WO2006129520A1

WO2006129520A1 - Compression bonding release sheet and roll

Info

Publication number: WO2006129520A1
Application number: PCT/JP2006/310216
Authority: WO
Inventors: Seiichi Takaoka; Tomoyoshi Nagayama
Original assignee: Nitto Denko Corporation
Priority date: 2005-05-30
Filing date: 2006-05-23
Publication date: 2006-12-07

Abstract

A compression bonding release sheet used in thermocompression bonding of electronic parts that while having a construction different from those of conventional compression bonding release sheets, simultaneously satisfies the requirements of release property and flexibility (cushioning property). There is provided a compression bonding release sheet comprising a layer of ultrahigh-molecular-weight polyethylene and a silicone rubber layer, wherein the layer of ultrahigh-molecular-weight polyethylene and the silicone rubber layer are unified together, and wherein the layer of ultrahigh-molecular-weight polyethylene has a thickness of 30 μm or greater.

Description

Specification

Crimp release sheet and wound body

Technical field

TECHNICAL FIELD [0001] The present invention relates to a pressure-sensitive release sheet used for joining electronic components by thermocompression bonding in a manufacturing process of an electronic device, and a wound body obtained by winding the pressure-sensitive release sheet.

Background art

[0002] Currently, in the manufacturing process of electronic equipment, a method using an anisotropic conductive film (ACF) as a method of electrically connecting various parts and members (electronic parts) used in the electronic equipment Is widely adopted. ACF has a structure in which conductive particles are dispersed in a strong adhesive film such as a thermosetting epoxy resin. Since the conductive particles are independent of each other in the film, the ACF is insulative as a whole.

For example, as shown in FIG. 4, there is a conductive property between a glass substrate 51 having a striped electrode 52 formed on the surface and a printed circuit board (PCB) 53 having a circuit pattern 54 formed on the surface. When the ACF55 containing the conductive particles 56 is placed and the glass substrate 51 and the PCB 53 are heat-pressed, the epoxy resin contained in the ACF55 is cured by heat, and the glass substrate 51 and the PCB 53 are bonded. At this time, as shown in FIG. 5, the force that electrically connects the electrode 52 and the circuit pattern 54 by the conductive particles 56 included in the ACF 55 is between the adjacent electrodes 52 or between the adjacent circuit patterns 54. Insulation, that is, insulation in a direction parallel to the main surfaces of the glass substrate 51 and the PCB 53 is maintained.

[0004] As described above, when ACF is used, electrical connection of an electronic component in a specific direction can be realized relatively easily. In particular, an electronic component having a fine circuit pattern or electrode pattern can be electrically connected. The effect is great when connecting. ACF is film-like and can reduce the volume required for joining electronic components. For this reason, bonding of electronic components using ACF is widely performed in the manufacturing process of flat display panels (FDP) such as liquid crystal displays (LCD), plasma display panels (PDP), and electroluminescent (EL) displays. I am [0005] In the actual manufacturing process (thermocompression bonding process), as shown in Fig. 6, the head 58 and the electronic component are usually placed between the heating and pressing head 58 and the electronic component (PCB53 in Fig. 6). A pressure release sheet 57 for preventing adhesion is disposed. Conventionally, a fluorine resin sheet has been used for the pressure-sensitive release sheet 57 because of its excellent release properties. However, with the increase in size of electronic components to be joined, such as FDP modules, it has become difficult to apply pressure uniformly to electronic components. In order to solve such a problem, for example, a pressure release sheet combining a fluorine resin layer and a heat conductive rubber sheet has been developed. Such a sheet is disclosed in, for example, JP-A-5-315401. This is disclosed in Japanese Laid-Open Patent Publication (Reference 1) and Japanese Laid-Open Patent Publication No. 7-214728 (Ref. 2). In the sheets described in Documents 1 and 2, the release property and the flexibility (tackiness) in the pressure-release release sheet are achieved by combining the fluorine resin layer and the heat conductive rubber sheet.

Disclosure of the invention

[0006] The present invention has a structure different from that of the conventional pressure release sheet as described in Documents 1 and 2, yet has a pressure release that achieves both releasability and flexibility (cushioning). The purpose is to provide a mold sheet.

