JP2003313518A - Heat-resistant adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a removable heat-resistant acrylic adhesive tape which is used for fixing semiconductor devices in a process for manufacturing the semiconductor devices and for protecting electrodes in a process for molding a resin, has an adhesive characteristic enough for holding chips on the electrodes in a wire bonding process and for preventing the contamination of a resin on the surfaces of the electrodes in a molding process, does not produce an outer gas, when heated, and can easily be peeled, after used. <P>SOLUTION: This removable heat-resistant adhesive tape for fixing the semiconductor devices is characterized by laminating a radiation-curable acrylic adhesive to the roughed surface of a heat-resistant film having a heat shrinkage constant of ≤0.2%, when heated at 200°C. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer provided on one surface of a base film and a separator provided on the pressure-sensitive adhesive layer side. For more details,
Used in manufacturing semiconductor devices, after fixing the wafer, wire-bonding, etc., semiconductor fixing used to suppress the leakage of mold resin while holding the chip against the flow of mold resin in the resin encapsulation process. The present invention relates to a removable heat resistant adhesive tape.

[0002]

2. Description of the Related Art In a process of assembling a semiconductor device such as an IC, a semiconductor wafer or the like after pattern formation is cut into individual chips (dicing), a process of mounting the chips on a lead frame or the like, a process of mounting the chips and electrodes. It is composed of a wire bonding step between them and a step of sealing with a resin or the like. In the assembly process of a QFN (Quad Flat Non-Lead) package, adhesive tape is used to hold the lead frame and chip and protect the lead frame electrode surface between the wire bonding process and the resin molding process. Exposed to high temperature around 180 ℃. Therefore, a silicone-based adhesive tape using a heat-resistant polyimide film base material is used as a heat-resistant adhesive tape whose adhesive force does not easily change before and after heating. It is required to hold the lead frame during wire bonding and to prevent resin leakage to the electrode surface in the resin molding process, and it is also necessary to be able to easily peel off after use and to prevent contamination due to adhesive residue. ing.

[0003]

The problem with the silicone adhesive used in the above process is that siloxane, which is a constituent of the adhesive, is released as a volatile gas component when heated. Since many of the released siloxanes have high boiling points, it is easy to form a film by contacting low temperature parts, and if they adhere to the solder balls to be wire bonded, they may easily cause wire bond failure. There is concern. It can be easily inferred that by changing the silicone adhesive to an acrylic adhesive, contamination by siloxane gas is eliminated and the material cost is reduced. However, it is considered that a general acrylic pressure-sensitive adhesive is difficult to use in the above process because its heat resistance is low and the pressure-sensitive adhesive property is likely to change before and after heating. Therefore, an object of the present invention is to provide a removable heat-resistant tape for fixing a semiconductor, which is suitable for fixing a semiconductor device in a semiconductor manufacturing process and protecting an electrode in a resin molding process. More specifically, it has an adhesive property sufficient to hold the electrode and the chip during wire bonding and to prevent resin contamination on the electrode surface during the molding process, but it does not generate outgas such as siloxane when heated and does not generate after-use. An object of the present invention is to provide a heat-resistant acrylic pressure-sensitive adhesive tape that can be easily peeled off.

[0004]

