JP4826728B2 - Thermosetting resin composition - Google Patents

Description

  The present invention relates to mounting a semiconductor device such as a chip size (scale) package (CSP) or a ball grid array (BGA) on which a semiconductor element such as an LSI or a bare IC chip is mounted on a wiring substrate. The present invention relates to an underfill sealant used.

  In recent years, miniaturization of LSI devices and IC chips has been demanded as small electronic devices such as mobile phones, camera-integrated VTRs, and notebook personal computers have become widespread. CSPs and BGAs are becoming widespread for the purpose of protecting the semiconductor bare chips such as LSIs and making the characteristics of the package that facilitates the test, downsizing and improving the characteristics of the bare chips.

  The CSP and BGA are connected to the wiring on the wiring board by solder or the like. However, if the board is subjected to a temperature cycle after mounting, the connection reliability between the board and the CSP or BGA may not be maintained. Usually, after the CSP or BGA is mounted on the wiring board, the gap between the CSP or BGA and the board is not maintained. Sealing resin is added (underfill sealing) to relieve stress due to temperature cycle, improve heat shock resistance, and improve the reliability of electrical connection. An underfill sealant is also used as a reinforcing agent for preventing CSP and BGA from falling off due to impact such as dropping.

  And as an underfill sealing agent used conventionally, the thermosetting epoxy resin (patent document 1, patent document 2), the photocurable acrylic resin, and patent document 3 have been used. However, when a thermosetting resin is used as the sealing material, when a defect of the chip or a connection failure between the chip and the wiring board is discovered after CSP or BGA is mounted on the wiring board, these There was a problem that it was extremely difficult to remove CSP and BGA by removing the cured product of the thermosetting resin. Patent Document 3 describes a mounting method in which a bare chip is fixedly connected to a wiring board using a photocurable adhesive and is removed when there is a defect. However, since a photocurable adhesive is used, There are problems such as being limited to transparent substrates such as glass that can be irradiated.

  Furthermore, Patent Document 4 describes a method in which a bare chip and a substrate are fixedly connected using a resin that cures at a predetermined temperature, and in the case of a defect, the resin is softened at a temperature higher than the predetermined temperature to remove the bare chip. Yes. However, there is no specific disclosure about the adhesive in this publication, and a method that satisfies both reliability and repair characteristics has not been known yet. Patent Document 5 describes a method using a thermosetting polyurethane composition, but Tg is low and there is a problem in reliability.

  The underfill agent having repairability is a plasticizer or a low-reactive material that lowers the Tg and lowers the elasticity at high temperatures. Therefore, there is a problem in that the reactivity is poor and the low-temperature rapid curability is poor.

  As a conventional low-temperature rapid curing technique, a method using a solid latent curing agent having a low melting point is common. As a special method, Patent Document 6 discloses a low-temperature rapid curing technique using a polythiol-based one-component epoxy resin composition. However, when this composition is used as an underfill agent, the polythiol component corrodes the electrode, and it is difficult to reduce the viscosity, so that the permeability is poor. In addition, since Tg is low in composition, there is also a problem that reliability at the time of high temperature and high humidity and heat cycle is poor.

  On the other hand, Patent Document 7 discloses an adhesive composition using a compound in which an oxirane ring and a thiirane ring are used in combination. The composition is described as being optimal as an adhesive for rubber metal or plastics and civil engineering, but it is neither described nor suggested to be used as an underfill agent.

JP-A-10-101906 JP-A-10-158366 Japanese Patent Laid-Open No. 5-102343 JP-A-6-69280 JP 2003-246828 A JP-A-11-256013 Japanese Patent No. 3253919

  The present invention has been intensively studied to solve the above-mentioned problems, and provides an underfill that can be cured at a low temperature and can peel an adhesive layer when desired and has excellent repairability.

In order to solve the above problems, the present invention provides: (a) an epoxy resin having one or more oxirane rings in the molecule and not having a thiirane ring; (b) an oxygen atom of the oxirane ring of the hydrogenated bisphenol epoxy resin. Episulfide resin having one or more thiirane rings in the molecule, all or part of which are substituted with sulfur atoms (c) Solid dispersion type amine adduct-based latent curing agent (a) and (b) for a total amount of 100 parts by weight 1 to 50 parts by weight, a low-temperature rapid curing characterized in that a thiirane ring abundance ratio is 5 to 30% with respect to the total abundance of thiirane ring and oxirane ring of the components (a) and (b). The present invention provides a thermosetting resin composition for an underfill sealant that is excellent in repairability.

