JPH0750318A - Low permittivity film carrier base material and film carrier - Google Patents

Abstract

PURPOSE:To form a high density pattern by using an opened and flattened glass cloth which has excellent impregnation of PTFE, no removal of glass powder, no residue of void, high hermetical sealability with a device, excellent soldering heat resistance and uniform relative permittivity. CONSTITUTION:The low permittivity film carrier base material comprises an opened and flattened glass cloth 1, a PTFE sintered layer 2 having a predetermined resin content and formed by repeatedly impregnating the cloth 1 with PTFE dispersion, drying and baking it, and a PTFE fine particle layer 3 the PTFE is dried at a melting point or lower and which is formed on an upper surface of the layer 2. Further, the material comprises a composite resin layer 4 of the PTFE and low melting point fluorine resin which is impregnated with fluorine resin dispersion having a lower melting point than that of the PTFE, dried and baked at the melting point or higher of the PTFE, a low melting point fluorine resin single element layer 5 of a thin layer of several mum or less formed on the upper surface of the layer 4, and metal layers 7, 8 arranged on both sides of a single resin cloth 6 made of the cloth 1 and the layers 2, 3, 4, 5 and heated and pressed at the melting point or higher of the PTFE.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, an IC (Inte
grated circuit), LSI (Large Scale Integrated C)
The present invention relates to a low dielectric constant film carrier substrate and a film carrier such as those used for mounting integrated circuit chips such as ircuit).

[0002]

2. Description of the Related Art Conventionally, film carrier bases and film carriers include film carrier bases and film carriers mainly containing resins other than fluororesin resins. That is, polyimide (Polyimid
e, PI) formed into a film, polyester (Polyester) formed into a film by a melt extrusion method using a die, modified polyimide (specifically, triazine resin reacted with bismaleimide, heat resistance) Regarding resins, there are those in which glass cloth is impregnated with a resin such as BT RESIN) or glass epoxy, and is formed into a film. Dielectric constant is 3.5 or more, and low dielectric properties cannot be secured (when low dielectric properties cannot be secured, signal propagation speed is slow,
There is a problem that it cannot be used in a high frequency range.

The lead portion of the film carrier base material mainly composed of a resin other than the above-mentioned fluororesin is formed by a plating means or a vacuum vapor deposition means or after the copper foil is laminated, the copper foil is etched. It is well known that the above is formed. On the other hand, in order to solve such problems and secure low dielectric properties, a film carrier base material and a film carrier mainly made of a fluororesin resin (PTFE, PFA, FEP, etc.) have been invented.

A film carrier base material and a film carrier mainly composed of this fluororesin resin are shown in FIG.
This will be described in detail with reference to FIGS. 14 and 15. First, describing the conventional configuration shown in FIG. 13, this film carrier is
The glass cloth 81 is impregnated with, for example, PTFE dispersion as a fluororesin dispersion, dried and fired to form resin cloths 82, 82, and a Cu foil 8 having a predetermined thickness is formed on at least one surface of the above-mentioned resin cloths 82, 82.
3 are arranged, and each of these elements has a melting point of the above-mentioned PTFE of 32.
The film carrier 84 is integrally molded by heating and pressing under a temperature condition of 7 ° C. or higher.

Here, as the above-mentioned glass cloth 81, JISR3413 is used because of the correlation between the resin impregnating property and the reinforcing effect.
Alkali-free glass thread displayed by ECD900 1
/ 2 or ECD450 1/0 is used, the thickness of this glass cloth is about 0.06 mm, and the density is 6 (vertical).
0 lines / 25 mm, weft (horizontal) is about 47 lines / 25 mm.

According to the conventional film carrier 84, there is an advantage that a low dielectric property can be secured, but there are various problems as follows. That is, since the open-woven plain weave glass cloth 81 is used,
As shown by the gap L2 in FIG. 13, the glass cloth 81 and the fluororesin have poor adhesion, and voids (small holes) due to water evaporation during the resin impregnation and drying steps are present in the glass yarn (particularly in the glass yarn). Intersection of glass cloth)
However, since it is difficult to remove the voids even when heated and pressed, there is a problem that the airtightness of the device becomes incomplete.

Further, when various necessary holes such as a device hole, a sprocket hole, and an outer lead hole are formed by punching, glass powder falls off from the fracture surface, and the glass powder dropped during bonding adheres to the chip surface. there were. This problem (dropping of glass powder) occurs due to insufficient impregnation of the glass cloth with the PTFE resin.

