JP2005112891A - Film substrate for packaging semiconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film substrate for packaging a semiconductor preventing cracking from occurring in an electroconductive material or a semiconductor chip and simultaneously responding even to speedup of signal processing. <P>SOLUTION: The film substrate for packaging the semiconductor has one or two or more layers of electroconductive layers. In the film substrate for packaging the semiconductor, a film composed of a polyimide obtained by reacting aromatic diamines having a benzoxazole structure with aromatic tetracarboxylic acid anhydrides is used as a substrate. An adhesive for bonding the electroconductive layers to the substrate preferably has a specific tensile modulus of elasticity in the film substrate for packaging the semiconductor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a film substrate suitable for application to a so-called COF in which a semiconductor chip is mounted on a film substrate using a flip chip bonding technique.

The COF technology is attracting attention as a new semiconductor substrate film substrate technology that replaces the TAB technology. Recently, mounting of semiconductor devices, in which the conventional TAb technology has been used, particularly mounting of driving ICs such as liquid crystal display elements, EL display elements, electrophoretic display elements, particle rotation type display elements, thin displays, electronic paper, etc. Widely used as a method. Recently, a packaging method for obtaining BGA: ball grid array, micro ball grid array, and chip scale package through a film substrate for semiconductor mounting has been widely put into practical use.
The COF technology has many excellent features such as being easy to cope with the thinning and multi-pin circuit element package, and being able to adopt batch bonding for mounting semiconductor chips and the like. Have. In particular, batch bonding can significantly reduce the bonding time compared to wire bonding using a lead frame. For example, in the case of a 300-pin package, 45 to 60 seconds are required depending on the wire bonding method. The bonding operation can be completed in only about 1 to 2 seconds.

  The film substrate has a structure in which a copper foil functioning as a conductive material is usually bonded to a long insulating material film (for example, a polyimide film), and desired by performing predetermined etching on the copper foil. The pattern pad is formed. These pad portions are subjected to gold, tin or solder plating, or gold plating at necessary portions in order to facilitate and surely perform a semiconductor chip bonding operation. In addition, protrusions called bumps are sometimes formed in the joint.

One major factor that hinders the reliability of semiconductor circuit element packages produced using COF technology is cracking due to thermal strain that occurs as a result of repeated cooling and heating (conductive material, semiconductor chip, chip / conductor connection) Breaking or cracking of the part. This type of crack is caused by a difference in thermal expansion between copper, which is a conductive material, a semiconductor (silicon) chip, and a supporting base material. As another factor that hinders reliability, a crack due to strain generated as a result of expansion and contraction due to moisture absorption of the support film can be exemplified as well.
The largest application to which the COF technology is applied is mounting a driving IC for a flat display such as a liquid crystal display element. Such a driving IC is attached to two to four sides of the flat display. The so-called outer leads of the COF are connected to the electrodes drawn from the two to four sides of the flat display element. From the viewpoint of rationalization of the assembly process, it is preferable that this connection be made at a time, that is, the larger the work width and the number of leads on the outer lead side of the COF, the better. At present, the number of leads is increasing more than the workpiece width is widened, and the distance between the lead wire width and the lead wire is becoming very narrow. When such narrowly spaced lead wires are arranged in a wide workpiece width, the lead terminal is displaced due to error accumulation, which is generally called an accumulated pitch problem. These characteristics are very important because errors are caused by differences in thermal expansion coefficient and humidity expansion coefficient.

In recent years, the chip area has been increased, and the number of input and output signal lines has increased at the same time. Therefore, the same problem has occurred on the pad side which is a connection portion with the semiconductor.
In order to solve these problems, the idea of using a material with the smallest possible temperature expansion coefficient and humidity expansion coefficient as the material used for the base material has been widely generalized. It has not been put into practical use.
Further, from the viewpoint of the conductor side, a proposal has been made to add an impurity to the conductive material so that the thermal expansion coefficient approaches that of silicon, which is a semiconductor. For example, as a conductive material, 42 alloy (nickel 42%, remaining iron alloy material) or Kovar (nickel 29% by weight, cobalt 17% by weight, remaining iron alloy) is used as the conductive material for the film substrate for semiconductor mounting. It is disclosed to use (see Patent Document 1). However, using an electrically conductive material as an alloy has problems such as significantly reducing the conductivity and limiting the chemical solution used for etching to form a circuit pattern. The conductivity of the conductive material has a significant adverse effect on the transmission rate of the electrical signal and also increases the heat generation of the circuit.
As described above, in conventional film substrates for semiconductor mounting, misalignment due to differences in expansion coefficient due to temperature and humidity, lower connection reliability between terminals, and stress distortion in conductive materials and semiconductor chips. It is a thing with the problem that it may arise and a crack may generate | occur | produce.
JP-A-5-275494

  An object of the present invention is to provide a film substrate for semiconductor mounting that is less stretched due to temperature and humidity, and as a result provides high reliability.

