JP2005340437A - Manufacturing method of multilayer wiring substrate, electronic device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of multilayer wiring substrates with which a height of a conductor post can be controlled, and an electronic device and an electronic apparatus are obtained each including the multilayer wiring substrate. <P>SOLUTION: A manufacturing method of multilayer wiring substrates each includes a step for at least forming two wiring layers on a substrate 10, a layer insulating film provided between the wiring layers and a conductor post for conducting the wiring layers. The conductor post and the layer insulating film are formed by repeating a plurality of times an inter-wiring processing step including a first process for forming either a part 13 (15) of the conductor post or a part 14 (16) of the layer insulating film on the substrate 10 by liquid drop discharging, and a second process for forming the other of a part of the conductor post and a part of the layer insulating film by a liquid drop discharge method after the first process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer wiring board, and an electronic device and an electronic apparatus having the multilayer wiring board obtained thereby.

Conventionally, as a method of manufacturing a multilayer printed wiring board, the following processes are known.
First, a single layer substrate patterned by etching is aligned and each layer is laminated. Next, in order to electrically connect the upper and lower wiring layers, a through hole is formed at a predetermined position of the substrate. Then, the periphery of the through hole is made conductive by plating or the like, or is filled with a conductive paste to form a multilayer printed wiring board.
However, such a method cannot form a component mounting pad in the through hole portion, and the diameter of the through hole is usually about 0.3 mm. It was difficult.

Against this background, a method of manufacturing a multilayer printed wiring board for high-density mounting without using a photosensitive resin to penetrate the board is disclosed (for example, see Patent Document 1 and Patent Document 2). ). However, since this manufacturing method includes steps of photolithography and screen printing, the process becomes complicated, and a fine pattern with a ratio of line width to space width (L / S) of about 30 μm / 30 μm. Is difficult to achieve.
Therefore, a method for forming a wiring or an insulating layer by a droplet discharge method such as an ink jet method has been proposed. (For example, see Patent Document 3 and Patent Document 4)
Japanese Patent Laid-Open No. 10-284841 Japanese Patent Laid-Open No. 10-200258 JP 2003-309369 A JP 2003-318542 A

  By the way, when forming a multilayer wiring such as a multilayer printed wiring board, a conductor post is required to conduct between the lower layer wiring and the upper layer wiring. When this conductor post is also formed by a droplet discharge method such as an ink jet method, the height of the conductor post obtained by wetting and spreading becomes unstable and its control becomes difficult. Therefore, when multiple conductor posts are formed on the same plane, it is difficult to control the height of the conductor posts, resulting in variations in height between the conductor posts. There is a risk of poor conduction between the two.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a multilayer wiring board capable of controlling the height of a conductor post, and a multilayer wiring board obtained thereby. It is providing the electronic device and electronic device which become.

  In order to achieve the above object, a method for manufacturing a multilayer wiring board according to the present invention comprises at least two wiring layers on a substrate, an interlayer insulating film provided between the wiring layers, and a conductor post for conducting the wiring layers. A method for manufacturing a multilayer wiring board comprising: a first process for forming either one of the conductor post or part of the interlayer insulating film on the substrate by a droplet discharge method; After the first process, an inter-wiring process step including a second process for forming the other of the part of the conductor post and the part of the interlayer insulating film by a droplet discharge method is repeated a plurality of times. Thus, the conductive post and the interlayer insulating film are formed.

  According to this method for manufacturing a multilayer wiring board, a first process of forming either one of a conductor post or a part of an interlayer insulating film by a droplet discharge method, and a conductor after the first process Since the inter-wiring process step having the second process of forming the other part of the post and the other part of the interlayer insulating film by the droplet discharge method is repeated a plurality of times, particularly in a single inter-wiring process step The amount of wetting and spreading of the material of the conductor post placed by the droplet discharge method is smaller than when forming the conductor post at a time, and therefore the height of the resulting conductor post can be controlled by suppressing the amount of wetting and spreading. Is possible. Therefore, particularly when a plurality of conductor posts are formed in the same process to form a multilayer wiring board, it is possible to prevent a conduction failure from occurring between the wiring layers due to the height variation between the conductor posts. .

