MXPA99005466A - Thermally reworkable binders for flip-chip devices - Google Patents

Abstract

A semiconductor device is attached to a supporting substrate by a plurality of solder connections that extend from the supporting substrate to the semiconductor device and the gap between the supporting substrate and the semiconductor device is filled with a reworkable composition comprising:(a) a thermally reworkable cross-linked resin produced by reacting at least one dienophile having a functionality greater than one and at least one 2,5-dialkyl substituted furan-containing polymer, and (b) at least one filler present in an amount from 25 to 75 percent by weight based upon the amount of components (a) and (b). Such a process provides a readily reworkable semiconductor assembly.

Description

THERMALLY REPROCESSABLE AGGLUTANTS FOR CHIP CHASQUIDO DEVICES FIELD OF THE INVENTION This invention relates to a thermosetting binder. In one aspect, the invention relates to suitable thermosetting binders for encapsulating the opening between a click chip (kick circuit) and a substrate.

BACKGROUND OF THE INVENTION The connection technology of the controlled dropping chip (4) or the click chip (hit circuit introduced in the 60s as a method to connect a passivated semiconductor device to a substrate such as a ceramic carrier by means of bumps welding (Microelectronics Packaging Handbook, R. Tum ala and EJ Rymasze ski, Van Nostrand Reinhold, NY 1989). The high-melting solder lugs on the device were coupled with corresponding pads on the substrate and the solder on the substrate was It made fluid to form a REF, 30472 conductive link between the device and the substrate.It was later found that the presence of a binder (snap chip encapsulant), usually a filled thermosetting binder greatly improved the life efficiency at the fatigue of the device in addition to protecting it from humidity and the surrounding environment.The technology of the click chip (go circuit) lpe) is rapidly gaining popularity due to a number of reasons, including "high density - in area and volume, small traces, high productivity, and the prevention of time consuming and costly processing steps involved in existing packaging technologies such as resin transfer molding to encapsulate the chips. A variety of substrates or chip carriers such as ceramic (e.g. alumina) and organic (e.g. epoxy resin / fiberglass laminated materials) are used in this technology. With the advent of packaging configurations such as multiple chip modules, the closest spacing of the matrix to matrix and the placement of the click chip on expensive multi-component boards, the repair and reprocessing of defective click chips It is quickly becoming a growing interest. A typical click chip process (Y. Thukada, Y. Mashimoto, N. atanuki, Proceedings of the 43rd Electronic Components and Technology Conference 1993, IEEE, pl99-204) may involve constructing weld overlays on the carrier, applying paste weld, place the chJLp snap with highlight along with other components such as SMT chips (surface mount technology), resistors, etc., if the carrier is a multi component board, reflow with infrared energy, inspect by X-ray , electrical test, click chip encapsulation and post-curing followed by final inspection. If the chip is found to be defective in the electrical test stage, then the chip is removed by applying heat, the boss is corrected, the replacement chip is placed and sent back to the previous process. If the chip is found to be defective after the final inspection, the heat is accompanied by a cut to break the crosslinked epoxy resin and remove the chip. This is followed by a very uncomfortable site correction stage due to the presence of a crosslinked material, chip placement, reflow with IR and the other successive steps in the previous process.

A conventional binder for click chip is a thermosetting system that is irreversibly crosslinked after being applied under the chip. An example formulation (D., ang, and KI Papatho as, IEEE Transactions on Components, Hybrids and Manufacturing Technology, 16 (8), December 1993, p 863-867) is a liquid epoxy resin such as an epoxy bisphenol resin -A or cycloaliphatic epoxy resin, a curing agent such as anhydride with a suitable accelerator, fillers such as silica and other additives. The reprocessing of the semiconductor device is an expensive and time-consuming process. Currently, if the device needs to be replaced, the device must be removed by destructive methods such as those described above. Thus, it is desirable to provide a click chip assembly and a process that allows reprocessing to be easier and non-destructive.

BRIEF DESCRIPTION OF THE INVENTION According to the invention, there is provided a click-chip assembly or thermally reprocessible encapsulated coupling circuit, comprising: a support substrate; at least one semiconductor device attached to the support substrate by means of a plurality of welding connections extending from the support substrate to the semiconductor device to form an opening between the support substrate and the semiconductor device; and a thermally reprocessible binder that fills the opening, the thermally reprocessible binder comprises: (a) a thermally reprocessable crosslinked resin produced by reacting at least one dienophile having a functionality greater than one and at least one furan-containing polymer substituted with 2, 5-dialkyl, and (b) at least one filler present in an amount from 25 to 75 percent by weight based on the amount of the components (a) and (b) thereby providing an assembly.