[Means for Solving the Problems] As a result of earnest studies to achieve the above-mentioned problems, as a result of laminating a specific radiation-curable acrylic pressure-sensitive adhesive on the roughened surface of a heat-resistant film, semiconductor manufacturing We found that an acrylic adhesive tape that does not generate siloxane gas in the process can reduce the change in adhesive properties before and after heating, and developed a heat-resistant adhesive tape. That is, the present invention provides (1) 200
A radiation-curable acrylic pressure-sensitive adhesive is laminated on the roughened surface of a heat-resistant film having a heat shrinkage rate of 0.2% or less when heated at 0 ° C. (2) The heat-resistant film has a surface roughness Rz of a pressure-sensitive adhesive coated surface of more than 1 μm, and the removable heat-resistant pressure-sensitive adhesive tape for semiconductor fixing according to (1), (3) The radiation-curable acrylic pressure-sensitive adhesive is mainly composed of an acrylic copolymer having a radiation-curable carbon-carbon double bond, a hydroxyl group and a carboxyl group in at least a side chain, and has a gel fraction of 60% or more. The releasable heat-resistant adhesive tape for fixing semiconductor according to (1) or (2) is provided. The radiation referred to here means a light ray such as an ultraviolet ray or an ionizing radiation such as an electron beam.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive used in the present invention preferably contains at least a side chain containing an acrylic polymer having a radiation-curable carbon-carbon double bond, a hydroxyl group and a carboxyl group. The acrylic copolymer (A) in the present invention may be produced by any method,
For example, a compound having a radiation-curable carbon-carbon double bond such as an acrylic copolymer or a methacrylic copolymer, and having a compound I having a functional group and a functional group capable of reacting with the functional group. The one obtained by reacting with Compound II is used. Of these, the compound I having a radiation-curable carbon-carbon double bond and a functional group is a monomer I-having a radiation-curable carbon-carbon double bond such as an acrylic acid alkyl ester or a methacrylic acid alkyl ester. It can be obtained by copolymerizing 1 with a monomer I-2 having a functional group.

The monomer I-1 is hexyl acrylate having 6 to 12 carbon atoms, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, decyl acrylate, or a monomer having 5 or less carbon atoms. Can be listed as pentyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl acrylate, methyl acrylate, or methacrylates similar to these. As the monomer I-1 having a larger carbon number is used, the glass transition point becomes lower, so that a monomer having a desired glass transition point can be prepared. In addition to the glass transition point, a low molecular weight compound having a carbon-carbon double bond such as vinyl acetate, styrene and acrylonitrile can be blended within the range of 5% by weight or less for the purpose of improving compatibility and various performances. . Examples of the functional group contained in the monomer I-2 include a carboxyl group, a hydroxyl group, an amino group, a cyclic acid anhydride group, an epoxy group and an isocyanate group. Specific examples of the monomer I-2 include: Acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, phthalic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, glycol monoacrylates, glycol monomethacrylates, N-methylol acrylamide, N- Methylol methacrylamide, allyl alcohol, N-alkylaminoethyl acrylates, N-alkylaminoethyl methacrylates, acrylamides, methacrylamides, maleic anhydride, itaconic anhydride, fumaric anhydride, phthalic anhydride, glycidyl acrylate, glycidyl Methacrylate, allyl glycidyl ether, a portion of the isocyanate groups of the polyisocyanate compound a hydroxyl group or a carboxyl group and a radiation-curable carbon - can enumerate such as those urethanization a monomer having a carbon-carbon double bond. In the compound II, the functional group used is a compound I, that is, a functional group contained in the monomer I-2,
When it is a carboxyl group or a cyclic acid anhydride group, it may include a hydroxyl group, an epoxy group, an isocyanate group, and the like, and when it is a hydroxyl group, it may include a cyclic acid anhydride group, an isocyanate group, etc., and an amino group. When it is, an epoxy group, an isocyanate group, etc. can be mentioned, and when it is an epoxy group, a carboxyl group, a cyclic acid anhydride group, an amino group, etc. can be mentioned,
Specific examples include the same as those listed in the specific examples of the monomer I-2. Compound I as described above
By leaving unreacted functional groups in the reaction of the compound II with the compound II, desired ones can be produced in terms of properties such as acid value or hydroxyl value.