In the method for manufacturing a multilayer wiring board, the first process is preferably a process for forming a part of the conductor post by a droplet discharge method.
In this way, by forming a part of the conductor post first, it is possible to secure a desired diameter for the obtained conductor post, and it is possible to reliably prevent poor conduction between the wiring layers.

In the method for manufacturing a multilayer wiring board, it is preferable to use a photo-curing insulating material as a material for forming the interlayer insulating film.
In this way, the interlayer insulating film can be selectively cured without affecting the material of the conductor post, for example, by performing the curing process of the interlayer insulating film by light irradiation at each inter-wiring processing step. Therefore, the continuity of the obtained conductor post can be ensured.

In this method of manufacturing a multilayer wiring board, it is preferable to use a solventless insulating material as a material for forming the interlayer insulating film.
By doing so, there is no reduction in the film thickness corresponding to the solvent during curing, and therefore it becomes easy to control the film thickness of the interlayer insulating film to a desired thickness.

In the method for manufacturing a multilayer wiring board, it is preferable that the inter-wiring processing step is repeated a plurality of times, and then the formed conductor post portions are collectively fired to form conductor posts.
In this way, the process is simplified, the continuity of the conductor post is ensured, and the conductivity is improved.

The electronic device of the present invention has a multilayer wiring board having at least two wiring layers on a substrate, an interlayer insulating film provided between the wiring layers, and a conductor post that conducts between the wiring layers. In this electronic device, the interlayer insulating film and the conductor post are manufactured by the manufacturing method described above.
According to this electronic device, since the height of the obtained conductor post can be controlled, the electronic device itself can be miniaturized and refined.

The electronic device of the present invention includes a multilayer wiring board having at least two wiring layers on a substrate, an interlayer insulating film provided between the wiring layers, and a conductor post that conducts between the wiring layers. In this electronic device, the interlayer insulating film and the conductor post are manufactured by the manufacturing method described above.
According to this electronic apparatus, since the height of the obtained conductor post can be controlled, the electronic apparatus itself can be miniaturized and refined.

The present invention will be described in detail below.
1 to 3 are process diagrams showing an embodiment of a method for producing a multilayer wiring board according to the present invention.
<Conductive ink>
First, the conductive ink as a liquid discharged from the droplet discharge device will be described. In this embodiment, a gold fine particle dispersion (trade name “Perfect Gold” manufactured by Vacuum Metallurgical Co., Ltd.) in which gold fine particles having a diameter of about 10 nm are dispersed in toluene is diluted with toluene, and the viscosity thereof is 5 [mPa · s]. The surface tension is adjusted to about 20 mN / m, and this liquid is used as a conductive ink for forming wiring and conductor posts.

<Ink repellent treatment process>
In addition, as a substrate on which such conductive ink is arranged (applied), for example, a substrate made of polyimide is used, and the ink application surface of such a substrate is previously repelled prior to application of the conductive ink. Ink treatment (liquid repellent treatment) is preferably performed. By performing the ink repellent treatment in this way, the position of the conductive ink or the like discharged (applied) onto the substrate 10 can be controlled with higher accuracy.

That is, first, as shown in FIG. 1A, a substrate 10 made of polyimide is prepared, washed with IPA (isopropyl alcohol), and then irradiated with ultraviolet rays having a wavelength of 254 nm at an intensity of 10 mW / cm ² for 10 minutes. Then, further cleaning (ultraviolet irradiation cleaning) is performed. Subsequently, in order to perform an ink-repellent treatment on the substrate 10, 0.1 g of hexadecafluoro 1,1,2,2 tetrahydrodecyltriethoxysilane and the substrate 10 are placed in a sealed container having a volume of 10 liters, and are heated at 120.degree. Hold for hours. Thereby, an ink-repellent monomolecular film can be formed on the surface of the substrate 10. The surface of the substrate 10 on which the monomolecular film is formed has a contact angle with the conductive ink of, for example, about 60 °.

