JP6448363B2 - Release film for semiconductor mold - Google Patents

Description

The present invention relates to a release film for a semiconductor mold that can exhibit excellent followability with respect to an uneven portion, suppress the flow of resin, and exhibit high releasability.

In the manufacture of semiconductor products, a semiconductor mold process is performed in which a semiconductor chip is sealed with a resin using a mold to obtain a molded product. In this semiconductor molding process, by performing resin molding in a state where the inner surface of the mold is covered with a release film, productivity is improved and contamination of the mold by the resin is prevented. Conventionally, fluorine-based films have been common as mold release films for semiconductor molds, but there are cost problems, generation of wrinkles due to heat shrinkage, and environmental aspects that incineration treatment cannot be performed because fluorine-based gas is generated at the time of disposal. Thus, there is a need for a new release film that does not use a fluorine-based film as a substrate.

On the other hand, a mold release film for a semiconductor mold having a structure in which a release layer is laminated on the surface of a substrate has been proposed. For example, Patent Document 1 describes a release film for sealing a semiconductor chip, which is a laminated film in which a film made of a fluororesin is laminated on at least one surface of a base film made of a stretched polyester resin film.

The mold used in the semiconductor molding process has an uneven portion such as a runner portion. In order to prevent the resin from overflowing to the outside of the mold (hereinafter, also simply referred to as “resin flow”), the mold release film for semiconductor mold is required to have excellent followability to uneven portions. However, the conventional mold release film for semiconductor mold has a problem that it is difficult to achieve both excellent followability to the uneven portion and mold release.

JP 2006-49850 A

In view of the above-mentioned present situation, the present invention provides a release film for a semiconductor mold that can exhibit excellent followability with respect to an uneven portion, suppress the flow of resin, and exhibit high releasability. Objective.

The present invention relates to a release film for a semiconductor mold having a base material and a release layer containing a base polymer and a low-polarity polymer, and the release layer is a tensile measured at 25 ° C. according to JIS K 7127. A release film for a semiconductor mold having a breaking elongation of 130 to 500%.
The present invention is described in detail below.

The present inventors examined a release film for a semiconductor mold that employs a highly flexible base material and has improved followability to a mold. However, when a highly flexible base material is used to improve the followability to the mold, there arises a problem that the releasability is lowered. When this cause was examined in more detail, in the release film that closely followed the uneven part of the mold, a part of the release layer was cracked due to the deformation of the release film, and the mold resin penetrated and peeled off the crack. I found it difficult.
As a result of further intensive studies, the inventors of the present invention can control the flow of the resin by controlling the tensile elongation at break of the release layer within a certain range, thereby suppressing the flow out of the resin and providing a high release. The present inventors have found that a release film for a semiconductor mold that can exhibit moldability can be provided, and the present invention has been completed.

The release film for semiconductor mold of the present invention (hereinafter also simply referred to as “release film”) has a release layer.
The release layer has a tensile elongation at break (hereinafter also simply referred to as “tensile elongation at break”) measured at 25 ° C. in accordance with JIS K 7127 of 130 to 500%. By setting the tensile break elongation of the release layer to 130% or more, even when following the concave and convex portions of the mold, the occurrence of cracks in the release layer can be prevented and excellent release properties can be exhibited. On the other hand, if the tensile elongation at break of the release layer is too large, the problem of cracking does not occur, but the release layer adheres to the mold resin at the time of peeling from the mold, resulting in a release failure. By setting the tensile breaking elongation of the release layer to 500% or less, practical peelability can be exhibited. A preferable upper limit of the tensile breaking elongation of the release layer is 300%.

The release layer contains a base polymer and a low polarity polymer. By containing the low-polarity polymer, excellent release properties are imparted to the release layer, and the tensile breaking elongation of the release layer is adjusted to the above range by the base polymer.

The low-polarity polymer is a component that imparts excellent release properties to the release layer.
Examples of the low-polarity polymer include silicone compounds, fluorine compounds, polymers having long-chain alkyl side chains, and cycloolefin polymers. These low polarity polymers may be used alone or in combination of two or more.

