JP2018170405A - Electronic part protection sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic part protection sheet which has a well-controlled paddling property and excellent heat shock resistance and also has a good heat flow property allowing application to a small substrate with complicated projections and depressions in shape.SOLUTION: An electronic part protection sheet to be heated to cover and protect an electronic part mounted on a substrate has a hot-melt resin composition layer containing a hot-melt resin. The hot-melt resin composition layer has a Martens hardness from 3 N/mmto 100 N/mminclusive after heat treatment at 150°C for 15 minutes, and an indentation elastic modulus from 50 MPa to 1500 MPa inclusive after heat treatment at 150°C for 15 minutes.SELECTED DRAWING: Figure 1

Description

    The present invention relates to an electronic component protective sheet for covering and protecting the surface of a substrate on which electronic components are mounted.

In order to prevent damage to an electronic component due to bending or impact on a substrate on which an electronic component such as an IC chip is mounted and to protect it from thermal shock due to temperature change, part or all of the substrate is covered and protected. In recent years, with the remarkable improvement in performance and miniaturization of electronic components and board circuits to be protected, the required level of protective functions required for materials for covering protection has increased.
As a method for covering and protecting a substrate, a heat-meltable electronic component protective sheet formed into a sheet containing no solvent has been proposed as a means to replace the conventional conformal coating.
For example, Patent Document 1 discloses a moisture-proof sheet for electronic device parts, comprising a moisture-proof layer made of a forming material mainly composed of an aromatic vinyl-conjugated diene block copolymer. .
Patent Document 2 discloses a substrate protecting sheet made of a graft copolymer of an olefin monomer, an ethylenically unsaturated carboxylic acid, and an aromatic ethylenically unsaturated monomer.
Patent Document 3 and Patent Document 4 disclose a sheet-shaped resin composition comprising an epoxy resin, an inorganic filler, and a flame retardant.

JP 2003-145687 A JP 2010-006954 A JP 2011-246596 A JP 2012-054363 A

  However, when the conventional electronic component protective sheet is attached to the substrate and the electronic component, there is a problem that the adhesion deteriorates due to a phenomenon of embedding air bubbles at the interface between the substrate and the electronic component and the electronic component protective sheet (hereinafter referred to as paddling). there were. Further, there has been a problem that peeling is caused (heat shock resistance) when heating and cooling are repeated. Furthermore, when trying to achieve both paddling properties and heat shock resistance, the heat flow properties may be extremely deteriorated.

  The present invention provides an electronic component protective sheet that is excellent in paddling property and heat shock resistance, and can be applied to a small substrate having complicated shape irregularities due to good heat flow properties.

As a result of intensive studies, the present inventors have found that the Martens hardness after heat treatment at 150 ° C. for 15 minutes is 3 N / mm ² or more and 100 N / mm ² or less, and the indentation elastic modulus after heat treatment at 150 ° C. for 15 minutes is 50 MPa or more. It has been found that the above-mentioned problems can be solved by using an electronic component protective sheet having a heat-meltable resin layer of 1500 MPa or less, and the present invention has been completed.

That is, the present invention is an electronic component protective sheet for covering and protecting an electronic component mounted on a substrate by heating, and has a heat-meltable resin composition layer containing a heat-meltable resin, The meltable resin composition layer has a Martens hardness of 3 N / mm ² or more and 100 N / mm ² or less after heat treatment at 150 ° C. for 15 minutes, and an indentation elastic modulus after heat treatment at 150 ° C. for 15 minutes of 50 MPa or more and 1500 MPa. This is solved by the following electronic component protection sheet.

  The present invention also relates to the electronic component protective sheet, wherein the heat-meltable resin composition layer further contains a scaly inorganic filler.

  Moreover, this invention relates to the said electronic component protection sheet characterized by the average particle diameter D50 of an inorganic filler being 0.6-25 micrometers.

  In addition, the present invention relates to the electronic component protective sheet, wherein the inorganic filler is talc.

  In the present invention, the heat-meltable resin is any one or more selected from the group consisting of a polyethylene resin, a maleic acid-modified polyolefin resin, an ethylene-glycidyl methacrylate copolymer resin, and an ethylene-vinyl acetate copolymer resin. It contains the said electronic component protection sheet characterized by including.