Further, when the Cu foil 83 as the metal foil is bonded after the necessary holes such as the device hole, the sprocket hole and the outer lead hole are formed, the resin impregnated glass cloth 81 is removed by the heat at the time of heating and pressurizing. Since it is reheated and stretched, distortion or warpage occurs in the resin cloth 82,
In addition, it is difficult to ensure good dimensional accuracy of various holes, and it is difficult to increase the density and accuracy of patterns. In addition, since there is a high possibility that the air in the voids will expand during soldering and the resin cloth 82 will peel off from the Cu foil 83, there was the problem of poor solder heat resistance.

In addition, because of the use of the above-mentioned open-woven plain weave glass cloth 81, the relative dielectric constant in the eyes is about 2.1 due to the resin rich, and the glass in the portion where the warp and weft threads cross. The relative permittivity is about 5.8 due to the richness.
Since the relative permittivity of the film carrier 84 varies greatly, there is a problem that the circuit characteristics are adversely affected especially in the high frequency band.

Next, the conventional structure shown in FIG. 14 will be described. This film carrier 86 includes resin cloth 82 and C.
PFA film 85 as an adhesive layer between the u foil 83
It is a structure that has been interposed. Since this PFA film 85 has a large thickness of about 25 μm or more, the PFA flows out into a necessary hole such as a device hole due to the press pressure at the time of integral molding, and the PFA that flows out is the Cu foil 83.
When it is adhered and solidified on the PFA film 85, it becomes impossible to form leads and bond chips.
Has a problem of forming a stress-strained step layer because of its high molding shrinkage. In FIG. 14, the same parts as those in FIG. 13 are designated by the same reference numerals, and detailed description thereof will be omitted.

Next, the conventional structure shown in FIG. 15 (Japanese Patent Laid-Open No. 2-2
(Structure described in Japanese Patent No. 05332), the film carrier 96 is obtained by impregnating a glass cloth 91, which is an open plain weave cloth, with PTFE resin to form an insulating layer 9 of the base.
2 is formed, the PF is formed on the upper surface of one side of the insulating layer 92.
An adhesive layer 93 made of A resin and having a thickness of 25 μm is placed on the adhesive layer 93 and lightly thermocompressed to temporarily fix the adhesive layer 93 to the lower insulating layer 92, and then a device hole and a sprocket hole are formed by press punching means. Various holes such as 94
After forming, the electrolytic copper foil 95 is placed on the upper surface of the adhesive layer 93, and the temperature is 370 ° C., the pressure is 30 kgf / cm ² , and the time is 3
Thermocompression-bonded under each condition for 0 minutes, and film carrier 96
Is configured.

However, this conventional film carrier 96
In the case of forming the hole 94 by the above-mentioned press punching, since there are only two resin-based layers of the insulating layer 92 and the adhesive layer 93, the mechanical strength at the time of forming the hole is insufficient, and the hole size is good. Since the precision cannot be ensured and the plain weave woven fabric is used in addition, there are various problems described above.

[0013]

The invention according to claim 1 of the present invention uses a glass cloth having a flattened spread, whereby the impregnation property of PTFE into the glass cloth is greatly improved, and the glass powder falls off. Of course, you can prevent it,
There are no voids (small holes) remaining in the glass substrate, improving the airtightness with the device, improving the heat resistance of the solder, homogenizing the relative permittivity, and yet sufficiently reinforcing the glass cloth while reducing its thickness. It is an object of the present invention to provide a low-dielectric-constant film carrier base material that can obtain an effect and achieve a high density pattern.

According to the invention of claim 2 of the present invention, in addition to the object of the invention of claim 1 described above, it is possible to make the relative dielectric constant even better, and to improve the handleability of the glass cloth and the impregnation property of PTFE. An object of the present invention is to provide a low dielectric constant film carrier base material that can achieve both

The invention according to claim 3 of the present invention, together with the object of the invention according to claim 1 or 2, is capable of forming a high-density pattern and ensuring sufficient mechanical strength during hole formation. With this, it is possible to improve the accuracy of hole processing, and at the same time, it is possible to prevent warpage, strain, and dimensional change during the integral molding by thermocompression bonding of the metal foil to be the conductive layer. For the purpose of provision.

