JP3063330B2 - Method for manufacturing multi-wire wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-wire wiring board using an insulated metal wire for a conductor circuit and a method of manufacturing the same.

[0002]

2. Description of the Related Art A multi-wire wiring board in which an adhesive layer is provided on a substrate or the like, wiring and fixing of an insulated coating wire for forming a conductive circuit, and connection between layers by through holes, is used to match characteristic impedance. And a printed wiring board that is advantageous for reducing crosstalk.

[0003] In recent years, printed wiring boards including multi-wires have been increasingly multi-layered and miniaturized in order to cope with high-density mounting. In the case where the multi-layer wiring and the miniaturization are performed using a multi-wire wiring board, the positional accuracy of the wires is extremely important. That is, it is necessary to prevent the wire from moving during the wiring or a process after the wiring, and as described in Japanese Patent Publication No. 33958, the conventional heat-curing method is used to wire the wire. A light-curing adhesive layer is provided on the mold, and while laying the wire by pushing the wire into the adhesive layer, locally irradiating light near the wired portion of the wire in the wiring, the wired A method of curing the part has been proposed. In addition, Japanese Unexamined Patent Publication
JP-A-2-20579 describes the photocurable adhesive layer material composition.

[0004]

As a method of laying and accurately fixing an insulated wire, there is the above-mentioned known example. However, the wire is pushed into a photo-curing adhesive layer and laid on the wire while the wire is laid. By simply irradiating and curing the adhesive layer,
There may be a problem that voids remain at the intersections of the wires.

Usually, a multi-wire wiring board is formed by fixing an insulating coating wire on an adhesive layer and then laminating a prepreg such as a glass cloth epoxy resin or a glass cloth polyimide resin and fixing the insulating coating wire in the substrate. This prevents the insulation-coated wire from being peeled off when drilling with a drill or the like, and prevents the coating layer of the insulation-coated wire from being damaged in a subsequent step, thereby reducing reliability.

[0006] On the other hand, the surface of the substrate wired at high density has large irregularities due to the insulated wire, and at the intersection of the insulated wire, there are many spaces without an adhesive layer. For this reason, the prepreg or the like is laminated as described above by simply embedding the insulated wire in the adhesive layer with a wiring, curing the adhesive layer by light irradiation and fixing the insulated wire, and heating and curing the prepreg. Resins such as the resin do not sufficiently flow into the space and remain as voids.

[0007] Such a void causes a short circuit in a through hole and lowers the corrosion resistance. In particular, this is a serious problem when forming a fine circuit. As described above, in the related art, there is a problem that it is difficult to achieve both fixing the wire accurately and eliminating voids.

Further, in the above-mentioned known example, while laying the wire by pushing the wire into the photo-curing type adhesive layer, light is locally irradiated to the vicinity of the already-wired portion of the wire in the wiring, thereby forming the wiring. After the wiring is completed, the entire surface of the adhesive layer is irradiated with light to cure the entire area of the adhesive layer. However, in order to achieve this method, an apparatus for locally irradiating light near the wired portion of the wire in the wiring must be manufactured and attached to the NC wiring machine, that is, The existing NC wiring machine cannot be used as it is. There is a problem that the cost is required for improving the NC wiring machine and the apparatus is complicated, so that the maintenance cost of the apparatus is increased.

According to the present invention, an insulated wire is accurately wired, and no void is generated at the intersection of the insulated wire.
Moreover, the present invention provides a multi-wire wiring board that can be manufactured by an existing manufacturing apparatus and a manufacturing method thereof.

[0010]

According to a method of manufacturing a multi-wire wiring board of the present invention, an adhesive layer is provided on a substrate or an insulating substrate on which a conductor circuit has been previously formed, and then an insulating-coated wire is wired on the adhesive layer. In the method for manufacturing a multi-wire wiring board in which a conductor circuit is formed by fixing a hole, then drilling a hole in a necessary portion and plating the surface as necessary and a surface as required, at least the photocurable adhesive material is formed on the adhesive layer. And using an insulated wire having an uncured thermosetting resin layer outside the insulated coating layer as the insulated wire, and laying the insulated wire. To completely cure the resin, and further, the substrate is heated and pressed to cure the thermosetting resin layer of the outer layer of the insulated wire.

The present invention will be described with reference to FIG. First, Figure 1
A shows a state in which a conductor circuit layer 2 such as a power supply and a ground is provided on the surface of the insulating substrate 1 in advance. This circuit can be formed from a glass cloth epoxy resin copper-clad laminate, a glass cloth polyimide resin copper-clad laminate, or the like by a known etching method or the like.
If necessary, this inner layer circuit can be multilayered or eliminated entirely.

