JP2002280692A - Method for manufacturing double-sided board having connecting conductor with metal thin film layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively manufacturing a double-sized board which is superior in precision, strength and connection reliability, and is integrated with a connecting conductor at only a necessary position. SOLUTION: A board integrated with a connecting conductor is one which comprises at least an insulating resin layer and a connecting conductor, of which insulating resin layer is composed of an organic insulating resin composition which can stand a vacuum film forming method, and which covers at least a side face of the connecting conductor. A method for manufacturing double-sized board integrated with a connecting conductor comprises the steps of: forming the connecting conductor on a base having conductivity and/or insulation properties; burying the connecting conductor in the organic insulating resin composition; exposing the connecting conductor; and forming a metal thin film layer on a face exposing the connecting conductor by the vacuum film forming method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting conductor built-in substrate having a metal thin film layer formed thereon and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the social environment surrounding us has changed drastically with the development of information communication networks. Among them, there is the growth of portable devices, and the market is expanding along with miniaturization and high functionality. For this reason, further miniaturization of semiconductor packages and a multilayer wiring board capable of mounting them at high density are required, and an interlayer connection capable of high-density wiring, that is, a high-density multilayer technology is important.

[0003] As a main multi-layering method, there is a through-hole connection combining a drilling and a plating process, which is widely and generally known. However, since holes are formed in all layers, the wiring capacity is limited. . Therefore, in order to reduce the volume of the hole in the connection portion, a build-up technique in which formation of an insulating layer, drilling, and circuit formation are repeated is becoming mainstream.
This build-up technology is roughly classified into a laser method and a photolithography method.The laser method is to irradiate a laser to make a hole in the insulating layer, while the photolithography method is a method in which a photosensitive hardening is applied to the insulating layer. Using an agent (photoinitiator), a photomask is overlaid, exposed and developed to form a hole.

Some interlayer connection methods have been proposed for the purpose of further reducing the cost and increasing the density. Among them, attention has been paid to a construction method that can omit the drilling and the conductive layer plating steps. In this method, first, a bump is formed on a wiring of a substrate by printing a conductive paste, an interlayer connection insulating material and a metal layer in a B stage state are arranged, and the bump is inserted into a molding resin by pressing. And electrically connected to the metal layer. The method of penetrating the bump has been announced in academic societies and newspapers, and is widely recognized in the printed circuit board industry. In addition, a material in which a plated wire is embedded in an elastomer such as silicon rubber in a thickness direction has been developed, and is used as a simple tool for connecting two layers of conductors.

[0005]

However, among the conventional techniques, the laser method has a wide selection range of insulating materials,
In addition to drilling holes between adjacent layers, it is also possible to drill holes to adjacent layers.However, desmearing is required to remove resin residue evaporated by laser irradiation, and processing costs increase in proportion to the number of holes There are issues. On the other hand, in the photo method, the conventional wiring board manufacturing equipment can be used, and a hole can be formed at one time, which is advantageous for cost reduction. However, the resolution of the interlayer insulating material, heat resistance, and adhesion between the circuit and the insulating layer are improved. There is a problem that it is difficult to balance strengths. Furthermore, the formation of bumps is a method of printing a conductive paste or plating, and the accuracy of bump formation is the limit of printing technology, or it is difficult to suppress variations in bump height due to plating. There are issues. In addition, the bumps made of the conductive paste have low mechanical strength, and may be broken by pressing pressure, and may require a drilling step, which may lower the efficiency. Embedding a plated wire in an elastomer such as silicon rubber in the thickness direction is easy, but it is difficult to embed the wire only at the desired point to be connected. There is a problem that the wire gets in the way where you do not want to. For this reason, a method of manufacturing a double-sided board that incorporates connection conductors only in necessary places and can cope with the formation of fine wiring is expected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently manufacturing a double-sided board having excellent precision, excellent strength, excellent connection reliability, and in which connection conductors are built in only necessary portions. .