The present invention also includes a step of placing an electronic component protective sheet on an electronic component mounted on a substrate,
Melting the electronic component protective sheet by heating or thermocompression bonding, filling the gap between the electronic components, and coating the electronic components;
An electronic component covering protection method comprising a step of solidifying an electronic component protective sheet filled in the gap by cooling,
The electronic component protective sheet has a heat-meltable resin composition layer containing a heat-meltable resin,
The heat-meltable resin composition layer has a Martens hardness after heat treatment at 150 ° C. for 15 minutes of 3 N / mm ² or more and 100 N / mm ² or less, and an indentation elastic modulus after heat treatment at 150 ° C. for 15 minutes of 50 MPa or more. The present invention relates to a method for protecting a coating of an electronic component, characterized by being 1500 MPa or less.

  According to the present invention, it is possible to provide an electronic component protective sheet excellent in paddling properties, heat shock resistance, and heat flow properties.

It is explanatory drawing of the protection method of the electronic component in this invention. It is a reference image of paddling property evaluation.

  Hereinafter, an example of an embodiment to which the present invention is applied will be described. In addition, the size and ratio of each member in the following drawings are for convenience of explanation, and are not limited to this. In the present specification, the description “any number A to any number B” includes the number A as a lower limit and the number B as an upper limit in the range. The “sheet” in this specification includes not only “sheet” defined in JIS but also “film”. Moreover, the numerical value specified in this specification is a value calculated | required by the method disclosed by embodiment or an Example.

The electronic component protective sheet of the present invention can cover and protect an electronic component mounted on a substrate by heating, and has a heat-meltable resin composition layer containing a heat-meltable resin, and the heat-meltable resin The composition layer has a Martens hardness of 3 N / mm ² or more and 100 N / mm ² or less after a heat treatment at 150 ° C. for 15 minutes, and an indentation elastic modulus of 50 MPa or more and 1500 MPa or less after a heat treatment at 150 ° C. for 15 minutes. .
Thereby, it can be set as the electronic component protective sheet excellent in paddling property, heat shock tolerance, and heat flow property.
The Martens hardness and the indentation elastic modulus can be determined by measurement according to ISO14577-1.

<Martens hardness>
In the electronic component protective sheet of the present invention, the Martens hardness of the heat-meltable resin composition layer after heat treatment at 150 ° C. for 15 minutes is 3 N / mm ² or more and 100 N / mm ² or less. Martens hardness 4N / mm ² or more, preferably 80 N / mm ² or less, 5N / mm ² or more, 60N / mm ² or less being more preferred. Heat shock resistance is improved by setting the Martens hardness to 3 N / mm ² or more. Paddling properties are improved by setting the Martens hardness to 100 N / mm ² or less.

<Indentation modulus>
In the electronic component protective sheet of the present invention, the indentation elastic modulus of the heat-meltable resin composition layer after heat treatment at 150 ° C. for 15 minutes is from 50 to 1500 MPa. The indentation elastic modulus is preferably 50 or more and 1500 MPa or less, more preferably 70 or more and 700 MPa or less, and further preferably 100 or more and 500 MPa or less. By setting the indentation elastic modulus within the above range, the heat flow property is improved.

The electronic component protective sheet of the present invention has a heat-meltable resin composition layer containing a heat-meltable resin.
<Hot-melting resin composition layer>
The hot melt resin composition layer can be formed of a hot melt resin composition containing at least a hot melt resin. Moreover, the heat-meltable resin composition may contain a thermosetting agent, an inorganic filler, etc. in addition to the heat-meltable resin. By using these, heat flow property, paddling property, heat shock resistance and the like can be further improved.

[Hot melt resin]
A heat-meltable resin is a resin that melts by heat. As the heat-meltable resin, one having a melting point lower than the temperature at the time of forming the protective sheet can be used.
Examples of heat-meltable resins include polyolefin resins, acid-modified polyolefin resins grafted with acids, polyolefin and unsaturated ester copolymer resins, vinyl resins, styrene / acrylic resins, diene resins, and cellulose resins. , Polyamide resin, polyurethane resin, polyester resin, polycarbonate resin, polyimide resin, or fluorine resin.
Among these, a polyolefin resin, an acid-modified polyolefin resin grafted with an acid, a copolymer resin of a polyolefin and an unsaturated ester, and a vinyl resin are preferable in terms of improving paddling properties and heat flow properties.
One type of heat-meltable resin can be used alone, or two or more types can be mixed and used at any ratio as required.