However, such a contact angle of about 60 ° is too large for ejecting (drawing) the conductive ink by a droplet ejection method to form a wiring. Therefore, the substrate 10 is irradiated with ultraviolet rays having the same wavelength (254 nm) as that for the cleaning, for example, for 2 minutes. As a result, the contact angle of the surface of the substrate 10 with the conductive ink can be adjusted to about 35 °.
A receiving layer may be formed instead of the ink repellent treatment. That is, for example, a porous layer having porous silica particles, alumina, alumina hydrate, and the like and a binder, or a polymer that swells and absorbs ink with a hydrophilic polymer is used as a receiving layer. You may form on the surface of this.

<Lower layer wiring formation process>
Next, as shown in FIG. 1A, the conductive ink is ejected as droplets 31 from the inkjet head 30 of the droplet ejection device onto the substrate 10 on which the ink repellent treatment has been performed. For this discharge, for example, a discharge method described in Japanese Patent Application Laid-Open No. 2003-136991 can be employed. That is, a plurality of droplets 31 of the conductive ink are ejected on the substrate 10 at intervals, and then the droplets 31 are ejected again so as to fill the intervals, and the conductive ink composed of the droplets 31 is discharged. A discharge method for making the lines continuous can be suitably employed as a method for forming the wiring. A plurality of wirings 11 having, for example, a line width of 50 μm can be formed before firing by discharging by such a droplet discharging method (inkjet method).

  Here, as the inkjet head 11, for example, a commercially available printer (trade name “PM950C”) head can be used. However, in this case, since the ink suction part is made of plastic, it is preferable to use a thing in which the suction part is changed to a metal jig so as not to dissolve in the organic solvent. When the conductive ink is ejected with the drive voltage of the inkjet head 11 being 20 V, a droplet 31 having a volume of 5 picoliters can be ejected.

Then, after the pattern is discharged as described above, hot air at 100 ° C. is applied to the substrate 10 for 15 seconds in order to dry the solvent of the conductive ink, and then naturally cooled for several minutes until the substrate 10 returns to room temperature.
As another drying method, heating may be performed for 30 seconds on a hot plate at 80 ° C.
Further, in order to increase the film thickness, the same droplet discharge and hot air drying as described above are repeated as appropriate, and then baking is performed at 300 ° C. for 30 minutes. As shown in FIG. A plurality of lower layer wirings 12 having a specific resistance of about 5 μΩcm are formed.

<Inter-wiring process>
Next, in order to form a part of the conductor post as a first treatment at a predetermined position on the lower layer wiring 12, the conductive ink is applied by a droplet discharge method using the inkjet head (not shown). As shown in FIG. 2A, a plurality of conductive portions 13 having a height of about 3 μm are formed before firing. At this time, the amount of the conductive ink that forms the conductive portion 13 is smaller than that in the case where the conductor post is formed at a time, so that the amount of wetting and spreading is suppressed, and therefore the height thereof is almost set without variation. As a result, there is almost no variation between the plurality of conductive portions 13 formed.

  Subsequently, in order to form a part of the interlayer insulating film as a second treatment around the formed conductive portion 13, the conductive portion 13 is formed by a droplet discharge method using the ink jet head (not shown). A liquid insulating material is disposed around the insulating layer 14 and an insulating layer 14 having the same height as the conductive portion 13 is formed in a state where the upper surface side of the conductive portion 13 is exposed as shown in FIG. As an insulating material for forming the insulating layer 14, that is, an insulating material for forming the interlayer insulating film, for example, an epoxy acrylate resin UVF-10G (product of Asahi Chemical Co., Ltd.) is used. Name) is used.