[0007]

The present invention is characterized by the following. (1) A substrate comprising at least an insulating resin layer and a connecting conductor, wherein the insulating resin layer is made of an organic insulating resin composition that can withstand a vacuum film forming method, and covers at least a side surface of the connecting conductor. Built-in connection conductor board. (2) The double-sided substrate with a built-in connection conductor according to (1), wherein the metal thin film layer is formed on at least one surface by a vacuum film forming method. (3) On a conductive and / or insulating substrate,
Forming a connecting conductor, embedding the connecting conductor in the organic insulating resin composition, exposing the connecting conductor,
A method for producing a double-sided board with a built-in connection conductor, comprising a step of forming a metal thin film layer on a surface where the connection conductor is exposed by a vacuum film forming method. (4) The connection according to (3), wherein in the step of exposing the connection conductor, at least a part of the connection conductor tip of the organic insulating resin composition covering the connection conductor is removed with a chemical solution. A method of manufacturing a double-sided board with a built-in conductor. (5) The method according to (3) or (4), further including a step of mechanically and / or a chemical solution removing the conductive and insulating base material and a step of forming a metal thin film layer by vacuum film formation on the removed surface. A method for producing the double-sided board with a built-in connection conductor according to the above. (6) The substrate with a built-in connection conductor according to any one of (3) to (5), further comprising a step of forming a wiring pattern by electroplating using the metal thin film layer formed on at least one surface as an underlying electrode layer. How to manufacture.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The insulating resin layer used in the present invention includes:
A thermosetting resin containing a polyimide resin as a main composition, a photocurable resin containing a polyimide resin as a main composition, or a thermoplastic resin containing a thermoplastic polyimide resin as a main composition can be used. First, as a thermosetting resin having a polyimide resin as a main composition, in addition to the polyimide resin, an epoxy resin, a bismaleimide triazine resin, a cyanoacrylate resin, a phenol resin, an unsaturated polyester resin, a melamine resin, a urea resin, a polyisocyanate resin, Furan resin, resorcinol resin, xylene resin,
Mix one or more selected from benzoguanamine resin, diallyl phthalate resin, silicone-modified epoxy resin, silicone-modified polyamide-imide resin, benzocyclobutene resin, etc., and, if necessary, their curing agent, curing accelerator, etc. Can be used. These resins can be applied and dried directly on the surface of the substrate on which the connecting conductors are formed. It is also possible to cut and cut the adhesive sheet into a required size as a dry film by heating and drying to form a dry film, and to laminate or press the laminate on a substrate on which a connecting conductor is formed. As the photocurable resin having a polyimide resin as a main composition, in addition to the polyimide resin, an unsaturated polyester resin, a polyester acrylate resin, a urethane acrylate resin, a silicone acrylate resin,
A semi-cured mixture of one or more selected from epoxy acrylate resins and, if necessary, a photoinitiator, a curing agent, a curing accelerator and the like can be used. These resins can be applied and dried directly on the surface of the substrate on which the connecting conductors are formed. It is also possible to cut it into a necessary size as an adhesive sheet which has been applied, exposed, dried by heating and dried to form a dry film, and can be used by laminating or pressing it on a substrate on which a connecting conductor is formed. As a thermoplastic resin having a thermoplastic polyimide resin as a main composition, in addition to the thermoplastic polyimide resin, polycarbonate resin, polysulfone resin, polyetherimide resin, polyethylene tetrafluoride resin, hexafluoropolypropylene resin, polyether Ether ketone resin, vinyl chloride resin, polyethylene resin,
A semi-cured mixture obtained by mixing at least one selected from a polyamideimide resin, a polyphenylene sulfide resin, a polyoxybenzoate resin, and the like, and, if necessary, a curing agent and a curing accelerator thereof can be used. .
These resins can be directly applied and dried on the substrate surface on which the connecting conductor is formed, but a plastic film such as a polyethylene terephthalate film or a metal foil such as a copper foil or an aluminum foil is used as a carrier,
The adhesive sheet coated on the surface, dried by heating and dried to form a dry film may be cut into a required size, and may be laminated or pressed on a substrate on which a connecting conductor is formed. It is an effective means to increase the effect of withstanding the vacuum film forming method by kneading these insulating resins with an inorganic filler such as silica or metal oxide.