That is, the present invention is obtained by reacting an aromatic diamine having a benzoxazole structure with an aromatic tetracarboxylic acid anhydride in a film substrate for semiconductor mounting having one or more conductive layers. A film substrate for semiconductor mounting, wherein a film made of polyimide is a base material. 2. The film mounting sub-layer according to claim 1, wherein the tensile elastic modulus of the adhesive for bonding the conductive layer and the base material is in the range of the following formula with respect to the tensile elastic modulus of the base material. Straight.
0.01 ≦ Tensile modulus of adhesive / Tensile modulus of substrate ≦ 0.7

  In the present invention, a conductive layer (such as a metal foil) and a semiconductor chip are mounted on a base material having high rigidity and high dimensional stability with an adhesive layer softer than the base material interposed therebetween. Since the adhesive layer can relax and absorb the stress strain of the substrate / conductor having a different linear expansion coefficient without affecting the base material, the result is reliable connection between the semiconductor and the conductive layer. There is an advantage that the effect of significantly improving the property can be obtained.

The polyimide of the present invention is a product obtained by condensation of a diamine having a benzoxazole structure and an aromatic tetracarboxylic acid anhydride.
Specific examples of the aromatic diamine having a benzoxazole structure in the present invention include the following.

を例示することができる。該ジアミンは、単独であっても良いし、２種以上を併用しても良い。

Can be illustrated. These diamines may be used alone or in combination of two or more.

  In the present invention, one or two or more diamines having no benzoxazole structure exemplified below may be used as long as they are 30 mol% or less of the total diamine. For example, 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3 -Aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3 , 3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diaminodiphenyl ether, 3,4′-diamino Diphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3, '-Diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [ 4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1, 1-bis [4- (4-aminophenoxy) phenyl Propane, 1,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-amino) Phenoxy) phenyl] propane, 1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4 -(4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphen Nyl] propane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4- Aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,4- Bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [ 4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 4,4 ′ -Bis (3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane, 3, 4'-diaminodiphenyl sulfide, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexaph Oropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] Ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3 -Aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4'-bis [4- (4-amino-α, α -Dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis 4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [ 4- (4-Amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] Benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α , Α-dimethylbenzyl] benzene, 3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4 ′ Diamino-4,5′-diphenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone, 4,4′-diamino-5-phenoxybenzophenone, 3,4′-diamino-4-phenoxybenzophenone, 3,4 '-Diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4 , 5′-dibiphenoxybenzophenone, 3,3′-diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4′-diamino-4-biphenoxybenzophenone, 3,4 '-Diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,4-bis (3-amino-4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino) -5-phenoxybenzoyl) benzene, 1,3-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis ( 4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) Phenoxy] benzonitrile and some or all of the hydrogen atoms on the aromatic ring of the above aromatic diamine are halogen atoms or alkyl groups having 1 to 3 carbon atoms. Or an alkoxy group, a cyano group, or an alkyl group or an aromatic diamine substituted with an alkyl group or a halogenated alkyl group having 1 to 3 carbon atoms substituted with a halogen atom or an alkoxy group Is mentioned.

The tetracarboxylic acid anhydrides used in the present invention are aromatic tetracarboxylic acid anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following.

の使用が好ましい。これらのテトラカルボン酸二無水物は単独でも二種以上を用いることも可能である。

Is preferred. These tetracarboxylic dianhydrides can be used alone or in combination of two or more.

