JP3071764B2 - Film with metal foil and method of manufacturing wiring board using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film with a metal foil suitably used for forming a wiring circuit layer in a wiring board used for, for example, a semiconductor device storage package, and a method of manufacturing a wiring board using the same. Things.

[0002]

2. Description of the Related Art Conventionally, a multilayer ceramic wiring board capable of relatively high-density wiring has been widely used as a wiring board, for example, a wiring board used for a package for housing a semiconductor element. This multilayer ceramic wiring board is composed of an insulator such as alumina and W or Mo formed on the surface thereof.
And a wiring conductor made of a metal having a high melting point, such as a high-melting-point metal. A recess is formed in a part of the insulator, the semiconductor element is accommodated in the recess, and the recess is hermetically sealed by a lid. Things.

Meanwhile, wiring boards used for multi-layer wiring boards and packages for housing semiconductor elements, etc., have become more and more dense in the future as the performance of various electronic devices has been improved, and the wiring width and wiring pitch have been reduced to 50 μm or less. It is required that the via hole be an interstitial via hole (IVH), and the mounting method of the IC chip also changes from the wire bonding to the flip chip, so that the flatness of the substrate itself needs to be reduced. ing. However, a multilayer ceramic wiring board is manufactured by printing metallized ink on a green sheet before sintering, laminating and sintering the printed sheets, and firing in a high-temperature firing process in the manufacturing process. Due to the shrinkage, the resulting substrate is liable to be deformed such as warpage or dimensional variation, etc., and therefore, in response to strict requirements regarding ultra-high density of circuit boards and flatness of substrates such as flip chips etc. However, there was a problem that it could not cope sufficiently.

Another problem of the multilayer ceramic wiring board is that ceramics are hard and brittle, so that chipping or cracking of the ceramics is likely to occur in a manufacturing process or a transporting process. Since the hermetic sealing of the device may be impaired, there are problems such as low yield.

On the other hand, as a wiring board other than a ceramic wiring board, a resin wiring board in which a surface wiring circuit layer made of a metal layer such as copper is formed on the surface of an insulating substrate containing an organic resin is used. Such a resin wiring board,
There is an advantage that there is no defect such as chipping or cracking as in the case of a ceramic wiring board, and that a multilayer heat treatment does not require heat treatment at a high temperature such as firing.

In general, a resin wiring board is formed by attaching a metal foil such as a copper foil on an insulating substrate and then removing unnecessary portions of the metal foil by etching or plating to form a circuit pattern. Forming a circuit layer involves the following various problems.

For example, when a circuit pattern is formed, the insulating substrate is deteriorated by a chemical such as etching, or the surface wiring circuit layer formed using a metal foil is merely placed on the surface of the insulating substrate. Poor adhesion of the surface wiring circuit layer to the insulating substrate is liable to occur, and a gap is likely to be formed at the interface between the two.

In addition, in forming a multilayer, there is a problem that the sequential lamination must be performed to form the IVH, and a batch lamination cannot be performed. Furthermore, since the convex portions are formed on the insulating substrate by forming the surface wiring circuit layer, the flatness is low, and the flatness required for flip-chip mounting has not been satisfied.

Therefore, recently, a copper circuit is adhered to a surface of an insulating substrate made of an organic resin, and then a wiring circuit layer is formed by an etching method and a plating method. Has been proposed.

In addition, a metal foil is adhered to a resin film, and a circuit pattern is formed by an etching method and a plating method,
After that, the method of transferring to an insulating substrate is also disclosed in JP-A-10-5110.
No. 8 and the like.

[0011]

Among the above-mentioned methods, a method of adhering a metal foil to a resin film, forming a circuit pattern on the resin film by etching or the like, and transferring the circuit pattern to an insulating substrate is described in the following. It is excellent in that it does not come into contact with the chemicals for pattern formation and does not affect the properties of the insulating substrate.