FIG. 1B is a diagram in which an insulating layer is formed as the underlay layer 3 . This is provided to improve the corrosion resistance and adjust the characteristic impedance, but it may not always be necessary. As the underlay layer 3 , a B-stage prepreg of ordinary glass cloth epoxy resin or glass cloth polyimide resin, a B-stage resin sheet containing no glass cloth, or the like can be used. After laminating these resin layers on a substrate, curing or pressing is performed as necessary.

Next, as shown in FIG. 1C, an adhesive layer 4 for wiring and fixing the insulated wire is formed. Adhesive layer
As a method of providing 4 , an adhesive material is directly applied to an insulating substrate by spray coating, roll coating, screen printing, or the like, and then dried, or roll-coated once on polypropylene or polyethylene terephthalate or the like, and then coated and dried. And hot-lamination or press-lamination on an insulating substrate. A photocurable material can be applied to this adhesive layer. For example, the photocurable material includes an initiator such as benzophenone and acrylate or methacrylate, or a photopolymerization initiator for cationically polymerizing epoxy and epoxy. Furthermore, in order to improve the wiring property and the handling property, a flexible agent such as polyvinyl butyral, a filler for adjusting the viscosity, and the like can be included.

[0014] Next, a FIG. 1D, the insulating coated wire 5
Wire. The insulated wire 5 having an uncured thermosetting resin layer 6 outside the insulated layer can be applied to the insulated wire 5 . This wiring is generally performed by heating using an NC wiring machine while applying ultrasonic vibration or the like. As a result, the adhesive layer 4 is softened, and the insulated wire 5 is
4 embedded. However, insulating the viscosity of the adhesive layer 4 is too low after the wiring for the residual stress of the insulating coated wire 5
In some cases, the covered wire 5 moves, and sufficient accuracy cannot be obtained. In order to prevent this, there is a method of adjusting the drying conditions and the amount of the fillers at the time of forming the adhesive layer so as to obtain an appropriate viscosity. However, as a simpler method, it is possible to irradiate the adhesive layer in advance with light before wiring, and to proceed the reaction to a viscosity and hardness suitable for the wiring.
Here, it is necessary to stop the photocuring reaction halfway. For this reason, it is necessary to control the light irradiation amount. Such control is much easier to control by light than by thermosetting. This is advantageous in that light can be produced in a shorter time in terms of time. As a light source for photocuring, an ultraviolet lamp can be used.

After completion of the wiring, in order to eliminate the movement and movement of the insulated wire 5 , a sufficient amount of light irradiation is performed on the entire surface of the adhesive layer to completely cure the adhesive layer 4 , and the adhesive layer is completely removed. Let it cure. An ultraviolet irradiation furnace can be used for light irradiation, and when the substrate is heated during the irradiation of the ultraviolet light, the adhesive layer is softened, and the wire may move or move. Furnaces are now generalized and can be used.

Next, as shown in FIG. 1E, a heat press is performed after light irradiation to melt the uncured thermosetting resin layer 6 as the outermost layer of the insulated wire 5 and then cure it. Here, a space 7 generated near the wire intersection shown in FIG. 1D is filled with a melt of the thermosetting resin layer 6 in the uncured state of the outermost layer of the insulated wire 5 and then cured. The space can be eliminated.

Next, as illustrated in FIG. 1F, insulation and wired
An overlay layer 9 is provided to protect the coated wire 5 . For the overlay layer 9 , a normal thermosetting or light-curing resin or a resin containing glass cloth is applied, and finally cured. In order to shorten the process, the above-mentioned heating press can be performed simultaneously with the formation of the overlay layer 9 .

Next, as shown in FIG. 1G, after drilling, through-hole plating 10 is performed to complete a multi-wire wiring board. Here, it is also possible to manufacture a multi-wire wiring board with a surface circuit by attaching a copper foil or the like to the surface via a prepreg after forming an overlay before drilling. Further, a multi-wire wiring board conventionally known as a variation of the present invention, for example, a multi-wire wiring board with a blind hole or the like can be manufactured.

[0019]