In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are 30 mol% or less of the total tetracarboxylic dianhydrides. Examples of the tetracarboxylic acid anhydride used include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3, 3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfide dianhydride, bis (3 4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1, 4- (3,4-dicarboxyphenoxy) benzene dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxyphenoxy) Phenyl] propane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, butane-1,2,3,4-tetra Carboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, cyclobutane tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane -1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3,5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- ( 1 2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane Sa-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-ethylcyclohexane-1- (1,2), 3,4-tetracarboxylic dianhydride, -Propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic acid Dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] heptane-2,3,5,6 lacarboxylic dianhydride, 1-propylcyclohexane -1- (2,3), 3,4-tetracarboxylic Acid dianhydride, 1,3-dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic Acid dianhydride, bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic Acid dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides can be used alone or in combination of two or more.
In addition, maleic anhydride or the like can be used to seal the molecular ends of the linear polyimide or linear polyamic acid of the present invention with terminal groups having a carbon-carbon double bond. The amount of maleic anhydride used is 0.001 to 1.0 molar ratio per mole of aromatic diamine component.

  The polyimide of the present invention is a green film obtained by applying a polyamic acid solution obtained by reacting the diamines and the tetracarboxylic anhydride in an organic solvent to a support and drying, and further forming a support. It is obtained by performing a dehydration ring-closing reaction by heat-treating the green film at a high temperature while being peeled off from the support.

The organic solvent used in the present invention is not particularly limited as long as it dissolves both the raw material monomer and the generated polyamic acid, and examples thereof include N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, halogenated phenols, etc. Organic solvents can be used alone or in combination. The organic solvent may be used in an amount sufficient to dissolve the charged monomer, and is usually 5 to 50% by weight, preferably 10 to 20% by weight.
The organic solvent solution of the polyamic acid used in the present invention preferably contains 5 to 40% by weight, more preferably 10 to 30% by weight of the solid content, and the viscosity is measured by a Brookfield viscometer. Those having a viscosity of 10 to 2000 Pa · s, preferably 100 to 1000 Pa · s are preferred because stable liquid feeding is possible. The polymerization reaction is continuously carried out in the temperature range of 0 to 80 ° C. for 10 minutes to 30 hours while stirring and / or mixing in an organic solvent. The polymerization reaction can be divided or the temperature can be increased or decreased as necessary. It doesn't matter. In this case, the order of addition of both reactants is not particularly limited, but it is preferable to add aromatic tetracarboxylic acids to the solution of aromatic diamines.

Moreover, you may perform polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction.
Specific examples of the ring-closing catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine and betapicoline. It is preferable to use at least one amine selected from tertiary amines.

  Vacuum defoaming during the polymerization reaction is an effective method for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction.

  In the present invention, a ring-closing catalyst may be used. Specific examples of the ring-closing catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine and betapicoline. It is preferable to use at least one amine selected from tertiary amines.

  Specific examples of the dehydrating agent used in the present invention include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride, Acetic anhydride and / or benzoic anhydride are preferred. The content of the ring-closing catalyst with respect to the polyamic acid is preferably in a range where the content (mol) of the ring-closing catalyst / the content (mol) of the polyamic acid is 0.5 to 8. In addition, the content of the dehydrating agent relative to the polyamic acid is preferably in a range where the content of dehydrating agent (mole) / polyamic acid content (mole) is 0.1 to 4. In this case, a gelation retarder such as acetylacetone may be used in combination.

  The polyimide film of the present invention is obtained by continuously extruding or applying a polyamic acid solution to a support in the form of a film, followed by drying, peeling the green film from the support, stretching, drying, and heat treatment. As a typical method for producing a polyimide film from an organic solvent of polyamic acid, an organic solvent solution of polyimide acid that does not contain a ring-closing catalyst and a dehydrating agent is cast on a support from a nozzle with a slit. The film is then formed into a film and heated to dry on the support to form a green film having self-supporting properties. Then, the film is peeled off from the support and further heat-dried at a high temperature for imidization, Then, an organic solvent of polydoic acid containing a ring-closing catalyst and a dehydrating agent is cast from a slit base onto a support. Examples include a chemical ring closure method in which a film is formed into a film and partially imidized on a support to form a film having self-supporting properties, then the film is peeled off from the support, dried / imidized by heating, and heat-treated. It is done.

  The support is, for example, a drum-shaped or belt-shaped rotating body used when the polyamic acid solution is formed into a film. The polyamic acid solution is applied on a support and is self-supporting by heat drying. The surface of the support may be metal, plastic, glass, porcelain, etc., preferably metal, and more preferably SUS material that does not rust and has excellent corrosion resistance. Further, metal plating such as Cr, Ni, or Sn may be performed. The surface of the support in the present invention can be mirror-finished or processed into a satin finish if necessary.