[0007] The pressure-sensitive release sheet of the present invention is a pressure-sensitive release sheet used for joining electronic components by thermocompression bonding, and includes an ultra-high molecular weight polyethylene layer and a silicone rubber layer, and the ultra-high molecular weight polyethylene layer and The silicone rubber layer is integrated with each other, and the ultrahigh molecular weight polyethylene layer has a thickness of 30 μm or more.

According to the present invention, it is possible to provide a pressure-sensitive release sheet that has both release properties and flexibility (cushion properties) by combining an ultrahigh molecular weight polyethylene layer and a silicone rubber layer.

[0009] The wound body of the present invention has a structure in which the above-mentioned pressure-sensitive release sheet of the present invention is wound.

Brief Description of Drawings

FIG. 1 is a cross-sectional view schematically showing an example of a pressure-release release sheet of the present invention.

FIG. 2 is a schematic view for explaining the wound body of the present invention and the joining of electronic components using the wound body.

[FIG. 3] FIG. 3 illustrates a method for evaluating the characteristics of a pressure-release mold sheet in an example. It is a schematic diagram for.

FIG. 4 is a schematic diagram for explaining the joining of electronic parts using an anisotropic conductive film (ACF).

FIG. 5 is a schematic diagram for explaining the joining of electronic components using ACF.

FIG. 6 is a schematic diagram for explaining the joining of electronic components using ACF.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same members may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0012] A pressure-release release sheet (hereinafter also simply referred to as "release sheet") 1 shown in FIG. 1 is a release sheet used for joining electronic parts by thermal pressure-bonding. High molecular weight polyethylene layer (UHMWPE layer) 3, and silicone rubber layer 2 and UHMWPE layer 3 are integrated with each other.

In such a configuration, first, excellent release properties can be obtained by the UHMWPE layer 3. Next, by combining the UHMWPE layer 3 and the silicone rubber layer 2, an excellent flexibility (cushioning property) can be obtained. That is, the release sheet 1 having both a release property and flexibility (cushioning property) can be obtained while having a configuration different from that of the conventional release sheet. In addition, since the release sheet 1 includes the silicone rubber layer 2 and the UHMWPE layer 3 that are integrated with each other, the release sheet 1 is excellent in handling properties and can be efficiently joined by thermocompression bonding of electronic components.

[0014] The release sheet 1 is suitable for electrical connection of electronic components using, for example, an anisotropic conductive film (ACF). However, the release sheet 1 is not limited to electrical connection using ACF, and can be widely used for joining electronic components by thermocompression bonding. There are no particular limitations on the types of electronic components to be joined (also commonly referred to as “connection workpiece” in the thermocompression bonding process). For example, various substrates such as metal substrates and glass substrates (electrodes may be formed on the substrates). Ii) Various circuits such as printed circuit board (PCB), TCP (Tape Carrier Package), FPC (Flexible Printed Circuit), etc. (Drive IC etc. are mounted on TCP and FPC, for example C OF (Chip On Film Transparent) such as ITO (Indium Tin Oxide) layer For example, a conductive layer. The release sheet 1 can also be used for joining electronic parts (integrated bodies) in which a plurality of different electronic parts are modularized. There is no particular limitation on the type of electronic equipment configured by the joined electronic components. For example, the FDP described above is representative.

[0015] The thickness of the UHMWPE layer 3 is 30 μm or more. If the thickness of the UHMWPE layer 3 is less than 30 μm, it is difficult to ensure the heat resistance of the release sheet 1 in the thermocompression bonding process. The upper limit of the thickness of the UHMWP E layer 3 is not particularly limited, but is preferably 200 m or less, for example. When the thickness of the UHMWPE layer 3 exceeds 200 m, the thermal conductivity as the release sheet 1 is lowered.

[0016] The molecular weight of the ultra high molecular weight polyethylene (UHMWPE) constituting the UHMWPE layer 3 should be from 500,000 to 10,000,000 in terms of viscosity average molecular weight (Mv). 1 million to 7 million is more preferable. When the molecular weight is too small, the release property of the release sheet 1 is lowered, and when the molecular weight is too large, the flexibility of the release sheet 1 is lowered. The viscosity average molecular weight (Μ V) of UHMWPE can be evaluated by the viscosity method, which is a common measurement method. For example, from the intrinsic viscosity [η] measured based on JIS K 7367-3: 1999, Μ V May be calculated.