DETAILED DESCRIPTION OF THE INVENTION There may be several ways by which the polymer chains of the thermally reprocessible crosslinked resin can be produced. The thermally reprocessable crosslinked resin can be produced by reacting at least one dienophile having a functionality greater than one and at least one polymer containing furan substituted with 2,5-dialkyl, connecting one to the other via the Diels-Alder addition. In one embodiment the furan groups substituted with 2,5-dialkyl are attached to or form part of the polymer chains. The reversible reaction of furan to dienophile to form the Diels-Alder adduct can be represented by: FURANO DIENOFILO SUBSTITUTED ADULT OF WITH 2.5-DIALS DIALS-ALDER where Y is any of C < or N- For a thermally reprocessible crosslinked resin, all or a portion of the Diels-Alder adduct can be reverted to the furan and the dienophile with heating, such that the resin is a liquid (flowable material).

A crosslinking agent that contains two or more dienophiles in its molecular structure can also be used in this embodiment. These dienophiles are connected to each other by chemical bonds or bridge groups. Accordingly, the present invention also contemplates a snap chip binder composition (encapsulant) containing a polymer comprising portions of a furan substituted with 2,5-dialkyl and a crosslinking agent comprising two or more dienophiles in its molecular structure. Dienophiles may also be linked to being part of the polymer chains. A crosslinking agent comprising in its molecular structure two or more furan groups substituted with 2,5-dialkyl can also be used. In yet another embodiment, the dienophile is attached to the polymer chains to which the furan groups substituted with 2,5-dialkyl are also attached or containing the furan groups substituted with 2,5-dialkyl as a part of their chains. polymer. Accordingly, the furan-containing polymer substituted with 2,5-dialkyl can also contain portions of a furan substituted with 2,5-dialkyl and portions of a dienophile.

Furans substituted with 2,5-dialkyl may or may not be substituted at their 3 and 4 positions. Preferred substituents are inert substituents such as for example alkyl or alkyloxy groups, typically having up to 10 carbon atoms, such as methyl groups , ethyl, 1-propyl, methoxy and 1-hexyloxy. Resins containing furans whose positions 2 and 5 are not substituted are susceptible to side reactions that can cause irreversible gelation and interfere with their reversibility. The furan groups substituted with 2,5-dialkyl can be attached to the polymer chains of the polymer or polymers on which the crosslinked resin is based. They can be attached to it directly via a chemical bond or via a divalent organic bridge group for which any of the furan substituents or the 3 or 4 positions of the furans can function as the point of attachment. The alkyl substituents at positions 2 and 5 of the furans can be the same or different and will typically have up to 10 carbon atoms. Examples of suitable alkyl groups are methyl groups, ethyl, 2-propyl and 1-hexyl. Examples of suitable furyl groups that can be attached to a polymer chain are the 2,5-dimethyl-3-yl, 2,5-di-ethyl-3-methyl-4-yl, 5-ethylfurfuryl or 5-methyl groups. (1-butyl) furfuryl. The type of polymer chains to which furan groups substituted with 2,5-dialkyl can be attached is not critical. Suitably the polymer chains are chains of a polyolefin, such as polyethene, polypropene, polystyrene, poly (acrylic acid) or a copolymer of ethene and acid or acrylic ester, chains of random or alternating copolymers of carbon monoxide and olefinically synthesized compounds unsaturated (for further elaboration on such copolymers compare the following), or chains containing heteroatoms, such as polyamide or polyester chains. It is preferred that furans substituted with 2,5-dialkyl form a structural element of the backbone of the polymer itself. In such a case it is particularly preferred that each of the 2,5-dialkyl substituents of the furans are alkylene groups which also form part of the polymer chain and which can or can not be substituted. Such a structure can be produced by furanizing copolymers of carbon monoxide and olefinically unsaturated compounds containing 1,4-dicarbonyl entities in their polymer chains, ie converting such 1,4-dicarbonyl entities into furan portions. Alternatively, a furan-containing polymer substituted with 2,5-dialkyl can be produced directly by reacting carbon monoxide and olefinically unsaturated compounds in the presence of a strong acid. The alternating copolymers of carbon monoxide and olefinically unsaturated compounds containing 1, -dicarbonilic entities in their polymer chains are well known. They can be prepared by palladium catalyzed polymerization using the known methods of, for example, EP-A-121965, EP-A-181014 and EP-A-516238. The polymers prepared in this way are alternating copolymers of carbon monoxide and olefinically unsaturated compounds, ie copolymers of which the polymer chains contain the monomer units originating in carbon monoxide (ie carbonyl groups) and the monomer units that originate from the olefinically unsaturated compounds in an alternating arrangement, so that every fourth carbon atom of the polymer chain belongs to a carbonyl group. Alternative carbon monoxide copolymers and olefinically unsaturated compounds containing 1,4-dicarbonyl entities can be random copolymers, ie copolymers of which the polymer chains contain monomer units in a random order. These latter copolymers can be prepared by radical initiated polymerization using the known methods of, for example, US-A-2495286 and US-A-4024326. The furanization of the carbon monoxide copolymer and olefinically unsaturated compounds can be effected by methods known in the art, for example, by applying phosphorus pentoxide as the dehydrating agent, as described by A. Sen et al. (J. Polym, Science, Part A. Polym, Chem. 32 (1994) p.8441), or by heating in the presence of a strong acid, such as p-toluenesulfonic acid, as described in US-A-3979373. These methods allow conversion of the 1,4-dicarbonyl portions in the polymer chains to furan portions at a variable conversion level, depending on the selected reaction conditions.