  Although the thermosetting resin composition of the present invention is cured at a relatively low temperature in a short time, the cured product is excellent in heat shock resistance, and the cured product can be easily heated to apply force. The cured product adhered to the substrate or the like can be easily removed by heating. By using the thermosetting resin composition of the present invention, the mounting process can be completed in a short time, so it is possible to reliably mount a semiconductor device such as CSP or BGA on a wiring board with high productivity. The mounted semiconductor has excellent heat shock resistance. And since a semiconductor device can be easily removed when a defect is found in electrical connection, etc., the semiconductor device, the wiring board, etc. can be reused, improving the production process yield and reducing the production cost. Can be achieved.

  Hereinafter, the present invention will be described in detail. The (a) epoxy resin used in the present invention is a compound having one or more oxirane rings (glycidyl groups) in the molecule. The component (a) does not have a thiirane ring. The number of oxirane rings is not particularly limited as long as it is one or more, and a polyfunctional epoxy resin may be used, but typically one having two or only one oxirane ring is suitable. A compound having only one oxirane ring is referred to as a monofunctional epoxy resin, and is preferably used for adjusting the properties (for example, viscosity) of the composition and adjusting the crosslinking density of the cured product. An epoxy compound having two or more functional groups is preferably used in order to improve heat resistance and adhesiveness.

  Examples of commercially available monofunctional epoxy resins include Cardura E10P manufactured by Japan Epoxy Resin, Denacol EX111, EX121, EX141, EX145, EX146 manufactured by Nagase ChemteX, and KBM403 manufactured by Shin-Etsu Chemical Co., Ltd. Is not to be done.

  In addition, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, and the like are typical examples of bifunctional or higher functional epoxy resins in the molecule, and commercially available products such as Epicoat manufactured by Japan Epoxy Resin Co., Ltd. 828, 1001, 801, 806, 807, 152, 604, 630, 871, YX8000, YX8034, YX4000, Epiklon 830, 835LV, HP4032D, 703, 720, 726, HP820, manufactured by Dainippon Ink Industries, Asahi Denka Kogyo Co., Ltd. EP4100, EP4000, EP4080, EP4085, EP4088, EPU6, EPR4023, EPR1309, EP49-20, and the like, which are manufactured, are not limited thereto.

  These epoxy resins described above may be used alone or in combination of two or more. In particular, a bisphenol-type epoxy resin is preferable because it is tougher and has a better balance between curability and storage stability. Moreover, (a) component may have another functional group besides an oxirane ring. For example, a hydroxyl group, vinyl group, acetal group, ester group, carbonyl group, amide group, alkoxysilyl group and the like.

  The component (b) of the present invention is an episulfide resin and is a compound having one or more thiirane rings in the molecule. Further, the component (b) may further have an oxirane ring as long as it has one or more thiirane rings. This means that an oxirane ring may remain from the manufacturing method of the component (b) described later, and even in that case, there is no problem. It is preferable to use only a thiirane ring without an oxirane ring because the abundance ratio between the oxirane ring and the thiirane ring can be easily calculated.

  The thiirane ring-containing compound is produced by various methods. For example, thermal hydrolysis of hydroxymercaptan, treatment with 1,2-chlorothiol with a weak alkaline solution, treatment with ethylenically unsaturated ethers such as sulfur or polysulfide dialkyl.

  Further, a method for obtaining a thiirane ring-containing compound by replacing all or part of oxygen atoms in an epoxy ring with a sulfur atom using an epoxy compound as a raw material is already known. Illustratively, J.M. Polym. Sci. Polym. Phys. 17, 329 (1979), a method using an epoxy compound and thiocyanate, Org. Chem. 26, 3467 (1961), a method using an epoxy compound and thiourea, a method disclosed in JP 2000-351829 A, and JP 2001-342253 A, and the like. It is not a thing.

  Specific examples of the component (b) include, for example, 2,2-bis (4- (2,3-epithiopropoxy) phenyl) propane, bis (4- (2,3-epithiopropoxy) phenyl) methane, 1,6-di (2,3-epithiopropoxy) naphthalene, 1,1,1-tris- (4- (2,3-epithiopropoxy) phenyl) ethane, 2,2-bis (4- (2 , 3-epithiopropoxy) cyclohexyl) propane, bis (4- (2,3-epithiopropoxy) cyclohexyl) methane, 1,1,1-tris- (4- (2,3-epithiopropoxy) cyclohexyl) Ethane, 1,5-pentanediol 2,3-epithiocyclohexyl) ether, 1,6-hexanediol di (3,4-epithiooctyl) ether, and the like. Not intended to be.

  In addition, when a compound having both a thiirane ring and an oxirane ring in one molecule is used to synthesize an episulfide resin by exchanging oxygen atoms in the epoxy ring with sulfur atoms using an epoxy compound as a raw material, the amount of episulfiding reagent used Or it can obtain by adjusting reaction conditions. Alternatively, partial episulfides obtained by separation by various purification methods can be obtained by mixing with all episulfides.