In the synthesis of the above-mentioned copolymer (A), ketone-based, ester-based, alcohol-based or aromatic-based solvents can be used as the organic solvent when the reaction is carried out by solution polymerization. Among them, toluene, ethyl acetate, isopropyl alcohol, benzene methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone and the like are generally good solvents for acrylic polymers, and have a boiling point of 60-
A solvent at 120 ° C. is preferable, and as the polymerization initiator, α,
azobis series such as α'-azobisisobutylnitrile,
Radical generators such as organic peroxides such as benzobell peroxide are usually used. At this time, a catalyst and a polymerization inhibitor can be used in combination, if necessary, and the copolymer (A) having a desired molecular weight can be obtained by adjusting the polymerization temperature and the polymerization time. Further, for adjusting the molecular weight, it is preferable to use a mercaptan or a carbon tetrachloride-based solvent. The polymerization reaction is not limited to solution polymerization, and other methods such as bulk polymerization and suspension polymerization may be used. The copolymer (A) can be obtained as described above, but in the present invention, the molecular weight of the copolymer (A) is preferably about 100,000 to 800,000. When the molecular weight is too small, the cohesive force of the pressure-sensitive adhesive becomes small, the peeling force in the final peeling step increases, and adhesive residue is likely to occur, which may contaminate the electrode surface. This is because if the molecular weight is too large, gelation may occur during synthesis and coating. Incidentally, the molecular weight in the present invention,
It is a weight average molecular weight in terms of polystyrene.

Next, the pressure-sensitive adhesive of the present invention contains, as one of the main components, polyisocyanates, a melamine-formaldehyde resin, or an epoxy resin (B) in an amount of 0 based on 100 parts by weight of the copolymer (A). 0.1 to 10 parts by weight, preferably 0.4 to 3 parts by weight. (B) acts as a cross-linking agent and has a cross-linking structure formed as a result of reaction with the copolymer (A) or the base film, so that the copolymer (A)
The cohesive force of the pressure-sensitive adhesive mainly composed of (B) and (B) can be improved after the pressure-sensitive adhesive is applied. The addition amount of (B) is 0.1 to 10 parts by weight with respect to 100 parts by weight of the copolymer (A). If the amount is less than 0.1 parts by weight, the effect of improving the cohesive force is not sufficient, and if it exceeds 10 parts by weight, the curing reaction proceeds rapidly during the mixing and application of the pressure-sensitive adhesive, and a crosslinked structure is formed. Workability is impaired. The pressure-sensitive adhesive obtained as described above improves the effect of reducing the pressure-sensitive adhesive strength after irradiation with radiation and does not impair the fluidity of the pressure-sensitive adhesive after irradiation with radiation. 0.1 to 10 parts by weight of a cyanurate compound or isocyanurate compound (C) having a molecular weight of less than 10,000 and having at least one radiation-curable carbon-carbon double bond may be contained. Further, the radiation-curable pressure-sensitive adhesive used in the present invention may contain a tackifier, a tackifier, a surfactant, etc., or other modifiers and conventional components, if necessary.

The thickness of the radiation-curable pressure-sensitive adhesive layer is not particularly limited, but is usually 2 to 50 μm. It is preferable to make it as thin as possible in order to transmit the ultrasonic vibration energy applied during wire bonding to the electrodes and wires without attenuating it, but in order to maintain the adhesive properties to resist resin leakage, it is about 2-10 μm. Is preferred, and the surface roughness of the adhesive surface in contact with the adherend is preferably small. The heat-resistant film in the present invention is preferably a metal such as copper foil, aluminum foil, alloy foil for lead frame, polyimide film, aromatic polyamide film, or plastic, and has a heat shrinkage ratio of 200 ° C. of 0. It is not particularly limited as long as it is 2% or less, preferably 0.18% or less, but a material having a linear expansion coefficient similar to that of a lead frame material used for semiconductor products is preferable. When the heat shrinkage rate of heating at 200 ° C exceeds 0.2%, the base material film shrinks due to heating, which causes stress in the direction of the adherend to act on the adhesive layer, causing the adhesive to bite firmly into the adherend and release. Is difficult to remove, and adhesive residue, etc. may occur. In addition, the thermal contraction rate of heating at 200 ° C. referred to here is J
It is the heat shrinkage ratio when measured at 200 ° C. by IS C2151. Further, the surface roughness Rz of the paste-coated surface of the heat resistant film is preferably more than 1 μm and about 12 μm or less in order to secure the adhesion with the acrylic pressure-sensitive adhesive layer. When the surface roughness is 1 μm or less, peeling easily occurs between the heat resistant film and the pressure-sensitive adhesive layer due to stress concentration on the adhesive interface due to curing shrinkage of the acrylic pressure-sensitive adhesive. Easy to transfer to the lead frame. When it is 12 μm or more, it is not economical because the amount of the adhesive used for absorbing the surface roughness and coating the surface of the adhesive increases, which is not economical, and also the organic gas component generated from the adhesive layer during heating. Also increases, which is not preferable.