[0017] For the UHMWPE layer 3, a commercially available ultra-high molecular weight polyethylene film can be used. Examples of such ultra-high molecular weight polyethylene films include Nitto Denko No. 440 (M v = 3 million), Asahi Kasei Chemicals Sun Fine UH-900 (M v = 3.3 million), Sun Fine UH — 950 (M v = 4.5 million).

[0018] The UHMWPE layer 3 may contain a material other than UHMWPE, if necessary.

[0019] The UHMWPE layer 3 may be porous, that is, it may be the porous UHMWPE layer 3. In this case, the amount of deformation may be larger than that of the non-porous UHMWPE layer 3. Therefore, the release sheet 1 can be made more flexible. Moreover, since the thickness of the UHMWPE layer 3 during thermocompression bonding can be reduced by deformation of the pores contained in the UHMWPE layer 3, the distance through which heat is transmitted can be reduced, and the release sheet 1 having better thermal conductivity can be obtained. be able to.

[0020] The specific structure of the porous UHMWPE layer 3 is not particularly limited, and may be the UHMWPE layer 3 having a homogeneous structure as a whole, and the structure changes in the thickness direction of the layer (for example, It may be a UHMWPE layer 3 in which the porosity and Z or the average pore diameter in the porous structure have changed.

[0021] The porosity of the porous UHMWPE layer 3 is not particularly limited as long as it can be used as the release sheet 1. For example, it may be in the range of 20% by volume to 50% by volume. If the porosity is excessive, it becomes difficult to use as the release sheet 1.

[0022] The average pore diameter of the porous UHMWPE layer 3 may be, for example, in the range of 10 μm to 50 μm. If the average pore size is too large, it may be difficult to use as the release sheet 1 or the flexibility as the release sheet 1 may be reduced. The average pore size and porosity of the porous UHMWPE layer 3 can be evaluated using a porosimeter.

[0023] For the porous UHMWPE layer 3, a commercially available ultra-high molecular weight polyethylene porous film can be used. Examples of such porous films include Sun Map LC (MV = 3 million) manufactured by Nitto Denko Corporation, Sun Map HP-5320 (M v = 3 million), Sun Fine AQ-100 (manufactured by Asahi Kasei Chemicals)ファイン ν = 3.3 million) and Sunfine AQ-800 (Μ ν = 4 500,000).

[0024] The specific structure of the silicone rubber layer 2 is not particularly limited, and may be the silicone rubber layer 2 having a homogeneous structure as a whole, and a combination of silicone rubbers having different viscoelastic properties and the like. Alternatively, the silicone rubber layer 2 may be used.

[0025] The thermal conductivity of the silicone rubber layer 2 is preferably 1.5 WZ (m'K) or more, and the release sheet 1 having better thermal conductivity can be obtained.

[0026] The thermal conductivity of the silicone rubber layer 2 can be controlled, for example, by adjusting the content of the thermally conductive material in the silicone rubber layer 2 to the silicone rubber layer 2 containing a thermally conductive material. As the heat conductive material, for example, a heat conductive filter such as alumina, aluminum nitride, magnesium oxide, silicon carbide, silica, titanium, or a conductive filter such as various carbon or graphite may be used. ,.

[0027] The thickness of the silicone rubber layer 2 is not particularly limited, but is usually in the range of 20 µm to 300 µm.

[0028] The specific arrangement of the UHMWPE layer 3 and the silicone rubber layer 2 in the release sheet 1 of the present invention is not particularly limited as long as both layers are integrated, but the release sheet is not limited. It is preferable that the UHMWPE layer 3 is disposed on one main surface of the rubber 1 and the silicone rubber layer 2 is disposed on the other main surface. In this case, if the silicone rubber layer 2 is placed on the heating and pressurizing head side in the thermocompression bonding process, the pressure and heat can be more uniformly transferred to the connected workpiece, and the surface in contact with the electronic component can be made UHMWPE layer 3 Therefore, adhesion between the release sheet 1 and the electronic component in the thermocompression bonding process can be more reliably prevented.

