JP2009241597A - Substrate material and substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate material in which a thick film can be produced through a simple production process and which hardly causes sinks during the mounting of chips, resulting in reduction of warpage. <P>SOLUTION: In the substrate material, a metal foil 12, polyimide layer 11 and transparent resin layer 13 are laminated in this order. When the coefficient of the thermal expansion, thickness and module of the elasticity of the polyimide layer 11 are denoted by E<SB>1</SB>, T<SB>1</SB>and M<SB>1</SB>respectively, and the coefficient of the thermal expansion, thickness and module of the elasticity of the transparent resin layer 13 are denoted by E2, T2 and M2 respectively, the formula (1) is satisfied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate material and a substrate.

  A flexible printed wiring board is a flexible wiring board in which a conductor circuit is formed on the surface of a polymer insulating film, and has recently been frequently used as a means for achieving miniaturization and high density of electronic devices. In particular, the demand for COF (Chip on Film) substrates is growing significantly.

  The COF substrate material is thicker than the normal flexible substrate material, and is required to have transparency. In the COF mounting process, the insulating material needs to exhibit high elasticity. In order to satisfy these conditions, conventional COF substrate materials have been manufactured by a method of forming a metal layer on a polyimide film by vapor deposition or sputtering (hereinafter referred to as “metallization method”) (Patent Documents 1 and 2). reference).

JP 2007-201216 A JP 2006-278371 A

  However, in the metallization method, a COF substrate having excellent transparency can be manufactured, but on the other hand, adhesion to a metal layer such as copper is insufficient, and a special apparatus for performing vapor deposition and sputtering is necessary. In addition, there is a problem that the manufacturing process becomes complicated because a plating process or heating and heating treatment may be required. Furthermore, depending on the surface state of the polyimide film, the ability to be plated is affected, causing a circuit failure.

  In recent years, attempts have been made to produce a COF substrate material by a casting method, which is an FPC production method using copper foil (Japanese Patent Laid-Open No. 2006-346874), but it is difficult to produce a thick film by the casting method. In addition, there is a problem that the manufacturing cost increases as the polyimide film becomes thicker.

  Further, a copper foil bonded to a polyimide film with a thermoplastic polyimide adhesive or an epoxy adhesive (JP 2006-37083 A, JP 2006-83731 A, etc.) is the elasticity of the adhesive on the surface. Due to the low rate, sinking occurred when mounting the chip, which was not necessarily suitable for practical use. In addition, there is a problem that the base material is warped by stacking the layer structures, and component mounting is difficult.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate material in which a thick film can be formed by a simple manufacturing process, subsidence hardly occurs during chip mounting, and warpage is reduced, and a substrate using the same.

２．ポリイミド層は、該層を構成するポリイミドの前駆体を金属箔上にキャストした後、ポリイミド化させた層である、前記の基板材料。
３．透明樹脂層は、上記ポリイミド層とは異なるポリイミドからなる、前記の基板材料。
４．金属箔を除く層全体の厚さが２０〜５０μｍである、前記の基板材料。
５．金属箔を除く層全体の透過率が、波長６００ｎｍの光において６０％以上である、前記の基板材料。
６．ポリイミド層と透明樹脂層との間に、接着剤層を備えており、接着剤層は、６０℃以上２００℃以下でポリイミド層と透明樹脂層を接着可能であり、５重量％分解温度が３３０℃以上であり、融点が３００℃以上の接着剤からなる、前記の基板材料。
７．金属箔は、銅箔である、前記の基板材料。
８．前記の基板材料から形成される基板。 The present invention relates to the following.
1. A substrate material in which a metal foil, a polyimide layer and a transparent resin layer are laminated in this order, and the thermal expansion coefficient, thickness and elastic modulus of the polyimide layer are E ₁ , T ₁ and M ₁ , respectively. A substrate material that satisfies the following formula (1) when the thermal expansion coefficient, thickness, and elastic modulus are E ₂ , T _2, and M ₂ , respectively.