However, as an internal wiring layer for manufacturing a multilayer wiring board, a circuit pattern having a wide wiring portion having a line width of 0.5 mm or more, a relatively large area such as a ground layer or a shield layer for noise suppression is used. When a wide circuit pattern is formed, there is a problem in that a lamination failure due to poor adhesion occurs between lamination structures in which this metal foil is sandwiched between insulating layers.

In order to prevent such a lamination defect,
Generally, the surface of a wiring circuit layer formed on the surface of an insulating substrate is etched and roughened before lamination.
However, if the wiring circuit layer made of metal foil is transferred to an insulating substrate and then the circuit surface is roughened by etching or the like, the roughening processing solution penetrates into via-hole conductors formed in the insulating substrate, and the processing solution is roughened. Problems such as bleeding and cracking of the substrate during reflow.

Further, when a fine wiring circuit layer is transferred by heating, there is a problem that a dimensional error occurs in the transferred wiring circuit layer due to a thermal change of the resin film, thereby causing a poor connection with a via hole. was there.

[0015]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found that a resin film having a predetermined thickness with a small dimensional change at high temperature is used as a resin film in a film with a metal foil. ,
When bonding a metal foil to a resin film via an adhesive layer, control the thickness of the resin film, the thickness of the adhesive layer, the thickness of the metal foil, the surface roughness of the metal foil, and the adhesive strength of the metal foil to appropriate ranges. As a result, it has been found that even when a wide or large area wiring circuit layer is formed in the inner layer of the multilayer wiring board, a wiring circuit layer having no lamination failure and excellent in dimensional accuracy after transfer can be formed, and the present invention has been achieved. Was.

That is, the film with a metal foil of the present invention comprises:
A metal foil is formed on the surface of the resin film having a dimensional change of 0.1% or less after holding at 00 ° C. for 1 hour via an adhesive layer, and the thickness of the resin film is 10 to 100 μm.
m, the thickness of the adhesive layer is 3 μm or more, the thickness of the metal foil is 1 to 35 μm, and the ten-point average roughness (Rz) of at least the side of the metal foil in contact with the adhesive layer is 1 to 6 μm;
In addition, the metal foil has an adhesive strength of 50 to 500 g / 25 mm.

Further, as a method of manufacturing a wiring board, there are 10 methods.
A metal foil is formed via an adhesive layer on the surface of a resin film having a dimensional change rate of 0.1% or less after holding at 0 ° C. for 1 hour, and the resin film has a thickness of 10 to 100 μm.
The thickness of the adhesive layer is 3 μm or more, and the thickness of the metal foil is 1
To a film with a metal foil having a ten-point average roughness (Rz) of 1 to 6 μm on at least a side of the metal foil which is in contact with the adhesive layer, and having an adhesive force of 50 to 500 g / 25 mm. After processing the metal foil on the film surface into a wiring circuit pattern, laminating the film with a metal foil on which a wiring circuit layer is formed and a semi-cured insulating substrate containing a thermosetting resin, Peeling the resin film and the adhesive layer to transfer the wiring circuit layer to the insulating substrate; laminating a plurality of layers of the single-layer wiring substrate to which the wiring circuit layer has been transferred; A step of heating at a temperature sufficient to completely cure the thermosetting resin therein, and completely curing the whole at once.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The film with metal foil of the present invention
A resin film and a metal foil are provided, and the metal foil is formed on the resin film via an adhesive layer. The resin film is
Known materials such as polyethylene terephthalate, polyethylene naphthalate, polyimide, polyphenylene sulfide, vinyl chloride, and polypropylene can be used.

The thickness of the resin film is suitably from 10 to 100 μm, preferably from 20 to 500 μm. This is because when the thickness of the resin film is smaller than 10 μm, the wiring circuit formed by deformation or bending of the film is liable to cause disconnection, and when the thickness is larger than 100 μm, the flexibility of the film is lost and it becomes difficult to peel off the sheet. is there.