Among the low-polar polymers, when the base polymer is made of a curable resin, a silicone compound having a functional group capable of crosslinking with the curable resin (hereinafter also simply referred to as “functional group-containing silicone compound”). .) Is preferred. When a functional group-containing silicone compound is combined with a curable resin to cure the curable resin to form a release layer, it reacts with the curable resin and is taken in, so that the bleed out from the release layer. Thus, it is possible to prevent the mold and the semiconductor product from being contaminated.

The silicone skeleton of the functional group-containing silicone compound is not particularly limited, and may be either D-form or DT-form. Moreover, it is preferable that the said functional group containing silicone compound has this functional group in the side chain or terminal of a silicone frame | skeleton.
As the functional group of the functional group-containing silicone compound, an appropriate functional group is selected according to the base polymer. For example, when the base polymer is a photocurable resin having a (meth) acryl group in the molecule, a functional group capable of crosslinking with the (meth) acryl group, such as a vinyl group, a (meth) acryl group, an allyl group And a functional group containing an unsaturated double bond such as a maleimide group.

Among the functional group-containing silicone compounds, high releasability is obtained, and particularly excellent in heat resistance. Therefore, it is represented by the following general formula (I), general formula (II), and general formula (III). A silicone compound having a (meth) acryl group in the siloxane skeleton is preferred.

In the formula, X and Y represent an integer of 0 to 1200, and R represents a functional group having an unsaturated double bond.

The commercially available functional group-containing silicone compounds include, for example, X-22-164, X-22-164AS, X-22-164A, X-22-164B, and X-22 manufactured by Shin-Etsu Chemical Co., Ltd. -164C, X-22-164E and other silicone compounds having methacrylic groups at both ends, and X-22-174DX, X-22-2426, X-22-2475, etc. manufactured by Shin-Etsu Chemical Co., Ltd. Silicone compounds having a group, silicone compounds having an acrylic group such as EBECRYL350 and EBECRYL1360 manufactured by Daicel Cytec, and silicones having an acrylic group such as AC-SQ TA-100 and AC-SQ SI-20 manufactured by Toagosei Co., Ltd. Compounds, MAC-SQ TM-100, MAC-SQ SI-20, M manufactured by Toagosei Co., Ltd. Silicone compounds having a methacryl group such as C-SQ HDM and the like.

Although the compounding quantity of the said low polarity polymer in the said mold release layer is not specifically limited, A preferable minimum is 0.5 weight part and a preferable upper limit is 10 weight part with respect to 100 weight part of said base polymers. Within this range, sufficient release properties can be imparted to the release layer, and the tensile break elongation of the release layer can be easily adjusted to 130 to 500% by combination with the base polymer. The more preferable lower limit of the blending amount of the low polarity polymer is 2 parts by weight, and the more preferable upper limit is 3 parts by weight.

The base polymer is not particularly limited as long as the tensile break elongation of the release layer can be adjusted to 130 to 500% by combination with the low polarity polymer, and various polymers can be used. Especially, the hardened | cured material of the curable resin composition containing urethane (meth) acrylate etc. is suitable from the ability to prepare a release layer easily by a coating method.

As the curable resin used as the raw material of the base polymer, for example, a mixed resin of a reactive polyurethane (meth) acrylate and a polyfunctional urethane (meth) acrylate is preferable. A urethane (meth) acrylate having a (meth) acryl group in the molecule can be easily photocured by combining with a photoinitiator to obtain a cured product. Also, by combining polyfunctional urethane (meth) acrylate with reactive polyurethane (meth) acrylate, it is possible to produce a cured product with a high crosslinking rate, and preparing release layers with various tensile breaking elongations depending on the blending ratio can do.
In the present specification, the reactive polyurethane (meth) acrylate means a reactive polymer in which a reactive group further exists in the urethane (meth) acrylate polymer.