Next, the manufacturing method of the film substrate for semiconductor mounting of this invention, what is called a COF tape is demonstrated using FIG. The COF tape of the present invention is produced by a usual method.
(1) First, a polyimide film slit to a predetermined width is used as a base tape.
(2) The adhesive is coated on the substrate except for both end portions of the substrate tape.
(3) Next, a conductive layer (metal foil such as copper foil) is bonded together.
(4) Drill holes for conveyance and alignment as necessary.
(5) The copper foil is patterned by a normal subtractive method, surface treatment is performed, and connection bumps are formed by a conventional method.
(6) Apply solder resist or cover coat as necessary.
The process up to here is the manufacturing method of the film substrate for semiconductor mounting. The obtained COF tape is further
(7) Mount an IC chip.
(8) It is mounted on the main substrate through a process of sealing the IC chip.

Here, the case where the number of conductive layers is one has been described as a basic configuration, but a generally known method can be applied to the case where there are two or more layers.
As the adhesive used in the present invention, as described in claim 2, it is preferable that the tensile elastic modulus of the adhesive is smaller than the tensile elastic modulus of the substrate. The tensile modulus of the adhesive / the tensile modulus of the base material (ratio of the tensile modulus) is preferably 0.01 to 0.7, more preferably 0.5 or less, still more preferably 0.2 or less, 0.1 The following are particularly preferred: If the tensile modulus of the adhesive is higher than that of the base film, the stress strain of the substrate / conductor with a different linear expansion coefficient cannot be relaxed and absorbed by the adhesive layer, resulting in the connection between the semiconductor and the conductive layer. This is not preferable because the effect of improving reliability is not exhibited.

  As the adhesive used in the present invention, epoxy-based, urethane-based, acrylic-based, silicone-based, polyester-based, imide-based, polyamide-imide-based, and the like can be used. In more detail, for example, a resin mainly containing a flexible resin such as a polyamide resin and a hard material such as phenol and containing an epoxy resin, an imidazole, or the like is exemplified. More specifically, dimer acid-based polyamideimide resin, room temperature solid phenol, room temperature liquid epoxy and the like can be exemplified, having moderate softness, hardness, adhesiveness, etc. The semi-cured state can be easily controlled. Further, as the polyamideimide resin, those having a weight average molecular weight of 5,000 to 100,000 are suitable. Furthermore, since the cohesive force of the amideimide resin also changes depending on the carboxylic acid and amine of the polyamideimide resin raw material, it is preferable to select the molecular weight, softening point, etc. of the phenol or epoxy resin as appropriate. Moreover, a polyamide resin, a polyester resin, an acrylonitrile butadiene resin, a polyimide resin, a butyral resin, or the like can be used instead of the polyamideimide resin. Furthermore, these silicone-modified materials and the like are more preferable because they exhibit flexibility. In addition to phenolic resins and epoxy resins, maleimide resins, resole resins, triazine resins and the like can also be used. Nitrile butadiene rubber can also be blended and copolymerized.

  In the adhesive of the present invention, the cured state is controlled to a semi-cured state. As a method for controlling the cured state, for example, heating with hot air when applying and drying the adhesive on a substrate, far / near Examples include heating with infrared rays and irradiation with electron beams. In the control by heating, it is preferable to heat at 100 to 200 ° C. for 1 to 60 minutes, more preferably at 130 to 160 ° C. for 5 to 10 minutes. Further, in a state where the TAB tape is wound in a roll shape, the cured state can be controlled by heat treatment at a relatively low temperature of, for example, about 40 to 90 ° C. for several hours to several hundred hours. The conditions for controlling the cured state are preferably determined in consideration of the composition of the adhesive, the curing mechanism, and the curing rate. In this way, it is possible to obtain a semi-cured adhesive by controlling the cured state.

The adhesive of the present invention is used once in a semi-cured state. Here, the semi-cured state is a solid state that can be softened or melted by heating. The adhesive of the present invention basically includes a component that imparts flexibility and a component that imparts heat resistance so that a semi-cured state can be maintained.
Note that plasma treatment, corona treatment, and alkali treatment on the polyimide film surface before applying the adhesive is a preferable method for increasing the adhesive force.

Hereinafter, the effectiveness of the present invention will be described with reference to examples, but the present invention is not limited thereto. In addition, the evaluation method of the physical property in the following examples is as follows.
1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube.
2. Film thickness The film thickness was measured using a micrometer (Millitron 1245D, manufactured by Fine Reef).