[0016]

According to a first aspect of the present invention, there is provided a flattened glass cloth and a predetermined resin which is obtained by repeatedly impregnating the glass cloth with PTFE dispersion, drying and firing. PTFE formed to the content rate
With respect to the sintered layer and the upper surface of the PTFE sintered layer, the PTFE
A PTFE fine particle layer dried at a temperature below the melting point,
The FE fine particle layer is impregnated with a fluororesin dispersion having a melting point lower than that of PTFE, dried, and then formed on the composite resin layer of PTFE and the low melting point fluororesin which are baked at the melting point of PTFE or higher and the composite resin layer. A low melting point fluororesin simple substance layer having a thickness of several μm or less and a single resin cloth composed of the above glass cloth and each layer,
It is a low dielectric constant film carrier substrate provided with a metal layer heated and pressed at a temperature equal to or higher than the melting point of PTFE.

According to a second aspect of the present invention, in addition to the constitution of the first aspect of the invention, the glass cloth is flattened to have an opening between warp and weft threads of about 0.004 mm ² or less. And a low dielectric constant film carrier substrate having a thickness of about 0.03 to 0.12 mm.

According to the invention of claim 3 of the present invention, in addition to the constitution of the invention of claim 1 or 2, a film carrier substrate from which the metal layer on the low melting point fluororesin single layer side has been removed, A low dielectric constant film carrier in which a necessary hole is formed by a press punching means, a metal foil to be a conductive layer is arranged on the side from which the metal layer is removed, and a predetermined pattern is formed after integral molding by thermocompression bonding. Is characterized in that.

[0019]

According to the invention described in claim 1 of the present invention, since the flattened glass cloth is used, the impregnation property of PTFE into the glass cloth is improved, and as a result, the glass powder at the time of forming holes is formed. Since it is possible to prevent the glass from falling off and voids (small holes) do not remain in the glass base material, it is possible to improve the airtightness with the device, improve the solder heat resistance and make the relative dielectric constant uniform. There is an effect that can be. Moreover, there is an effect that a sufficient reinforcing effect can be obtained while reducing the thickness of the glass cloth.

In addition, since a PTFE cloth is impregnated with PTFE dispersion, dried and fired repeatedly to form a PTFE sintered layer having a predetermined resin content, and thus a sintered layer is formed through the firing step, The coating is smooth and void-free.

Further, since the PTFE fine particle layer is formed on the upper surface of the above-mentioned PTFE sintered layer, the composite resin layer can be easily formed, and the interlayer adhesive strength can be improved in cooperation with this composite resin layer. There is an effect that can be done. Furthermore, since the above-mentioned composite resin layer acts as a stress strain buffer zone, there is an effect that the strain can be significantly reduced.

In addition, since a low melting point fluororesin simple substance layer having a thickness of several μm or less is formed, distortion is suppressed to a minimum while
Since a sufficient adhesive effect can be obtained and the layer thickness of the low melting point fluororesin simple substance layer is extremely thin, the low melting point fluororesin does not flow out at the time of heating and pressing, and as a result, high pressure pressing becomes possible. Further, there are effects that the surface flatness can be improved, the mechanical strength can be improved, and the dimensional change rate can be significantly reduced. Further, since the metal layer is heated and pressed under the condition that it is disposed on both sides of the resin cloth, there is an effect that the surface flatness is improved and the high density patterning is further facilitated.

According to the invention of claim 2 of the present invention,
In addition to the effect of the invention described in claim 1, the glass cloth is flattened to have an opening between the warp and weft of about 0.004 mm ² or less, so that there is no variation in the relative dielectric constant and it is even better. This has the effect of achieving uniform uniformity.

The thickness of the glass cloth should be about 0.03 to 0.1.
Since it is set within the range of 2 mm, it is possible to improve the handleability of the glass cloth and the impregnation property of PTFE. Incidentally, when the thickness of the glass cloth is less than 0.03 mm, the rigidity of the glass cloth becomes weak and handling becomes impossible.
If it exceeds 12 mm, impregnation with PTFE will not be possible, so it is set within the above range.

According to the invention of claim 3 of the present invention,
In addition to the effect of the invention described in claim 1 or 2, since the metal layer on the low melting point fluororesin single layer side is removed, a flattened surface is obtained, and leads (inner leads and outer leads) are formed on this flattened surface. ) Can be formed,
There is an effect that a high-density pattern can be formed.

While the metal layer on the side of the low melting point fluororesin simple substance layer is removed while the metal layer on the glass cloth side is left, necessary holes (sprocket hole, device hole, outer lead) are formed by press punching means. Since the holes are formed, the remaining metal layer improves the mechanical strength at the time of forming the holes, and as a result, the hole processing accuracy can be improved.