The connection conductor may be used as a wiring conductor, and can be formed by selectively etching and removing unnecessary portions of a metal foil such as a copper foil. It can also be formed by electroless plating or electrolytic plating only on the connecting conductor portion. The thickness of the connection conductor is preferably in the range of 5 to 100 μm. If the thickness is less than 5 μm, the distance between the conductor circuits to be connected is reduced, and the insulation may decrease. If the thickness exceeds 100 μm, unnecessary portions of the metal foil are selectively etched away. Alternatively, the precision of fine processing when plating is reduced, which is not preferable. More preferably, 20 to 8
The range is 0 μm.

It is important that the connecting conductor is formed so as to penetrate the insulating resin layer in the thickness direction. With this, among the conventional techniques, in a connecting tool in which a wire is embedded in an elastomer, Since wires are embedded at regular intervals, it is difficult to connect a fine circuit to be formed later, whereas the method of the present invention in which a conductor is not formed at a place where connection is not planned is accurate. Excellent for connection between circuits.

The connection conductor built-in substrate 11 is, for example, as shown in FIG.
As shown in (a), the insulating resin layer 12 and the connecting conductor 13
The connecting conductor 13 is formed so as to penetrate the insulating resin 12 in the thickness direction only at a portion where the conductor circuit is to be connected in the layer direction, and is exposed from both surfaces of the insulating resin 12. . Further, as shown in FIG. 1B, a circuit having a conductor circuit 101 on one surface of the insulating resin layer 12 may be used. As shown in FIG. There may be. As shown in FIG. 1D, a thin film metal layer 112 is formed on at least one surface of the connecting conductor substrate having such a structure where the connecting conductor is exposed, as shown in FIG. The exposed portion of the connection conductor 13 may have a structure in which a part of the tip of the connection conductor is exposed as shown in FIG.

In order to manufacture a double-sided board with a built-in connection conductor on which such a metal thin film layer is formed, for example, FIG.
As shown in (a), at least the first metal layer 21 serving as a connecting conductor and the second metal layer 22 having different removal conditions from the first metal layer 21 are formed of a composite metal foil 23 of the first metal layer 21. 2 is selectively removed, and as shown in FIG. 2 (b), the connection conductor 1
2 and an insulating resin layer 12 is formed so as to bury the connection conductor 13 as shown in FIG.
As shown in (d), the insulating resin layer 12 is polished so that the connection conductor 13 is exposed. Since the thickness of the first metal layer 21 forms the connecting conductor 13, the first metal layer 21 must be thicker than that, and the degree of the thickness is determined in the insulating resin layer 1 in the next step.
It must be determined according to the amount by which the first metal layer 21 is polished and removed in the second polishing step. Therefore, the thickness of the first metal layer 21 is preferably in the range of 5 to 100 μm. When the thickness is less than 5 μm, the distance of the conductor circuit to be connected becomes small, and the insulation property may be reduced. When the thickness exceeds 100 μm, the processing accuracy when the connection conductor is finely etched and removed. Is undesirably reduced. More preferably, it is in the range of 20 to 80 μm.
The thickness of the second metal layer 22 is preferably in the range of 5 to 100 μm. If the thickness is less than 5 μm, the mechanical strength decreases, and the first metal layer 21 is selectively removed by etching. Sometimes it is easy to bend or bend, and there is no particular problem if it exceeds 100 μm.
Is time consuming and uneconomical when removing the entire surface.
More preferably, it is in the range of 20 to 80 μm.

Further, in order to fabricate the connection conductor built-in substrate shown in FIG. 1A, the insulating resin layer 12 is polished so that the connection conductor 13 is exposed, and then the entire second metal layer 22 is removed. In order to manufacture a connection substrate as shown in FIG. 1B, the second metal layer 22 can be selectively removed to form the conductor circuit 101.