It is preferred to employ in the furanization an alternating copolymer of carbon monoxide and olefinically unsaturated compounds, because these have a higher content of 1,4-dicarbonyl groups in the polymer backbone, so that the furanization can be efficiently carried out at a high level of incorporation of furan groups. However, if a low degree of furanization is desired, the conversion of carbonyl groups to furan groups can be kept low. The copolymers of carbon monoxide and olefinically unsaturated compounds can be based on hydrocarbons such as the olefinically unsaturated compounds. It is preferred that the copolymer be based on an olefinically unsaturated hydrocarbon, suitably an α-olefin, in particular an α-olefin having up to 10 carbon atoms. Very suitable are the aliphatic α-olefins, in particular those having from 3 to 6 carbon atoms and more particularly those having a straight carbon chain, such as propene, 1-butene, 1-pentene and 1-hexene. Propene is more preferred. The copolymer can be regregregular or irregular, stereorregular or atactic.

A polymer containing furan substituted with 2,5-dialkyl, wherein a polymer based on propene and carbon monoxide are furanized, can be represented by the formula: The precise nature of the dienophile from which the Diels-Alder adduct is obtained is not critical, since the Diels-Alder adduct has such thermal stability that the crosslinked resin is reprocessible. Usually the minimum temperature above which reprocessed crosslinked resin will be reprocessed depends on the maximum temperature requirements for the semiconductor device used. The reprocessing is suitably carried out at a temperature of 100 ° C, preferably from 130 ° C to 250 ° C, preferably at 200 ° C. The proper functionality of the dienophile can be represented by Y = Y, where Y is any of C < or N-, or -C = C-. Preferably the dienophiles are, for example, alkynes having electron attracting groups attached to both sides of the ethyne portion, such as the ester and keto groups. Examples are the mono- and diesters of butindioic acid (ie acetylene dicarboxylic acid) and substituted but-2-in-l, 4-diones. Other suitable dienophiles are compounds containing a portion of but-2-en-1,4-dione included in a 5- or 6-membered ring, in particular the compounds of the general formula: O = C C = O _c = c_ where X means O, S, N, P or R, where R is alkylene, where at least one of the free valencies is occupied by a bridge group connecting the dienophile with one of the polymer chains or with another dienophile , and wherein the remaining valencies, if any, are occupied by lower alkyl or acyl substituents or, preferably, hydrogen. The lower alkyl substituents suitably contain up to 4 carbon atoms and are, for example, methyl or ethyl groups. The dienophiles of this general formula are preferably cyclic derivatives of maleic anhydride and, in particular, maleimide (ie X means O or, in particular, N-). Examples of other suitable dienophiles include, bis (triazolinediones), bis (phthalazindiones), quinones, bis (tricyanoethylenes), bis (azodicarboxylates); di-acrylates, maleate or fumarate polyesters, acetylene dicarboxylate polyesters. As indicated above, in one embodiment use is made of a crosslinking agent comprising in its molecular structure two or more dienophiles from which the Diels-Alder adducts are obtainable. The dienophiles can be connected to each other by one or more bridge groups. For example, three dienophiles can be connected together by a group of trivalent bridges. However, it is sufficient that a crosslinking agent is used in which two dienophiles are connected to each other by a bivalent bridge group. Dienophiles can also be connected to each other by chemical bonds. Both the molecular weight and the chemical nature of the bridging group of the crosslinking agent can be varied to a high degree. It has been found that such variations of the crosslinking agent give rise to re-moldable crosslinked resins that cover a wide range of mechanical properties. The bridge group may contain only carbon atoms in the bridge, but it is also possible that it contains heteroatoms in the bridge, such as oxygen, silicon or nitrogen atoms. The bridge group can be flexible or rigid. For example, polymer bridge groups having flexible polymer chains, such as poly (alkylene oxide) or polysiloxanes, having an average molecular weight of, say, more than 300, provide reprocessible crosslinked resins similar to rubber. When the polymeric flexible chain has a number average molecular weight in the order of 1500-5000 or more, reprocessable crosslinked resins which could replace the thermoplastic rubbers can be obtained. Accordingly, suitable crosslinking agents of this class are the polyalkylene oxide capped with bis-maleimido, such as polyethylene oxide or polypropylene oxide, and polysiloxanes capped with bismaleimido, example the bismaleimides of polysiloxanes of the general formula H2N-CH2 [-0-SiR2] n-0-CH2-NH2, wherein n is an integer number, on average, of more than 10 and in particular in the range of 20- 70, and each R is independently an alkyl group, in particular having up to 5 carbon atoms, preferably a methyl group. Very good results can be obtained with the bismaleimide of poly (propene oxide) capped with bisamine, in particular having a number average molecular weight of at least 300, more in particular in the range of 1500-5000. Low molecular weight bridging groups can also be used, i.e. bridging groups that typically have up to 20 carbon atoms in the bridge. The cycloaliphatic and aromatic bridge groups become rigid to the bridge groups. Low molecular weight cycloaliphatic and aromatic bridge groups tend to provide re-moldable cross-linked resins that are hard and brittle, and have a relatively high glass transition temperature. Examples of low cycloaliphatic and aromatic molecular weight bridge groups are groups containing a norbornane skeleton in the bridge, 1,3-phenylene groups and groups of the following formulas: -f-CH2-f-, -fOfO- f -, -f-0-f-S02-fOf and -fC (CH3) 2-f-, wherein -f- means a 1,4-phenylene group. Other suitable bridge groups are the alkylene and oxycarbonyl '(ester) groups and combinations thereof. Suitable low molecular weight crosslinking agents are, for example, the bismaleimides of hydrazine, 2,4-diaminotoluene, hexamethylenediamine, dodecamethylenediamine, diamines of the general formula: and (poly) siloxanes capped with low molecular weight bisamino, such as polysiloxanes of the general formula H2N-CH2 [-0-SiR2] n-0-CH2-NH2, wherein n is in the range, on average, from 1 to 10, preferably from 1 to 5 and the groups r are preferably methyl groups. A mixture of isomers of the diamines of the above formula is commercially available from HOECHST. Very good results can be obtained with bis (4-maleimidophenyl) methane and di-ethylbis [(N-maleimidomethyl) oxy] silane.