Since this insulating material is an ultraviolet irradiation curable type (photo-curable type) and a solvent-free type (solvent-free type), almost no change (decrease) in film thickness occurs before and after curing. It is easy to form at almost the same height as the portion 13. Therefore, when such an insulating material is arranged around the conductive portion 13, the insulating material is then fully cured by irradiating the insulating material with, for example, ultraviolet light having a wavelength of 357 nm at an illuminance of 50 mW / cm ² for about 1 minute. As described above, the insulating layer 14 is formed at substantially the same height as the conductive portion 13.
Here, the surface of the insulating material disposed around the conductive portion 13 becomes flat due to the self-leveling effect, and thus the surface of the obtained insulating layer 14 also becomes flat.
In addition, the conductive portion 13 formed earlier is not affected by the irradiation of ultraviolet rays, and therefore does not cure.

When the conductive portion 13 (part of the conductor post) and the insulating layer 14 (part of the interlayer insulating film) are sequentially formed in the inter-wiring processing step including the first processing and the second processing, Repeat the inter-wiring process.
That is, as shown in FIG. 2C, the conductive ink is again disposed on the conductive portion 13 by a droplet discharge method (inkjet method), and the conductive portion 15 is formed continuously with the conductive portion 13. Also here, the amount of the conductive ink forming the conductive portion 15 is smaller than that in the case where the conductor post is formed at a time, so that the amount of wetting and spreading is suppressed, and therefore the height thereof is almost set without variation. Thus, there is almost no variation between the plurality of conductive portions 15 formed.

Subsequently, the insulating material is again disposed around the formed conductive portion 15 by a droplet discharge method (inkjet method), and an insulating layer having substantially the same height as the conductive portion 15 as shown in FIG. 16 is formed in a state where the upper surface side of the conductive portion 15 is exposed. Also in forming the insulating layer 16, only the insulating material can be selectively fully cured without affecting the conductive portions 13 and 15 by irradiating with ultraviolet rays as described above.
In this way, the inter-wiring process comprising the first process and the second process is repeated a plurality of times, and the thickness of the interlayer insulating film 17 formed by laminating the insulating layer 14 (16) by the number of repetitions is The desired thickness is set to about 8 μm in this embodiment.

<Conductor post formation process>
Next, as in the first process, the conductive ink is again disposed on the conductive portion 15 by a droplet discharge method (inkjet method) as shown in FIG. The conductive portion 18 is formed in a continuous state. Again, the amount of the conductive ink that forms the conductive portion 18 is smaller than that in the case where the conductor post is formed at a time, so that the amount of wetting and spreading is suppressed, and therefore the height thereof is almost set without variation. Thus, there is almost no variation between the plurality of conductive portions 18 formed.
The conductive portion 18 is formed by evaporating and removing liquid components (dispersion medium or solvent) in the conductive ink when the conductive portions 13, 15, 18 are collectively baked in the next step. This is to compensate for the decrease in thickness. That is, the conductive portion 18 is formed so as to have a thickness corresponding to a reduction in the thickness of the entire conductive portion when the conductive portions 13, 15, 18 are baked in the next step.

Next, the substrate 10 is heat-treated at 300 ° C. for 30 minutes, and the conductive portions 13, 15 and 18 are baked together. Then, the liquid component is evaporated and removed from these conductive portions 13, 15, and 18, and the remaining metal fine particles are sintered and brought into electrical contact to form a conductor post 19 as shown in FIG. The thickness (height) of the conductor post 19 obtained is reduced with respect to the sum of the film thicknesses of the conductive portions 13, 15, 18 by removing the liquid from the conductive portions 13, 15, 18 by evaporation. doing. However, since the decrease corresponds to the thickness of the conductive portion 18 as described above, the thickness (height) of the obtained conductor post 19 matches the thickness of the interlayer insulating film 17. become. At this time, the obtained plurality of conductor posts 19 have almost no variation in height (thickness), and all of them have a thickness of about 8 μm. Therefore, the top surfaces thereof are almost flush with the surface of the interlayer insulating film 17. It has become.
In the present embodiment, ten conductor posts 19 are formed in the same process. The lowest one is about 7.5 μm, and the highest one is about 8.5 μm.