Further, when the metal foil to be the conductive layer is integrally formed by thermocompression bonding, the above-mentioned metal layer on the glass cloth side remains, so that warping, distortion, and dimensional change occur during the thermocompression bonding. There is an effect that can be prevented by.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The drawings show a low dielectric constant film carrier base material and a film carrier in the order of manufacturing steps thereof, and the glass cloth 1 flattened in FIG. 1 is provided.

Specifically, alkali-free glass thread ECD450
Using 1/0 by hydraulic pressure or roll forming means, the opening between warps and wefts is flattened to about 0.004 mm ² or less, and the thickness T is within the range of about 0.03 to 0.12 mm. And the above-mentioned glass cloth 1 is configured. In this embodiment, the thickness T is set to about 0.04 mm and the interval L1 corresponding to the opening is set to 0.06 mm or less.

Next, as shown in FIG. 2, a PTFE sintered layer 2 having a predetermined resin content of 60 to 80 vol% was formed by repeatedly impregnating the above glass cloth 1 with PTFE dispersion, drying and firing. Form.

Next, as shown in FIG. 3, a PTFE fine particle layer 3 is formed by drying PTFE at a melting point of 327 ° C. or lower on the upper surface of the above-mentioned PTFE sintered layer 2. This PT
The FE fine particle layer 3 is formed by impregnation of PTFE dispersion and drying (drying at a temperature below the melting point of PTFE).

Next, as shown in FIG. 4, the above-mentioned PTFE fine particle layer 3 is impregnated with a fluororesin dispersion having a melting point lower than that of PTFE, dried, and then the PTFE and the low-melting fluorine are fired at a melting point of 327 ° C. or higher of PTFE. At the same time as forming the composite resin layer 4 with the resin, as shown in FIG. 5, the composite resin layer 4 has an upper surface with a thickness of several μm or less, specifically 2 to 5 μm.
A low melting point fluororesin simple substance layer 5 having a thin thickness of μm is formed. That is, since a low melting point fluororesin, such as PFA, originally has a large molding shrinkage and a molding strain remains, the low melting point fluororesin simple substance layer 5 is formed as an extremely thin layer to suppress the strain to a minimum.

In this embodiment, PFA (melting point 310 ° C.) is used as the fluorine resin having a melting point lower than that of PTFE, but other low melting point fluorine resin such as FEP (melting point 275 ° C.) may be used in addition to PFA. . Note that, in FIG. 3, FIG. 4, and FIG. 5 described above, the PTFE fine particle layer 3, the composite resin layer 4, and the low melting point fluororesin simple substance layer 5 are schematically illustrated as being divided into layers for convenience of illustration. Is as shown in FIG.

In FIG. 6, the white circles indicate PTFE, and the hatched circles indicate PFA. That is, in the drawing, the composite resin layer 4 in which the PFA changes from lean to rich is formed from the PTFE fine particle layer 3 on the lower side to the low melting point fluororesin simple substance layer 5 on the upper side. The following figures (Fig. 7)
~ FIG. 10 and FIG. 12), the same applies, but is shown schematically for convenience of illustration.

The above-mentioned glass cloth 1 shown in FIG. 5 and a single resin cloth 6 composed of the layers 2, 3, 4, 5 are provided with Cu foils 7, 8 of a predetermined thickness on the upper and lower surfaces thereof. ,
The low dielectric constant film carrier base material 9 is formed by heating and pressing at a temperature equal to or higher than the melting point of PTFE (FIG. 7).

Here, PTFE has a remelting temperature of 327.
C., melt viscosity does not flow at 10 <10> to ¹⁰ < ¹¹ > poise under conditions of 380 <0> C. Although the melt viscosity of PFA is as low as 10 ⁴ to 10 ⁵ poise under the condition of 380 ° C., the layer thickness of the low melting point fluororesin simple substance layer 5 used as the adhesive layer is formed into a thin layer of 2 to 5 μm to prevent the PFA outflow. Since the possibility is eliminated, the conditions for the integral molding after the above-mentioned Cu foils 7 and 8 are arranged are
The temperature can be set to 0 ° C. and the pressure can be set to 40 kgf / cm ² or more. By this high pressure molding, the surface flatness and the mechanical strength are improved, and the low dielectric constant film carrier base material 9 having a small dimensional change rate is constituted. can do.