2. The polyimide layer is the substrate material described above, which is a layer obtained by casting a polyimide precursor constituting the layer onto a metal foil and then forming a polyimide.
3. The transparent resin layer is the substrate material described above, which is made of polyimide different from the polyimide layer.
4). The said board | substrate material whose thickness of the whole layer except metal foil is 20-50 micrometers.
5. The said board | substrate material whose transmittance | permeability of the whole layer except metal foil is 60% or more in the light of wavelength 600nm.
6). An adhesive layer is provided between the polyimide layer and the transparent resin layer, and the adhesive layer can bond the polyimide layer and the transparent resin layer at 60 ° C. or more and 200 ° C. or less, and the 5% by weight decomposition temperature is 330. Said board | substrate material which consists of an adhesive agent whose melting | fusing point is 300 degreeC or more.
7). The substrate material as described above, wherein the metal foil is a copper foil.
8). A substrate formed from the above substrate material.

  Provided are a substrate material suitable for a COF (Chip on Film) substrate and a substrate using the same, in which a thick film can be formed by a simple manufacturing process, subsidence does not easily occur during chip mounting, and warpage is reduced. .

It is sectional drawing of the board | substrate material which concerns on 1st Embodiment. It is sectional drawing of the board | substrate material which concerns on 2nd Embodiment. It is sectional drawing of the board | substrate which concerns on 1st Embodiment. It is sectional drawing of the board | substrate which concerns on 2nd Embodiment. It is sectional drawing of the board | substrate which concerns on 3rd Embodiment.

  Hereinafter, preferred embodiments will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the drawings are exaggerated for easy understanding, and the dimensional ratios do not necessarily match those described. Since the substrate material and the substrate of the present invention can be used for COF, they may be expressed as COF substrate materials and COF substrates.

  FIG. 1 is a cross-sectional view of the substrate material according to the first embodiment, and FIG. 2 is a cross-sectional view of the substrate material according to the second embodiment.

  A substrate material 1a shown in FIG. 1 has a configuration in which a transparent resin layer 13 is laminated on the surface of a polyimide layer 11 of a polyimide film 10 with a metal foil in which a metal foil 12 is provided in close contact with one surface of a polyimide layer 11. Have.

  The substrate material 1b shown in FIG. 2 is a polyimide film 10 with a metal foil in which a metal foil 12 is provided in close contact with one surface of a polyimide layer 11. It has a joined configuration.

  The polyimide film 10 with a metal foil is obtained by a casting method (after casting a solution of a precursor of a polyimide, for example, a polyamic acid solution onto the metal foil 12, removing the solvent and allowing the reaction to proceed, thereby forming a polyimide film. Of the metal foil 12 and the polyimide layer 11, manufactured by a metallization method or a laminate method, or manufactured by a cast method. A low adhesive may be inserted.

  However, those manufactured by the metallization method may have weak copper foil peeling strength, and those that adhere to the copper foil using an adhesive may cause surface sinking, so the casting method What was manufactured by is preferable.

  By using the polyimide film 10 with metal foil manufactured by the casting method, the peeling strength of the metal foil 12 is improved, and by using the transparent resin together, the polyimide film 10 with metal foil manufactured by the casting method is used. In addition to overcoming manufacturing difficulties, it is possible to control film repulsion, improve transportability, improve transparency, improve dimensional stability, control hygroscopicity, and improve chip mounting compared to existing COF materials It is.

  The thickness of the polyimide layer 11 is usually 1 to 10 μm. As the metal foil 12, a foil of copper, aluminum, iron, gold, silver, nickel, palladium, chromium, molybdenum or an alloy thereof is preferably used. Among these, copper foil is preferable.

  In order to increase the adhesive strength with the polyimide layer 11, the surface of the metal foil 12 is mechanically or chemically treated by chemical roughening, corona discharge, sanding, plating, aluminum alcoholate, aluminum chelate, silane coupling agent, or the like. It may be processed.