The polyolefin resin is preferably a homopolymer or copolymer such as ethylene, propylene, and α-olefin compound. Specific examples include low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene homopolymer, and polypropylene copolymer.
Among these, a polyethylene resin and a polypropylene resin are preferable, and a polyethylene resin is more preferable.

The acid-modified polyolefin resin is preferably a polyolefin resin grafted with maleic acid, acrylic acid, methacrylic acid, itaconic acid or the like.
Among these, maleic acid-modified polyolefin resin is preferable.

The unsaturated ester in the copolymer resin of polyolefin and unsaturated ester is methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methyl methacrylate, isobutyl methacrylate, dimethyl maleate, Examples include diethyl maleate and glycidyl methacrylate.
Among these, an ethylene-glycidyl methacrylate copolymer resin composed of ethylene as a polyolefin and glycidyl methacrylate as an unsaturated ester is preferable.

The vinyl resin is preferably a polymer obtained by polymerization of vinyl ester such as vinyl acetate or a copolymer of vinyl ester and olefin compound such as ethylene. Specific examples include an ethylene-vinyl acetate copolymer, an ethylene-vinyl propionate copolymer, and a partially saponified polyvinyl alcohol.
Among these, an ethylene-vinyl acetate copolymer is preferable.

  The styrene / acrylic resin is preferably a homopolymer or copolymer made of styrene, (meth) acrylonitrile, acrylamides, maleimides or the like. Specific examples include syndiotactic polystyrene, polyacrylonitrile, acrylic copolymer, and the like.

  The diene resin is preferably a homopolymer or copolymer of a conjugated diene compound such as butadiene or isoprene and a hydrogenated product thereof. Specifically, for example, styrene-butadiene rubber, styrene-isoprene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butylene Examples thereof include a butadiene-styrene block copolymer, a mixture of a styrene-ethylene / butylene-styrene block copolymer and a styrene-ethylene / butylene block copolymer.

  The cellulose resin is preferably a cellulose acetate butyrate resin. The polycarbonate resin is preferably bisphenol A polycarbonate.

  The polyimide resin is preferably a thermoplastic polyimide, a polyamideimide resin, or a polyamic acid type polyimide resin.

  The heat-meltable resin may have a plurality of functional groups that can be used for a crosslinking reaction by heating. Examples of the functional group include a hydroxyl group, a phenolic hydroxyl group, a carboxyl group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, and a silanol group. .

[Thermosetting agent]
When the hot-melt resin has a reactive functional group, it is preferable to use a thermosetting agent. The thermosetting agent heat-melts the electronic component protective sheet and adheres to the base material and the electronic component, and then heat-crosslinks with the reactive functional group of the hot-melt resin to further enhance the adhesion and improve the water resistance. . The thermosetting agent has a plurality of functional groups that can react with the functional groups of the heat-meltable resin. Examples of the thermosetting agent include known compounds such as epoxy compounds, acid anhydride group-containing compounds, imidazole compounds, isocyanate compounds, aziridine compounds, amine compounds, and phenol compounds, and imidazole compounds and epoxy compounds are particularly preferable.

The epoxy compound is a compound having two or more epoxy groups in one molecule. The property of the epoxy compound may be liquid or solid.
As the epoxy compound, for example, a glycidyl ether type epoxy compound, a glycidyl amine type epoxy compound, a glycidyl ester type epoxy compound, a cyclic aliphatic (alicyclic type) epoxy compound and the like are preferable.

  Examples of the glycidyl ether type epoxy compound include bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, bisphenol AD type epoxy compound, cresol novolac type epoxy compound, phenol novolac type epoxy compound, α-naphthol novolak. Type epoxy compound, bisphenol A type novolak type epoxy compound, dicyclopentadiene type epoxy compound, tetrabromobisphenol A type epoxy compound, brominated phenol novolac type epoxy compound, tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) ethane Etc.

  Examples of the glycidylamine-type epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, triglycidylmetaaminophenol, tetraglycidylmetaxylylenediamine, and the like.

  Examples of the glycidyl ester type epoxy compound include diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, and the like.

  Examples of the cycloaliphatic (alicyclic type) epoxy compound include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, bis (epoxycyclohexyl) adipate, and the like.

  Examples of the imidazole compound include imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, and 2-phenylimidazole, and further imidazole compounds. And latent curing accelerators with improved storage stability, such as a type in which an epoxy resin is reacted with an epoxy resin and a type in which an imidazole compound is encapsulated in a microcapsule. From the viewpoint of starting curing after heat melting, a latent curing accelerator is preferred.