Other suitable crosslinking agents on the basis of maleic anhydride are the compounds of the general formula: wherein A means a bridge group described in the above, in particular a bridge group having up to 20 carbon atoms in the bridge. More particularly, the bridging group A is an alkylene group, such as a hexamethylene group, or -DO-CO- or -CO-ODO-CO- groups, where D means a bivalent hydrocarbyl group, for example an alkylene group , such as a hexamethylene group. Again other suitable crosslinking agents are polyesters based on butindioic acid and a diol, such as ethylene glycol, a poly (ethylene glycol), propylene glycol or a poly (propylene glycol). These polyesters can be low molecular weight crosslinking agents, such as those described above, or they can have a number average molecular weight of, for example, more than 400, such as in the range of 2000-6000.

The present invention also relates to crosslinking agents such as poly (alkylene oxide) s crowned with bis-maleimido, in particular poly (propene oxide) s crowned with bismaleimido. Such agents have a number average molecular weight of at least 300, preferably in the range of 1500-5000. The polysiloxane bis bisons have the general formula H2N-CH2 [-0-SiR2] n-0-CH2-NH2, where n is an integer of at least 1 and each R is independently an alkyl group, in particular it has up to 5 carbon atoms, preferably a methyl group. The polysiloxanes capped with bismaleimido can be prepared by N-hydroxy-methylation of the maleimide with formaldehyde and subsequent reaction with the appropriate dichlorodialkylsilane in the presence of a base and water using generally known methods. As noted in the foregoing, certain embodiments relate to a crosslinking agent which comprises in its molecular structure portions of 2,5-dialkyl furan. In this crosslinking agent, the furan groups substituted with 2,5-dialkyl can be connected together via a chemical bond or via a bridge group. The nature of this bridge group is generally the same as the bridge group of the crosslinking agents comprising two or more dienophiles, as described above. Examples of suitable crosslinking agents are bis (5-ethylfurfuryl) adipate and (5-ethylfurfuryl) acetic acid bis-amines and the diamines mentioned in the preceding paragraphs. The furan portions substituted with 2,5-dialkyl and / or portions of a dienophile may be connected to the polymer chains by means of a chemical bond or by means of a bridge group. This bridge group may be of the same type as the bridge groups of the crosslinking agents. Examples can be given as follows. When the polymer is a polystyrene, the maleimide, like the dienophile, can be bound thereto by alkylation catalyzed by tin (IV) chloride of the polystyrene with N-chloromethylmaleimide, and when the polymer is a copolymer of (styrene / maleic anhydride) , a 5-ethylfurfuryl group can be attached thereto by esterifying the styrene / maleic anhydride copolymer with 5-ethylfurfuryl alcohol in pyridine. When the polymer is a copolymer of carbon monoxide and olefinically unsaturated compounds comprising 1,4-dicarbonyl entities in their polymer chains, the 2, 5-dialkylfurans and the dienophiles can be attached thereto by reacting the copolymer with an appropriately substituted primary hydrocarbylamine, for example, using the known methods of US-A-3979374. In this reaction, the 1,4-dicarbonyl entities are converted into pyrrole entities that are part of the polymer chain and which are N-substituted with the substituted hydrocarbyl group. For example, a copolymer of carbon monoxide and olefinically unsaturated compounds, which comprises 1,4-dicarbonyl entities, can be reacted with the monoamide of maleic acid and hexamethylenediamine or with the monoamide of maleic acid and bis (4). -aminophenyl) ethane, followed by ring closure of the acid-amide portions to maleimide portions. This will provide a polymer having N- (6-maleimidohexyl) pyrrole or N- entities. { 4 - [(4'-malei idophenyl) ethyl] phenyl} pyrrole in the polymer chain. When it is desired to use a polymer containing portions of furan substituted with 2,5-dialkyl and portions of a dienophile portion of the 1,4-dicarbonyl entities of a copolymer of carbon monoxide and olefinically unsaturated compounds can be converted into portions of furan and another portion of the 1,4-dicarbonyl entities can be converted into N-substituted pyrrole entities, of which the N-substituent comprises a dienophile. The molecular weight of the polymer or polymers on which the reprocessed crosslinked resin is based can vary between wide limits. Suitably the polymer can have a number average molecular weight in the range of at least 500, preferably 700, to 30,000, preferably 20,000. The amount of Diels-Alder adducts present in the thermally reprocessible crosslinked resin depends on the amount of furan groups with 2,5-dialkyl and the amount of the dienophile present in the composition from which the Diels-Alder adducts are formed. . One skilled in the art will appreciate that it is necessary that a certain minimum amount of Diels-Alder adducts be present for the effect that the crosslinked resin is a solid material below the temperature at which the Diels-Alder adducts are reversed to the furan substituted with 2,5-dialkyl and the dienophile. It will also be appreciated that this minimum amount depends on the molecular weight and type of the polymer on which the resin is based and, if any cross-linking agent is used, on the number of dienophiles or furan groups substituted with 2,5-dialkyl per molecule (ie, functionality) of the crosslinking agent. Low molecular weights of the polymer will require a greater amount of Diels-Alder adducts. The number of Diels-Alder adducts may be lower when a crosslinking agent having higher functionality is used. Generally good results can be achieved by using the furan-containing polymer substituted with 2,5-dialkyl having a ratio of furan groups to ketone groups from 1:16 to 4: 1. The molar ratio of the furan groups substituted with 2,5-dialkyl at amounts of dienophiles typically from 10: 1 to 1: 5, preferably from 5: 1 to 1: 3. A click chip assembly or snap circuit encapsulated between a semiconductor device and a support substrate is provided: by attaching the semiconductor device to the support substrate by a plurality of welding connections extending from the support substrate to the semiconductor device for forming an aperture between the support substrate and the semiconductor device, filling the aperture with a thermally reprocessible composition comprising: (a) a thermally reprocessable crosslinked resin produced by reacting at least dienophile having a functionality greater than one and at least one polymer containing furan substituted with 2,5-dialkyl, and (b) at least one filler present in an amount from 25 to 75 percent by weight based on the amount of components (a) and (b), providing with this a montage. The opening between the support substrate and the semiconductor device can be filled with the thermally reprocessable composition using a standard equipment such as a syringe or a static mixer, which mixes the components of the thermally reprocessible composition and accurately applies the composition on one or more sides of the device to fill the opening. Welding ridges, typically an alloy of 95 parts of lead to 5 parts of tin, provide the means of attachment of the chip to the substrate for subsequent use and testing. For a further discussion of the technique of connecting the controlled drop chip of the face-down junction of the semiconductor chips to the substrate, see U.S. Patent Nos. 3,401,126 and 3,429,040, which are incorporated herein by reference. Typically the weld bosses are formed on the contact site of the passivated semiconductor device, while the lower melting point solder on the pads of the corresponding substrate flows and forms conductive paths between the device and the substrate. Usually, semiconductor devices are mounted substrates made of materials with coefficients of expansion that differ from the coefficient of expansion of the material of the semiconductor device, ie silicon. The thermally reprocessable composition typically contains filler from 25%, preferably 40%, to 75%, preferably 60% by weight of the binder based on the weight of the composition (resin and filler). The filler can be any inorganic filler suitable for semiconductor packaging applications such as high purity amorphous or fused silica or commercial synthetic glass fillers. The filler may optionally be treated with a coupling agent such as a silane. The filler and the resin should be at least substantially free of ionic impurities such as chloride, sodium and potassium (less than 20 ppm each). The process of the invention provides a process that removes most of the ionic impurities found in traditional processes using binders based on epoxy resin. In addition, the thermally reprocessable composition in the opening can be processed and / or reprocessed at a temperature where the thermally reprocesable composition is melted. Typically, the reprocessible composition can be processed and / or reprocessed at a temperature within the range of 100 ° C, preferably from 130 ° C, to 250 ° C, preferably 200 ° C. If the resin is heated for a prolonged period at a high temperature, for example, for 12 hours at 200 ° C, the resin undergoes an irreversible crosslinking and is no longer thermally reversible. The encapsulating composition of the thermally reprocessible crack chip can also contain other additives such as ion scavengers (for example tricalcium phosphate), free radical inhibitors (for example hydroquinone, phenothiazine), elastomeric modifiers (for example silicones) and other conventional additives. used in click chip encapsulating compositions. For a longer reprocessing time, it is preferable to use ion scavengers and / or free radical inhibitors. The click chips are linked to various substrates such as ceramic or organic chip carriers and multi-component printed circuit board substrates. The carrier can also be a multiple chip module in which several chips are mounted at a close spacing on a carrier floor. In most cases, substrate and device costs are high and manufacturers can not afford to reject the entire substrate if one or more defective click chips are discovered during the test. The present invention allows the user to replace defective chips easily without having to throw away the complete package. The invention could also enable the user to eliminate a test step that is typically done prior to encapsulation, because the thermally reprocessible click chip encapsulating composition of the present invention allows for easy reprocessing and repair. The snap chip assembly encapsulated between the substrate and the semiconductor device made by the process of the invention can be reprocessed by heating the solder connections and the thermally reprocessible composition deposited in the aperture at a temperature that is high enough to melt or soften the welding connection and for converting the thermally reprocessable composition into a liquid, thereby providing a liquid composition. Then the semiconductor device and the liquid composition of the support substrate are removed to provide a support with the device removed. If it is desired to provide a new device to the substrate, another device can optionally be attached to the support with the device removed after rectification of the site (cleaning and re-deposition of the weld and / or weld flow on the substrate pads if it is necessary) by reworking the solder on the pads of the substrate to form conductive connections between the device and the substrate, to form an opening between the support substrate and the other device, then filling the aperture formed in this manner with a thermal composition. Recent reprocessable comprising: (i) a thermally reprocessable resin produced by reacting at least one dienophile having a functionality greater than one and at least one polymer containing furan substituted with, 5-dialkyl, and (ü) at least one filler present from 25 to 75 percent by weight based on the amount of components (i) and (ii). The fresh reprocessible composition filled in the opening is cooled to a temperature that is sufficiently low to solidify the resin, thereby producing a reprocessed assembly. The thermally reprocessable composition can be post-cured to improve the thermal and mechanical properties (e.g., vitreous transition temperature and mechanical strength). To preserve the thermal reversibility of the crosslinked resin, the thermally reprocessable composition can be post-heated to a temperature within the range of 50 ° C, preferably 80 ° C, 200 ° C, preferably 160 ° C for a period of time of up to 4 hours. If thermal reversibility is not required, the binder composition can be post-cured at a temperature within the range of 150 ° C, preferably from 180 ° C, to 300 ° C, preferably 250 ° C for a period of time of up to 4 hours, to improve the thermal properties.