Next, when a low dielectric constant film carrier is constructed from the above-mentioned low dielectric constant film carrier base material 9, first, as shown in FIG.
Only the u foil 7 is removed by etching means.

Next, as shown in FIG. 9, under the condition that the lower Cu foil 8 remains, the necessary holes 10 such as the sprocket hole 10S, the device hole 10D, and the outer lead hole 10A (see FIG. 11) are formed by press punching. Form.

Next, as shown in FIG. 10, on the side where the Cu foil 7 has been removed by the etching means, a metal foil to be a conductive layer, specifically, a Cu foil 11 having a predetermined thickness is provided, and is reheated and pressure-bonded. After integrally molding each element of FIG. 10, Cu foil 11
A predetermined pattern P is formed by etching means as shown in FIG. 11 to form the double-sided conductive layer type low dielectric constant film carrier 12. Note that FIG. 10 and FIG.
Double-sided conductive layer type low dielectric constant film carrier 1
By removing the Cu foil 8 from 2 to the lower side by etching means, a single-sided conductive layer type low dielectric constant film carrier can be formed.

When a low-dielectric constant film carrier base material or film carrier of a single-sided conductive layer type is constituted,
As shown in FIG. 12, it is also possible to adopt an asymmetrical structure in which the resin layers 3, 4, 5 and the Cu foils 8, 11 are arranged on one side of the glass cloth impregnated with the PTFE dispersion.

In summary, since the low dielectric constant film carrier base material 9 of this embodiment uses the spread and flattened glass cloth 1, the impregnation property of PTFE into the glass cloth 1 is greatly improved. As a result, It is possible to prevent the glass powder from falling off when forming the holes 10, and voids (small holes) do not remain in the glass substrate. This voiding has the effects of improving the airtightness with the device, improving the heat resistance of the solder, and making the relative dielectric constant uniform. Moreover, there is an effect that a sufficient reinforcing effect can be obtained while reducing the thickness of the glass cloth 1.

The glass cloth 1 is impregnated with PTFE dispersion, dried and fired repeatedly to form a PTFE sintered layer 2 having a predetermined resin content, and the PTFE sintered layer 2 is passed through the firing step in this manner. Since it is formed, the film has the effect of smoothing and eliminating voids.

Further, since the PTFE fine particle layer 3 is formed on the upper surface of the above-mentioned PTFE sintered layer 2, the composite resin layer 4 can be easily formed, and in cooperation with this composite resin layer 4, the interlayer adhesive strength is improved. There is an effect that can be achieved. Furthermore, since the above-mentioned composite resin layer 4 acts as a stress / strain buffer zone, there is an effect that the strain can be significantly reduced.

In addition, a thin layer of low melting point fluororesin single layer 5
Since it is formed, a sufficient adhesive effect can be obtained while suppressing distortion to a minimum.
Since the layer thickness of PFA is extremely thin, PFA as a low melting point fluororesin does not flow out at the time of heating and pressurization, and as a result, high pressure pressing becomes possible, improving the surface flatness,
The mechanical strength can be improved and the dimensional change rate can be significantly reduced. Also, Cu foil 7, 8 as a metal layer
Since the resin cloth 6 is heated and pressed under the condition that the resin cloth 6 is disposed on both sides, the surface flatness is improved and high density patterning is further facilitated.

Further, the glass cloth 1 is flattened so that the openings between the warp and weft threads are about 0.004 mm ² or less, so that there is no variation in the relative permittivity and it is possible to achieve even better uniformity. There is an effect that can be done.

Furthermore, the thickness of the glass cloth 1 is set to about 0.0.
Since it is set within the range of 3 to 0.12 mm, it is possible to improve the handleability of the glass cloth 1 and the impregnation property of PTFE. When the thickness of the glass cloth is less than 0.03 mm, the rigidity of the glass cloth becomes weak and handling becomes impossible, while when it exceeds 0.12 mm, impregnation of PTFE becomes impossible. , Set within the above range.

In addition, since the low dielectric constant film carrier 12 of this embodiment removes the Cu foil 7 as the metal layer on the low melting point fluororesin simple substance layer 5 side, a flattened surface is obtained and this flatness is obtained. Since the inner leads 13IN and the outer leads 130UT (see FIG. 11) can be formed on the converted surface, there is an effect that a high-density pattern can be formed.