As shown in FIG. 3, the composite metal foil comprises a first metal layer 31, a second metal layer 32, and a third metal layer 33. Metal layer 3
Those having different removal conditions 3 can also be used. The reason for this is that it is not economical to form a composite metal layer only with the first metal layer 31 and the second metal layer 32. This is because copper is preferably used for the first metal layer 31 for economic reasons, and nickel or an alloy thereof is used as the second metal layer 32 having different etching removal conditions from copper. However, nickel or its alloy is more expensive than copper, and the second metal layer 31 serving as a support when the first metal layer 31 made of copper is selectively etched away to form the connection conductor 13 is preferred. The metal layer 32 of
The mechanical strength must be high, and therefore require a thick second metal layer 32, but a large amount of expensive metal must be used, which is not economical. Therefore, in order to reduce the thickness of the second metal layer 32 under different etching removal conditions and increase the mechanical strength, as shown in FIG.
Is used. In such a composite metal foil 3, the thinner the second metal layer 32 is, the better.
It is preferably in the range of 0.05 to 5 μm. 0.0
If the thickness is less than 5 μm, so-called pits (chip missing) occur because the plating film forming a layer of nickel or an alloy thereof has a deposition defect and is not sufficiently covered with the plating film because it is thin. When the layer 31 is removed by etching, the third metal layer 33 may be eroded or the etchant may remain, and the reliability of the connection may be reduced. 5μ
If it exceeds m, there is no problem in the process, but the cost of the material is high and it is not economical. The thickness of the third metal layer 33 is 5
１００100 μm, and a thickness of 5 μm
m, the mechanical strength decreases and the first metal layer 31
Is easily broken or bent when selectively removed by etching, and there is no particular problem if the thickness exceeds 100 μm, but it takes time and is not economical to remove the third metal layer 33 over the entire surface thereafter. More preferably 20-80 μm
Range.

When the three composite metal layers are used, the structure shown in FIG. 1C can be realized after polishing the insulating resin layer 12 so that the connection conductor 13 is exposed. Thereafter, the third metal layer 33 is selectively removed, and the conductor circuit 10 is removed.
1 is formed, and the structure shown in FIG. Similarly, after the step shown in FIG. 1C, the third metal layer 33 is entirely removed, and the structure shown in FIG. 1A can be obtained. After removing the third metal layer 33, the exposed second metal layer 32 can be removed. When the conductor circuit 102 is formed, the second metal layer 32 other than the conductor circuit 102 is removed. can do.

[0016]