Illustrative Modality The following illustrative embodiments describe the novel resin composition of the invention and are provided for illustrative purposes and are not to be construed as limiting the invention.

Example 1 An autoclave was charged. with methanol and propene (approximately 1.7: 1 ratio by weight), heated to 90 ° C, and then charged with carbon monoxide at a pressure of 73.4 kg / cm2 (72 bar). A catalyst solution of palladium acetate, 1,3-bis (diethylphosphino) propane, trifluoromethane sulfonic acid, in a weight ratio of 0.6: 0.62: 1 and 0.3 pyridine, in a solution of tetrahydrofuran and methanol (ratio of volume 15: 1) were injected and the reactor pressure was kept constant at 73.4 kg / cm2 (72 bar) during the reaction by means of a continuous supply of carbon monoxide. Removal of the solvent provided an alternating propene / CO copolymer with an average number-average molecular weight of 733.

Example 2 An alternating CO-olefin copolymer (27% ethylene, 73% propylene) with a number average molecular weight of 1472 was prepared in a manner similar to Example 1 from propene and ethylene. The copolymer was dissolved in toluene and cyclized in the presence of a catalytic amount of p-toluenesulfonic acid by heating under reflux. The resulting polymer was analyzed by 13 C NMR, which showed that 56% of the ketones in the starting polyketone were cyclized to furans (furan: ketone ratio of 0.64: 1) by the appearance of 13 C NMR signals (resonance of furan) centered at around 107, 114, 147 and 153 ppm.

Example 3 A gel plate was cured at 171 ° C (340 ° F) and the furanized polyketone made in Example 2 was applied to the plate. A stoichiometric amount of toluenediamine bis aleimide (Co pimide Resin TDAB, Technochemie Gmbh) was mixed with the furanized polyketone until a homogeneous mixture was obtained. The mixture was removed from the gel plate and stored at room temperature.