  Examples of the resin film that forms the transparent resin layer 13 include heat resistant resins such as polyimide (which may be the same as or different from the polyimide constituting the polyimide layer), polyamideimide, polyetherimide, polyethersulfone, polybenzoxazole, and the like. The transparent film manufactured more is mentioned.

  The bonding method between the polyimide layer 11 and the transparent resin layer 13 may be direct bonding or bonding using an adhesive. As a method of directly bonding, activation of the surface of the polyimide layer 11 by plasma treatment, ultraviolet treatment, corona treatment, flame treatment, etc., thermal lamination at a temperature higher than the glass transition temperature of the polyimide layer 11 or the transparent resin layer 13, etc. can give. The total thickness of the substrate material excluding the metal foil 12 is preferably 20 to 50 μm. If the thickness is less than 20 μm or more than 50 μm, it may be difficult to convey with existing COF manufacturing equipment.

  As a method for bonding the polyimide layer 11 and the transparent resin layer 13 using an adhesive, a method of performing heat lamination by sandwiching the adhesive layer 13 between the polyimide layer 11 and the transparent resin layer 13 can be used. In this case, it is preferable to heat in the range of 60-200 degreeC, and 100 to 150 degreeC is more preferable. If it is less than 60 ° C., it becomes difficult to bond with sufficient adhesive strength, and if it exceeds 200 ° C., the polyimide layer 11 may be thermally deformed. Further, the part to be bonded is preheated to 25 ° C. to 200 ° C., and the thermocompression-bonding roll and the part to be bonded are heated to 80 ° C. to 200 ° C. for effective bonding. It can be performed. It is preferable to pressurize together with heating, and the pressurization is performed at 1 kN / m or more, preferably 5 kN / m or more and 50 kN / m or less.

  When forming the adhesive layer 14, it is preferable that the adhesive which comprises the adhesive layer 14 has 5 weight% decomposition temperature of 330 degreeC or more. An adhesive having a 5% by weight decomposition temperature of less than 330 ° C. tends to cause swelling during chip mounting. Further, the melting point of the adhesive (referred to as the temperature at which it can be softened and bonded) is preferably 300 ° C. or higher. If an adhesive having a melting point of less than 300 ° C. is used, it will cause sinking during chip mounting. It becomes. Moreover, it is preferable to show the adhesiveness with the polyimide layer 11 and the transparent resin layer 13 in the laminate of 60 degreeC or more and 200 degrees C or less. An adhesive that can be bonded at a temperature lower than 60 ° C. may cause a problem of storage stability of the adhesive itself. A laminate exceeding 200 ° C. tends to cause a warp in the MD direction because the difference in elongation between the substrates during lamination becomes large.

The substrate material has the thermal expansion coefficient, thickness and elastic modulus of the polyimide layer 11 as E ₁ , T ₁ and M ₁ , respectively, and the thermal expansion coefficient, thickness and elastic modulus of the transparent resin layer 13 as E ₁ , respectively. _{When it is set to 2} , T ₂ and M ₂ , it is necessary to satisfy the following formula (1).

By satisfy | filling Formula (1), a thick film can be created with a simple manufacturing process, and curvature will be reduced. The value of (E ₂ · T ₂ · M ₂ ) / (E ₁ · T ₁ · M ₁ ) is more preferably from 0.7 to 1.5, and even more preferably from 0.9 to 1.5.

  The curl (warp) after etching the metal foil (copper foil) of the substrate material is curled to the metal foil (copper foil) side in the range of −1 to 3 mm when the material is cut into 50 mm square. Preferred (a negative number means curling to the opposite side of the metal foil). If the curl exceeds 1 mm on the transparent resin side or the curl exceeds 3 mm on the metal foil (copper foil) side, it tends to cause defects during chip mounting. Further, the transmittance of the film after etching the metal foil (copper foil) (that is, the transmittance of the entire layer excluding the metal foil) is preferably 60% or more, and 70% or more in light having a wavelength of 600 nm. More preferred. If it is less than 60%, it may be difficult to connect the chip to the COF substrate in an existing manufacturing facility.