The thickness of the release layer is not particularly limited, but a preferable lower limit is 0.1 μm and a preferable upper limit is 10 μm. When the thickness of the release layer is less than 0.1 μm, the release property of the release layer may not be sufficiently exhibited. When the thickness of the release layer exceeds 10 μm, the cost becomes high and problems such as poor drying in the coating process may occur. A more preferable lower limit of the thickness of the release layer is 0.3 μm, and a more preferable upper limit is 5 μm.

The substrate is not particularly limited. For example, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polystyrene, styrene / acrylonitrile copolymer, styrene / butadiene / acrylonitrile copolymer / polyethylene, ethylene / vinyl acetate copolymer. , Polypropylene, polyacetal, polymethyl methacrylate, methacryl / styrene copolymer, cellulose acetate, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyurethane, polyether ether ketone, polyphenylene sulfide, polyether imide, polyamide imide, polyimide, poly A film made of benzimidazole or the like can be used.
Among them, a polybutylene terephthalate film having a single layer structure or a multilayer structure having at least one layer containing a polybutylene terephthalate resin (hereinafter also referred to as “polybutylene terephthalate layer”) is flexible under high temperature molding conditions. It is preferable because it is high, can sufficiently follow the mold, can suppress the flow of the resin, and can suppress the appearance of the product.

In this specification, the polybutylene terephthalate resin includes 1,4-butanediol (diol component) and polybutylene terephthalate obtained by polycondensation reaction of terephthalic acid or dimethyl terephthalate (acid component), the diol component and It may also be a modified polybutylene terephthalate obtained by adding a comonomer to each of the above acid components and obtaining a polycondensation reaction.
Examples of the comonomer of the diol component include ethylene glycol, propylene glycol, tetramethylene glycol, and cyclohexanedimethanol. Examples of the acid component comonomer include isophthalic acid, adipic acid, and sebacic acid. The comonomer of the diol component and the comonomer of the acid component may be used alone or in combination of two or more.
In addition, as the polybutylene terephthalate resin, a PBT elastomer (a copolymer of a hard segment and a soft segment) such as a copolymer of polybutylene terephthalate and polyalkylene glycol can also be used.
The polybutylene terephthalate layer may contain each of the polybutylene terephthalate, modified polybutylene terephthalate, and PBT elastomer alone, or may contain two or more of these in combination.

The polybutylene terephthalate layer preferably has a melting point of 200 ° C. or higher measured using a differential scanning calorimeter. By using a polybutylene terephthalate resin having a melting point of 200 ° C. or more, it is not melted or broken under normal hot press conditions of less than 200 ° C., and excellent release properties can be exhibited. The melting point is more preferably 220 ° C. or higher.
An example of the differential scanning calorimeter is DSC 2920 (manufactured by TA Instruments).

The minimum with preferable content of polybutylene terephthalate resin in the said polybutylene terephthalate layer is 60 weight%, More preferably, it is 70 weight%, More preferably, it is 80 weight%. By containing 60% by weight or more of the polybutylene terephthalate resin, it is possible to reliably exhibit the excellent effect of the present invention that suppresses the resin from flowing out even under high temperature molding conditions and suppresses the appearance of the product. The upper limit of the content of the polybutylene terephthalate resin is not particularly limited, and 100% by weight may be a polybutylene terephthalate resin.

The polybutylene terephthalate layer may contain a thermoplastic resin or a rubber component other than the polybutylene terephthalate resin as long as the effects of the present invention are not impaired.
The thermoplastic resin is not particularly limited, and examples thereof include polyolefin, modified polyolefin, polystyrene, polyvinyl chloride, polyamide, polycarbonate, polysulfone, and polyester.
The rubber component is not particularly limited. For example, natural rubber, styrene-butadiene copolymer, polybutadiene, polyisoprene, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer (EPM, EPDM), polychloroprene, butyl rubber. , Acrylic rubber, silicon rubber, urethane rubber and the like.

The polybutylene terephthalate layer contains additives such as a stabilizer, a fiber, an inorganic filler, a flame retardant, an ultraviolet absorber, an antistatic agent, an inorganic substance, a higher fatty acid salt, and the like as long as the effects of the present invention are not impaired. Also good.