Example 4 An ICI cone and plate viscometer was set at a temperature of 175 ° C and allowed to equilibrate to the set point. A small amount of mixture of Example 3 was placed on the plate and allowed to reach the temperature. The cone was lowered and rotated to obtain a good film between the cone and the plate. This was verified by raising the cone to check the good formation of the film. Subsequently the mixture was allowed to equilibrate for 90 seconds and two viscosity readings were taken while the cone was rotating at a fixed speed. The cone was raised and the mixture recovered from both the cone and the plate. The mixture was allowed to cool to room temperature to give a cross-linked solid. The sequence of previous events is the charge on the cone and the ICI plate, the measurement of the viscosity at 175 ° C, removal of the mixture, cooling at room temperature, was repeated three times with the same mixture. The three consecutive readings for viscosity were 3-5 poises, 3-5 poises and 3-5 poises. This experiment demonstrates that the mixture can alternate the reversibility between a cross-linked state at room temperature and a non-crosslinked liquid of low viscosity at 175 ° C.

Example 5 The furanized polyketone made in the Example 2 was mixed with a stoichiometric amount of TDAB at 171 ° C (340 ° F) on a gel plate. The mixture was cooled to room temperature. This mixture was further mixed with silica filler (50% by weight of the total formulation) at 171 ° C (340 ° F). The filled formulation was then removed from the gel plate and cooled to room temperature.

Example 6 An ICI cone and plate viscometer was set at a temperature of 175 ° C and allowed to equilibrate to the set point. A small amount of mixture of Example 5 was placed on the plate and allowed to reach the temperature. The cone was lowered and rotated to obtain a good film between the cone and the plate. This was verified by raising the cone to check the good formation of the film. Subsequently the mixture was allowed to equilibrate for 90 seconds and two viscosity readings were taken while the cone was rotating at a fixed speed. The cone was raised and the mixture recovered from both the cone and the plate. The mixture was allowed to cool to a cross-linked solid at room temperature. The sequence of events above, ie the load on the cone and the ICI plate, the measurement of the viscosity at 175 ° C, removal of the mixture, cooling at room temperature was repeated three times with the same mixture. The three consecutive readings for viscosity were 20-25 poises, 20-25 poises and 25-30 poises. This experiment demonstrates that the mixture can alternate the reversibility between a cross-linked state at room temperature and a non-crosslinked liquid at 175 ° C.

Example 7 An autoclave was charged with methanol and propene (approximately 1.7: 1 ratio by weight), heated to 90 ° C, and then charged with carbon monoxide at a pressure of 73.4 kg / cm2 (72 bar). A catalyst solution of palladium acetate, 1,3-bis (di-o-methoxyphenylphosphino) propane, trifluoromethanesulfonic acid, in a molar ratio of 1: 1.05: 2.1, in a solution of tetrahydrofuran and methanol (volume ratio 15: 1) was injected twice and the reactor pressure was maintained at 73.4 kg / cm2 (72 bar) during the reaction by means of a continuous supply of carbon monoxide. Removal of the solvent provided an alternating propene / CO copolymer with a number average molecular weight of 1765 and a furan: ketone ratio of 0.19: 1.

Example 8 The furanized polyketone made in the previous example was mixed with a stoichiometric amount of TDAB and 2.4% by weight of phenothiazine were mixed on a gel plate at 171 ° C (340 ° F). The mixture was removed from the gel plate and cooled to room temperature. The mixture was reheated on the gel plate and mixed with silica filler (50% by weight of the total formulation). The filled formulation was removed from the gel plate and cooled to room temperature.

Example 9 An 8-layer printed circuit board (epoxy resin-fiberglass) with masked welding was placed on the gel plate at 171 ° C (340 ° F) and allowed to warm up for 2 minutes. A click chip was placed on the board and the filled mixture made in the previous example was allowed to fill the chip on the bottom from both sides of the chip for 2-3 minutes. The board was removed from the hot surface and allowed to cool to room temperature. The chip remained attached to the board by means of the cross-linked formulation between the device and the board. The board was placed again on the gel plate. Within 40 seconds, the chip could be removed from the board since the formulation had changed its state from a solid crosslinked to a liquid. A click chip was then adhered to the original site by means of the adhesive already present on the site. The board was removed from the gel plate and cooled to room temperature. The board was placed again on the hot surface and the above procedure of removing and replacing was repeated twice more.

Example 10 An alternating propene-CO copolymer (54.4% head to tail) with a number average molecular weight of 1616 was prepared in a manner similar to Example 1, except that 1,3-bis (di-o) was used. -methoxyphenylphosphino) propane in the catalyst solution instead of 1,3-bis (diethylphosphino) propane. The copolymer was dissolved in toluene and cyclized in the presence of a catalytic amount of p-toluenesulfonic acid by heating under reflux. The resulting polymer was analyzed by 13 C NMR, which showed that 57% of the ketones in the starting polyketone were cyclized to furans (ratio of furan: ketone 0.66: 1).