  The amount of the thermosetting agent is preferably 3 to 100 parts by weight, more preferably 5 to 60 parts by weight, and more preferably 5 to 40 parts by weight with respect to 100 parts by weight of the total heat-meltable resin. More preferably.

[Inorganic filler]
The hot melt resin composition layer of the present invention preferably further contains an inorganic filler. By including the inorganic filler, heat flow properties, paddling properties, and heat shock resistance are improved. Examples of inorganic fillers include silica, alumina, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, kaolinite, mica, basic magnesium carbonate, sericite, and montmoroli. Examples thereof include inorganic compounds such as knight, kaolinite, and bentonite.
Among these, talc, mica, kaolinite, or montmorillonite is preferable, and talc is more preferable from the viewpoint of further improving paddling properties, heat flow properties, and heat shock resistance.

  The shape of the inorganic filler is preferably scaly (flakes). By making the shape of the inorganic filler scaly, the warp of the electronic component protection sheet at the time of cooling can be suppressed, and the heat shock resistance can be further increased. Here, the scaly shape includes a flake shape and a plate shape. The inorganic filler may have a scaly shape as a whole particle, and may have an oval shape, a circular shape, or a cut around the fine particles.

The average particle diameter D50 of the inorganic filler is preferably 0.6 to 25 μm, and more preferably 0.8 to 25 μm. More preferably, it is 0.8-20 micrometers. Heat shock resistance improves by making an average particle diameter 0.6 or more. By setting the average particle diameter D50 to 25 μm or less, paddling properties can be further improved.
The average particle size is a D50 average particle size obtained by measuring an inorganic filler with a tornado dry powder sample module using a laser diffraction / scattering particle size distribution analyzer LS 13320 (manufactured by Beckman Coulter, Inc.). The cumulative value in the cumulative particle size distribution is a particle size of 50%. In the measurement, the refractive index of the inorganic filler was set to 1.6.
The average particle diameter of the inorganic filler can also be obtained from a numerical value obtained by averaging about 20 fine particles randomly selected from an enlarged image (about 1,000 to 10,000 times) of an electron microscope. In this case, the average particle size is preferably 2 to 70 μm, more preferably 5 to 50 μm.

  The content of the inorganic filler is preferably 5 to 40% by weight and more preferably 10 to 30% by weight in the solid content (100% by weight) of the heat-meltable resin composition layer. More specifically, the amount is preferably 5 to 67 parts by weight and more preferably 11 to 43 parts by weight with respect to 100 parts by weight of the heat-meltable resin. By setting the content of the inorganic filler in the above range, paddling properties and heat flow properties are improved.

  The heat-meltable resin composition and the heat-meltable resin composition layer may be provided with a colorant, a silane coupling agent, an ion scavenger, an antioxidant, a tackifier resin, a plasticizer, an ultraviolet absorber, and leveling as necessary. Conditioners, flame retardants and the like can be included.

  The electronic component protective sheet of the present invention can have an adhesive layer for imparting temporary tension in addition to the heat-meltable resin composition layer. Moreover, a hard-coat layer and a fiber layer can be laminated | stacked from a viewpoint of improving protective property. In addition to laminating individual layers, the fiber layer is preferably a single layer impregnated in the heat-meltable resin composition layer.

<Method for manufacturing electronic component protective sheet>
The electronic component protective sheet of the present invention has a heat-meltable resin composition layer obtained by molding a heat-meltable resin composition containing the above-described heat-meltable resin. There are no particular limitations on the molding method, but generally known methods include a T-die method, an inflation molding method, a calender roll molding method, and a press molding method. In the T-die method, the inflation molding method, and the calender roll molding method, the heat-melted resin is extruded with an extruder and is formed into a film by a predetermined method. From the viewpoint of ease of sheet thickness control, the T-die method and the calender roll forming method are preferable. The temperature at the time of using the extruder or the press temperature at the time of press molding may be within the range where the heat-meltable resin is sufficiently softened and thermal decomposition at a high temperature does not cause a practical problem. The temperature is 20 ° C. or more higher than the softening point of the sheet composition, and is generally in the range of 100 to 300 ° C.
When an inorganic filler and a thermosetting agent are used in combination, the hot-melt resin, the inorganic filler, and the thermosetting agent are melt-kneaded, and then the hot-melt resin composition is formed by extrusion.
When a thermosetting agent is used, it is melt kneaded and extruded at a temperature lower than the reaction start temperature of the curing agent.

