JP2005112916A - Under-filling adhesive film and semiconductor device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an under-filling adhesive film which can mount a semiconductor element to a flexible print board by an ultrasonic joining method in enhanced electric connection stability without needing a process for injecting a liquid resin and without causing a warp on the flexible print board or the semiconductor element and the cracking of the semiconductor element even when connecting the semiconductor with the flexible print board by the ultrasonic joining. <P>SOLUTION: This under-filling adhesive film to be adhered to the joining surface of a bump-having semiconductor element or flexible print board to be joined by an ultrasonic joining method is characterized by having a thickness of 0.4 to 1.1 times the height of the bump, tensile elastic modulus of 0.01 to 3 GPa after cured, and a glass transition temperature (Tg) of ≤250°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an adhesive film for underfill used for sealing when mounting a semiconductor element on a printed circuit board such as a mother board or a daughter board by a face-down method using ultrasonic bonding, and the adhesive film for underfill The present invention relates to a semiconductor device using.

  With the recent improvement in performance of semiconductor devices, there are demands for thinner and lighter semiconductor devices and faster information transmission. In view of this, a method of mounting a semiconductor element on a wiring circuit board such as a mother board or a daughter board on which a wiring circuit is formed in a face-down manner (a flip chip method, a direct chip attach method, etc.) has attracted attention.

  As a face-down type mounting method, a mounting method based on a so-called pressure welding method in which a semiconductor element is mounted on a printed circuit board with a heavy load or for a long time has been conventionally employed. When the construction method is used, a problem has been pointed out that connection reliability is lowered due to damage to a semiconductor element or a printed circuit board or generation of residual stress.

  In recent years, from the viewpoint of increasing the throughput of semiconductor devices and improving connection reliability, a so-called ultrasonic bonding method in which bumps formed on a semiconductor element and a connection portion of a substrate are connected by heating and pressurizing while applying ultrasonic waves. The flip chip mounting method used has attracted attention (see Patent Documents 1 and 2).

Also, in the flip chip mounting method using the ultrasonic bonding method, in order to further increase the reliability of the electrical connection of the electrode portion, a liquid thermosetting called an underfill material is formed in the gap between the semiconductor element and the printed circuit board. A method has been adopted in which a stress concentrated on an electrode portion is dispersed also in the resin layer by injecting and curing a functional resin to form a cured resin layer (see Patent Documents 1 and 2).
JP 2000-608440 A JP 2001-368039 A

Also, a method of arranging a thermoplastic resin on a printed circuit board in advance and face-down the semiconductor element in a state where the thermoplastic resin is heated and melted (see Patent Document 3), a resin layer on the printed circuit board In addition, a face down method (see Patent Documents 4 and 5) of a semiconductor element is also disclosed.
JP 2001-156110 A JP 2000-339648 A JP 2002-270642 A

  On the other hand, with the demand for thinner and lighter semiconductor devices, flexible printed boards with excellent flexibility tend to be frequently used as printed circuit boards for mounting semiconductor elements. However, there is a need to relieve stress concentration on the electrode portion and improve electrical connection reliability.

  However, as disclosed in Patent Documents 1 and 2, in a method in which a semiconductor element and a printed circuit board are ultrasonically bonded and then a thermosetting resin is injected therebetween, a space for arranging an injection nozzle is provided in the semiconductor element. As the demand for downsizing and thinning increases, it becomes difficult to secure such a space, and it becomes difficult to inject liquid resin.

  In addition, when a resin liquid or a resin layer is preliminarily disposed on a printed circuit board as described in Patent Documents 3 to 5, and a method for mounting a semiconductor element by ultrasonic bonding is applied to the flexible printed circuit board. In addition, there is a problem that distortion occurs in the resin layer during ultrasonic bonding, warping occurs in the flexible printed circuit board and the semiconductor element, and cracks occur in the semiconductor element depending on circumstances.