In the ordinary manufacturing process of a multi-wire wiring board, an insulating coating wire is laid using a thermosetting adhesive layer, and then cured by heating. At this time, the viscosity of the adhesive layer temporarily decreases, so the wiring is performed. The wire rises and moves due to the internal stress accumulated in the wire itself, and the wire moves due to the flow of the adhesive layer even when heated while being pressed. On the other hand, the photocurable adhesive layer is not heated and can be cured with the wire fixed. In the above-mentioned known example, the ultraviolet irradiation furnace generates high heat.However, since an ultraviolet irradiation furnace having a mechanism for removing light having a wavelength that generates heat is now common, if this is used, heating can be performed. The photo-curable adhesive layer can be cured without performing. Also, if the viscosity of the adhesive layer is too low,
The viscosity suitable for the wiring by irradiating the adhesive layer with light before wiring,
By proceeding the reaction by the hardness, it is possible to prevent the wire from moving due to the residual stress of the wire after wiring. That is, as in the known example described above, locally irradiating light near the wired portion of the wire in the wiring,
It is not necessary to take a method of preventing the movement of the wire after the wiring by hardening the wired portion. In addition, by using an insulated wire having an uncured thermosetting resin layer as the outermost layer, even if a space is formed at the intersection of the insulated wire after wiring, the thermosetting resin can be heated and pressed. By melting the conductive resin layer, filling the intersections of the insulating coated wires, and then curing, the voids can be prevented even after the overlay layer is provided. At this time, after the wiring, the entire surface of the photo-curable adhesive layer is irradiated with light in advance, and only the adhesive layer is completely cured. This makes it possible to manufacture a highly reliable multi-wire wiring board without voids.

[0020]

EXAMPLES Example 1 Step 1) Double-sided copper-clad laminate (manufactured by Hitachi Chemical Co., Ltd., M
CL-E-168) to form a circuit by an ordinary etching method. Next, an underlay layer was formed by pressing and curing a glass cloth epoxy resin prepreg (GEA-168, manufactured by Hitachi Chemical Co., Ltd.) on both sides of the substrate. Step 2) Next, a photo-curing type adhesive layer (Fotech SR-1300G, 75 μm, manufactured by Hitachi Chemical Co., Ltd.)
Was laminated on both sides. Subsequently, the thickness of 15 μm
m coated polyimide wire having an uncured thermosetting resin layer as the outermost layer (Hitachi Cable Co., Ltd., Wire HA
W, copper wire diameter: 0.1 mm) were wired one by one using an NC wiring machine while applying ultrasonic heating. Step 3) Following the wiring, both sides were irradiated with light of 3 J / cm ² using an ultraviolet irradiation device (Model QRM-2082-A-R2 manufactured by Oak Manufacturing Co., Ltd.) to cure the adhesive layer. . Next, the substrate was heated and pressed at 170 ° C. for 60 minutes at 2 MPa using silicone rubber as a cushion material. Step 4) Next, a glass cloth cloth epoxy resin prepreg (GEA-168, manufactured by Hitachi Chemical Co., Ltd.) is applied to both surfaces, and silicon rubber is used as a cushion material at 170 ° C.
Pressing and curing were performed at 3 MPa for 60 minutes to form an overlay layer. Subsequently, a polyethylene film was laminated on the surface of the overlay layer, and holes were made in necessary places. After drilling holes, pretreatments such as hole cleaning were performed, and further immersed in an electroless copper plating solution. 30 μm
After plating the through holes, the polyethylene film was peeled off to produce a multi-wire wiring board.

Example 2 A multi-wire wiring board was manufactured in exactly the same steps as in Example 1 except that Step 2 of Example 1 was performed as in the following step 2 '. Step 2 ') Then, a photo-curing type adhesive layer (Fotech SR-1300G, manufactured by Hitachi Chemical Co., Ltd., 75 μm)
m) was formed by lamination on both sides. Next, an ultraviolet irradiation device (Model QRM-2082 manufactured by Oak Manufacturing Co., Ltd.)
-A-R2), both surfaces were irradiated with light of 500 mJ / cm ² to partially promote photocuring. Subsequently, a film thickness of 15 μm
Coated wire having an uncured thermosetting resin layer as the outermost layer (Hitachi Cable Industries, Ltd., Wire HA
W, copper wire diameter: 0.1 mm) were wired one by one using an NC wiring machine while applying ultrasonic heating.

Example 3 In step 3 of Example 1, a silicone rubber was used as a cushion material following irradiation with light of 4 J / cm ² at 170 ° C. for 60 minutes, 2M
Example 1 except that the heating press was not performed under the condition of Pa
A multi-wire wiring board was manufactured in exactly the same steps as in the above.

Comparative Example 1 In step 2 of Example 1, a thermosetting adhesive layer (Adhesive sheet AS-102, manufactured by Hitachi Chemical Co., Ltd.) was used instead of the photocurable adhesive layer, and after wiring. A multi-wire wiring board was manufactured in the same process as in Example 1 except that light irradiation was not performed.

Comparative Example 2 In step 2 of Example 3, a polyimide-coated wire having an uncured thermosetting resin layer having a thickness of 15 μm as the outermost layer (Hitachi Cable Co., Ltd., wire HAW, copper wire diameter: 0.3 mm) was used. 1mm)
Was previously heated at 170 ° C. for 60 minutes to cure the thermosetting resin layer, and was wired in the same manner as in Example 3 except that the wiring was performed while applying ultrasonic heating using an NC wiring machine. A multi-wire wiring board was manufactured.