  As a more preferable component (b) in the present invention, the carbon-carbon unsaturated bond of the aromatic ring of the epoxy compound having a bisphenol skeleton as shown in JP 2000-351829 A is hydrogenated (hydrogenated). A compound containing a thiirane ring in which all or part of oxygen atoms of the oxirane ring of the hydrogenated bisphenol epoxy resin is substituted with a sulfur atom, particularly a thiirane ring-containing compound containing a hydrogenated bisphenol A skeleton, and a composition using this compound The product is particularly excellent in curability, workability and storage stability.

  The blending amount of the component (a) and the component (b) is the ratio of the oxirane ring existing in the component (a) and the component (b) and the amount (molar amount) of the thiirane ring present in the component (b), that is, thiirane. The percentage value calculated by ring / (thiirane ring + oxirane ring) × 100 is 5% to 30%. If the amount of thiirane ring is decreased from 5%, the curability and repair properties are lowered. On the other hand, when the amount of thiirane ring is increased from 30%, storage stability and heat shock resistance are lowered. In addition, since the corrosivity increases, it cannot be used as an underfill agent.

  The (c) latent curing agent used in the present invention is a compound that does not have activity with respect to an epoxy resin at room temperature, and is activated by dissolution, decomposition, transfer reaction, etc. when heated, and functions as an accelerator. Examples include, but are not limited to, imidazole compounds and derivatives thereof that are solid at room temperature, salts of various amines and acids, solid dispersion-type amine adduct latent curing agents, and the like. Further, examples of solid dispersion type amine adduct-based latent curing accelerators include reaction products of amine compounds and epoxy compounds (amine-epoxy adduct systems) and reaction products of amine compounds with isocyanate compounds or urea compounds ( Urea type adduct system) and the like, but are not limited thereto. Among these latent curing agents, preferably a solid dispersion type amine adduct based latent curing agent, more preferably a urea type adduct based latent curing agent is excellent in the low curing temperature and storage stability of the composition of the present invention. Show the effect. The blending amount of these latent curing agents is not particularly limited, but is preferably added in the range of 1 to 50 parts by weight with respect to 100 parts by weight of the resin component of the components (a) and (b). The If the amount of the curing agent is small, the curing is slow, and if the amount is too large, the viscosity increases and the storage stability also deteriorates.

  Examples of products that are commercially available as the latent curing agent include imidazole compounds 2PZ, 2PHZ, 2P4MHZ, C17Z, 2MZ-A, 2E4MZ-CNS, 2MA-OK, manufactured by Shikoku Kasei Kogyo Co., Ltd., and Ajinomoto Fine Techno Co., Ltd. Amicure PN23, PN31, PN40J, PN-H, MY24, MY-H, manufactured by Asahi Denka Co., Ltd. EH-3293S, EH-3366S, EH-3615S, EH-4070S, EH-4342S, EH-4360S, EH-3331S, Asahi Kasei Chemicals Co., Ltd. NovaCure HX-3742, HX-3721, Fuji Chemical Industry Co., Ltd. FXE-1000, FXR-1030, FXR-1080, FXR-1110 etc. are mentioned, However It is not limited to these.

  In the thermosetting resin composition of the present invention, colorants such as pigments and dyes, inorganic fillers such as calcium carbonate, talc, silica, alumina, and aluminum hydroxide, flame retardants, and the like within a range that does not impair the characteristics of the present invention. An appropriate amount of additives such as an organic filler, a plasticizer, an antioxidant, an antifoaming agent, a coupling agent, a leveling agent, and a rheology control agent may be blended. By these additions, a composition excellent in resin strength, adhesive strength, workability, storage stability, and the like and a cured product thereof can be obtained.

Various thermosetting resin compositions were prepared by mixing the blends shown in Table 1 described later at the blending ratio described. However, the abbreviations in the table are as follows.
Epicoat 806: Bisphenol F type epoxy resin (Japan Epoxy Resin Co., Ltd.) (a) component,
Denacol EX146: p-tertiary butylphenyl glycidyl ether (manufactured by Nagase ChemteX) (a) component,
Episulfide compound A: 100% episulfide product of hydrogenated bisphenol A type epoxy (Japan Epoxy Resin Co., Ltd.) (b) component,
Episulfide compound B: 80% episulfide product of hydrogenated bisphenol A type epoxy (Japan Epoxy Resin Co., Ltd.) (b) component,
FXR-1080: amine adduct-based latent curing agent (Fuji Kasei Kogyo Co., Ltd.) (c) component FXE-1000: amine adduct-based latent curing agent (Fuji Kasei Kogyo Co., Ltd.) (c) component Powder silica Aerology R972 (manufactured by Nippon Aerosil Co., Ltd.)