<Upper wiring formation process>
Next, the conductive ink is ejected in the same manner as the formation of the lower layer wiring 12, and then baked at 300 ° C., so that the conductor post 19 is formed on the interlayer insulating film 17 as shown in FIG. The upper layer wiring 20 in contact is formed. Thereby, the multilayer wiring board 21 of the present invention is obtained.

  In such a method of manufacturing the multilayer wiring board 21, when the conductor post 19 is formed at a time by using the wet spread amount of the material of the conductor post disposed by the droplet discharge method in one inter-wiring processing step. Since the amount of wetting and spreading can be suppressed as a whole, the height of the obtained conductor post 19 can be accurately controlled. Therefore, particularly when a plurality of conductor posts 19 are formed in the same process to form the multilayer wiring board 21, there is a difference in height between the conductor posts 19 between the lower layer wiring 12 and the upper layer wiring 20. It is possible to prevent poor conduction.

  Further, in particular, in the inter-wiring processing step, a part of the conductor post 19 (conductive portion 13 (15)) is formed by the droplet discharge method as the first processing, and thus the conductive portion 13 (15) is thus formed. Is formed at the tip of the insulating layer 14 (16), so that the conductor post 19 obtained can be easily formed to have a desired diameter. Therefore, the conduction between the lower layer wiring 12 and the upper layer wiring 20 is facilitated. Defects can be reliably prevented.

Further, since an ultraviolet irradiation curable (photo curable) insulating material is used as a material for forming the interlayer insulating film 17 (insulating layers 14 and 16), the insulating layer 14 (by the ultraviolet irradiation is performed for each inter-wiring processing step) Even if the curing process of 16) is performed, the insulating layers 14 and 16 can be selectively cured without affecting the conductive portion 13 (15), and therefore, the continuity of the obtained conductor post 19 is secured. The conductivity can be improved.
Further, since a solventless type insulating material is used as a material for forming the interlayer insulating film 17 (insulating layers 14 and 16), there is no reduction in the film thickness corresponding to the solvent during curing. The film thickness can be easily controlled to a desired thickness.

  In addition, after repeating the inter-wiring process step a plurality of times, the formed conductive portions 13, 15 and 18 are collectively baked to form the conductor post 19, thereby simplifying the process and improving productivity. Furthermore, the continuity of the conductor post 19 can be ensured to improve the conductivity.

<Comparative example>
For comparison with the above embodiment, a multilayer wiring was formed as follows by a conventional method using an inkjet method.
First, in the same manner as shown in FIGS. 1A and 1B, the lower layer wiring 12 was formed on the substrate 10.
Next, the conductive ink is continuously discharged onto the substrate 10 so as to have a height (thickness) of about 8 μm before firing, in the same manner as in the above embodiment, and 10 conductive portions ( A conductor post before firing) was formed. At that time, the discharged conductive ink wets and spreads to form a bowl shape, and therefore, 15 times of overcoating are required. Moreover, it was difficult to make each height equal.

Thereafter, the formed 10 conductive portions were baked at 300 ° C. to form conductor posts. When the height (thickness) of the obtained conductor post was measured, the lowest one was about 6 μm, and the highest one was about 11 μm.
Therefore, the conductor post 19 in the present embodiment described above has less variation compared to the conductor post of the comparative example. Therefore, the method of manufacturing the multilayer wiring board of the present embodiment varies in the height (thickness) of the conductor post 19. It was found that these can be formed uniformly while suppressing the above.

In the above embodiment, the insulating layers 14 and 16 are completely cured by ultraviolet irradiation. However, the insulating layers 14 and 16 are all irradiated by ultraviolet irradiation in a short time during the curing process. Semi-curing may be performed without curing, and when the insulating layer is finally cured to form the interlayer insulating film 17, ultraviolet rays may be irradiated for a sufficient time to be fully cured. In this way, manufacturing time can be shortened and productivity can be increased.
In the above embodiment, as the first process in the inter-wiring process, a part of the conductor post 19 (conductive portion 13 (15)) is formed. Instead, the insulating layer 14 (16 ) May be formed first.