While the Cu foil 7 on the low melting point fluororesin simple substance layer 5 side is removed, while the Cu foil 8 on the glass cloth 1 side is left, the necessary holes 10 are formed by the press punching means.
(Sprocket hole 10S, device hole 10D,
Since the outer lead hole 10A) is formed, the remaining Cu foil 8 improves the mechanical strength at the time of forming the hole, and as a result, the hole processing accuracy can be improved. That is, since the Cu foil 8 described above is also used as a backup member during hole processing, it is possible to improve the accuracy of hole processing dimensions.

Further, when the Cu foil 11 to be the conductive layer is integrally formed by thermocompression bonding, C on the glass cloth 1 side described above is formed.
Since the u foil 8 remains, the Cu foil 8 has an effect of preventing the occurrence of warpage, strain, and dimensional change at the time of heating and pressure bonding.

In the correspondence between the constitution of the present invention and the above-mentioned embodiment, the fluororesin dispersion having a melting point lower than that of PTFE of the present invention corresponds to the PFA dispersion of the embodiment. Cu metal layer
The metal foil that corresponds to the foils 7 and 8 and serves as the conductive layer according to claim 3 corresponds to the Cu foil 11, but the present invention is not limited to the configuration of the above-described embodiment.

[Brief description of drawings]

FIG. 1 is an explanatory view of a crow cloth used as a low dielectric constant film carrier base material of the present invention.

FIG. 2 is a sectional view showing a step of forming a PTFE sintered layer.

FIG. 3 is a sectional view showing a step of forming a PTFE fine particle layer.

FIG. 4 is a cross-sectional view showing a step of forming a composite resin layer.

FIG. 5 is a cross-sectional view showing a step of forming a low melting point fluororesin simple substance layer.

FIG. 6 is an explanatory diagram showing a specific configuration of a PTFE fine particle layer, a composite resin layer, and a low melting point fluororesin simple substance layer.

FIG. 7 is a sectional view of a low dielectric constant film carrier substrate of the present invention.

FIG. 8 is a sectional view showing a Cu foil removing step.

FIG. 9 is a sectional view showing a hole forming step.

FIG. 10 is a sectional view of a low dielectric constant film carrier of the present invention.

FIG. 11 is a plan view of the film carrier.

FIG. 12 is a cross-sectional view showing another embodiment of the low dielectric constant film carrier of the present invention.

FIG. 13 is a sectional view showing a conventional film carrier.

FIG. 14 is a sectional view showing a conventional film carrier.

FIG. 15 is a sectional view showing a conventional film carrier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Glass cloth 2 ... PTFE sintered layer 3 ... PTFE fine particle layer 4 ... Composite resin layer 5 ... Low melting point fluororesin single layer 6 ... Resin cloth 7,8 ... Cu foil 10 ... Hole 10A ... Outer lead hole 10D ... Device hole 10S ... Sprocket hole 11 ... Cu foil P ... Pattern

Claims (3)

[Claims] 1. A spread-flattened glass cloth, and a PTF formed into a predetermined resin content by repeating impregnation of the glass cloth with PTFE dispersion, drying and firing.
E sintered layer and PTFE on the upper surface of the PTFE sintered layer
A PTFE fine particle layer in which E is dried at a temperature equal to or lower than the melting point;
The TFE fine particle layer is impregnated with a fluororesin dispersion having a melting point lower than that of PTFE, dried, and then formed on the composite resin layer of PTFE and the low-melting point fluororesin which are baked at a melting point of PTFE or higher and the composite resin layer upper surface. And a low melting point fluororesin simple substance layer having a thickness of several μm or less, and a metal layer which is disposed on both sides of a single resin cloth composed of the above glass cloth and the above layers and which is heated and pressed at a temperature equal to or higher than the melting point of PTFE. A low dielectric constant film carrier substrate provided. 2. The film carrier according to claim 1, wherein the glass cloth has a mesh opening between warp and weft threads of about 0.004.
mm ² is opened繊偏Tairaka below, thickness of about 0.03 to 0.
A low dielectric constant film carrier substrate characterized by being formed to 12 mm. 3. The film carrier base material according to claim 1 or 2, wherein necessary holes are formed by press punching means in the film carrier base material from which the metal layer on the low melting point fluororesin single layer side has been removed. A low dielectric constant film carrier in which a metal foil to be a conductive layer is disposed on the side from which the metal layer is removed, and a predetermined pattern is formed after integral molding by thermocompression bonding.