The thickness of the electronic component protection sheet is preferably set to 0.5 to 2 times the thickness of the electronic component to be protected. By setting the thickness within the above range, the entire electronic component can be covered and protected, and the reliability of the electronic component can be improved.
The thickness of the electronic component protective sheet may be appropriately adjusted depending on the shape and size of the electronic component to be protected, but is preferably 0.01 to 3 mm, and more preferably 0.1 to 1 mm.

<Use of electronic component protection sheet>
The electronic component protective sheet of the present invention exhibits practically sufficient adhesion even when the substrate is any of metal, resin, fiber, ceramic, glass, and conductive silicon. As a metal, it can be used for aluminum, copper, brass, stainless steel, iron, chromium and the like. As the resin, epoxy resin, polyethylene terephthalate, polyimide, polyamide, polyethylene, polypropylene, polyolefin-based graft polymer, polystyrene, polyvinyl chloride and the like can be used. Therefore, the electronic component protective sheet can be suitably used for adhesion between different materials having different polarities.
The electronic component protective sheet of the present invention can be suitably used for protecting various substrates, that is, various substrates such as a rigid substrate and an FPC substrate.

<Coating protection method for electronic parts>
The electronic component covering protection method of the present invention is a step of placing an electronic component protective sheet on an electronic component mounted on a substrate (step i), heating, or melting the electronic component protective sheet by thermocompression bonding, The step of filling the gap between the electronic components and covering the electronic component (step ii), the step of solidifying the electronic component protective sheet filled in the gap by cooling (step iii), the electronic component is heated and melted according to the present invention. It can be covered and protected by the resin composition layer.

  Hereinafter, the method for protecting the covering of electronic components by thermocompression bonding using the electronic component protective sheet will be described with reference to FIG.

(Process i; Electronic component protection sheet placement process)
An electronic component protective sheet 5 cut to a predetermined size is placed on the upper surface of the electronic component 2 mounted on the substrate 1. Here, the electronic component 2 is mounted on the substrate 1 via the bump 3, and a gap exists between the electronic component 2 and the substrate 1 between the bumps. After placement, it can be temporarily stretched by lightly pressing it with an iron or the like to prevent displacement. As described above, the thickness of the electronic component protective sheet is preferably set to 0.5 to 2 times the thickness T of the electronic component to be protected.

(Process ii: Electronic component covering step with electronic component protection sheet)
Next, the electronic component protection sheet 5 is melted by heating and pressurizing with the pressurizing member 7, covers the entire surface of the electronic component 2, fills the gap between the electronic components, and comes into contact with the substrate 1. Here, the gap between the electronic components is shown as an example of the gap existing between the electronic component 2 and the substrate 1 in FIG. 1, but is not limited to this. For example, adjacent electronic components (not shown) ) Is also included. In addition, the electronic component protection sheet 5 may be filled in the gap as long as it is filled in the gap or only partially, and in any case, the electronic component can be sufficiently protected.
In order to prevent the pressure member 7 and the electronic component protection sheet from adhering at the time of thermocompression bonding, this is performed via the peelable sheet 6.
The peelable sheet 6 is a sheet obtained by performing a known peeling process on a substrate such as paper or plastic. A plastic sheet having a low polarity such as Teflon (registered trademark) can also be used.
The heating temperature is selected in a range exceeding the softening point of the electronic component protective sheet. Usually, it is 100-260 degreeC and 120-240 degreeC is preferable. If the temperature is too low, the adhesive force may be reduced, and the penetration of the electronic component protective sheet into the gap between the mounted electronic component and the substrate may be reduced. On the other hand, if the temperature is too high, thermal decomposition and oxidation of the hot-melt resin of the electronic component protective sheet of the present invention are likely to occur, and the possibility of a decrease in the reliability of the adhesion site due to reaction products and the like increases.
The pressure for thermocompression bonding is preferably 0.01 to 1 MPa, and more preferably 0.05 to 0.5 MPa. By thermocompression bonding with the above pressure, the embedding property and the adhesion force are further improved without damaging the electronic component.
The heating time is usually 0.5 to 30 minutes, preferably in the range of 1 to 20 minutes. If the heating time is too short, the adhesive force may be reduced, and the electronic component protection sheet resin may enter into the gap between the mounted electronic component and the substrate. On the other hand, if the time is too long, thermal melting and oxidation of the hot-melt resin are likely to occur, and the possibility of a decrease in the reliability of the adhesion site due to a reaction product or the like increases.
As a method of thermocompression bonding, a method in which a metal plate is used as the pressure member 7 so as to have a predetermined pressure, and this laminate is put into an oven is preferable because the process is simplified. It is also preferable to use a hot press.