  The present invention has been made in view of the above-described conventional problems, and does not require a step of injecting a liquid resin when a semiconductor element is mounted on a flexible printed board by ultrasonic bonding. Even when a semiconductor element and a flexible printed circuit board are bonded by ultrasonic bonding, the electrical connection stability of the flexible printed circuit board and the semiconductor element is improved without causing warpage or cracking in the semiconductor element. Is one of the issues.

  In view of the above problems, the present invention is an underfill adhesive film bonded to a bonding surface of a semiconductor element with a bump or a flexible printed board bonded by an ultrasonic bonding method, and having a height of 0.4 to An underfill adhesive film having a thickness 1.1 times, a tensile elastic modulus after curing of 0.01 to 3 GPa, and a glass transition temperature (Tg) of 250 ° C. or lower is provided.

  The present invention also relates to a semiconductor device in which a semiconductor element with bumps and a flexible printed circuit board are bonded by an ultrasonic bonding method with an underfill adhesive film bonded to either one, and the underfill adhesive film Is a semiconductor device in which the thickness before bonding is 0.4 to 1.1 times the height of the bump, the tensile modulus after curing is 0.01 to 3 GPa, and the glass transition temperature (Tg) is 250 ° C. or less. I will provide a.

  Furthermore, when the thickness of the said semiconductor element is 100 micrometers or less, the semiconductor device whose tensile elasticity modulus after hardening of the said underfill adhesive film is 0.01-0.5 GPa is provided.

  The underfill adhesive film according to the present invention is used by adhering to any bonding surface of a semiconductor element or a flexible printed board, and therefore does not require injection by an injection nozzle or the like after mounting. In addition, by setting the thickness of the underfill adhesive film before bonding to 0.4 to 1.1 times the height of the bump, the electrode does not hinder the electrical connection between the semiconductor element and the flexible printed board by ultrasonic bonding. The stress applied to the portion can be relaxed. Furthermore, by setting the tensile elastic modulus after curing to 0.001 to 3 GPa and the glass transition temperature (Tg) to 250 ° C. or less, distortion of the resin due to ultrasonic bonding can be prevented, and the semiconductor element and the flexible printed board are warped. And no cracks.

  Moreover, since the semiconductor device of the present invention is formed by ultrasonic bonding of the semiconductor element and the flexible printed circuit board through the underfill adhesive film, there is no warping or cracking and excellent electrical connection reliability. It will be.

  Hereinafter, the best mode of the underfill adhesive film and the semiconductor device of the present invention will be described.

  1 to 4 are schematic views showing an example of a manufacturing method for a semiconductor device of the present invention. First, as shown in FIG. 1, an underfill adhesive film 2 is temporarily bonded to a semiconductor element 3 having an Au stud bump 1 from above the stud bump 1 to obtain a semiconductor element with an underfill adhesive film.

  Next, as shown in FIG. 2, the semiconductor device 10 as shown in FIG. 3 can be obtained by mounting the semiconductor element with the underfill adhesive film on the flexible printed circuit board 4 with an ultrasonic flip chip bonder. .

  Moreover, as shown in FIG. 4, the underfill adhesive film 2 may be temporarily bonded onto the flexible printed circuit board 4, and the semiconductor element 3 and the flexible printed circuit board 4 may be mounted by ultrasonic bonding in the same manner. .

Examples of the method of temporarily bonding the underfill adhesive film on a semiconductor element or a flexible printed board include a method of temporarily bonding by heating and pressurizing using a roller or a press. There are no particular limitations on the temperature, pressure, or the like at the time of temporary bonding, and it is sufficient that the underfill adhesive film can be temporarily bonded and the bumps such as Au stud bumps are not deformed.
For example, when an underfill adhesive film using a polycarbodiimide resin composition is temporarily bonded, the temperature is preferably from room temperature to 150 ° C, and more preferably from 40 to 120 ° C.
Moreover, as a pressure which does not deform | transform a bump, it is preferable to set it as 0.1-30 gf / bump, for example, and it is more preferable to set it as 5-25 g / bump.