According to the present invention, it is important that the dimensional change of the resin film used is small.
It is desirable that the dimensional change when held at 1 ° C. for 1 hour is 0.1% or less, particularly ± 0.05% or less. This dimensional change rate is used to reduce the variation between the wiring pitches of fine wiring and transfer with high dimensional accuracy when transferring a metal foil as a wiring circuit layer formed on a resin film to an insulating substrate. When the above dimensional change rate is larger than 0.1%, it becomes impossible to transfer a wiring layer with high dimensional accuracy.

Such a resin film having a small shrinkage is
It can be manufactured by performing a predetermined heat treatment. Specifically, the temperature of the heat treatment depends on the material of the film, but is preferably in the range of 70 to 170 ° C., preferably 100 ° C.
~ 170 ° C is good. If the processing temperature is lower than 70 ° C., the dimensional change rate during the process of the resin film is large, the variation between wiring pitches tends to be large, and the processing temperature is 17 ° C.
If the temperature is higher than 0 ° C., deformation of the resin film occurs, and variation between wiring pitches increases. Also, the dimensional change rate of the resin film can be reduced by lowering the bonding tension between the metal foil and the resin film.

As the adhesive layer of the resin film, known adhesives such as acrylic, rubber, silicon, and epoxy can be used. The thickness of the adhesive layer is 3 μm or more, preferably 5 μm or more. If the thickness of the adhesive layer is thinner than 3 μm, it cannot follow the surface of the metal foil, discoloration of the pattern,
Peeling of the pattern occurs.

The metal foil is formed of a metal suitable for forming a wiring circuit layer as a wiring board. For example, a low-resistance metal containing at least one of gold, silver, copper and aluminum, particularly a copper metal Foil is preferably used. The thickness of the metal foil is preferably 1 to 35 μm, preferably 5 to 1 μm.
8 μm is good. If the thickness of the metal foil is smaller than 1 μm, the resistivity of the circuit increases, and if the thickness is larger than 35 μm, the deformation of the insulating substrate during lamination increases, or the amount of metal embedded in the insulating substrate increases. There is a problem that the distortion is increased and the substrate is easily deformed after the resin is cured. There is also a problem that it is difficult to etch the metal foil itself, so that a fine circuit with high accuracy cannot be obtained.

The adhesive strength of the metal foil adhered to the surface of the resin film via an adhesive layer is 50 to 500 g / 25 m
m is good, and desirably 70 to 350 g / 25 mm. If the adhesive strength is less than 50 g / 25 mm, the metal foil is peeled off from the resin film during the etching treatment for forming the circuit, causing a break in the circuit. Also, 500g
If it is larger than / 25 mm, after the circuit is formed, it is transferred to the insulating substrate, and when the resin film is peeled off, deformation of the insulating substrate and disconnection of the circuit are caused.

The above-mentioned adhesive strength is, as shown in FIG.
Resin film 9 to which metal foil 8 is adhered via adhesive layer 7
Represents the stress when the resin film 9 is peeled off from the metal foil 8 in the direction of 180 °.

The ten-point average roughness (Rz) of at least the side of the metal foil in contact with the adhesive layer is 1 to 6 μm, particularly 2 to 6 μm.
It is important that it is 5 μm. This means that at least the side in contact with the adhesive layer is a surface that forms the exposed surface side of the wiring circuit layer after transfer to the insulating substrate, and the insulating substrate laminated on this wiring circuit layer during multilayering. When the ten-point average roughness is smaller than 1 μm, the line width in the inner layer of the multilayer wiring board is 0.5 mm or more, particularly 1 mm.
When a circuit pattern having a width of at least mm or a large-area pattern such as a ground layer and a shield layer is formed, lamination failure occurs. If the pattern is larger than 6 μm, the wiring circuit layer may be transferred to an insulating substrate. When peeling the resin film,
This is because the adhesive layer is likely to remain on the surface of the wiring circuit layer or to cause poor transfer.