3. Tensile modulus, tensile breaking strength and breaking elongation of polyimide film Test piece by cutting the dried film into a strip of 100 mm length and 10 mm width in the longitudinal direction (MD direction) and the width direction (TD direction), respectively. And using a tensile tester (Autograph (R) model name AG-5000A manufactured by Shimadzu Corp.) at a tensile speed of 50 mm / min and a distance between chucks of 40 mm to obtain the tensile modulus, tensile breaking strength and breaking elongation. It was.
4). Tensile modulus of adhesive Adhesive is applied to a polytetrafluoroethylene sheet so that the thickness is 10 μm after drying, and cured under predetermined curing conditions (temperature, time) of each adhesive shown in the examples I let you. The cured film was peeled from the polytetrafluoroethylene sheet, and the tensile modulus was measured in the same manner as the polyimide film.

5). Linear expansion coefficient (CTE) of polyimide film
The expansion / contraction rate was measured under the following conditions, and the range from 30 to 300 ° C. was divided at 15 ° C. intervals and obtained from the average value of the expansion / contraction rate / temperature of each divided range.
Device name: TMA4000S manufactured by MAC Science
Sample length; 20mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

6). Melting point of polyimide film, glass transition temperature A sample was subjected to DSC measurement under the following conditions, and a melting point (melting peak temperature Tpm) and a glass transition point (Tmg) were determined under the following measurement conditions in accordance with JIS K7121.
Device name: DSC3100S manufactured by MAC Science
Pan ： Aluminum pan (non-airtight)
Sample weight; 4mg
Temperature rising start temperature: 30 ° C
Temperature increase rate: 20 ° C / min
Atmosphere: Argon

7). Thermal decomposition temperature The thermal decomposition temperature was defined by 5% weight loss by TGA measurement (thermobalance measurement) of a sufficiently dried sample under the following conditions.
Device name: TG-DTA2000S manufactured by MAC Science
Pan ： Aluminum pan (non-airtight)
Sample weight: 10mg
Temperature rising start temperature: 30 ° C
Temperature increase rate: 20 ° C / min
Atmosphere: Argon

(Example 1)
(Polyamide acid polymerization and polyimide film production)
After the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 500 parts by weight of 5-amino-2- (p-aminophenyl) benzoxazole was charged. Next, after adding 5000 parts by weight of N-methyl-2-pyrrolidone and completely dissolving it, adding 485 parts by weight of pyromellitic dianhydride and stirring for 15 hours at a reaction temperature of 25 ° C., a brown and viscous polyamide An acid solution was obtained. Ηsp / C of this product was 2.0.

  Subsequently, this polyamic acid solution was coated on a stainless steel belt to a wet film thickness of 180 microns and dried at 80 ° C. for 60 minutes. The polyamic acid film that became self-supporting after drying was peeled from the stainless steel belt to obtain a green film. The obtained green film was passed through a continuous drying furnace, heated from 200 ° C. to 400 ° C. almost linearly in 20 minutes, cooled in 10 minutes, and a brown polyimide film having a thickness of 25 μm was obtained.

Using the polyimide film obtained by the above method, a film substrate for semiconductor mounting was produced using the COF manufacturing method described above. First, it was slit to a width of 508 mm and subjected to corona treatment. Then, RV50 manufactured by Toyobo Co., Ltd. was applied as an adhesive on the surface of the base film so as to have a coating thickness of 18 μm, and then for 15 minutes in a dry oven at 80 ° C. Dried. Next, the rolled surface of Japan Energy rolled copper foil, BHY-22-T (18 μm) adhesion-treated surface and the adhesive-coated surface of the film were combined, and a roll temperature of 120 ° C. and a feed rate of 60 cm / min were obtained using a silicon rubber roller laminator. After laminating and winding, the adhesive was cured by treatment at 150 ° C. for 5 hours in a vacuum dryer to obtain a flexible copper-clad laminate film.
The obtained copper-clad laminated film was slit to 140 mm width, and the sprocket hole for transporting was punched in the amount of shame, and set in a continuous processing machine for FPC. According to the processing process, a photoresist was applied to the surface of the rolled copper foil, a predetermined pattern was exposed and developed, and then the patterned resist was used as a mask and an etching process was performed using a ferric chloride aqueous solution. A liquid resist type solder resist was applied and dried, mask exposure and development were performed while leaving the pad portion, and 1.5 μm thick tin plating was applied to the pad portion to obtain 500 COF film substrates.
The thinnest line width portion of the obtained COF tape is line width / line spacing = 60/60 μm.