  A substrate (COF substrate) can be obtained by a method of forming a conductor pattern by removing a part of the metal foil in the substrate material described above.

  FIG. 3 is a sectional view showing the first embodiment of the substrate. The board | substrate 2a is provided with the insulating layer which bonded the polyimide film 11 and the transparent resin layer 13, and the conductor pattern 20 formed in the single side | surface of an insulating layer. The conductor pattern 20 is formed by removing a part of the metal foil 12 included in the substrate material 1a and patterning it. The metal foil 12 is patterned by a method such as photolithography. Alternatively, the metal foil 12 is removed from the substrate material 1a, and the conductive material is directly drawn on the exposed polyimide layer 11 to form a conductive pattern, whereby the substrate 2a can be obtained.

  Moreover, after removing a part of metal foil and forming a conductor pattern, resin can also be adhere | attached on the conductive pattern side. FIG. 4 is a cross-sectional view showing a second embodiment of the substrate. A substrate 2b shown in FIG. 4 is formed on the polyimide layer 11 so as to cover the insulating layer obtained by bonding the polyimide layer 11 and the transparent resin layer 13, the conductor pattern 20 formed on one surface of the insulating layer, and the conductor pattern 20. The resin film 14 is provided. The substrate 2b is formed by patterning in the same manner as the substrate 2a, and then bonding the resin film 14 from the conductive pattern 20 side.

  At this time, instead of the resin film 14 in FIG. 4, a protective film cover lay 1 c in which the transparent resin layer 13 is formed on one surface of the protective film 15 may be used. FIG. 5 is a cross-sectional view showing a third embodiment of the substrate having such a configuration. A substrate 2c shown in FIG. 5 is formed on the polyimide layer 11 so as to cover the insulating layer obtained by bonding the polyimide layer 11 and the transparent resin layer 13, the conductor pattern 20 formed on one surface of the insulating layer, and the conductor pattern 20. The transparent resin layer 13 and the resin film 14 formed on the transparent resin layer 13 are provided.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

(Configuration example 1)
MCF-5000IS (Hitachi Chemical Industry Co., Ltd .: Cu / PI = 15 μm / 5 μm) which is a polyimide film with copper foil, Hibon 10-808 (Hitachi Chemical Polymer Co., Ltd .: 5 μm) which is an adhesive sheet, and a transparent resin. Kapton H (Toray DuPont Co., Ltd .: 25 μm) was stacked, and a sample was molded with a press at 180 ° C. and 4 MPa for 1 hour.

(Configuration example 2)
MCF-5000IS (Hitachi Chemical Industry Co., Ltd .: Cu / PI = 15 μm / 10 μm) which is a polyimide film with copper foil and Ultem B1000 (GE Plastics Co., Ltd .: 25 μm) which is a transparent resin are stacked and pressed. Samples were molded under conditions of 180 ° C., 4 MPa, and 1 hour.

(Configuration example 3)
MCF-5000IS (Hitachi Chemical Industry Co., Ltd .: Cu / PI = 15 μm / 35 μm), which is a polyimide film with copper foil, was used.

(Configuration example 4)
DFF (Mitsui Metal Mining Co., Ltd .: Cu = 15 μm) which is a copper foil, Hibon 10-808 (Hitachi Chemical Polymer Co., Ltd .: 5 μm) which is an adhesive sheet, and Kapton H (Toray DuPont Co., Ltd .: 25 μm) which is a transparent resin ), And a sample was molded by a press at 180 ° C. and 4 MPa for 1 hour.

(Configuration example 5)
Esperflex (Sumitomo Metal Mining Co., Ltd .: Cu / PI = 9 μm / 38 μm), which is a COF substrate material by a metallization method, was used.

(Examples 1-2, Comparative Examples 1-3)
A subsidence test and a copper foil peeling test were performed on the manufactured samples, and the results are shown in Table 1. The method of the subsidence test is as follows.

(Subduction test)
A sample of 5 cm square with etched copper foil was placed on a hot plate heated to 400 ° C. with the etching surface facing up, and pressed with a 2 cm square metal jig for 10 seconds with a force of 50 g, and the jig contact part The amount of subsidence was measured.

(Copper foil peeling test)
Cut copper foil line pattern with a thickness of 8mm, cut copper foil line pattern, and measure the peel strength of copper foil when peeled off at a rate of 50mm / min. did.

  In Examples 1-2 and Comparative Examples 1 and 3 having a polyimide film layer on the surface after copper foil etching, the amount of subsidence during the subsidence test was small, but a comparison having an adhesive layer on the surface after copper foil etching In Example 2, the jig contact portion was greatly submerged and was not suitable for practical use. In Comparative Example 3, the copper foil peeling strength was low.

(Configuration examples 6 to 10)
According to the structural example 1, the sample was produced using polyimide AE instead of Kapton H (Toray DuPont Co., Ltd .: 25 micrometers). Polyimide A is a silica hybrid type polyimide, polyimide B is a silica hybrid type polyimide, polyimide C is a pyromellitic acid type polyimide, polyimide D is a biphenyl type polyimide, and polyimide E is a pyromellitic acid / biphenyl type polyimide.

(Examples 3-4, Comparative Examples 1-7)
The curl after etching of the produced sample was measured. The copper foil of a 50 mm square sample was etched and the warpage when placed on a horizontal surface was measured and is shown in Table 2. The elastic modulus and thermal expansion coefficient are measured values under the following conditions.

(Elastic modulus measurement and thermal expansion coefficient)
As for the amount of warpage, the amount of warpage toward the etched surface of the copper foil was positive. In Comparative Example 3 of the current distribution product, almost no warping occurred, but in Comparative Example 1 produced by a cast method and using no transparent resin, the film warped greatly on the polyimide side and was not suitable for practical use. Moreover, the sample exceeding 150% of the value calculated by the formula (1) warped largely to the copper foil side and was not suitable for practical use.

  By using the means of the present invention, it becomes possible to produce a substrate material suitable for a COF substrate, which can produce a thick film by a simple manufacturing process, hardly cause sinking during chip mounting, and has reduced warpage. It was.

DESCRIPTION OF SYMBOLS 1a, 1b ... board | substrate material, 2a, 2b ... board | substrate, 10 ... polyimide film with metal foil, 11 ... polyimide layer, 12 ... metal foil, 13 ... transparent resin layer, 14 ... resin film, 20 ... conductor pattern.

Claims (8)

A substrate material in which a metal foil, a polyimide layer and a transparent resin layer are laminated in this order, and the thermal expansion coefficient, thickness and elastic modulus of the polyimide layer are E ₁ , T ₁ and M ₁ , respectively. A substrate material that satisfies the following formula (1) when the thermal expansion coefficient, thickness, and elastic modulus are E ₂ , T _2, and M ₂ , respectively.

  2. The substrate material according to claim 1, wherein the first polyimide layer is a layer obtained by casting a polyimide precursor constituting the layer onto the metal foil and then forming a polyimide. 3.   The substrate material according to claim 1, wherein the transparent resin layer is made of polyimide different from the polyimide layer.   The board | substrate material as described in any one of Claims 1-3 whose thickness of the whole layer except the said metal foil is 20-50 micrometers.   The board | substrate material as described in any one of Claims 1-4 whose transmittance | permeability of the whole layer except the said metal foil is 60% or more in the light of wavelength 600nm. An adhesive layer is provided between the polyimide layer and the transparent resin layer,
The adhesive layer is
The polyimide layer and the transparent resin layer can be bonded at a temperature of 60 ° C or higher and 200 ° C or lower, the 5% by weight decomposition temperature is 330 ° C or higher, and the melting point is 300 ° C or higher. The board | substrate material as described in any one.   The substrate material according to any one of claims 1 to 6, wherein the metal foil is a copper foil.   The board | substrate formed from the board | substrate material as described in any one of Claims 1-7.

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