) respectively. And the wiring conductor 13. in this case,
If the shrinkage rate to reach the insulating layer 12 and the shrinkage rate to reach the wiring conductor 13 are substantially the same,
In the step shown in (5), the metal-containing fluid 9 may be applied to the pre-baked insulating layer 3 so as not to cause a step.

Therefore, in order to make the shrinkage ratios equal to each other as described above, for example, the amount of the binder that may be used in the metal-containing fluid 9 is adjusted, or the metal-containing fluid 9 contains ultrafine metal particles. When the particle size is changed, the particle size of the ultrafine metal particles may be adjusted, or the particle size of the ultrafine metal particles may be plural types instead of one type, or the ultrafine metal particles may be mixed with a metal resinate as an organic metal. Things are done.

When it is difficult to make the shrinkage ratios substantially the same, the thickness of the wiring conductor 13 shown in FIG. 1 (6) should be the same as the thickness of the insulating layer 12 after post-baking. The method of adjusting the thickness of the metal-containing fluid 9 shown in FIG. 1 (5) can be adopted.

The structure shown in FIG. 1 (6) can be used as a so-called single-layer circuit board 14. On the other hand, when manufacturing the multilayer circuit board 21 as shown in FIG. 2, the steps substantially similar to the steps shown in FIG. 1 are repeated. In FIG. 2, elements corresponding to those shown in FIG. 1 are designated by the same reference numerals, and redundant description will be omitted.

Referring to FIG. 2, after the circuit board 14 shown in FIG. 1 (6) is obtained, the steps shown in FIGS. 1 (1) to 1 (4) are performed on the insulating layer 12 after post-baking. A second pre-baked insulating layer is formed through substantially the same steps as described above, and the negative pattern portion 22 of the pre-baked insulating layer is formed.
Then, the metal-containing fluid is poured into, and then heat-treated, so that the insulating layer after pre-baking becomes the second insulating layer 23 after post-baking, and the metal-containing fluid becomes the wiring conductor 24.

Further, by repeating the same steps, the third insulating layer 25 and the wiring conductor 26 after the post-baking are formed, and thereafter, these steps are repeated if necessary.

In the multilayer circuit board 21 shown in FIG. 2, the wiring conductor 1 is provided on each of the insulating layers 12, 23, 25, ....
3, 24, 26, ... Are provided, but an insulating layer without such a wiring conductor may be formed.

Although the present invention has been described above with reference to the illustrated embodiment, various other modifications are possible within the scope of the present invention.

For example, in the manufacturing method shown in FIG. 1, sintering of the metal-containing fluid 9 for obtaining the wiring conductor 13 and heat treatment of the pre-baked insulating layer 3 for obtaining the post-baked insulating layer 12 are performed. However, instead of this,
After obtaining the post-baked insulating layer 12, the metal-containing fluid 9 may be poured into the negative pattern portion 8 and thereafter the metal-containing fluid 9 may be sintered.

When the multilayer circuit board 21 shown in FIG. 2 is to be obtained, the steps shown in FIGS. 1 (1) to 1 (5) are repeated, and thereafter, heat treatment is collectively performed so that the insulating layer 12 is formed. , 23, 25, ... may be post-baked and the wiring conductors 13, 24, 26 ,.

In the above-mentioned case, a heat-resistant plate or film which has been subjected to a peeling treatment is prepared, and the process shown in FIGS. 1 (1) to 1 (5) is carried out while using this instead of the substrate 1. Then, from a heat-resistant plate or film,
The insulating layer 3 and the metal-containing fluid 9 after pre-baking are transferred one by one on the substrate 1 to obtain a laminated structure, and finally the insulating layer 3 is post-baked and the metal-containing fluid 9 is sintered. You may do it.

Next, an embodiment carried out according to the present invention will be described.