Example 11 The furanized polyketone made in Example 10 and a stoichiometric amount of TDAB together with 6.5% by weight of phenothiazine were heated to 180 ° C, mixed and poured into a 3.2 mm (1/8 inch) metal mold. of thickness. The mold was quickly cooled and the resulting molding was tested to determine its properties. It was found that the flexural modulus of the sample was 44 kg / cm 2 (43 bar (628 psi)), a value similar to that of a crosslinked epoxy resin made with an epoxy bisphenol-A resin cured with an anhydride hardener. The dielectric constant and the dissipation factor were 3.17 and 0.013 respectively.

Example 12 The furanized polyketone made in Example 7 was reacted with a 2: 1 stoichiometric ratio of methylenedianiline bis aleimide (Compimide Resin MDAB, Technochemie G bh), 0.1 moles of phenothiazine / mole of MDAB and 0.015 gram of acid 2- ethylhexanoic / furanised polyketone gram. A scanning by differential scanning calorimetry was performed on the sample, at a gradient speed of 20 ° C / minute. The start of vitreous transition temperature occurred at 105 ° C.

Example 13 The furanized polyketone made in Example 4 was reacted with a stoichiometric amount of TDAB and 0.1 moles of phenothiazine / mole of TDAB on a gel plate at 171 ° C (340 ° F). This sample was ground and placed in a Parr pump with water in a 10: 1 ratio (water: sample). The Parr pump was maintained at 60 ° C for 20 hours and the water extract was analyzed to determine the ions by ion chromatography. The extract contained 14 ppm acetate, < 3 ppm glycolate, formate, propionate, < 0.25 ppm chlorine, < 1 ppm of nitrate, 1.7 ppm of sulfate, 4.8 ppm of sodium, 0.8 ppm of magnesium, 2.5 ppm of calcium and 0.2 ppm of ammonium ion. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (10)

1. Having described the invention as above, the content of the following claims is claimed as property:

   1 • A click chip assembly or snap circuit, encapsulated, characterized in that it comprises: a support substrate; at least one semiconductor device "attached to the support substrate by means of a plurality of welding connections extending from the support substrate to form an opening between the support substrate and the semiconductor device, and a thermally reprocessible binder that fills the aperture, the thermally reprocessible binder comprises: (a) a thermally reprocessable crosslinked resin produced by reacting at least one dienophile having a functionality greater than one and at least one polymer containing furan substituted with 2,5-dialkyl, and (b) at least one filler present in an amount from 25 to 75 percent by weight based on the amount of the components (a) and (b) thereby providing an assembly.
2. 2. The click chip assembly or blow circuit according to claim 1, characterized in that the crosslinked resin is reprocessible at a temperature within the range of 100 ° C to 250 ° C.
3. • The click chip assembly or blow circuit according to claim 2, characterized in that the dienophile is an alkyne having electron attracting groups attached on either side of a portion of ethyne or a cyclic derivative.
4. 4. The click chip assembly or blow circuit according to claim 3, characterized in that the dienophile is selected from the group consisting of compounds containing portions of but-2-en-1,4-dione in 5-membered rings, and compounds containing portions of but-2-en-l, 4-dione in 6-membered rings.
5. • The click chip assembly or blow circuit according to claim 3, characterized in that the thermally reprocessable resin further comprises a residue of a crosslinking agent selected from the group consisting of poly (alkylene oxide) s topped with bismaleimido , polysiloxanes capped with bismaleimido, hydrazine bismaleimides, 2,4-diaminotoluene, hexamethylenediamine, dodecamethylenediamine, and substituted and unsubstituted diamines of the formula:
6. 6 • The click chip assembly or blow circuit according to claim 1 6 2, characterized in that the furan-containing polymer substituted with 2,5-dialkyl is produced by reacting carbon monoxide with at least one olefinically active compound. unsaturated
7. ^ • The click chip assembly or stroke circuit according to claim 1 or 2, characterized in that the furan groups substituted with 2,5-dialkyl in the furan-containing polymer substituted with 2,5-dialkyl • the dienophiles. combine in a molar ratio "from 10: 1 to 1: 5.
8. • The snap chip or shock chip assembly according to claim 1 or 2, further characterized in that it comprises (c) a free radical inhibitor and / or an ion scavenger.
9. 9. A process for providing an encapsulated snap chip assembly, characterized in that it comprises the steps of: attaching at least one semiconductor device to a support substrate by a plurality of welding connections extending from the support substrate to the semiconductor device for forming an aperture between the support substrate and the semiconductor device, filling the aperture with a thermally reprocessible click chip binder comprising: (a) a thermally reprocessable crosslinked resin produced by reacting at least one dienophile having a functionality greater than one and at least one polymer containing furan substituted with 2,5-dialkyl, and (b) at least one filler present in an amount from 25 to 75 percent by weight based on the amount of components (a) and (b) providing with this a click chip assembly.
10. 10. The process according to claim 9, further characterized in that it comprises the steps of: heating the encapsulated snap chip assembly to a temperature that is high enough to melt or soften the solder connections and to convert the thermally reprocessible composition into a liquid , thereby providing a liquid composition, removing the semiconductor device from the support substrate, providing a substrate with the device removed.