Although the thickness of the said base material is not specifically limited, A preferable minimum is 10 micrometers and a preferable upper limit is 200 micrometers. When the thickness of the support layer is less than 10 μm, the strength is impaired, and the release film may be broken during hot pressing or peeling. When the thickness of the base material exceeds 200 μm, the flexibility of the release film under high temperature molding conditions is lowered, the followability to the mold is lowered, and the resin flow may not be suppressed. The more preferable lower limit of the thickness of the substrate is 30 μm, and the more preferable upper limit is 100 μm.

In the release film of the present invention, the preferable lower limit of the elastic modulus at 170 ° C. of the release film is 20 MPa, and the preferable upper limit is 150 MPa. When the release film has an elastic modulus at 170 ° C. of less than 20 MPa, wrinkles occur in the release film during adsorption to the mold or during hot pressing, and the wrinkles are transferred to a molded product or released during hot pressing. The film may be torn. When the elastic modulus at 170 ° C. of the release film exceeds 150 MPa, the flexibility of the release film under high-temperature molding conditions is lowered, the followability to the mold is lowered, and the resin flow may not be suppressed. The more preferable lower limit of the elastic modulus at 170 ° C. of the release film is 40 MPa, and the more preferable upper limit is 70 MPa.
In this specification, the elastic modulus at 170 ° C. can be measured by using a universal testing machine (for example, AUTOGRAPH AGS-X manufactured by Shimadzu Corporation).

The method for producing the release film of the present invention is not particularly limited, and examples thereof include a method in which a curable resin composition that is a raw material for the release layer is applied on a film-formed substrate, and is thermally cured or photocured. It is done.
Examples of the method for forming a film on the substrate include a water-cooled or air-cooled coextrusion inflation method, a method of forming a film by a coextrusion T-die method, and the like. Especially, the method of forming into a film by coextrusion T die method is preferable.

The release film of the present invention is preferably used in the semiconductor molding process to improve the productivity by coating the inner surface of the mold and prevent the mold from being contaminated by the resin. The release film of the present invention exhibits excellent followability with respect to the concave and convex portions of the runner portion of the mold and can suppress the flow of resin, and even if the release film is deformed by the follow-up, the release layer is cracked. It is possible to exhibit excellent releasability without doing so.

The use of the release film of the present invention is not limited to the above-mentioned use. For example, a copper-clad laminate or a copper foil is hot-pressed on a substrate via a prepreg or a heat-resistant film, and a printed wiring board, a flexible printed board or a multilayer printed wiring is used. When manufacturing the board, it may be used to prevent adhesion between the hot press board and the obtained printed wiring board, flexible printed board or multilayer printed wiring board, or via a thermosetting adhesive Used to prevent adhesion between the hot press plate and the cover lay film or between the cover lay films when a cover lay film is bonded to the circuit-formed substrate by hot pressing to produce a flexible printed circuit board. May be.

ADVANTAGE OF THE INVENTION According to this invention, the release film for semiconductor molds which can exhibit the outstanding followable | trackability with respect to an uneven | corrugated | grooved part, can suppress the flow-out of resin, and can exhibit high mold release property can be provided.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
A mixed resin of 75 parts by weight of polybutylene terephthalate (PBT) and 25 parts by weight of a PBT elastomer (a copolymer of polybutylene terephthalate and polytetramethylene glycol) was extruded into an extruder (GM Engineering Co., Ltd., GM30-28 (screw diameter 30 mm). , L / D28)) and extruded with a T die width of 400 mm to form a substrate having a thickness of 50 μm.

Next, 100 parts by weight of reactive polyurethane acrylate (UN-5500, manufactured by Negami Kogyo Co., Ltd.) as a base polymer and 5 parts by weight of 10 functional urethane acrylate (U-10PA, manufactured by Negami Kogyo Co., Ltd.), and silicon diacrylate ( EBECRYL350 (manufactured by Daicel Ornex Co., Ltd.) and 2 parts by weight of α-hydroxyalkylphenone (Irgacure 127, manufactured by BASF Corp.) as a photoinitiator mixed with a curable resin composition on the obtained substrate The film was irradiated with ultraviolet light having a wavelength of 365 nm with an intensity of an integrated light amount of 2000 mJ and photocured to form a release layer having a thickness of 3.5 μm.