Furthermore, the pressure condition for ultrasonically bonding the semiconductor element and the flexible printed board and filling the gap between the semiconductor element and the flexible printed board is appropriately determined depending on the material and number of bumps. Although set, for example, it is set in the range of 0.01 to 0.3 kgf / bump, and preferably in the range of 0.02 to 0.1 kgf / bump.
The amplitude of the ultrasonic wave is preferably 1 to 3 μm, and the oscillation time is preferably 0.5 to 1.0 second.

The underfill adhesive film of the present invention is formed using a thermosetting resin composition from the viewpoint that it is preferable to have a low melt viscosity and high heat resistance capable of sticking to a flexible printed circuit board or a semiconductor element. Good.
Examples of the thermosetting resin include polyester resin, polyamide resin, polycarbodiimide resin, phenoxy resin, epoxy resin, acrylic resin, and saturated polyester resin.
Furthermore, an underfill adhesive film formed using a polycarbodiimide resin is preferable from the viewpoints of storage stability and adhesiveness of the underfill adhesive film, filling properties in gaps, and the like.

  Below, a polycarbodiimide copolymer and its manufacturing method are demonstrated as an example of a thermosetting resin.

  The polycarbodiimide resin as a preferred embodiment has, for example, a total of m structural units represented by the following formulas (1) and (2) and n structural units represented by the following formula (3), and has a quantity terminal. And a copolymer having a terminal structural unit derived from monoisocyanate.

  Here, m is usually an integer of 2 or more and 1000 or less, preferably an integer of 2 to 10. Moreover, n is an integer of 1 or more and 500 or less normally, Preferably it is an integer of 1-10. Further, m + n is 3 to 1500, preferably 3 to 20, and m / (m + n) is 1/50 to 1/30, preferably 1/11 to 1/3.

Examples of the terminal structural unit include a substituted or unsubstituted aryl group and an alkyl group. Examples of the unsubstituted aryl group include phenyl and naphthyl. Typical examples of the aryl group having a substituent include tolyl, isopropylphenyl, methoxyphenyl, and chlorophenyl.
Moreover, as an alkyl group, C1-C10 alkyl groups, such as n-butyl, n-hexyl, n-octyl, are mentioned.

  The polycarbodiimide resin as described above is obtained by reacting a difunctional liquid rubber having a carboxyl group at the terminal with an organic diisocyanate in an aprotic solvent, and then converting the organic monoisocyanate and carbodiimidization for chain length control. It can be obtained by acting a catalyst.

Examples of the bifunctional liquid rubber include liquid polybutadiene (for example, Hycar CTB (registered trademark) manufactured by Ube Industries, Ltd. and C-1000 manufactured by Nippon Soda Co., Ltd.), liquid polybutadiene-acrylonitrile copolymer (for example, Ube Industries, Ltd. ) Hycar CTBN (registered trademark) or Nippon Soda Co., Ltd. Cl-1000).
These may be used alone or in admixture of two or more, or these modified products may be used.

  As the organic diisocyanate, aromatic or aliphatic diisocyanates can be used. These may be used alone or in admixture of two or more.

As the aromatic diisocyanate, those having a structure represented by the following formula (4) or (5) can be used.
(Wherein X ¹ represents an alkyl group having 1 to 5 carbon atoms, an alkoxyl group or a halogen)
(Wherein X ² represents an alkylene group having 0 to 5 carbon atoms, an oxy group, a sulfo group or a sulfoxyl group, X ³ and X ⁴ represent an alkyl group having 1 to 5 carbon atoms, an alkoxyl group or a halogen)

  Examples of the aromatic disoocyanate having the structure represented by the formula (4) include m-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 6-methoxy-2,4. -Phenylene diisocyanate and 5-bromo-2,4-tolylene diisocyanate can be mentioned.

  Examples of the aromatic disoocyanate having the structure represented by the formula (5) include 4,4′-diphenylmethane diisocyanate and 3,3 ′, 5,5′-tetraethyl-4,4′-diphenylmethane diisocyanate. Narate, 4,4'-diphenylisopropylidene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl sulfide diisocyanate, 4,4'-diphenyl sulfoxide diisocyanate, 3,3 ' , 5,5'-Tetramethyl-4,4'-biphenyl diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dibromo-4,4'-biphenyldi Isocyanates can be mentioned.