[0010]

EXAMPLES Next, the present invention will be described based on Examples and Comparative Examples.
Although described in more detail, the present invention is not limited to this embodiment, and various embodiments can be taken within the scope of the claims. Synthesis Example of Acrylic Copolymer A By using butyl acrylate, 2-hydroxyethyl acrylate, and acrylic acid as raw materials, polymerization was performed by a known solution polymerization method at a compounding ratio shown in Table 1 below to obtain a copolymer A. . 2-Isocyanate ethylmethacrylate was added to this polymer at a compounding ratio shown in Table 1 below to obtain copolymers A1 and A2. For A3, 2-
Isocyanate ethyl methacrylate is not added.

[0011]

[Table 1]

Example of making an adhesive tape (Example 1) 100 parts by weight of the above-mentioned copolymer A1
Polyisocyanate compound as a curing agent
Mixing ratio of 1 part by weight of Retan Co., Ltd., trade name Coronate L)
To obtain an adhesive. The thickness of the obtained adhesive is 18μ
m Heat-resistant copper foil film (Furukawa Circuit Foil,
STD-GTS, mass thickness 158 g / m^Two, 200 ℃
Heat shrinkage of 0% in both MD and TD directions on the M surface (front)
After applying a surface roughness Rz = 8 μm using a comma coater,
Heat-dried removable heat-resistant 27 μm thick semiconductor fixing
An adhesive tape was created. (Example 2) In Example 1, the heat-resistant copper foil film was added.
STD-GTS 35 μm (Furukawa Circuit Foil Co., Ltd.
Made, mass thickness 285g / m^Two, Heat shrinkage of 200 ℃ heating
0%, M surface roughness Rz = 10 μm) and after heat drying
Same as Example 1 except that the thickness of the adhesive tape was 40 μm.
In the same way, we made a removable heat-resistant adhesive tape for fixing semiconductors.
I made it. (Example 3) In place of the copolymer A1 in Example 1.
Use A2 for heat resistant copper foil film F3-WS18
μm (Furukawa Circuit Foil, mass thickness 158g
/ M ^Two, Heat shrinkage of heating at 200 ℃ 0%, surface roughness of treated surface
For fixing semiconductors in the same manner except that Rz = 2 μm)
A removable heat-resistant adhesive tape was prepared.

(Comparative Example 1) In Example 1, a heat-resistant copper foil film was used as F0-WS 18 μm (manufactured by Furukawa Circuit Foil Co., mass thickness 158 g / m ² , heat shrinkage rate at heating at 200 ° C. 0%, treated surface). A removable heat-resistant adhesive tape for fixing a semiconductor was prepared in the same manner except that the roughness Rz was set to 1 μm. (Comparative Example 2) A removable heat-resistant adhesive tape for fixing a semiconductor was prepared in the same manner as in Example 1 except that the copolymer A3 was used instead of the copolymer A1. Comparative Example 3 In Example 1, a polyethylene terephthalate film having a thickness of 25 μm (heat shrinkage in MD direction at 200 ° C. of 2%, heat shrinkage in TD direction at 0.5%) was used instead of the heat resistant copper foil film. A removable heat-resistant adhesive tape for fixing semiconductor was prepared in the same manner as in Example 1 except that the thickness of the tape after heating and drying was 30 μm.