In the above embodiment, the multilayer wiring board 21 to be manufactured has a two-layer structure having the lower layer wiring 12 and the upper layer wiring 20 on the substrate 10 and the conductor posts 19 that conduct between these wirings. The present invention is not limited to this, and can also be applied to the production of a multilayer wiring board having a three-layer structure or a structure having four or more layers.
In addition, the multilayer wiring board obtained by such a manufacturing method of the multilayer wiring board is used for various electronic devices configured to include, for example, a semiconductor element, etc. All electronic devices are the electronic devices of the present invention.

In addition to electronic devices, the multilayer wiring board can be applied to various display devices and drive devices, such as portable information processing devices such as word processors and personal computers, cellular phones, and wristwatch-type electronic devices. For example, it can be suitably used as a display unit in various electronic devices.
FIG. 4 is a perspective view showing a mobile phone using the multilayer wiring board as an example of such an electronic apparatus. In FIG. 4, reference numeral 1000 denotes a mobile phone body, and reference numeral 1001 denotes a display unit.
Since the electronic device (mobile phone) shown in FIG. 4 includes the multilayer wiring board, miniaturization and refinement are improved.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. Specifically, the materials and manufacturing conditions described in the embodiments are merely examples, and can be appropriately changed.

(A), (b) is process drawing which shows the manufacturing method of the multilayer wiring board of this invention. (A)-(d) is process drawing following FIG. (A)-(c) is process drawing following FIG. It is a perspective view which shows an example of an electronic device.

Explanation of symbols

10 ... substrate, 12 ... lower layer wiring (wiring layer),
13, 15, 18 ... conductive part (part of conductor post),
14, 16 ... Insulating part (part of the interlayer insulating film), 17 ... Interlayer insulating film, 19 ... Conductor post,
20 ... upper layer wiring (wiring layer), 21 ... multilayer wiring board

Claims (7)

A method for producing a multilayer wiring board comprising at least two wiring layers on a substrate, an interlayer insulating film provided between the wiring layers, and a conductor post for conducting the wiring layers,
A first process for forming either one of the conductor post or a part of the interlayer insulating film on the substrate by a droplet discharge method; and a part of the conductor post after the first process. The conductor post and the interlayer insulating film are formed by repeating an inter-wiring process step having a second process of forming the other of the interlayer insulating film and a part of the interlayer insulating film by a droplet discharge method a plurality of times. A method for manufacturing a multilayer wiring board.   2. The method of manufacturing a multilayer wiring board according to claim 1, wherein the first process is a process of forming a part of the conductor post by a droplet discharge method.   3. The method for manufacturing a multilayer wiring board according to claim 1, wherein a photo-curing type insulating material is used as a material for forming the interlayer insulating film.   4. The method of manufacturing a multilayer wiring board according to claim 3, wherein a solvent-free insulating material is used as a material for forming the interlayer insulating film.   5. The multilayer wiring according to claim 1, wherein, after the inter-wiring processing step is repeated a plurality of times, the formed conductor post portions are collectively fired to form a conductor post. A method for manufacturing a substrate. An electronic device having a multilayer wiring board having at least two wiring layers on a substrate, an interlayer insulating film provided between the wiring layers, and a conductor post that conducts between the wiring layers. And
The said interlayer insulation film and the conductor post are manufactured by the manufacturing method as described in any one of Claims 1-5, The electronic device characterized by the above-mentioned. An electronic device having a multilayer wiring board having at least two wiring layers on a substrate, an interlayer insulating film provided between the wiring layers, and a conductor post that conducts between the wiring layers. And
The said interlayer insulation film and a conductor post are manufactured by the manufacturing method as described in any one of Claims 1-5, The electronic device characterized by the above-mentioned.

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