Moreover, as an aliphatic diisocyanate, the thing of the structure shown by following (6), (7) or (8) can be used.
(Wherein, X ⁵ and X ⁶ represent an alkylene group having 0 to 5 carbon atoms, and X ⁷ represents an alkyl group having 1 to 5 carbon atoms or an alkylene group having 0 to 5 carbon atoms)
(Wherein X ⁸ represents an alkylene group having 1 to 18 carbon atoms)
(Wherein X ⁹ and X ¹⁰ represent an alkylene group having 0 to 5 carbon atoms)

  Examples of the aliphatic diisocyanate having the structure represented by the formula (6) include 4,4′-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 4,4′-cyclohexane diisocyanate, and isophorone diisocyanate. Methylcyclohexane-2,4-diisocyanate and 2,4-bis (isocyanatomethyl) cyclohexane.

  Examples of the aliphatic diisocyanate having the structure represented by the formula (7) include hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate. Examples thereof include nato, octamethylene diisocyanate, and dodecamethylene diisocyanate.

  Examples of the aliphatic diisocyanate having the structure represented by the formula (8) include xylylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate, 4-isocyanatomethyl-phenyl isocyanate. You can list nato.

  Examples of monoisocyanates used for chain length control include substituted and unsubstituted aryl groups such as phenyl isocyanate, naphthyl isocyanate, tolyl isocyanate, isopropylphenyl isocyanate, methoxyphenyl isocyanate, and chlorophenyl isocyanate. Examples thereof include isocyanates or alkyl isocyanates having 1 to 10 carbon atoms such as n-butyl isocyanate, n-hexyl isocyanate, and n-octyl isocyanate.

  The monoisocyanate is preferably used in an amount of 1 to 10 mol per 100 mol of the diisocyanate component. If the amount of monoisocyanate used is less than this, the molecular weight of the resulting polycarbodiimide will become too high, or the viscosity of the solution will increase due to the crosslinking reaction and the solution will solidify, significantly reducing the storage stability of the polycarbodiimide solution. There is a risk of causing. On the other hand, if the amount of monoisocyanate used is larger than this, the solution viscosity of the resulting polycarbodiimide solution is too low, and film formation by coating and drying the solution may adversely affect film formation.

  Various catalysts can be used for the polymerization reaction. Among them, 3-methyl-1-phenyl-2-phospholene-1-oxide, 1-phenyl-2-phospholene-1-oxide, 1- Phenyl-2-phospholene-1-sulfide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 3-methyl-1-phenylphosphole-1-oxide and the corresponding isomers, and 3- Phosphorene is preferred. Further, phosphine oxides such as triphenylphosphine oxide, tolylphosphine oxide, and bis (oxadiphenylphosphino) ethane can also be used.

  The amount of the catalyst is preferably 0.001 to 5 mol% with respect to the total amount of the isocyanate component to be used. If the amount used is less than this range, the polymerization takes too much time and is not practical. On the other hand, if the amount exceeds this range, the reaction may be too fast and solidify in the middle of the reaction, or the storage stability may be significantly reduced. There is.

In order to obtain a polycarbodiimide resin, a chain liquid rubber having a carboxyl group at both ends and a diisocyanate in an aprotic organic solvent at 10 to 150 ° C., preferably 40 to 110 ° C. in the presence of a carbodiimidization catalyst. To carry out the polymerization reaction.
If the reaction temperature at the time of polymerization exceeds 150 ° C., the reaction may be too fast, a side reaction may occur and the gel may solidify during the reaction, or the storage stability may be significantly reduced.
Moreover, when the reaction temperature at the time of superposition | polymerization is less than 10, there exists a possibility that reaction may be too slow or stability of a solution may fall by an isocyanate functional group remaining in a polycarbodiimide copolymer solution.