(Process iii; electronic component protection sheet solidification process)
By cooling to room temperature after thermocompression bonding, the electronic component protective sheet is solidified and firmly adhered to the electronic component and the substrate. Thus, the electronic component is prevented from being damaged due to bending or impact of the substrate, and functions as a protective layer for protecting from thermal shock due to temperature change.

  As mentioned above, although thermocompression bonding was demonstrated, the electronic component protection sheet of this invention can fully heat-melt only by heating, and can cover-protect an electronic component. Further, the structure of the electronic component and the substrate is not particularly limited, and there may or may not be a gap between the bumps.

  The electronic component using the electronic component protecting sheet of the present invention is preferably provided in an electronic device such as a notebook PC, a mobile phone, a smartphone, and a tablet terminal in addition to a liquid crystal display and a touch panel.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited only to a following example. The following “parts” and “%” are values based on “parts by weight” and “% by weight”, respectively.

The raw materials used in the examples are shown below.
<Hot-melting resin>
PO-1: polyolefin resin “Petrocene 205 (low density polyethylene resin, melt flow rate 3.0 g / 10 min (190 ° C. × 2.16 kg), melting temperature 113 ° C.)” manufactured by Tosoh Corporation PO-2: Acid-modified polyolefin resin “UBE BOND F1100 (maleic acid-modified polyolefin resin, melt flow rate 5 g / 10 min (190 ° C. × 2.16 kg), melting temperature 115 ° C.)” manufactured by Ube Maruzen Polyethylene Co., Ltd.
PO-3: polyolefin resin “Novatech PP FB3B (polypropylene resin, melt flow rate 7.5 g / 10 min (230 ° C. × 5 kg), melting temperature 160 ° C.)” manufactured by Nippon Polypro Co., Ltd. • EGMA: Unsaturated with polyolefin Copolymer resin with ester “bond first E (ethylene-glycidyl methacrylate copolymer, melt flow rate 3 g / 10 min (190 ° C. × 2.16 kg), glycidyl methacrylate content 12%, melting temperature 103 ° C.) "Sumitomo Chemical Co., Ltd., SBS: Diene resin" Kraton D1155 (styrene-butadiene-styrene block copolymer, specific gravity 0.96, melt flow rate 3 g / 10 min (190 ° C x 2.16 kg), styrene content 40% ) ”Kraton Polymer, SEBS: Diene resin“ Clayton G1726 (styrene-ethylene-butylene-styrene block copolymer, specific gravity 0.91, melt flow rate 65 g / 10 min (230 ° C. × 5 kg), styrene content 30%) manufactured by Kraton Polymer Co., Ltd. PA: polyamide resin “Platamide” H005 (melt volume rate 7 g / 10 min (150 ° C.)) manufactured by Arkema Co., Ltd. PVC: Polyvinyl chloride “Kane Vinyl S1001 (average polymerization degree 1050 / K value 67 / apparent density 0.57 g / ml)” Made by Kaneka

<Thermosetting resin>
・ Thermosetting resin 1: Liquid bisphenol type epoxy resin “DER383J” manufactured by Dow Chemical Co. ・ Thermosetting resin 2: Solid polyfunctional epoxy resin “NC3000” manufactured by Nippon Kayaku Co., Ltd.

<Curing agent>
・ Curing agent 1: Dicyandiamide “DICY” manufactured by Nippon Carbide Co., Ltd. ・ Curing agent 2: Urea “U-CAT3502T” manufactured by Sun Apro