Next, a method of manufacturing a wiring board according to the present invention will be described with reference to FIG. FIG. 1 is a diagram for explaining steps of a method for manufacturing a multilayer wiring board according to the present invention. First,
Resin film 1 having a thickness of 10 to 100 μm and a dimensional change rate of 0.1% or less after holding at 100 ° C. for 1 hour has a thickness of 3
The adhesive layer 2 having a thickness of not less than μm is applied. The application of the adhesive layer 2 can be performed by a method such as a comma coater method, a doctor blade method, or a calendar method.

Next, the surface of the adhesive layer 2 of the resin film 1 is previously roughened to a 10-point average roughness (Rz) of 1 to 6 μm, particularly 2 to 5 μm, by etching or the like on the side in contact with the adhesive layer 2. The metal foil 3 having a thickness of 1 to 35 μm is bonded.
At this time, the material and thickness of the adhesive layer 2 are adjusted so that the adhesive strength of the metal foil 3 to the resin film is 50 to 500 g / 25 mm for the above-described reason.

Next, as shown in FIG. 1C, an unnecessary portion of the metal foil 3 bonded to the resin film 1 is removed by an etching method to form a wiring circuit layer 4. For example, FIG.
After a resist is formed in a wiring circuit pattern on the metal foil 3 of (b) by a method such as photoresist or screen printing, an unnecessary portion is removed by etching to obtain a wiring circuit layer 4 having a desired pattern. it can.

At this time, the resist generally requires a step of removing unnecessary portions of the metal foil by etching, removing the resist with a resist stripping solution such as sodium hydroxide, and washing the resist. The same material, including an organic resin, for example, an insulating material composed of an organic resin and an inorganic filler, it is not necessary to remove the resist or the like, which is advantageous in that the process can be simplified. Also, the adhesive strength between the wiring circuit and the insulating substrate can be increased.

The surface of the wiring circuit layer 4 on the side opposite to the adhesive layer 2 also has a ten-point average roughness (Rz) of 1 μm or more.
In particular, it is desirable that the surface is roughened to 2 μm or more.
In particular, this surface is a surface that is in direct contact with the insulating substrate at the time of transfer. The larger the roughness, the higher the adhesion to the insulating substrate and the better the transferability. It is desirable that the layer 4 be larger than the side in contact with the adhesive layer 2.

The roughening of the surface of the wiring circuit layer 4 on the side opposite to the adhesive layer 2 can be easily performed by performing a predetermined etching process before or after the formation of the wiring circuit pattern. be able to.

The roughening treatment includes formic acid, NaClO ₂ , NaO
It is preferable to use an acidic solution such as H, Na ₂ PO ₄ , or a mixture thereof, and it is particularly preferable to use formic acid in that the surface roughness can be finely controlled.

Next, the wiring circuit layer 4 is transferred to the insulating substrate 5 from a film with a metal foil formed with the wiring circuit layer 4 formed on the surface of the resin film 1. As a method of transferring, as shown in FIG. 1D, a film with a metal foil and an insulating substrate 5 are laminated and a pressure of 10 to 500 kg is applied.
/ Cm ² is applied. Then, as shown in FIG. 1E, the wiring circuit layer 4 is transferred to the surface of the insulating substrate 5 by peeling the resin film 1 together with the adhesive layer 2 and transferring the wiring circuit layer 4 to the insulating substrate 5. it can.

At this time, if a semi-cured sheet is used as the insulating substrate 5, the wiring circuit layer 4 can be embedded in the insulating substrate 5 by mechanical pressure as shown in FIG. Can be provided with flatness without convex portions due to the wiring circuit layer 4.

Thereafter, the insulating substrate 5 to which the wiring circuit layer 4 has been transferred is heated at a temperature sufficient to completely cure the organic resin in the insulating substrate, thereby obtaining the single-layer structure shown in FIG. A wiring substrate can be manufactured.

When manufacturing a multilayer wiring board,
After a plurality of layers of the uncured single-layer wiring board to which the wiring circuit layer 4 has been transferred are laminated and pressure-bonded, heating is performed at a temperature sufficient to completely cure the organic resin in the insulating substrate, and the entire board is completely cured. Thereby, a multilayer wiring board can be manufactured.

In the above manufacturing method, the insulating substrate 5
It contains at least an organic resin, and desirably comprises a composite material containing at least one selected from inorganic fillers, inorganic fibers, and organic fibers together with the organic resin. The inorganic filler, the inorganic fiber, and the organic fiber are preferably used as those uniformly dispersed in the organic resin at a ratio of 20 to 80% by volume in total.

The organic resin constituting such a composite material includes thermosetting PPE (polyphenylene ether resin), BT resin (bismaleide triazine), epoxy resin, polyimide resin, fluororesin, phenol resin, polyaminobismaleimide and the like. It is preferable that the raw material is a thermosetting resin which is liquid at room temperature.

On the other hand, as the inorganic filler, SiO 2
₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , AlN, Si
Known materials such as C, BaTiO ₃ , SrTiO ₃ , MgTiO ₃ , zeolite, CaTiO ₃ , and aluminum borate can be used. In addition, the shape can be any shape such as a spherical shape and a needle shape.

Further, examples of the inorganic or organic fiber include glass fiber, aramid fiber, cellulose fiber and the like, and any property such as woven fabric and non-woven fabric may be used. In any case, in order to increase the strength of the multilayer wiring board and obtain a highly reliable substrate, it is desirable to include at least one or more layers of the insulating substrate 5 containing fibers.

First, in order to fabricate the insulating substrate 5, for example, an insulating composition obtained by adding a liquid organic resin to an inorganic filler is sufficiently mixed by means of a kneader (kneader) or a three-roll mill. A slurry is prepared, and after the slurry is formed into a sheet by a rolling method, an extrusion method, an injection method, or a doctor blade method, the organic resin is semi-cured.
For semi-curing, if the organic resin is a thermoplastic resin, cool the mixture under heating, and in the case of a thermosetting resin,
Heat to a temperature slightly below that sufficient to fully solidify.

The above-mentioned insulating slurry is preferably prepared by adding toluene, butyl acetate, methyl ethyl ketone, methanol, methyl cellosolve acetate, isopropyl alcohol, methyl isobutyl to a composite material of the above-mentioned organic resin and inorganic filler constituting the insulator. It is composed of a fluid having a predetermined viscosity by adding a solvent such as ketone and dimethylformamide. The viscosity of the slurry is suitably 100 to 3000 poise, although it depends on the sheet forming method.

When a woven or nonwoven fabric is used, a varnish resin is impregnated into a woven or nonwoven fabric and dried to produce a semi-cured prepreg insulating substrate.

Next, a desired via hole is formed in the semi-cured insulating substrate 5 produced as described above by a punching method or a laser processing, and filled with a conductive paste. The metal powder to be blended in the conductor paste is desirably made of at least one low-resistance metal among copper, aluminum, silver, and gold, and a paste can be obtained by adding an organic solvent and a binder.

[0046]

EXAMPLES Example 1 (Resin Film Thickness) (Preparation of Film with Metal Foil)
The dimensional change after holding at 00 ° C for 1 hour is -0.01%
After forming an adhesive layer made of an acrylic resin having a thickness of 5 μm on various polyethylene terephthalate films having a thickness of 5 to 200 μm, the thickness was 12 μm, the ten-point average roughness of the adhesive layer side was 3.2 μm, and the adhesive was formed. A copper foil having a ten-point average roughness of 0.5 μm (mirror surface) on the surface opposite to the layer side is 100 g /
A film with a metal foil for forming a wiring circuit layer was formed with an adhesive force of 25 mm.

(Formation of Circuit Pattern) Then, a photosensitive resist is applied to the surface of the copper foil of the film with a metal foil, and the circuit pattern is exposed through a glass mask.
This was immersed in a ferric chloride solution to remove the non-pattern portion by etching, and the resist was peeled off to form a copper foil circuit pattern. In addition, the wiring using the produced metal foil has a maximum line width of 2 mm, a minimum line width of 50 μm, and a wiring pitch of 50 μm.
m and a ground electrode pattern having an area equivalent to 60% of the area of the insulating substrate were formed.

Thereafter, the circuit pattern of this copper foil was
The copper foil was roughened to a 10-point average roughness of 3.5 μm on the free surface (surface opposite to the adhesive layer side) of the copper foil.

(Preparation of Wiring Board) Spherical molten SiO ₂ having an average particle size of 5 μm was added to a thermosetting polyphenylene ether resin.
Was added as a solvent, butyl acetate, toluene and methyl ethyl ketone were added as solvents, a catalyst for accelerating the curing of the organic resin was further added, and the mixture was mixed for 1 hour to prepare an insulating slurry. Then, this insulating slurry was formed into an insulating substrate sheet having a thickness of 200 μm by a doctor blade method.

The sheet for insulating substrate was cut into 150 mm square, and a via hole having a diameter of 100 μm was formed by a CO ₂ laser. A copper paste containing copper-silver alloy powder as a main component was embedded in the via hole by screen printing. .

Then, the film with a metal foil on which the formed wiring circuit layer is formed and the insulating substrate sheet on which the via-hole conductor is formed are aligned with each other, and the film is formed by a vacuum laminator.
After applying a pressure of 30 kg / cm ² for 30 seconds, only the resin film and the adhesive layer were peeled off to transfer the wiring circuit layer, and the wiring circuit layer was embedded in the surface of the insulating substrate sheet. Finally, six insulating substrate sheets on which the wiring circuit layers were formed were superposed, and were heated at 200 ° C. for 5 hours under a pressure of 30 kg / cm ² and completely cured to obtain a multilayer wiring substrate. Note that one ground layer having an area of 60% of the entire area of the insulating substrate was formed as an internal wiring circuit layer.

(Characteristics Evaluation) With respect to the obtained multilayer wiring board, the disconnection rate of the circuit, the variation of the wiring pitch, and the flatness of the wiring board were measured, and the wiring board was cut.
In particular, the vicinity of the wiring layer having a line width of 2 mm and the place where the ground layer was formed were observed to determine the incidence rate of lamination failure. The results are shown in Table 1.

[0053]

[Table 1]

As is clear from the results shown in Table 1, in Sample No. 1-1 where the thickness of the resin film in the film with a metal foil was thinner than 10 μm, the film was bent and a large number of circuit breaks occurred. The thickness is 100μ
Sample No. 1-7, which is thicker than m, did not have flexibility of the film, and a large number of circuit breaks occurred with the peeling of the film. In the present invention having a resin film thickness of 10 to 100 μm, the occurrence rate of circuit disconnection was 2/40 or less, and in particular, when the thickness was 25 to 50 μm, there was no occurrence of circuit disconnection.

Example 2 (Dimensional change rate of resin film) For various polyethylene terephthalate films having a thickness of 38 μm, a heat treatment temperature in the range of 50 to 200 ° C., and a dimensional change rate of 0.01 to 0.20%. , Thickness 5μm
After forming an adhesive layer made of an acrylic resin,
A copper foil having a 10-point average roughness of 2 μm, a ten-point average roughness of 3.2 μm on the adhesive layer side, and a
A film with a metal foil for forming a wiring circuit layer was formed with an adhesive force of 0 g / 25 mm.

Thereafter, in the same manner as in Example 1, a wiring board was prepared using each film with a metal foil.
Evaluation was performed in the same manner as described above, and the results are shown in Table 2.

[0057]

[Table 2]

As is clear from the results in Table 2, the dimensional change of the resin film in the film with metal foil was 0.1%.
2-1 and 2-2, the variation in the wiring pitch was 10 μm or more, whereas in the present invention in which the dimensional change rate was within 0.1%, Variation of 7 μm or less, especially dimensional change rate of 0.0
When it was within 4%, it could be suppressed to 5 μm or less.

Example 3 (Adhesive Strength) A heat treatment at 120 ° C. and a thickness of 38 μm
After forming a 5-μm-thick adhesive layer made of various acrylic resins having different adhesive strengths on a polyethylene terephthalate film having a dimensional change rate of −0.01% after holding for 10 hours, a ten-point average on the adhesive layer side is formed. A thickness of 3.2 μm and a thickness of 10 μm on the surface opposite to the adhesive layer side of 0.5 μm is 1
Films with metal foils for forming various wiring circuit layers, in which 2 μm copper foils were formed with various adhesive strengths of 10 to 700 g / 25 mm, were produced.

Thereafter, a wiring board was prepared using each film with a metal foil in exactly the same manner as in Example 1.
The same evaluation was performed, and the results are shown in Table 3.

[0061]

[Table 3]

As is evident from the results in Table 3, in the samples No. 3-1 and No. 3-2 in which the adhesive force of the film with the metal foil was smaller than 50 g / 25 mm, the pattern was peeled off from the film at the time of etching, and a substrate could be produced. In the sample No. 3-7 having an adhesive force larger than 500 g / 25 mm,
Although a large number of circuit breaks occurred, the adhesive strength was 50 to 5
In the product of the present invention of 00 g / 25 mm, the occurrence of disconnection of the circuit is suppressed to 1/40 or less, and particularly, 50 to 300 g / 25 m
In the case of m, no disconnection occurred in the circuit.

Example 4 (Adhesive Layer Thickness) The thickness was 38 μm.
After forming various adhesive layers made of an acrylic resin and having a thickness of 1 to 30 μm on a polyethylene terephthalate film having a dimensional change rate of −0.01% after holding for 10 hours, the ten-point average roughness on the adhesive layer side Is a film with a metal foil for forming various wiring circuit layers, wherein a copper foil having a thickness of 3.2 μm and a ten-point average roughness of the surface opposite to the adhesive layer side of 0.5 μm and a thickness of 12 μm is formed with an adhesive force of 100 g / 25 mm. Was prepared.

Thereafter, in the same manner as in Example 1, a wiring board was produced using each film with a metal foil.
Evaluation was performed in the same manner as described above and the results are shown in Table 4.

[0065]

[Table 4]

As is evident from the results in Table 4, in Sample No. 4-1 where the thickness of the adhesive layer was smaller than 3 μm, a large number of circuit breaks occurred. In the invention product, the occurrence of disconnection in the circuit was suppressed to 1/40 or less, and was not found at 7 μm or more.

Example 5 (Metal foil thickness) Thickness was 38 μm, heat treated at 120 ° C.
After a 5-μm-thick adhesive layer made of an acrylic resin is formed on a polyethylene terephthalate film having a dimensional change rate of −0.01% after holding for a time, the ten-point average roughness of the adhesive layer side is 3.2 μm. The ten-point average roughness of the surface opposite to the adhesive layer side is 0.5 μm, and the thickness is 0.5 to 75 μm.
Various types of films with metal foils for forming wiring circuit layers were prepared by forming copper foils of various thicknesses with an adhesive force of 100 g / 25 mm.

Thereafter, in the same manner as in Example 1, a wiring board was produced using each film with a metal foil.
The same evaluation was performed, and the results are shown in Table 5.

[0069]

[Table 5]

As is clear from the results shown in Table 5, in the samples Nos. 5-7 and 5-8 in which the thickness of the metal foil is larger than 35 μm, the wiring circuit layer made of the metal foil becomes convex on the surface of the insulating substrate. Decreased in flatness. The thickness of the metal foil is 1 μm
In the sample No. 5-1 which is thinner, the metal foil was disconnected at the time of transfer or the resistivity of the wiring was increased. On the other hand, in the present invention in which the thickness of the metal foil was 1 to 35 μm, The substrate was suitable for flip-chip mounting with a flatness of 7 μm or less.

Example 6 (Surface Roughness on Adhesive Layer Side of Metal Foil) Thickness was 38 μm, heat treated at 120 ° C., and 1 hour at 100 ° C.
After a 5-μm-thick adhesive layer made of an acrylic resin was formed on a polyethylene terephthalate film having a dimensional change rate of −0.01% after holding for 10 hours, the ten-point average roughness on the adhesive layer side was 0.5%. -7.0 μm, the ten-point average roughness of the surface opposite to the adhesive layer side is 0.5 μm, and the thickness is 12 μm.
Various types of films with a metal foil for forming a wiring circuit layer were prepared by forming a copper foil having a thickness of 100 g / 25 mm with an adhesive force of 100 g / 25 mm.

Thereafter, in the same manner as in Example 1, a wiring board was produced using each film with a metal foil.
The same evaluation was performed, and the results are shown in Table 6.

[0073]

[Table 6]

As is clear from the results in Table 6, the sample No. having a ten-point average roughness on the adhesive layer side of the metal foil smaller than 1 μm.
In 6-1, a large number of lamination failures occurred in which a gap was formed between the ground layer forming portion and the insulating substrate. In Sample No. 6-7, in which the ten-point average roughness was larger than 6 μm, the adhesive layer remained on the copper foil surface, whereas the ten-point average roughness on the adhesive layer side of the metal foil was 1 to 6 μm. In the present invention, the adhesive layer did not remain on the copper foil, and no lamination failure occurred.

[0075]

As described in detail above, the film with a metal foil of the present invention can be used as a resin film to have a dimensional change at a high temperature, a thickness of a resin film, a thickness of an adhesive layer, a thickness of a metal foil, and a surface roughness of the metal foil. By controlling the adhesive strength of the metal foil to an appropriate range, even when the large-area wiring circuit layer is formed as an inner layer, there is no lamination failure, and no chemical solution or the like penetrates into the via-hole conductor, Moreover, since a wiring circuit layer having excellent dimensional accuracy after transfer can be formed, a highly reliable wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is a view for explaining steps of a manufacturing method of the present invention.

FIG. 2 is a diagram for explaining a method for measuring the adhesive force of a metal foil according to the present invention.

[Explanation of symbols]

 A Film with metal foil 1 Resin film 2 Adhesive layer 3 Metal foil 4 Wiring circuit layer 5 Insulating substrate

Claims (2)

(57) [Claims] A metal foil is formed on a surface of a resin film having a dimensional change rate of 0.1% or less after holding at 100 ° C. for one hour via an adhesive layer, and the resin film has a thickness of 1%.
0 to 100 μm, the thickness of the adhesive layer is 3 μm or more, the thickness of the metal foil is 1 to 35 μm, and the ten-point average roughness (Rz) of the metal foil at least on the side in contact with the adhesive layer is 1 to 6
μm, and the adhesive strength of the metal foil is 50 to 500 g.
/ 25 mm, a film with a metal foil. 2. A resin film having a dimensional change rate of 0.1% or less after holding at 100 ° C. for 1 hour, a metal foil formed on the surface of the resin film via an adhesive layer, and the resin film having a thickness of 1%.
0 to 100 μm, the thickness of the adhesive layer is 3 μm or more, the thickness of the metal foil is 1 to 35 μm, and the ten-point average roughness (Rz) of the metal foil at least on the side in contact with the adhesive layer is 1 to 6
μm, and the adhesive strength of the metal foil is 50 to 500 g.
For a film with a metal foil of / 25 mm, after processing the metal foil on the film surface into a wiring circuit pattern,
The film with a metal foil on which a wiring circuit layer is formed and a semi-cured insulating substrate containing a thermosetting resin are laminated, and the resin film and the adhesive layer are peeled off to form the wiring circuit layer on the insulating substrate. Transferring, bonding and laminating a plurality of layers of the single-layer wiring substrate to which the wiring circuit layer has been transferred, and heating and heating at a temperature sufficient to completely cure the thermosetting resin in the insulating substrate. And completely curing the substrate.