[0029] The number of layers of the UHMWPE layer 3 and the silicone rubber layer 2 included in the release sheet 1 of the present invention is not particularly limited. However, as shown in Fig. 1, the release sheet 1 includes both layers one by one. Is preferred. That is, the release sheet 1 of the present invention preferably has a structure in which the silicone rubber layer 2 is laminated on one main surface of one UHMWPE layer 3 and both layers are combined. Such a release sheet is excellent in manufacturing cost and handling property in the thermocompression bonding process.

[0030] The release sheet of the present invention can be formed, for example, by applying a liquid or pasty silicone rubber to the surface of the UHMWPE layer 3 and heat-treating it. At this time, if silicone rubber is applied to one main surface of the UHMWPE layer 3, the release sheet 1 shown in FIG. 1 can be formed.

[0031] The release sheet of the present invention can also be formed by separately forming the UHMWPE layer 3 and the silicone rubber layer 2 and then thermally bonding them together.

[0032] Commercially available products can be used for the liquid or pasty silicone rubber. For example, SE4450 manufactured by Toray 'Dowcoung Co., Ltd., TSE3281-G manufactured by Toshiba Silicone Corp., KE- 1867 manufactured by Shin-Etsu Silicone Co., Ltd. X-32-2020, X-32-2151, etc. may be used. Alternatively, a solution in which solid silicone rubber is dissolved in a solvent or a paste in which solid silicone rubber and a solvent are kneaded may be used.

[0033] The silicone rubber layer 2 containing a heat conductive material is obtained by mixing a liquid or paste-like silicone rubber and a heat conductive material, and then coating the obtained mixture on the surface of the UHMWPE layer 3. It can be formed by heat treatment.

[0034] When the silicone rubber layer 2 is separately formed, a liquid or pasty silicone rubber may be applied on the substrate, and the solvent contained in the liquid or pasty silicone rubber may be removed and Z or heat treatment may be performed. . The silicone rubber layer 2 containing the heat conductive material can be formed by mixing the heat conductive material in advance before coating on the substrate. UHMWPE layer 3 The silicone rubber layer 2 may be thermocompression bonded using a general method.

[0035] In addition to the UHMWPE layer 3 and the silicone rubber layer 2, the release sheet 1 of the present invention may include an optional member as necessary. For example, the release sheet of the present invention may include a (porous) fluorine resin layer that is provided in a conventional pressure release sheet. However, in the release sheet 1 of the present invention, such a fluorine resin layer can be omitted, and when the fluorine resin layer is omitted, halogen free as an industrial waste after use in the thermocompression bonding process, Realization of element free.

[0036] The wound body of the present invention has a structure in which the above-mentioned pressure-sensitive release sheet of the present invention is wound. In such a wound body, for example, as shown in FIG. 2, the substrate 21 and the connection work 23 are passed through the ACF 22 while feeding the crimp release sheet 1 from the wound body 24 gradually or step by step. Can be thermocompression bonded. The pressure-release release sheet 1 after thermocompression bonding may be wound, for example, as shown in FIG. That is, with the wound body of the present invention, it is possible to more efficiently join electronic components by thermocompression bonding. Note that reference numeral 25 in FIG. 2 denotes a heating and pressing head.

Example

[0037] Hereinafter, the present invention will be described more specifically with reference to Examples. The present invention is not limited to the examples shown below.

[0038] In this example, 11 types of sample samples (sample 1 to: L 1), 2 types of comparative example samples (samples A and B), and 1 type of conventional example sample as release sheet samples (Sample C) was prepared, and the release property, flexibility (tackiness) and thermal conductivity of each release sheet sample were evaluated.

[0039] First, a method for manufacturing each sample is described.

[0040] —Sampnore 1—

UHMWPE film (Nitto Denko No. 440, thickness 30 μm) was prepared as the UHMWPE layer, and liquid silicone rubber (TSE-3281-G, Toshiba Silicone, Thermal conductivity 1.