The adhesive tapes prepared in Examples and Comparative Examples were tested for their respective properties as follows, and the obtained results are shown in Tables 2 and 3 below. (1) Gel fraction: About 0.05 g of the pressure-sensitive adhesive layer was weighed and immersed in 50 ml of xylene at 120 ° C. for 24 hours, and then 200
The mixture is filtered through a mesh stainless steel wire net, and the insoluble matter on the wire net is dried at 110 ° C. for 120 minutes. Next, the weight of the dried insoluble matter was weighed, and the gel fraction was calculated by the formula shown below. Gel fraction (%) = (weight of insoluble matter / weight of weighed pressure-sensitive adhesive layer) × 100 (2) Peeling force: peeling speed of 50 mm / after attaching a heat resistant tape to a copper plate as an adherend The peeling force required for 180 degree peeling was measured in minutes. "Initial" means the case of peeling after being left for 60 minutes after bonding, and "after heating" is the case of heating at 180 ° C for 30 minutes and then returning to room temperature and peeling. (3) Adhesive residue: 180 after attaching a heat-resistant tape to a copper plate
After heating at 30 ° C. for 30 minutes, the temperature was returned to room temperature, irradiation with ultraviolet rays was performed in the same manner as above, and the adhesive residue on the surface of the copper plate when peeled 180 degrees at a peeling speed of 50 mm / min was visually inspected. Evaluation Criteria ◯: No adhesive residue is present ×: Adhesive residue is present, or all the adhesive is transferred to the adherend. (4) Mold evaluation (resin leakage): Lead frame with slit shape with 0.3 mm interval (Furukawa Electric, EFTE
C64T) with a heat-resistant adhesive tape, and transfer resin molding of a molding resin (Sumitomo Bakelite Co., Ltd., EME-6300) into a shape of 10 x 10 x 3 mm from the lead frame surface side at 180 ° C, and between the lead frame slits. Of the resin was inspected by a microscope. Evaluation Criteria: 0.3 mm slit spacing can be clearly recognized by microscope observation at a magnification of 50 times, and the boundary between the resin and the frame is clear. Δ: The boundary between the resin and the frame is unclear by a microscope observation at the magnification of 50 times. Yes, if slit width variation of about 0.01 mm can be confirmed x: If slit shape deformation can be visually confirmed

[0015]

[Table 2]

[0016]

[Table 3]

[0017]

EFFECTS OF THE INVENTION The removable heat-resistant adhesive tape for fixing a semiconductor of the present invention is obtained by laminating an acrylic adhesive on a heat-resistant film having a low heat shrinkage, and can be used from the wire bonding step to the resin molding step. . Further, since the adhesive force at the time of heating is sufficient and siloxane gas is not generated, defective insulation or defective wire bond does not occur, and there is almost no resin contamination on the electrode surface. Moreover, peeling after use is easy and no adhesive residue can be detected. Further, it is cheaper than the silicone adhesive tape.

Claims (3)

[Claims] 1. A semiconductor fixing remanufacturing characterized by laminating a radiation-curable acrylic pressure-sensitive adhesive on the roughened surface of a heat-resistant film having a heat shrinkage of 200% or less when heated at 200 ° C. Peelable heat resistant adhesive tape. 2. The releasable heat-resistant adhesive tape for semiconductor fixing according to claim 1, wherein the heat-resistant film has a surface roughness Rz of an adhesive coated surface of more than 1 μm. 3. The radiation-curable acrylic pressure-sensitive adhesive mainly contains an acrylic copolymer having a radiation-curable carbon-carbon double bond, a hydroxyl group and a carboxyl group in at least a side chain, and has a gel fraction of 60. % Or more, the removable heat-resistant adhesive tape for fixing semiconductor according to claim 1 or 2.