(Example 1) On a substrate made of alumina,
A negative pattern portion was formed by applying a photosensitive polyimide precursor solution (manufactured by Hitachi Chemical DuPont Micro Systems), prebaking at 150 ° C., exposing, and developing with an aqueous solution of trimethylammonium hydroxide.
Next, a slurry containing ultrafine silver particles (“perfect silver” made by vacuum metallurgy: particle size 8 nm) is poured into the negative pattern portion, and heat-treated at 350 ° C., the ultrafine silver particles are sintered to form a wiring conductor. While being formed, the polyimide precursor solution was thermoset, and the polyimide precursor solution was thermoset to form an insulating layer after post-baking.

It has been confirmed that the above-mentioned silver ultrafine particles are sintered even at a temperature of about 250 ° C.

Example 2 On a substrate made of alumina,
A negative pattern portion was formed by applying a photosensitive polyimide precursor solution (manufactured by Hitachi Chemical DuPont Micro Systems), prebaking at 150 ° C., exposing, and developing with an aqueous solution of trimethylammonium hydroxide.
Next, silver resinate (manufactured by Daiken Chemical Industry Co., Ltd.) is poured into the negative pattern portion and heat-treated at 350 ° C., the silver resinate is sintered to form a wiring conductor, and the polyimide precursor solution is thermally cured. The insulating layer after the post-baking was formed.

It has been confirmed that the above-mentioned silver resinate has a low thermal decomposition temperature and is sintered even at a temperature of about 200.degree.

Example 3 Barium titanate ultrafine particles (average particle size: 20 nm) were added to a photosensitive polyimide precursor solution (manufactured by Hitachi Chemical DuPont Microsystems), and these were mixed to uniformly disperse the particles. By doing so, a paste was obtained. Next, the paste was screen-printed on a glass substrate, prebaked at 150 ° C., exposed, and developed with an aqueous trimethylammonium hydroxide solution to form a negative pattern portion. Next, a slurry containing ultrafine silver particles (“perfect silver” made by vacuum metallurgy: particle size 8 nm) is poured into the negative pattern portion, and heat-treated at 350 ° C., the ultrafine silver particles are sintered to form a wiring conductor. At the same time as the formation, the polyimide precursor solution was thermally cured to form a post-baking insulating layer having a high dielectric constant and containing barium titanate ultrafine particles.

[0055]

As described above, according to the present invention, the wiring conductor is formed by introducing the organic metal and / or ultrafine metal particles into the negative pattern portion of the insulating layer and sintering it. Therefore, the patterning step such as etching for forming the wiring conductor can be omitted, and the wiring conductor can be formed with respect to the insulating layer.
It can be formed in a state where there is substantially no step.
Therefore, when applied to manufacture a multilayer circuit board, it is possible to prevent the step due to the wiring conductor from deteriorating the quality of the multilayer circuit board.

In the present invention, an uncured photosensitive resin film made of a precursor of a photosensitive resin is formed on a substrate, and the uncured photosensitive resin film is heat-cured to form an insulating layer, which is exposed and developed. If the insulating layer is applied to pattern the insulating layer, the negative pattern portion described above can be easily formed on the insulating layer.

When the patterned insulating layer is at a stage where the photosensitive resin is pre-baked, the organic metal and / or the ultrafine metal particles may be sintered in the step of post-baking the photosensitive resin. if,
The number of steps can be reduced.

When introducing the organometallic and / or ultrafine metal particles, a fluid containing the organometallic and / or ultrafine metal particles is prepared, and the fluid is poured into the negative pattern portion of the insulating layer. The metal and / or ultrafine metal particles can be introduced efficiently.

In the above case, the step of pouring the fluid may be performed by injecting the fluid into the negative pattern portion of the insulating layer using a dispenser or by using a scraper.
If the overflowed portion is scraped off while pouring the fluid into the negative pattern portion of the insulating layer, it is easy to introduce the organic metal and / or ultrafine metal particles into only the negative pattern portion of the insulating layer.