<Contact failure rate>
A semiconductor chip was mounted on the obtained COF tape, subjected to a bonding process using flip chip bonding, and then sealed with a resin by a potting method to manufacture a semiconductor package. The number of contacts between the chip / substrate of the obtained semiconductor package is 256.
The package was loaded into an Etak (R) temperature cycle test apparatus (manufactured by Enomoto Kasei Co., Ltd.) and a heating / cooling test was performed. The test was performed by repeatedly heating and cooling between a low temperature of −50 ° C. and a high temperature of 150 ° C. every 30 minutes. The test time was 3000 hours. A continuity test was conducted after the test to determine the defect rate at the connection point. The evaluation results are shown in Table 1.

(Example 2)
(Polyamide acid polymerization and polyimide film production)
A polyamic acid solution was obtained in the same manner as in Example 1 except that 653 parts by weight of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was used as the tetracarboxylic dianhydride. Ηsp / C of this was 1.5, and a brown polyimide film having a thickness of 25 μm was obtained in the same manner as in Example 1.
(Manufacture of COF tape and semiconductor package)
A semiconductor circuit element package was obtained in the same manner as in Example 1 except that the polyimide film obtained by the above method was used. The same evaluation was made hereinafter. The evaluation results are shown in Table 1.

(Comparative Example 1)
A semiconductor circuit element package was obtained in the same manner as in Example 1 except that a polyimide film manufactured by Toray DuPont Co., Ltd. and Kapton (R) H (25 μm) were used as the base film. The same evaluation was made hereinafter. The evaluation results are shown in Table 2.
(Comparative Example 2)
A semiconductor circuit element package was obtained in the same manner as in Example 1 except that a polyimide film manufactured by Ube Industries, Ltd. and Upilex (R) S (25 μm) were used as the base film. The same evaluation was made hereinafter. The evaluation results are shown in Table 2.

(Example 3)
A semiconductor circuit element package was manufactured and evaluated in the same manner as in Example 1 except that UPA-8517C manufactured by Ube Industries, Ltd. was used as an adhesive. The evaluation results are shown in Table 1. In addition, the drying conditions after application | coating of an adhesive agent are 90 degreeC x 5 minutes, and the heat processing after a lamination are 180 degreeC x 90 minutes in a vacuum dryer.
Example 4
A semiconductor circuit element package was manufactured and evaluated in the same manner as in Example 2 except that UPA-8517C manufactured by Ube Industries, Ltd. was used as the adhesive. The evaluation results are shown in Table 1.

(Comparative Example 3)
A semiconductor circuit element package was manufactured and evaluated in the same manner as in Comparative Example 1 except that UPA-8517C manufactured by Ube Industries, Ltd. was used as the adhesive. The evaluation results are shown in Table 2.
(Comparative Example 4)
A semiconductor circuit element package was manufactured and evaluated in the same manner as in Comparative Example 2 except that UPA-8517C manufactured by Ube Industries, Ltd. was used as the adhesive. The evaluation results are shown in Table 2.

  As described above, the film substrate for semiconductor mounting according to the present invention uses a polyimide film having a low coefficient of thermal expansion as a base material. As a result, it is possible to suppress the occurrence of defects at the connection points due to changes in temperature and humidity in the usage environment of the semiconductor circuit element package, such as the occurrence of cracks caused by stress distortion of conductive materials and semiconductor chips. It realizes high connection reliability and is very useful for improving the reliability of electronic devices, and contributes greatly to the industry.

It is the figure explaining the manufacturing process of the film substrate for semiconductor mounting by the cross section.

Explanation of symbols

1. 1. Base film 2. Adhesive Copper foil 4. 4. Solder resist IC chip 6. Sealing material

Claims (2)

  A film made of polyimide obtained by reacting an aromatic diamine having a benzoxazole structure with an aromatic tetracarboxylic acid anhydride in a film substrate for semiconductor mounting having a single layer or two or more conductive layers. A film substrate for semiconductor mounting, characterized by being a substrate. 2. The film substrate for semiconductor mounting according to claim 1, wherein the tensile elastic modulus of the adhesive for bonding the conductive layer and the base material is in the range of the following formula with respect to the tensile elastic modulus of the base material.
0.01 ≦ Tensile modulus of adhesive / Tensile modulus of substrate ≦ 0.7

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