Examples of the aprotic organic solvent include toluene, xylene, alkyltoluene having 3 to 5 carbon atoms, benzene, alkylbenzene having 3 to 36 carbon atoms, naphthalene, tetrahydrofuran, dioxane, acetone, butanone, cyclohexane, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide and the like can be mentioned.
These solvents may be used singly or in combination of two or more, and other components not involved in the reaction may be mixed.
The amount of these solvents used is such that 70 parts by weight of liquid rubber, 30 parts by weight of tolylene diisocyanate, 2 moles of 1-naphthyl isocyanate with respect to tolylene diisocyanate are mixed in the polymer solution. After stirring for 1 hour at 50 ° C., the carbodiimidization catalyst is added to the mixture. While confirming the progress of the reaction by infrared spectroscopy, the temperature is raised to 100 ° C., and the carbodiimidization reaction is carried out at this temperature for 2 hours.

  In order to produce the underfill adhesive film of the present invention, for example, a resin solution such as the above-mentioned polycarbodiimide copolymer solution is formed to an appropriate thickness using a known method such as casting, spin coating, roll coating or the like. Film. The formed film is usually dried at a temperature necessary for removing the solvent. That is, the coating temperature is, for example, 20 to 350 ° C., preferably 50 to 250 ° C., and most preferably 70 to 200 ° C., so that the curing reaction of a resin such as polycarbodiimide does not proceed so much. The drying time is, for example, 30 seconds to 30 minutes, preferably 1 to 10 minutes, and most preferably 2 to 5 minutes. When the drying temperature is lower than 20 ° C., the solvent remains in the film, and the reliability of the film becomes poor. On the other hand, if the drying temperature is higher than 350 ° C., the resin may be thermally cured. When the drying temperature is shorter than 30 seconds, the solvent remains in the film, and the reliability of the film becomes poor. Moreover, when drying time is longer than 30 minutes, there exists a possibility that thermosetting of resin may advance.

  In the production of the underfill adhesive film of the present invention, a fine inorganic filler may be blended within a range that does not impair the workability and heat resistance. Moreover, you may add various additives, such as a smoothing agent, a leveling agent, and a defoaming agent for giving surface smoothness as needed. These compounding quantities are 0.1-100 weight part with respect to 100 weight part of resin, Preferably you may be 0.2-50 weight part.

  In addition, various additives such as silane coupling agents, titanium-based coupling agents, nonionic surfactants, fluorine-based surfactants, and silicone-based additives are added to the adhesive film as necessary to improve adhesion. May be.

  Furthermore, in order to improve thermal conductivity and adjust the elastic modulus, for example, metals or alloys such as aluminum, copper, silver, gold, nickel, chromium, lead, tin, zinc, palladium, solder, alumina, silica, magnesia In addition, various inorganic powders composed of ceramics such as silicon nitride and other carbons may be blended, if necessary, in combination of one or more.

The underfill adhesive film of the present invention is formed using a thermosetting resin as described above, and is configured such that the tensile modulus after curing is 0.01 to 3 GPa.
By setting the tensile modulus after curing to 0.01 to 3 GPa, even when the semiconductor element and the flexible printed board are ultrasonically bonded, the underfill adhesive film is less likely to be distorted by heat. It is possible to prevent warping of the substrate and cracking of the semiconductor element.
In particular, when a semiconductor device is manufactured using a semiconductor element having a thickness of 100 μm or less, the tensile modulus after curing of the underfill adhesive film is preferably 0.01 to 1 GPa, and preferably 0.01 to 0.5 GPa. More preferably.

  In the present invention, the tensile modulus (GPa) is a sample of a cured underfill adhesive film (10 mm width × 20 mm length) using a dynamic viscoelasticity measuring device (DMS210, manufactured by Seiko Instruments Inc.). The value at 35 ° C. when measured under the measurement conditions of 10 ° C./min, frequency (sine wave) 10 Hz, −50 to 300 ° C.

The thickness of the underfill adhesive film of the present invention is 0.4 to 1 with respect to the height before bonding of the bumps from the viewpoint of not hindering electrical connection between the bumps formed on the semiconductor element and the flexible printed circuit board. .1 times, preferably 0.6 to 1.0 times.
If it is less than 0.4 times, the space between the semiconductor element and the flexible printed board is not sufficiently filled, and it becomes difficult to sufficiently perform the function of relaxing the stress concentration on the electrode portion. Reliability will deteriorate. Moreover, when it exceeds 1.1 times, the electrical connection by ultrasonic bonding of a semiconductor element and a flexible printed circuit board will be obstructed.

  Furthermore, the glass transition temperature (Tg) of the underfill adhesive film of the present invention is 250 ° C. or lower, preferably 230 ° C. or lower. When the glass transition temperature (Tg) exceeds 250 ° C., the flexible printed circuit board may be warped and adversely affect the electrical connection.

  In the present invention, the glass transition temperature (Tg) is a sample of a cured underfill adhesive film (10 mm width × 20 mm length) using a thermomechanical analyzer (manufactured by Seiko Instruments Inc., TMA SS / 100). Is a value measured when the temperature is increased from room temperature to 300 ° C. at a rate of temperature increase of 10 ° C./min.

  The underfill adhesive film of the present invention is preferably protected on both sides with a releasable plastic film until it is used. By protecting with a releasable plastic film, adhesion of dust and the like can be prevented, and the strength of the underfill adhesive film can be reinforced to prevent damage during transportation.

The releasable film can withstand heat and pressure when the underfill adhesive film is temporarily bonded to a semiconductor element or a flexible printed board, and does not remain on the underfill adhesive film when peeled off. Those are preferred. Examples of materials having such properties include polyethylene terephthalate film, polyester film, release-treated with known release agents such as silicone, long-chain alkyl, fluorine, aliphatic amide, and silica. Examples thereof include plastic films such as a polyvinyl chloride film, a polycarbonate film, and a polyimide film. Moreover, fluororesin films, such as a polytetrafluoroethylene film, a polypropylene film, and a polyethylene film may be sufficient.
The thickness of the releasable film may be, for example, 10 to 200 μm, preferably 20 to 150 μm.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. In addition, all the synthesis | combination of resin was performed under nitrogen stream.

(Example 1)
In a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer, 70.57 g (282 mmol) of 4,4′-diphenylmethane diisocyanate was used as a bifunctional liquid rubber. F. Goodrich Hycar CTB2000X162 (27.34 g), Nippon Soda Nisso-PB Cl-1000 (54.68 g), and cyclohexane (217.96 g) were charged and mixed. The mixture was stirred at 40 ° C. for 1 hour, then p-isopropylphenyl isocyanate 10.91 (67.68 mmol) and 3-methyl-1-phenyl-2-phospholene-2-oxide 0.54 g (2.82 mmol). ) Was added as a carbodiimidization catalyst, the temperature was raised to 100 ° C. with stirring, and the mixture was further maintained for 2 hours. The progress of the reaction was confirmed by infrared spectroscopy. Specifically, FT / IR-230 manufactured by JEOL Ltd. is used to absorb N—C—O stretching vibration (2270 cm ⁻¹ ) of isocyanate and N—C—N stretching vibration (2135 cm ⁻¹ ) of carbodiimide. And the end point was confirmed by observing the absorption of CO and the absorption of C—O stretching vibration (1695 cm ⁻¹ ) of the amide group in the bonding portion. After completion of the reaction, the reaction solution was cooled to room temperature to obtain a polycarbodiimide solution.

Next, the polycarbodiimide solution was coated on a 50 μm thick release film made of a polyethylene terephthalate film treated with a release agent, heated at 130 ° C. for 1 minute, and then heated at 150 ° C. for 1 minute, An underfill adhesive film was prepared.
The obtained film was cured by after-curing at 175 ° C. for 5 hours, and the cured film was subjected to glass transition temperature (Tg) using the dynamic viscoelasticity measuring apparatus (DMS210, manufactured by Seiko Instruments Inc.). ) And the tensile elastic modulus (E ′) at 35 ° C. was measured using the thermomechanical analyzer (manufactured by Seiko Instruments Inc., TMA SS / 100). The glass transition temperature (Tg) was 230. The tensile modulus (E ′) at 0.0 ° C. was 0.03 GPa.

  A semiconductor device was manufactured according to the manufacturing method of a semiconductor device as described above using the unfilled underfill adhesive film thus prepared. That is, as shown in FIG. 1, the underfill adhesive film is pasted at 100 ° C. on bumps (material Au stud bump, height 50 μm, 128 bumps / chip, bump pitch 280 μm, peripheral) of a semiconductor element having a thickness of 100 μm as shown in FIG. Then, as shown in FIG. 2, after placing a flexible printed circuit board (thickness 25 μm) provided with Cu wiring (height 18 μm, electroless Ni / Au plating treatment), an ultrasonic flip bonder (Nippon Avionics Co., Ltd.) NAW-1260B), underfill adhesion under the conditions of heating temperature: horn 150 ° C., stage 100 ° C., load: 7 kg / piece (bump), ultrasonic oscillation time: 0.5 seconds, oscillation frequency: 40 kHz The film is heated and melted to fill the gap between the semiconductor element and the flexible printed circuit board, and at the same time, the bumps are contacted. The connecting electrode part was placed in contact with the metal. Thereafter, the semiconductor device is left at 175 ° C. for 5 hours, and the underfill adhesive film is thermally cured, so that the gap between the semiconductor element and the flexible printed circuit board is resin-sealed with the underfill adhesive film as shown in FIG. 10 were produced.

(Example 2)
A semiconductor device was fabricated in the same manner as in Example 1 except that a semiconductor element having a thickness of 50 μm was used.

(Comparative Example 1)
In a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer, TDI (a mixture of 2,4-tolylene diisocyanate 80% and 2,6-tolylene diisocyanate 20%) was added. 125.39 g (720 mmol), 30.27 g (180 mmol) of hexamethylene diisocyanate, and toluene were charged and mixed. The mixture was stirred at 40 ° C. for 1 hour, then 9.14 g (54 mmol) of 1-naphthyl isocyanate and 0.86 g (4.5 mmol) of 3-methyl-1-phenyl-2-phospholene-2-oxide were added. The mixture was added as a carbodiimidization catalyst, heated to 100 ° C. with stirring, and further maintained for 2 hours. The progress of the reaction was confirmed in the same manner as in Example 1, and after completion of the reaction, the reaction solution was cooled to room temperature to obtain a polycarbodiimide solution. Using the polycarbodiimide solution, an underfill adhesive film was produced in the same manner as in Example 1. When the glass transition temperature (Tg) and tensile elastic modulus (E ′) after curing were measured, the glass transition temperature (Tg) was 201 ° C. and the tensile elastic modulus (E ′) was 3.543 GPa. A semiconductor device was also manufactured in the same manner as in Example 1.

(Comparative Example 2)
An underfill adhesive film was produced in the same manner as in Example 1 except that the thickness was 64 μm. A semiconductor device was also manufactured in the same manner as in Example 1.

(Comparative Example 3)
Using the same underfill adhesive film as in Example 1, a semiconductor device was fabricated by bonding the bumps of the semiconductor element and the electrode portions on the circuit by heating and pressing with a flip chip bonder (DB100, manufactured by Kasuya Kogyo). The heating and pressing conditions were heating temperature: horn 150 ° C., stage 100 ° C., pressure: 30 kgf / piece (bump), treatment time: 3 minutes. Further, in the same manner as in Example 1, the underfill adhesive film was cured for the semiconductor device after mounting.

(Comparative Example 4)
In a 500 mL four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser, and a thermometer, TDI (a mixture of 2,4-tolylene diisocyanate 80% and 2,6-tolylene diisocyanate 20%) was added. 16.63 g (95 mmol), 4,4′-diphenylmethane diisocyanate 71.7 g (286.5 mmol), Hycar CTB2000X162 (same as above) 13.78 g, NISSO-PB Cl-1000 27.56 g, cyclohexanone 244. 95 g was charged and mixed. The mixture was stirred at 40 ° C. for 1 hour, then 7.39 (45.84 mmol) of p-isopropylphenyl isocyanate and 0.73 g (3.82 mmol) of 3-methyl-1-phenyl-2-phospholene-2-oxide. ) Was added as a carbodiimidization catalyst, the temperature was raised to 100 ° C. with stirring, and the mixture was further maintained for 2 hours. The progress of the reaction was confirmed in the same manner as in Example 1, and after completion of the reaction, the reaction solution was cooled to room temperature to obtain a polycarbodiimide solution. Using the polycarbodiimide solution, an underfill adhesive film was produced in the same manner as in Example 1. When the glass transition temperature (Tg) and tensile elastic modulus (E ′) after curing were measured, the glass transition temperature (Tg) was 263 ° C., and the tensile elastic modulus (E ′) was 1.28 GPa. Further, a semiconductor device was manufactured in the same manner as in Example 1 except that a semiconductor element having a thickness of 50 μm was used.

  All the semiconductor devices obtained as described above were subjected to an initial energization test at 25 ° C. Then, a JEDEC level 1 (85 ° C./85 RH × 168 hr) test was performed using the semiconductor device from which initial energization was obtained, followed by an IR reflow test (260 ° C. × 10 s). Furthermore, a thermal cycle test (conditions: -55 ° C. × 30 minutes and 125 ° C. × 30 minutes, 1000 cycles) was performed on the semiconductor device in which conduction was obtained. The test results are shown in Table 1 below.

  As shown in Table 1 above, with respect to the semiconductor device of the example, no defects occurred in the initial continuity test, JEDEC level 1, IR reflow, and TCT (1000 cycles). On the other hand, in the semiconductor device of Comparative Example 1, it was difficult to obtain initial continuity, and it was confirmed that the sample in which the initial continuity was obtained also warped the chip in IR reflow and TCT, resulting in poor connection. In the semiconductor device of Comparative Example 2, the thickness of the underfill adhesive film with respect to the bump height was too large, and no initial conduction was obtained. In the semiconductor device of Comparative Example 3, no defect occurred in the initial continuity test, but a defect occurred in JEDEC level1. Furthermore, in the semiconductor device of Comparative Example 4, the semiconductor element warped after the after cure, and a connection failure occurred.

  Thus, according to the semiconductor device of the embodiment of the present invention, even when the semiconductor element is mounted on the flexible printed circuit board by ultrasonic bonding, the flexible printed circuit board or the semiconductor element is not warped. Connection reliability can be obtained over a long period of time.

Sectional drawing which showed an example of the manufacturing process of a semiconductor device. Sectional drawing which showed an example of the manufacturing process of a semiconductor device. FIG. 14 is a cross-sectional view illustrating an example of a semiconductor device of the invention. Sectional drawing which showed an example of the manufacturing process of a semiconductor device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Au stud bump 2 Underfill adhesive film 3 Semiconductor element 4 Flexible printed circuit board 6 Electrode part for connection

Claims (3)

  An underfill adhesive film bonded to a bonding surface of a bumped semiconductor element or a flexible printed circuit board bonded by an ultrasonic bonding method, having a thickness of 0.4 to 1.1 times the height of the bump An underfill adhesive film having a tensile elastic modulus after curing of 0.01 to 3 GPa and a glass transition temperature (Tg) of 250 ° C. or lower.   A semiconductor device in which a semiconductor element with a bump and a flexible printed circuit board are bonded by an ultrasonic bonding method with an underfill adhesive film bonded to either one, wherein the underfill adhesive film has a thickness before bonding Is 0.4 to 1.1 times the height of the bump, the tensile modulus after curing is 0.01 to 3 GPa, and the glass transition temperature (Tg) is 250 ° C. or less.   3. The semiconductor device according to claim 2, wherein the semiconductor element has a thickness of 100 μm or less, and a tensile elastic modulus after curing of the underfill adhesive film is 0.01 to 0.5 GPa.