EXAMPLE 1 As shown in FIG. 3A, the first metal layer 31 has a thickness of 70 mm.
A composite metal layer 3 made of copper having a thickness of 0.2 μm, the second metal layer 32 being nickel having a thickness of 0.2 μm, and the third metal layer 33 being made of copper having a thickness of 35 μm was prepared. As shown in FIG. 3, an etching resist 34 is formed on the surface of the first metal layer 31 in the shape of the connection conductor 13, and as shown in FIG. The first metal layer 31 was selectively etched away by spraying a process liquid (trade name, manufactured by Merstrip Co., Ltd.) to form the connection conductor 13. At this time, the etching resist 34 has a resist 401y.
25 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name)
The resist is laminated at a roll temperature of 110 ° C. and a roll speed of 0.6 m / min, and the integrated exposure amount is about 80 mJ.
Baking under an exposure condition of / cm ² and developing with a sodium carbonate solution, 20
And post-exposure in 0mJ / cm ^2. After the first metal layer 31 is selectively etched away to form the connection conductor 13,
The etching resist 34 was stripped and removed with a sodium hydroxide solution. Next, as shown in FIG. 3 (c), on the side of the connecting conductor 13 of the composite metal foil with the connecting conductor 13 thus produced, first, as the insulating resin layer 12, a silicone-modified polyamideimide was formed. An uncured resin film (20 μm thick) is placed on the side of the connection conductor 13, and silicone rubber is arranged from the outside so that the uncured film follows the connection conductor, and is placed at 175 ° C. at 4.5 MPa.
Pressed in 60 minutes. This insulating layer was obtained by the following method. BAPP (2,2-bis [4-diamine) as a diamine having three or more aromatic rings was placed in a 1-liter separable flask equipped with a faucet connected to a reflux condenser with a 25 ml water content receiver, a thermometer and a stirrer. (4-aminophenoxy) phenyl] propane) 65.7 g (0.16 mol), 33.3 g of reactive silicone oil X-22-161AS (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., amine equivalent 416) as siloxane diamine ( 0.04 mol),
80.7 g (0.42 mol) of TMA (trimellitic anhydride) and 560 g of NMP (N-methyl-2-pyrrolidone) as an aprotic polar solvent were charged.
Stirred for minutes. Then, 100 ml of toluene was charged as an aromatic hydrocarbon capable of azeotropic distillation with water, and then the temperature was increased to about 1
Reflux at 60 ° C. for 2 hours. Water is about 7.
After confirming that no more than 2 ml of water had accumulated and that no outflow of water was observed, the temperature was increased to about 190 ° C. while removing the outflow liquid accumulated in the water content measurement receiver to remove toluene. Thereafter, the solution was returned to room temperature, and 60.1 g (0.24 mol) of MDI (4,4'-diphenylmethane diisocyanate) was used as an aromatic diisocyanate.
l) was charged and reacted at 190 ° C. for 2 hours. After completion of the reaction, an NMP solution of the siloxane-containing polyamideimide was obtained. This solution varnish is applied to a glass plate,
After drying, remove the film from the glass
A μm siloxane-containing polyamideimide film was obtained. Then, an FTF (trade name, manufactured by Hitachi Chemical Co., Ltd.) made of an epoxy resin mixed with fine particles of silica at a high filling rate of 75% or more using an oligomer as a dispersant and having a thickness of 45 μm after pressure molding is used. In order to overlap and smooth the surface of the insulating resin layer 12, a copper foil 35 having a thickness of 18 μm as shown in FIG. 185 ℃
And a pressure of 4 MPa for 40 minutes.
The copper foil 35 having a thickness of 18 μm was manually peeled off by pressing and laminating and integrating. Thereafter, as shown in FIG. 3 (e), the insulating resin layer 12 is polished with an abrasive liquid obtained by mixing water-soluble olive oil and ethylene glycol as main components and diamond particles having a diameter of 3 to 6 μm. Then, the connection conductor 13 was exposed. Thereafter, as shown in FIG. 3F, the third metal layer 33 is etched and removed with the same etchant as the first metal layer 31, and further, a mel strip N950 (nickel etchant) is removed. Made by Meltex,
By using (trade name), the second metal layer 32 was removed by etching to produce the connection substrate 11 with the connection conductor 13 exposed. In the polishing step of FIG. 3E, both surfaces can be polished at once by roll polishing as shown in FIG. FIG.
As shown in FIG. 4A, a resist film is formed on both sides of an epoxy substrate 40 having a thickness of 1 mm, and a supporting substrate whose adhesive strength is adjusted by exposure is prepared. As shown in FIG. Then, the substrate 36 where the connection conductor was not exposed was temporarily fixed by roll thermocompression bonding. Next, as shown in FIG. 4C, the gap between the rotating polishing rolls 46 was polished by adjusting the load and the rotation speed. After polishing, the substrate 36 could be easily separated from the resist interface of the support substrate. It was confirmed that the productivity was dramatically improved by this. Thus, the connection conductor built-in substrate shown in FIG. 3E was obtained.
Thereafter, the third metal layer 33 and the second metal layer 32 are selectively etched, and the substrate having the built-in connection conductor 13 penetrating the insulating resin layer in the layer direction as shown in FIG. I got

Example 2 As a paste, Upicoat FS- manufactured by Ube Industries, Ltd. was used.
After screen printing using 100 L, drying was performed at 80 ° C. for 30 minutes, and curing was performed at 150 to 160 ° C. for 60 minutes to bury the conductor for connection. At the time of curing, the copper foil 35 is pressed with the roughened surface inside, and the portion of the copper foil 35 corresponding to the tip of the connection conductor is removed by photolithography, and distilled water 60 w
t%, potassium hydroxide 20 wt%, ethylenediamine 2
With a mixture of 0 wt%, the mixture is brought to 50 ° C.
After the residual polyimide was etched, the copper foil 35 was removed by etching to obtain FIG. 1 (e).