<Inorganic filler>
Inorganic filler 1: Talc “Nanoace D-600 (flaky, average particle size D50; 0.6 μm)” manufactured by Nippon Talc Co., Ltd. • Inorganic filler 2: Talc “Nanoace D-800 (flaky, average particle size D50) 0.8 μm) ”manufactured by Nippon Talc Co., Ltd., inorganic filler 3: Talc“ Nanoace SG-2000 (flaky, average particle size D50; 1 μm) ”manufactured by Nippon Talc Co., Ltd., inorganic filler 4: talc“ MS- T (scale-like, average particle size D50; 20 μm) ”manufactured by Nippon Talc Co., Ltd., inorganic filler 5: Talc“ MS-KY (scale-like, average particle size D50; 25 μm) ”manufactured by Nippon Talc Co., Ltd., inorganic filler 6: Silica “FB-950 (spherical, average particle diameter D50; 23.8 μm)” manufactured by Denki Kagaku Kogyo Co., Ltd., inorganic filler 7: Mica “S-400 (scale-like, average (Diameter D50; 24 μm) ”manufactured by Repco Co., Ltd., inorganic filler 8: Kaolinite“ hydrated kaolin ASP 400P (scale-like, average particle size D50; 3.5 μm) ”manufactured by Hayashi Kasei Co., Ltd., inorganic filler 9: montmorillonite “Kunipia-F (scale-like, average particle diameter D50; 1.0 μm)” manufactured by Kunimine Industries, Ltd.

<Average particle diameter D50 of inorganic filler>
The average particle diameter D50 is a numerical value of D50 average particle diameter obtained by measuring conductive fine particles with a tornado dry powder sample module using a laser diffraction / scattering particle size distribution analyzer LS13320 (manufactured by Beckman Coulter, Inc.). The cumulative value in the cumulative particle size distribution is a particle size of 50%. The refractive index was set to 1.6.

[Example 1]
100 parts of PO-1 (polyolefin-based resin “Petrocene 205”) was melt-kneaded using a twin screw extruder (PMT-32 manufactured by IK Corporation) with a screw diameter of 32 mmφ, and then cooled with a rotary blade. The pellet was cut into a thickness of 3 mm to prepare a pellet-shaped hot-melt resin composition.
Next, the pellet-shaped heat-meltable resin composition is melt-kneaded using a single-layer T-die film molding machine (Musashi Nokikai Co., Ltd.) and extruded to form a thickness comprising a heat-meltable resin composition layer. An electronic component protective sheet of 500 μm was obtained. The processing temperature was appropriately adjusted in the range of 150 to 300 ° C. by the melt flow rate of the resin.

[Examples 2 to 26, Comparative Example 1]
By changing the composition of the resin and inorganic filler of Example 1 and the blending amount (parts by weight) as described in Tables 1 and 2, in the same manner as in the manufacture of the electronic component protective sheet of Example 1, The electronic component protective sheets of Examples 2 to 26 and Comparative Example 1 were obtained.

[Comparative Example 2]
100 parts of PVC (polyvinyl chloride “Kane Vinyl S1001”), 20 parts of trioctyl trimellitate, 20 parts of heavy calcium carbonate, 10 parts of clay, a twin screw extruder with a screw diameter of 32 mmφ (IK KK Corporation) PMT-32) was melt-kneaded and cooled, and then cut to a length of 3 mm with a rotary blade to prepare a pellet-shaped hot-melt resin composition.
Subsequently, the pellet-shaped heat-meltable resin composition was melt-kneaded using a single-layer T-die film molding machine (manufactured by Musashinokikai Co., Ltd.) and extruded to obtain an electronic component protective sheet having a thickness of 500 μm. The processing temperature was 170 ° C.

  The obtained electronic component protective sheet was measured for the following physical properties and evaluated for paddling properties, heat flow properties, and heat shock resistance. The results are shown in Tables 1 and 2.

<Measurement of Martens hardness and indentation elastic modulus>
The Martens hardness and the indentation elastic modulus were placed on a polyimide film having a thickness of 125 μm (“Kapton 500H” manufactured by Toray DuPont), and an electronic component protective sheet cut to 2 × 2 cm was placed at 150 ° C. for 15 minutes. And then measured as follows.
Using a Fischerscope H100C (Fischer Instruments) type hardness tester and using a Vickers indenter (a diamond indenter with a 100φ tip), a test force of 0.3 N is maintained in a constant temperature room at 25 ° C. The test was carried out with a time of 20 seconds and a test force addition time of 5 seconds. Values obtained by repeatedly measuring the same film surface of the electronic component protective sheet at five random locations were averaged to obtain a Martens hardness value and an indentation elastic modulus.