Was applied (thickness of application: 50 111) and heat-treated at 120 ° C. for 24 hours to prepare a release sheet (sample 1) in which the UHMWPE layer and the silicone rubber layer were integrated. Use an applicator to apply silicone rubber [0041] Samples 2-5—

Except for changing the thickness of the UHMWPE film, the release sheets of Samples 2 to 5 were prepared in the same manner as Sample 1. The composition of each sample is shown in Table 1 below.

[0042] —Sampnore 6—

Except for preparing UHMWPE porous film (Sunmap LC manufactured by Nitto Denko Corporation, thickness 30 / ζ πι, porosity 30%, average pore size 17 m) as the UHMWPE layer, A release sheet (Sample 6) in which a UHMWPE layer and a silicone rubber layer were combined was prepared.

[0043] Samples 7 to 10—

Except that the thickness of the UHMWPE porous film was changed, each release sheet of Sample 7 to LO was prepared in the same manner as Sample 6. The composition of each sample is shown in Table 1 below.

[0044] Sample 11

Mold release in the same way as Sample 1 except that a silicone rubber with a thermal conductivity of 1.1 W / (mK) (KE 1223 manufactured by Shin-Etsu Silicone) was used as the liquid silicone rubber applied to the UHMWPE film. A sheet (Sample 11) was produced. Since the silicone rubber layer in sample 11 has a different thermal conductivity from the silicone rubber layer in samples 1-10, it is shown as silicone rubber layer B in Table 1.

[0045] Sample A (Comparative Example)

A release sheet (sample A), which is a comparative example, was prepared in the same manner as sample 1, except that the thickness of the UHMWPE film was 25 μm.

[0046] Sample B (comparative example)

A release sheet (sample B) as a comparative example was prepared in the same manner as in sample 6, except that the thickness of the UHMWPE porous film was 25 μm.

[0047] Sampu Nore C (conventional example)

80 parts by weight of polytetrafluoroethylene (PTFE) fine powder (CD 123, manufactured by Asahi Glass Co., Ltd.) and 20 parts by weight of liquid paraffin as a liquid lubricant are mixed to form a paste, and the resulting paste is extruded. Thus, a cylindrical preform was formed. Next, the formed preform is rolled in the same direction as the previous extrusion direction and then fired (350 ° C, 5 minutes). An FE film (thickness 50 μm) was formed.

[0048] Next, on one side of the formed PTFE film, liquid silicone rubber (Toshiba Silicone

(Coating thickness 50 111) and heat-treated at 120 ° C. for 24 hours to prepare a release sheet (sample C) in which a PTFE layer and a silicone rubber layer were combined. An applicator was used to apply the silicone rubber.

[0049] [Table 1]

[0050] Next, each sample prepared in this manner was used to join electronic components using ACF, and in each of the thermocompression bonding steps, the mold release property, flexibility (cushioning property), heat resistance and Thermal conductivity was evaluated.

[0051] As shown in FIG. 3, the evaluation was performed by sequentially laminating a glass substrate 11, ACF (AC2102 manufactured by Hitachi Chemical Co., Ltd.) 1, 2, FPC 13 and release sheet sample 14, and then heating and pressing head 15 (Nikka) The glass substrate 11 and the FPC 13 were thermocompression-bonded through ACF12 by Equipment Engineering Co., Ltd., a thermo-compressor AC-S50). The thermocompression bonding conditions were as follows: the heating caloric pressure head 15 was set at 300 ° C, the pressure was 3 MPa, and the pressure was 20 seconds. [0052] In the evaluation of releasability, the sample 14 and the FPC 13 after the thermocompression bonding were passed without any problem (◯), and if the adhesion between the sample 14 and the FPC 13 was confirmed, the sample was rejected (X). It was.

[0053] In the cushioning evaluation, after thermocompression bonding, the deformation of the conductive particles contained in the ACF12 was confirmed by the glass substrate 11 side, and if the deformation was uniform throughout the ACF, it passed (○), and the deformation was slightly. If it is non-uniform, it is regarded as holding (△), and if the deformation is non-uniform, it is regarded as reject (X). In addition, the deformation | transformation of electroconductive particle was observed using the optical microscope.

[0054] In the heat resistance evaluation, after thermocompression bonding, the presence or absence of the sheet in the release sheet sample 14 was confirmed. If the sheet did not generate a pass (O), and if the sheet had generated, it failed. (X).

[0055] When the glass substrate 11 or the like is laminated in order, the thermal conductivity is determined by placing a thermocouple 16 between the ACF 12 and the FPC 13 in advance, and the temperature reached 20 seconds after the start of thermocompression bonding. The time required for the temperature in the vicinity of AC F 12 to reach 190 ° C was evaluated.

[0056] The evaluation results are shown in Table 2 below.

[0057] [Table 2] Sample arrival temperature Arrival time Release property Cushioning property Heat resistance

N 0. CC) (seconds)

1 ○ ○ ○ 205 1. 8

2 ○ ○ ○ 201 1. 8

3 ○ ○ ○ 195 2. 0

4 ○ ○ ○ 191 2. 2

5 ○ ○ ○ 186-

6 ○ ○ ○ 207 1. 8

7 ○ ○ ○ 204 1. 8

8 ○ ○ ○ 199 1. 9

9 ○ ○ ○ 196 2. 1

1 0 ○ ○ ○ 188-

1 1 ○ ○ ○ 189-

A

○ Δ X 207 1. 8

(Comparative example)

B

○ Δ X 209 1. 8

(Ratio example)

C

○ ○ ○ 198 2. 2

(Conventional example) [0058] As shown in Table 2, Samples 1 to L 1 were release sheets having both release properties and flexibility (cushion properties). Samples A and B with a UHMWPE layer thickness of less than 30 μm had the same releasability as samples 1 to: L 1 Results of slightly inferior flexibility and inferior heat resistance It became.

[0059] Comparing sample C, which is the conventional example, with sample 2, which is approximately the same thickness as sample C, it is possible to increase the ultimate temperature of sample 2 and to shorten the arrival time. It was. In other words, if sample 2 is used instead of sample C, the tact time in the thermocompression bonding process can be shortened.

[0060] Compared with the same sample thickness, samples 6-10 with porous UHMWPE layer have higher forces than samples 1-5 with non-porous UHMWPE layer. Could be made shorter.

[0061] The present invention can be applied to other embodiments without departing from its intent and essential characteristics. The embodiments disclosed in this specification are illustrative in all respects and are not limited thereto. The scope of the present invention is shown not by the above description but by the appended claims, and all modifications that are equivalent in meaning and scope to the claims are included therein.

Industrial applicability

[0062] As described above, according to the present invention, a pressure-release mold that achieves both mold release properties and flexibility (cushion properties) by combining an ultrahigh molecular weight polyethylene layer and a silicone rubber layer. Can provide a sheet.

Claims

The scope of the claims

[1] A pressure release sheet used for joining electronic parts by thermocompression bonding,

Including an ultra-high molecular weight polyethylene layer and a silicone rubber layer;

The ultra high molecular weight polyethylene layer and the silicone rubber layer are integrated with each other,

A pressure-sensitive release sheet, wherein the ultrahigh molecular weight polyethylene layer has a thickness of 30 μm or more.

[2] The pressure-sensitive release sheet according to claim 1, wherein the ultrahigh molecular weight polyethylene constituting the ultrahigh molecular weight polyethylene layer has a viscosity average molecular weight of 1 million or more and 7 million or less.

[3] The pressure-sensitive release sheet according to claim 1, wherein the ultrahigh molecular weight polyethylene layer has a thickness of 200 m or less.

[4] The pressure-release mold sheet according to claim 1, wherein the ultrahigh molecular weight polyethylene layer is porous.

[5] The pressure-sensitive release sheet according to claim 1, wherein the silicone rubber layer has a thermal conductivity of 1.5 WZ (m′K) or more.

6. The pressure-sensitive release sheet according to claim 1, wherein the ultra-high molecular weight polyethylene layer is arranged on one main surface of the pressure-sensitive release sheet, and the silicone rubber layer is arranged on the other main surface.

[7] The pressure-sensitive release sheet according to claim 1, comprising the ultrahigh molecular weight polyethylene layer and the silicone rubber layer one by one.

[8] A wound body obtained by winding the pressure-release release sheet according to claim 1.