Comparative Example 3 In step 2 of Example 1, a polyimide-coated wire having a 15 μm-thick uncured thermosetting resin layer as the outermost layer (Hitachi Cable Co., Ltd., wire HAW, copper wire diameter: 0.3 mm) was used. 1 mm), except that a polyimide-coated wire having a 15 μm-thick uncured photocurable resin layer having the following composition outside the polyimide-coated wire having a copper wire diameter of 0.1 mm and a polyimide film thickness of 10 μm was used. Manufactured a multi-wire wiring board in the same process as in Example 1. Epoxy acrylate (LS-51P) 40 parts by weight Phenoxy resin (Y-50) 10 parts by weight Epoxy resin (EP-828) 30 parts by weight Epoxy resin (ESB-400T) 20 parts by weight Polyvinyl butyral (# 5000A) 5 parts by weight Silica Powder 10 parts by weight Cationic photopolymerization initiator (UVI-6970) 5 parts by weight Photoinitiator (I-651) 6 parts by weight Palladium chloride 0.01 part by weight

Comparative Example 4 In step 2 of Example 3, a polyimide-coated wire having an uncured thermosetting resin layer having a thickness of 15 μm as the outermost layer (manufactured by Hitachi Cable, Ltd., wire HAW; 1 mm), except that a polyimide-coated wire having a 15 μm-thick uncured photocurable resin layer having the following composition outside the polyimide-coated wire having a copper wire diameter of 0.1 mm and a polyimide film thickness of 10 μm was used. Manufactured a multi-wire wiring board in the same process as in Example 3. Epoxy acrylate (LS-51P) 40 parts by weight Phenoxy resin (Y-50) 10 parts by weight Epoxy resin (EP-828) 30 parts by weight Epoxy resin (ESB-400T) 20 parts by weight Polyvinyl butyral (# 5000A) 5 parts by weight Silica Powder 10 parts by weight Cationic photopolymerization initiator (UVI-6970) 5 parts by weight Photoinitiator (I-651) 6 parts by weight Palladium chloride 0.01 part by weight

The positions of the wired wires and the cross sections of the multi-wire wiring boards manufactured in Examples 1 to 3 and Comparative Examples 1 to 4 were examined. As a result, Example 1
In Comparative Examples 2 to 4 and Comparative Examples 2 to 4, the positions of the wired wires were shifted by 50 μm or less. Particularly, in the second embodiment, 30 μm
m or less. In contrast, the displacement of the wire of Comparative Example 1 exceeded 200 μm in some parts. Also,
As a result of the cross-sectional observation, in Examples 1 to 3 and Comparative Example 1,
No void was found at the wire intersection. In contrast, in Comparative Examples 2 to 4, voids were observed at the wire intersections.

[0028]

According to the present invention, it is possible to manufacture a multi-wire wiring board which does not include voids at the intersections of the wires and has little movement of the wires by using an existing manufacturing apparatus. That is, according to the present invention, a multi-wire wiring board having high density and excellent reliability can be manufactured using an existing manufacturing apparatus.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multi-wire wiring board manufacturing process showing one embodiment of the present invention.

FIG. 2 is a flowchart of a manufacturing process showing one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating board 2 Inner layer circuit copper 3 Underlay layer 4 Adhesive layer 5 Insulation coating wire 6 Uncured thermosetting resin layer 7 Space at wire intersection 8 Thermosetting resin filled at wire intersection 9 Overlay layer 10 Through Hole plating

────────────────────────────────────────────────── (5) References JP-A-59-6596 (JP, A) JP-A-59-121992 (JP, A) JP-A-59-6591 (JP, A) JP-A-2- 125498 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 3/46 H05K 3/10

Claims (2)

(57) [Claims] 1. An adhesive layer is provided on a substrate or an insulating substrate on which a conductor circuit has been formed in advance, and an insulation-covered wire is laid and fixed on the adhesive layer. In a method for manufacturing a multi-wire wiring board in which a conductor circuit is formed by plating a surface as necessary, at least using a photocurable adhesive material for the adhesive layer,
And, as the insulating coating wire, using an insulating coating wire having an uncured thermosetting resin layer outside the insulating coating layer, after laying the insulating coating wire, irradiating the entire surface of the adhesive layer with light. Wherein the substrate is heated and pressed to harden the thermosetting resin layer of the outer layer of the insulated wire. 2. The method according to claim 1, further comprising: irradiating an insufficient amount of light to completely cure the adhesive layer to partially cure the adhesive layer prior to laying the insulated wire. 2. The method for manufacturing a multi-wire wiring board according to 1.