  Examples 1 to 6 The following tests were performed using the various thermosetting resin compositions of Comparative Examples 1 to 4 (hereinafter referred to as various compositions).

[Tiirane ring abundance]
The abundance of thiirane rings in various compositions was determined by the following formula. Thiirane ring abundance (%) = (i) number of thiirane rings present in component (b) (i) number of thiirane rings present in component (b) + oxirane rings present in component (b) + oxirane rings present in component (b)). However, the number of thiirane rings is calculated by the compound mass / thiirane equivalent, and the number of oxiranes is the same.

[Penetration test]
Using a CSP having an outer diameter (length of one side) of 12 mm and a terminal number of 176 pins, a penetration test of the mounting was performed. Solder paste was printed and supplied onto an electrode of an electronic substrate (glass epoxy), CSP was mounted, and solder bonding was performed in a reflow furnace. Thereafter, various compositions were applied around the CSP using a dispenser, and subsequently heated at 80 ° C. for 30 minutes to cure the various compositions. At this time, regarding the various compositions, the one that penetrated between the semiconductor device and the wiring board before being completely cured was indicated by ◯, and the one that did not penetrate was indicated by ×.

[Adhesive strength test]
Various tensile compositions are applied at 25 ° C after applying various compositions to two 10mm overlapped surfaces of 1.6x25x100mm SPCC-SD steel plates and bonding them together. Was measured at a pulling speed of 10 mm / min. Those having a tensile shear bond strength of 15 MPa or more were evaluated as ◎, and those having a tensile shear bond strength of 10-15 MPa were evaluated as ○. Less than that was marked with x.

[Repairability test]
A hot air generator is used to heat the vicinity of the CSP fixed to the wiring board with various compositions by applying hot air of about 260 ° C. for 10 seconds, and it is picked up by tweezers between the CSP and the glass epoxy board and lifted. The CSP was removed. Next, the hardened material and the solder remaining on the glass epoxy substrate were removed using a soldering iron heated to 350 ° C. (having a flat tip shape). Further, the solder remaining on the glass epoxy substrate that could not be completely removed by itself was removed with a braided wire for sucking out the solder, and the substrate surface was cleaned with alcohol or the like.

  The solder paste was again applied on the glass epoxy substrate from which the CSP was removed in this manner, and a new CSP was mounted. At this time, solder paste may be printed on the new CSP side. In the same manner as described above, various compositions were applied around the CSP, and subsequently heated at 80 ° C. for 30 minutes to cure the various compositions. The thus-repaired CSP mounting board is also securely connected, and in the heat shock resistance test, those showing the same characteristics as those in the case of not being repaired were set as acceptable, and otherwise set as x. Of the passes, those for which removal and residue treatment were easy were marked with ◎, and those for which either removal or residue treatment was easy were marked with ○. Moreover, the chip | tip was damaged by removal and the thing which cannot remove a solid residue was set as x.

[Heat shock resistance test]
Create a CSP mounted on the substrate in the same manner as described above, and perform it under the condition of 1 cycle 1 hour with each holding time of 30 minutes at -40 ° C on the low temperature side and 80 ° C on the high temperature side. A test was conducted to confirm the electrical connection between the CSP and the substrate. Those that were conductive even after 500 cycles or more were evaluated as “good”, and those that were conductive even after 1000 cycles or more were evaluated as “good”. Those which became non-conductive due to disconnection or the like before 500 cycles were rated as x.

[Preservation test]
Various compositions whose viscosity was less than twice the initial value after 3 months of refrigeration were marked with ◎, various compositions whose viscosity was less than twice the initial value after 3 months of freezing were marked with ○, did.

[Comprehensive evaluation]
The case where there was no x in each of the items of viscosity, curability, repairability, heat shock resistance, and storage stability was rated as ◯, and the others were marked as x.

  The present invention relates to mounting a semiconductor device such as a chip size (scale) package (CSP) or a ball grid array (BGA) on which a semiconductor element such as an LSI or a bare IC chip is mounted on a wiring substrate. Used for underfill sealant.

Claims (1)

(A) Epoxy resin having one or more oxirane rings and no thiirane ring in the molecule
(B) an episulfide resin having one or more thiirane rings in the molecule in which all or part of the oxygen atoms of the oxirane ring of the hydrogenated bisphenol epoxy resin are substituted with sulfur atoms (c) a solid dispersion type amine adduct-based latent curing agent It consists of 1 to 50 parts by weight with respect to 100 parts by weight of the total amount of (a) and (b). A thermosetting resin composition for an underfill sealant that is excellent in repairability by low-temperature rapid curing, characterized by being 5 to 30%.