About the obtained mold release layer, 0.1 g sample was collected using tweezers, and after being put on a shaker for 24 hours in a state immersed in ethyl acetate, unmelted material was taken out and 110 ° C. 2 using an oven. When the gel fraction was measured by the method of measuring the mass of the residual substance dried for a period of time, it was 83%.

The same curable resin composition as that for which the release layer was prepared was coated on a polyethylene terephthalate film that had been subjected to a release treatment, and then photocured by irradiating UV light having a wavelength of 365 nm with an intensity of 2000 mJ. Thus, a measurement sample having a thickness of 50 μm was obtained.
With respect to the obtained sample for measurement, the tensile elongation at break at 25 ° C. was measured according to JIS K 7127, and it was 420%.

(Examples 2 and 3, Comparative Examples 1 and 2)
In the formation of the release layer, the release film was prepared in the same manner as in Example 1 except that the compounding amounts of the reactive polyurethane acrylate and the 10-functional urethane acrylate in the release layer coating liquid were as shown in Table 1. Obtained.

<Evaluation>
The following evaluation was performed about the release film obtained by the Example and the comparative example. The results are shown in Table 1.

(1) Evaluation of mold resin release force After setting a mold resin tablet on the release layer side of the release film, and placing a 50 μm PET film (Lumirror manufactured by Toray Industries Inc.) on it, hot pressing at 170 ° C. and 220 kN for 2 minutes A 180 ° peel test was conducted at a test speed of 500 mm / min, and the peel force was measured.

(2) Mold actual machine evaluation Using the release film, a molding process was performed by a molding apparatus. Here, an epoxy resin was used as the mold resin, and the temperature at the time of molding was set to 170 ° C. After processing, the state of peeling between the semiconductor package and the release film was observed, and the actual machine was evaluated according to the following criteria.
○: Sticking did not occur, and it peeled off smoothly.
Δ: Slight sticking occurred, but no film remained.
X: Sticking occurred and could not be peeled off naturally.
When the release layer of the release film in the runner portion was observed with a microscope, fine cracks were observed in the release layer of the release film of Comparative Example 2.

ADVANTAGE OF THE INVENTION According to this invention, the release film for semiconductor molds which can exhibit the outstanding followable | trackability with respect to an uneven | corrugated | grooved part, can suppress the flow-out of resin, and can exhibit high mold release property can be provided.

Claims (8)

A release film for a semiconductor mold having a base material, a base polymer, and a release layer containing a silicone compound ,
The release layer has a tensile elongation at break of 130 to 500% measured at 25 ° C. according to JIS K 7127. Release layer, Ri Do a cured product of the curable resin composition,
The curable resin composition, curable resin and claim 1 semiconductor mold release film, wherein that you contain a functional group-containing silicone compound. 3. The mold release film for a semiconductor mold according to claim 2, wherein the curable resin is a photocurable resin having a (meth) acryl group. 4. The mold release film for a semiconductor mold according to claim 3, wherein the curable resin contains urethane (meth) acrylate. The release film for a semiconductor mold according to claim 4 , wherein the urethane (meth) acrylate is a mixed resin of a reactive polyurethane (meth) acrylate and a polyfunctional urethane (meth) acrylate. 6. The mold release film for a semiconductor mold according to claim 2, 3, 4 or 5, wherein the functional group of the functional group-containing silicone compound is a functional group containing an unsaturated double bond. The functional group-containing silicone compound is a silicone compound having a (meth) acryl group in a siloxane skeleton represented by the following general formula (I), general formula (II), or general formula (III): Item 7. A mold release film for a semiconductor mold according to 2, 3, 4, 5 or 6.

In the formula, X and Y represent an integer of 0 to 1200, and R represents a functional group having an unsaturated double bond. 8. The release film for a semiconductor mold according to claim 1, wherein the substrate has at least one polybutylene terephthalate layer.