Example 3 On the surface of the substrate with a built-in connection conductor shown in FIG. 3E obtained in Example 1 on which the connection conductor was exposed, the metal layer was deposited in the order of a base metal layer and a copper layer by a vapor deposition method. Formed. Before the vapor deposition, as a cleaning of the polished surface, one type was selected from among argon, oxygen, and freon using a PR-501A type plasma processing apparatus manufactured by Yamato Scientific Co., Ltd.
The surface treatment was performed at 00 W and 80 Pa for 5 minutes. As a device used for the vapor deposition method, a vacuum vapor deposition device EBV-6DA type or a DC magnetron sputtering device MLH-6315D type manufactured by Japan Vacuum Engineering Co., Ltd. was used, and aluminum, cobalt, chromium, iron, One of molybdenum, nickel, titanium, vanadium, tungsten, zinc, zirconium, calcium, magnesium, and manganese is selected, and the pressure is set to 80 to
Adjustment was performed between 330 Pa, and a film thickness of 20 nm was formed. Thereafter, a copper layer was further formed to a thickness of 20 nm. As a result, FIG.
A substrate with a connection conductor built-in corresponding to (d) was obtained. Further, thereafter, copper sulfate plating was performed to obtain a copper layer having a predetermined thickness.

[0019]

As described above, according to the present invention, there is provided a method for manufacturing a double-sided board having excellent accuracy, excellent strength, excellent connection reliability, and in which connection conductors are built in only necessary portions. Can be provided.

[Brief description of the drawings]

FIGS. 1A to 1E are cross-sectional views for describing an embodiment of the present invention.

FIGS. 2A to 2D are cross-sectional views illustrating an embodiment of the present invention.

FIGS. 3A to 3F are cross-sectional views showing an embodiment of the present invention.

FIGS. 4A to 4C are cross-sectional views showing a polishing step of the present invention.

[Explanation of symbols]

 11: Built-in connection conductor substrate 12: Insulating resin layer 13: Connection conductor 101: Conductor circuit 111: Metal layer 21: First metal layer 22: Second metal layer 23: Composite metal layer 3: Composite metal foil 31 : First metal layer 32: Second metal layer 33: Third metal layer 34: Etching resist 35: Copper foil 36: Substrate with no connecting conductor exposed 40: Epoxy substrate 41: Resist 46: Polishing roll

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Akishi Nakaso 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. Within the Research Institute, Inc. (72) Nozomi Takano 1500, Oji, Shimodate, Ibaraki Pref.Hitachi Kasei Kogyo Co., Ltd. F-term in the laboratory (reference) 5E317 AA24 BB01 BB02 BB03 BB12 CC31 CC44 CC52 CD01 CD25 GG11 GG14 GG16

Claims (6)

[Claims] 1. A substrate comprising at least an insulating resin layer and a connecting conductor, wherein the insulating resin layer is made of an organic insulating resin composition which can withstand a vacuum film forming method, and at least a side surface of the connecting conductor is provided. A board with a built-in connection conductor that covers it. 2. The double-sided substrate with built-in connection conductor according to claim 1, wherein a metal thin film layer is formed on at least one surface by a vacuum film forming method. 3. A step of forming a connecting conductor on a conductive and / or insulating base material, embedding the connecting conductor in an organic insulating resin composition, exposing the connecting conductor, A method for manufacturing a double-sided board with a built-in connection conductor, comprising a step of forming a metal thin film layer on a surface where a conductor for use is exposed by a vacuum film forming method. 4. The method according to claim 3, wherein, in the step of exposing the connection conductor, at least a part of the connection conductor tip of the organic insulating resin composition covering the connection conductor is removed with a chemical. Of manufacturing a double-sided board with a built-in connection conductor. 5. The method according to claim 3, further comprising a step of mechanically and / or a chemical solution removing the conductive and insulating base material, and a step of forming a metal thin film layer by vacuum film formation on the removed surface. A method for producing the double-sided board with a built-in connection conductor according to the above. 6. The connection conductor built-in substrate according to claim 3, further comprising a step of forming a wiring pattern by electroplating using the metal thin film layer formed on at least one surface as an underlying electrode layer. How to manufacture.