[Brief description of drawings]

FIG. 1 is a cross-sectional view sequentially illustrating schematically typical steps included in a method for manufacturing a circuit board according to an embodiment of the present invention.

2 is a sectional view schematically showing a multilayer circuit board 21 obtained by applying the manufacturing method shown in FIG.

[Explanation of symbols]

1 base 2 Photosensitive resin film 3 Insulation layer after prebaking 4 photo mask 5 rays 6 Exposure section 7 Unexposed area 8,22 Negative pattern part 9 Fluid containing organic metal and / or ultrafine metal particles 10 dispensers 11 scrapers 12,23,25 Insulation layer after post bake 13, 24, 26 wiring conductors 14 circuit board 21 Multilayer circuit board

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4E351 AA04 BB01 BB31 CC20 CC22                       DD04 DD05 DD06 DD19 DD20                       DD52 GG20                 5E343 AA02 AA18 BB02 BB23 BB24                       BB25 BB44 BB48 BB49 BB72                       CC63 DD20 ER12 ER18 ER35                       FF04 FF05 GG20                 5E346 AA12 AA15 CC10 CC32 CC37                       CC38 CC39 CC52 DD03 DD34                       EE32 GG19 GG22 GG28 HH21

Claims (11)

[Claims] 1. A step of producing a substrate on which an insulating layer made of a photosensitive resin patterned by exposure and development is formed, and organometallic and / or ultrafine metal particles on a negative pattern portion of the insulating layer. And a step of sintering the organic metal and / or ultrafine metal particles in the negative pattern portion to form a wiring conductor. 2. The step of forming the base comprises the steps of forming an uncured photosensitive resin film made of a precursor of the photosensitive resin on the base, and heating and curing the uncured photosensitive resin film. The method for manufacturing a circuit board according to claim 1, further comprising: a step of forming the insulating layer and a step of exposing and developing the insulating layer to pattern the insulating layer. 3. The step of producing the substrate, wherein the patterned insulating layer is at a stage of pre-baking the photosensitive resin, and further comprising a step of post-baking the photosensitive resin, The step of sintering metal and / or ultrafine metal particles is performed simultaneously with the step of post-baking the photosensitive resin.
Alternatively, the method for manufacturing a circuit board according to the item 2. 4. The step of introducing the organometallic and / or ultrafine metal particles includes the step of preparing a fluid containing the organometallic and / or ultrafine metal particles, and the fluid, the negative pattern portion of the insulating layer. The method for manufacturing a circuit board according to any one of claims 1 to 3, further comprising: 5. The method for manufacturing a circuit board according to claim 4, wherein the step of pouring the fluid is performed so as to inject the fluid into the negative pattern portion of the insulating layer using a dispenser. 6. The method according to claim 4, wherein the step of pouring the fluid is carried out by scraping the overflowed portion while pouring the fluid into the negative pattern portion of the insulating layer using a scraper. Circuit board manufacturing method. 7. The method according to claim 1, wherein in the step of introducing the organic metal and / or ultrafine metal particles, the organic metal and / or ultrafine metal particles are introduced only in a negative pattern portion of the insulating layer. A method for manufacturing a circuit board according to any one of the above. 8. The method for manufacturing a circuit board according to claim 1, wherein the photosensitive resin contains photosensitive polyimide. 9. The ultrafine metal particles have an average particle size of 1
The method for manufacturing a circuit board according to claim 1, wherein the method has a thickness of 00 nm or less. 10. The organic metal and / or ultrafine metal particles contain at least one selected from silver, platinum, gold, palladium, copper and nickel.
A method for manufacturing a circuit board according to any one of 1. 11. After the step of introducing the organic metal and / or ultrafine metal particles, further on the insulating layer,
Exposing and developing to form a second insulating layer made of a patterned photosensitive resin;
11. The method for manufacturing a circuit board according to claim 1, further comprising the step of introducing organic metal and / or ultrafine metal particles into the negative pattern portion of the insulating layer.