<Paddling properties>
On a polyimide film with a thickness of 125 μm (“Kapton 500H” manufactured by Toray DuPont), an electronic component protective sheet cut to 2 × 2 cm / a release PET film with a thickness of 38 μm / stainless steel plate was placed in this order. Got. The thickness and size of the stainless steel plate were adjusted to 50 gf / cm ² . The above laminate was put into a 150 ° C. oven for 10 minutes and thermocompression bonded. After cooling, the stainless steel plate and the release PET film were removed to obtain a measurement sample. The presence or absence of bubbles at the polyimide film interface was visually confirmed on the electronic component protective sheet surface of the measurement sample.
The evaluation criteria are as follows.

A: No bubbles. Very good.
◯: One bubble. Good.
Δ: Two bubbles. There is no problem in practical use.
X: 3 or more bubbles. Not practical.

<Heat flow properties>
The thermal flow property was evaluated using the measurement sample used in the paddling property evaluation. First, a rectangular shape is used so that the area of the electronic component protective sheet of the measurement sample is minimized, the vertical and horizontal lengths of the square are measured, and the longer one is selected. And the heat flow property was calculated | required by subtracting the length (2 cm) before thermocompression bonding from the measured length.
The evaluation criteria are as follows.

A: 0.1 mm or more and less than 1.0 mm Good B: 1.0 mm or more and less than 3.0 mm. There is no problem in practical use.
X: 3.0 mm or more, or less than 0.1 mm Not practical.

<Heat shock resistance>
The measurement sample produced by the paddling property evaluation was subjected to a thermal cycle test of 10 minutes at −40 ° C. and 10 minutes at 85 ° C. in a programmed thermostatic bath 10 times, and the electronic component protective sheet from the polyimide film (Kapton 500H) The peeled state was observed visually.
The evaluation criteria are as follows.

A: No change. Very good.
○: Slightly floating at the edge. Good.
Δ: Slightly floating at the end and inside. There is no problem in practical use.
X: All peeled off. Not practical.

In the results of Tables 1 and 2, the electronic component protective sheet of the present invention was excellent in all of paddling properties, heat shock resistance, and heat flow properties. As shown in FIG. 2 which is a reference image of paddling evaluation of Example 10 and Comparative Example 2 shown for reference, in Example 10, no bubbles are found at the interface between the substrate and the electronic component and the electronic component protective sheet. However, in Comparative Example 2, bubbles were generated.
Thereby, it has confirmed that it was an electronic component protection sheet applicable also to the small board | substrate which has a complicated shape unevenness | corrugation.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Electronic component 3 Bump 4 Electronic component mounting board 5 Electronic component protection sheet 6 Peelable film 7 Pressure member

Claims (6)

An electronic component protective sheet for covering and protecting an electronic component mounted on a substrate by heating,
Having a heat-meltable resin composition layer containing a heat-meltable resin,
The heat-meltable resin composition layer has a Martens hardness after heat treatment at 150 ° C. for 15 minutes of 3 N / mm ² or more and 100 N / mm ² or less, and an indentation elastic modulus after heat treatment at 150 ° C. for 15 minutes of 50 MPa or more. An electronic component protective sheet, which is 1500 MPa or less.   The electronic component protective sheet according to claim 1, wherein the heat-meltable resin composition layer further contains a scaly inorganic filler.   The average particle diameter D50 of an inorganic filler is 0.6-25 micrometers, The electronic component protection sheet of Claim 2 characterized by the above-mentioned.   The electronic component protective sheet according to claim 2 or 3, wherein the inorganic filler is talc.   The heat-fusible resin includes any one or more selected from the group consisting of polyethylene resin, maleic acid-modified polyolefin resin, ethylene-glycidyl methacrylate copolymer resin, and ethylene-vinyl acetate copolymer resin, The electronic component protective sheet according to any one of claims 1 to 4. A step of placing an electronic component protection sheet on an electronic component mounted on a substrate;
Melting the electronic component protective sheet by heating or thermocompression bonding, filling the gap between the electronic components, and coating the electronic components;
An electronic component covering protection method comprising a step of solidifying an electronic component protective sheet filled in the gap by cooling,
The electronic component protective sheet has a heat-meltable resin composition layer containing a heat-meltable resin,
The heat-meltable resin composition layer has a Martens hardness of 3 N / mm ² or more and 100 N / mm ² or less after heat treatment at 150 ° C. for 15 minutes, and an indentation elastic modulus after heat treatment at 150 ° C. for 15 minutes of 50 MPa or more and 1500 MPa. A method for protecting a coating of an electronic component, comprising: