JP2021193725A - Electronic part protection sheet - Google Patents

Abstract

To provide an electronic part protection sheet which is excellent in temporary sticking properties, releasability and migration resistance, and which can be applied also to an electronic part group mounting board having electronic parts with different heights by further good embeddability.SOLUTION: There is provided an electronic part protection sheet for coating and protecting a plurality of electronic parts that are mounted on a board and have different heights. The electronic part protection sheet has a plurality of insulating resin layers with different Young's modulus at 23°C. In the electronic part protection sheet, the adhesive force of a surface in contact with an electronic part group, the adhesive force being measured by a probe tack test, is 0.3-5 N; the adhesive force of an opposite surface, the adhesive force being measured by a probe tack test, is 1 N or less; and the adhesive force of a surface in contact with the electronic part group, the adhesive force being measured by a probe tack test, is greater than a probe tack on the opposite surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electronic component protective sheet for covering and protecting at least a part of the surface of an electronic component mounted on the surface of a substrate and composed of a plurality of electronic components having different heights.

In order to protect electronic components such as IC chips mounted on the board from bending and impact on the board and from thermal impact due to temperature changes, the electronic components are covered and protected with resin on a part or the entire surface of the board. Is being done. In recent years, with the remarkable improvement and miniaturization of the performance of protected electronic components and board circuits, the required level of protective functions required for covering and protecting materials has increased.
As a method for covering and protecting electronic components, a heat-meltable electronic component protective sheet molded into a solvent-free sheet has been proposed as a means to replace the conventional conformal coating.
For example, Patent Document 1 discloses a moisture-proof sheet for electronic equipment parts, which comprises a moisture-proof layer made of a forming material containing an aromatic vinyl-conjugated diene-based block copolymer as a main component. ..
Patent Document 2 discloses a substrate protective sheet composed of a graft copolymer of an olefin-based monomer, an ethylenically unsaturated carboxylic acid, and an aromatic ethylenically unsaturated monomer.
Patent Document 3 and Patent Document 4 disclose a sheet-like resin composition composed of an epoxy resin, an inorganic filler, and a flame retardant.
Patent Document 5 discloses a sealing film provided with an insulating layer and an electromagnetic wave shielding layer as a sealing film for sealing an electronic component mounting substrate.
Patent Document 6 discloses a method for manufacturing a mounting structure that covers a mounting component and a substrate with a laminated sheet including a first heat conductive layer and a second heat conductive layer, and is shown in FIG. 3 (b). Discloses a manufacturing method in which a space between a mounted component and a mounted component is completely filled with a cured product of the laminated sheet.

Japanese Unexamined Patent Publication No. 2003-145678 Japanese Unexamined Patent Publication No. 2010-06954 Japanese Unexamined Patent Publication No. 2011-246596 Japanese Unexamined Patent Publication No. 2012-054363 Japanese Unexamined Patent Publication No. 2019-021757 WO2019 / 065976

However, as shown in FIGS. 2 (a) and 3 (a), when the electronic component mounting substrate whose height of the mounted electronic component is not constant is covered and protected by a conventional protective sheet, FIG. 2 (b) is used. As shown in, the protective sheet is displaced in the horizontal direction, and as shown in FIG. 3 (b), the protective sheet is tilted by a tall electronic component. There was a problem of forming. That is, it is required that the protective sheet does not stick to the target electronic component and does not shift or tilt (hereinafter referred to as temporary tension).
In addition, the surface opposite to the planned mounting surface of the protective sheet sticks to the pickup device used when mounting the protective sheet on the electronic component mounting board, so that the protective sheet can be quickly mounted on the electronic component mounting board. There was a problem that the placement was impaired and the productivity was lowered. In other words, the protective sheet is required to be released promptly from the pickup device (hereinafter referred to as release property).
Further, the conventional protective sheet has a problem that migration occurs at a conductive portion (for example, a solder bump) between electronic components due to long-term use after forming a covering protective film (hereinafter referred to as migration resistance).
Further, the conventional protective sheet has insufficient embedding property in gaps between electronic components and unevenness of electronic components (hereinafter referred to as embedding property).

The present invention provides an electronic component protective sheet that is excellent in temporary tensioning property, release property, migration resistance, and can be applied to an electronic component group mounting substrate having electronic components having different heights due to good embedding property.

As a result of diligent studies, the present inventors have obtained an electronic component protective sheet for covering and protecting an electronic component group mounted on a substrate by heating and pressurizing, and the electronic component protective sheet is a thermosetting resin. It has an insulating resin layer containing, and the adhesive force of the surface opposite to the surface in contact with the electronic component group is within a predetermined range, respectively, and the adhesive force of the surface in contact with the electronic component group is opposite. By using an electronic component protective sheet characterized by having a greater adhesive strength than that of the above, it was found that the above-mentioned problems could be solved, and the present invention was completed.

That is, the present invention is an electronic component protection sheet for covering and protecting a group of electronic components composed of a plurality of electronic components having different heights mounted on a substrate.
The electronic component protective sheet has an insulating resin layer containing a thermosetting resin, and has an insulating resin layer.
The adhesive strength of the surface in contact with the electronic component group by the probe tack test is 0.3 to 5N.
The present invention relates to an electronic component protective sheet having an adhesive force of 1 N or less in the probe tack test on the opposite surface and a larger adhesive force in the probe tack test on the surface in contact with the electronic component group than the adhesive force in the probe tack test on the opposite surface.

Further, the present invention is a process of mounting an electronic component group composed of a plurality of electronic components having different heights on a substrate.
The step of preparing the electronic component protection sheet according to the present invention,
A process of placing an electronic component protective sheet so that the tallest electronic component in the electronic component group and the first insulating resin layer in the electronic component protective sheet are in contact with each other.
A process of deforming an electronic component protective sheet to follow the shape of each electronic component by heating and pressurizing, and covering at least a part of the electronic component group and the substrate.
And, including the step of thermally curing the deformed electronic component protective sheet in a deformed state to form a covering protective layer.
The present invention relates to a coating protection method for a board on which an electronic component group is mounted.

Furthermore, the present invention is a process of mounting an electronic component group composed of a plurality of electronic components having different heights on a substrate.
The step of preparing the electronic component protection sheet according to the present invention,
A process of placing an electronic component protective sheet so that the tallest electronic component in the electronic component group and the first insulating resin layer in the electronic component protective sheet are in contact with each other.
A process of deforming an electronic component protective sheet to follow the shape of each electronic component by heating and pressurizing, and covering at least a part of the electronic component group and the substrate.
And, including the step of thermally curing the deformed electronic component protective sheet in a deformed state to form a covering protective layer.
The present invention relates to a method of manufacturing a substrate for mounting an electronic component group with a covering protective layer.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an electronic component protective sheet which is excellent in temporary tensioning property and release property, and further excellent in migration resistance and embedding property. As a result, it is possible to provide a highly reliable electronic component mounting board with a high yield.

It is explanatory drawing of the coating protection method of the electronic component using the electronic component protection sheet in this invention. It is explanatory drawing at the time of placing the conventional electronic component protection sheet. It is explanatory drawing at the time of placing the conventional electronic component protection sheet. It is a schematic side view for demonstrating the migration resistance test in an Example. It is a schematic cross-sectional view for demonstrating the embedding property test in an Example.

Hereinafter, an example of an embodiment to which the present invention is applied will be described. The sizes and ratios of the members in the following figures are for convenience of explanation and are not limited thereto. Further, in the present specification, the description "arbitrary number A to arbitrary number B" includes the number A as the lower limit value and the number B as the upper limit value in the range. Further, the "sheet" in the present specification includes not only the "sheet" defined in JIS but also the "film". In addition, the numerical value specified in the present specification is a value obtained by the method disclosed in the embodiment or the embodiment.
In addition, the adhesive force obtained by the probe tack test may be abbreviated as probe tack adhesive force or adhesive force.

<How to protect the coating of the board on which the electronic component group is mounted>
First, a coating protection method (hereinafter, may be abbreviated as a coating protection method, a coating method, or a protection method) of an electronic component group mounting substrate using the electronic component protection sheet of the present invention will be described.
As the method for protecting the coating of the electronic component group mounting substrate of the present invention, a step (step i) of mounting an electronic component group composed of a plurality of electronic components having different heights on the substrate, and a electronic component protection sheet of the present invention described later are prepared. Step (step ii), a step of placing the electronic component protective sheet so that the tallest electronic component in the electronic component group and the first insulating resin layer in the electronic component protective sheet are in contact with each other (step ii). Step iii, also referred to as temporary tensioning step), a step of deforming the electronic component protective sheet so as to follow the shape of each electronic component by heating and pressurizing, and covering at least a part of the electronic component group and the substrate (step iv). ), By the step (step v) of thermally curing the deformed electronic component protective sheet in a deformed state to form a covering protective layer, the electronic component group mounting substrate is formed by the covering protective layer formed from the electronic component protective sheet of the present invention. The coating can be protected. (Step iv) and (Step v) can also be a series of steps.

Hereinafter, a method for protecting the coating of the substrate on which the electronic component group is mounted by heating and pressurizing using the electronic component protection sheet will be described with reference to FIGS. 1 for steps iii to v.

(Process iii; Electronic component protection sheet mounting process)
An electronic component mounting board 4 on which an electronic component 2a and an electronic component 2b are mounted by a solder bump 3 is prepared on the substrate 1. The electronic component 2 is a semiconductor chip, a capacitor, a transistor, an inductor, a thermistor, etc., and is mounted on the substrate 1 via a solder bump 3, and there is a gap between the electronic components 2a and 2b and the substrate 1. Further, the electronic component 2a is designed to be higher than the electronic component 2b.
Next, the first insulating resin layer 11 of the electronic component protective sheet 10 cut to a predetermined size is placed on the mounting surface of the electronic components 2a and 2b so as to be in contact with the electronic components 2a. Due to the height of the electronic component 2a, the first insulating resin layer 11 comes into contact with the electronic component 2a and is temporarily attached. The electronic component protection sheet 10 may bend and come into contact with the electronic component 2b (not shown in FIG. 1). The first insulating resin layer 11 has a Young's modulus of 5 MPa to 200 MPa at 23 ° C. and has a tack property, so that misalignment is unlikely to occur after mounting.

The cushion material 13 may be laminated on the outer side of the insulating resin layer located farthest, and FIG. 1 shows an example in which the cushion material is used. The cushion material 13 may be laminated after the electronic component protection sheet 10 is placed, or a laminated body in which the electronic component protection sheet 10 and the cushion material 13 are stacked in advance may be placed. The cushion material 13 is a material that softens or melts when heated and pressed, and has a function of promoting followability of the electronic component protective sheet 10 to the electronic components 2a and 2b and to the gaps between the electronic components.
The cushion material 13 is not particularly limited as long as it is a material having thermoplasticity, for example, but preferably has a melting temperature lower than the temperature at the time of pressurization and a glass transition point (Tg). As a suitable example, a polyolefin-based film, a vinyl chloride film, and a PVA film can be exemplified. It depends on the depth of the groove, but is usually about 100 μm to 1 mm. When a plurality of cushioning materials 13 are laminated, it is preferable that the total thickness is within this range.

The thickness of the electronic component protection sheet 10 is preferably set to be 0.05 to 2 times the height of the highest electronic component among the electronic components to be protected.
The electronic component mounting substrate shown in the present application is an example, and the structure of the electronic component and the substrate is not particularly limited, and there is no gap between the electronic components 2a and 2b and the substrate 1. It is also good. The arrangement position of the electronic components to be mounted is not limited, and the number of electronic components is two or more.

(Process iv; Covering process with electronic component protection sheet)
Next, by heating and pressurizing with the heating and pressurizing machine 20, the electronic component protective sheet 10 is deformed so as to follow the shape of each electronic component, that is, along the upper surfaces and side surfaces of the electronic components 2a and 2b. It is deformed to follow at least a part of the electronic component group and the substrate 1. The cushion material 20 is softened or melted by heat to promote the follow-up to the unevenness between the electronic components of the electronic component mounting substrate 4 of the electronic component protective sheet 10.
A method in which a peelable sheet is interposed between the heating and pressurizing machine 20 and the cushioning material 13 at the time of heating and pressurizing is also preferable. The peelable sheet is a sheet obtained by performing a known peeling treatment on a base material such as paper or plastic. Further, a plastic sheet having a low polarity such as Teflon (registered trademark) can also be used.

The heating temperature may be any temperature as long as the electronic component protective sheet is appropriately softened, deformed along the shape of each electronic component, and can enter the gap between the individual electronic components, and is preferably 100 to 260 ° C. , 120-240 ° C., more preferably. If the temperature is too low, the penetration of the electronic component protective sheet 10 into the gap between the mounted electronic components is reduced. On the other hand, if the temperature is too high, the thermosetting reaction of the thermosetting resin of the electronic component protective sheet 10 proceeds rapidly, and the penetration of the electronic component protective sheet between the mounted electronic components decreases.
The pressure in the case of heating and pressurizing is preferably 0.01 to 10 MPa, more preferably 0.1 to 6.0 MPa. By heating and pressurizing with the above pressure, the embedding property is further improved without damaging the electronic components.
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 penetration of the electronic component protective sheet between the mounted electronic components is reduced. On the other hand, if the time is too long, thermal decomposition and oxidation of the thermosetting resin are likely to occur, and the possibility of deterioration of the reliability of the bonded portion due to the reaction product or the like increases. The heating and pressurizing step is preferably performed in a vacuum state.
As a method of heating and pressurizing, in addition to using a heating and pressurizing machine, a method of laminating a metal plate having an appropriate weight so as to have a predetermined pressure and putting this laminate into an oven is also preferable.
On the other hand, as a heating and pressurizing method other than the heating and pressurizing machine, a vacuum forming method or a vacuum pressure pneumatic molding is also preferable.

(Step v; Hardening step of deformed electronic component protective sheet)
After heating and pressurizing, the deformed electronic component protective sheet is further heated at a temperature of 150 ° C. to 230 ° C. for 10 to 60 minutes to insulate the most distant insulating resin layer and the first insulation. The thermosetting resin in the sex resin layer is thermoset to form a coating protective layer. The coating protective layer firmly adheres to the electronic component and the substrate, and functions as a protective layer for preventing and protecting the electronic component from damage from external impacts and scratches. By setting the heating and pressurizing temperature to 150 ° C. or higher and the time to 30 minutes or longer in the step (step iv), the thermosetting can be completed and the coating protective layer can be formed. The covering protective layer is indispensable to be an insulator in order to prevent short circuits between electronic components, and the surface resistance value is required to be 1 + E10Ω or more.

<Electronic component protective sheet>
Next, the electronic component protection sheet of the present invention will be described. The electronic component protection sheet is for covering and protecting the electronic component group mounted on the substrate as described above, and has an insulating resin layer containing a thermosetting resin.
The insulating resin layer has an adhesive strength of 0.3 to 5 N in the probe tack test on the surface in contact with the electronic component group, and an adhesive strength of 1 N or less in the probe tack test on the opposite surface, and is different from the electronic component group. The adhesive strength of the contact surface according to the probe tack test is greater than the adhesive strength of the opposite surface. The adhesive strength of the surface in contact with the electronic component group is more preferably 0.5 to 4N, further preferably 1 to 3.5N. By setting the adhesive strength of the surface in contact with the electronic component group to 0.5 N or more, the temporary tension property is improved. Reworkability can be imparted by setting the adhesive strength of the surface in contact with the electronic component group to 5 N or less.
The adhesive strength of the opposite surface by the probe tack test is preferably 1N or less, more preferably 0.5N or less, still more preferably 0.3N or less. By setting the adhesive strength on the opposite surface to 1N or less, the release property is improved. Further, since the adhesive force of the surface in contact with the electronic component group by the probe tack test is larger than the adhesive force of the opposite surface, the reworkability and the release property are improved.
The difference between the adhesive force obtained by the probe tack test on the surface in contact with the electronic component group and the adhesive force obtained by the probe tack test on the opposite surface is preferably 0.3 N or more, more preferably 0.5 N or more, and further preferably 0.7. Within the above range, both release and temporary tension can be achieved at a high level.

The adhesive strength according to the probe tack test in the present application is that a stainless steel probe (200 g including a weight) having a diameter of 5 mmφ is brought into contact with the surface of the insulating resin layer to be measured for 1 second, and then the probe is 10 mm / sec. The force (peeling force) that is detected when the insulating resin layer is separated from the surface at the speed of.
When the electronic component protection sheet is composed of a single layer, the probe tack can be controlled by a method of UV curing one surface or by orienting the content in the layer of the inorganic filler described later to one surface.

An embodiment in which the electronic component protective sheet is formed of a plurality of insulating resin layers is also preferable from the viewpoint of controlling probe tack. In this case, the insulating resin layer is composed of at least a first insulating resin layer in contact with the electronic component group and a second insulating resin layer located farthest from the electronic component group. At this time, the adhesive strength of the first insulating resin layer by the probe tack test is 0.3 to 5N, and the adhesive strength of the second insulating resin layer by the probe tack test is 1N or less.

Further, the Young's modulus of the first insulating resin layer at 23 ° C. described above is preferably 5 MPa to 200 MPa, and the Young's modulus of the second insulating resin layer at 23 ° C. is 23 of the first insulating resin layer. It is preferably 8 MPa or more higher than the Young's modulus at ° C., more preferably 20 MPa or more, and even more preferably 50 MPa or more.
Since the Young's modulus of the second insulating resin layer at 23 ° C. is higher than the Young's modulus of the first insulating resin layer at 23 ° C., the temporary tension property, release property, migration resistance, and embedding property are excellent. It can be an electronic component protection sheet.

<First insulating resin layer>
The Young's modulus of the first insulating resin layer at 23 ° C. (hereinafter abbreviated as Young's modulus (1)) is preferably 5 MPa to 200 MPa, more preferably 20 MPa to 150 MPa, and even more preferably 30 MPa to 100 MPa. By setting the Young's modulus (1) to 5 MPa or more, the followability to the groove between the electronic components is improved, and by setting it to 200 MPa or less, the temporary tension property is improved.
The "Young's modulus at 23 ° C." in the present invention can be obtained as follows. The sample is allowed to stand in an environment of 23 ° C. and a relative humidity of 50% for 24 hours, and then the measurement is performed in the same environment. Specifically, a sample with a chuck distance of 25 mm is pulled by a tensile tester under the condition of a tensile speed of 50 mm / min, the stress-strain curve is measured, and the strain (elongation) is linear in the region of 0.1 to 1%. Let the regression (slope) be the Young's modulus at 23 ° C.
Young's modulus (1) can be controlled by adjusting the types and amounts of thermosetting resins, thermosetting agents, and inorganic fillers, which will be described later, or by using a tackifier resin and a thermoplastic resin in combination. ..

Further, the first insulating resin layer preferably has a storage elastic modulus at 23 ° C. (hereinafter, abbreviated as the storage elastic modulus (1)) of 1.0 + E04Pa to 1.0 + E07Pa. By setting the storage elastic modulus (1) to 1.0 + E04Pa or more, the embedding property is improved, and by setting it to 1.0 + E07Pa or less, the migration resistance is improved.
The storage elastic modulus in the present invention is a deformation mode "tensile", a frequency of 10 Hz, and a temperature rise rate of 10 ° C./ It is a value of the storage elastic modulus at 23 ° C. measured under the condition of -50 to 300 ° C. in the measurement temperature range.

The first insulating resin layer can be formed by a thermosetting resin composition containing a thermosetting resin. Since the first insulating resin layer has an adhesive strength of 0.3 to 5 N in the probe tack test, the first insulating resin layer is firmly attached to the electronic component at the time of temporary tensioning to prevent misalignment. Furthermore, it is also excellent in reworkability because it can be peeled off and rearranged once when the temporary pasting position is corrected.
Further, the thermosetting resin composition preferably contains a thermosetting agent, an inorganic filler, a flame retardant and the like. By using these, the Young's modulus at 23 ° C., the storage elastic modulus and the probe tack described above can be adjusted in a suitable range.
[Thermosetting resin]
Suitable examples of thermosetting resins are polyurethane resins, polyurethane urea resins, acrylic resins, polyester resins, polyamide resins, epoxy resins, polystyrenes, polycarbonate resins, polyamideimide resins, polyesteramide resins, polyether ester resins, and Examples include polyimide resin. The thermosetting resin may have a self-crosslinkable functional group. For example, the thermosetting resin when used under harsh conditions during reflow may contain at least one of an epoxy resin, a urethane resin, a urethane urea resin, a polycarbonate resin, and a polyamide. preferable. Further, the thermosetting resin and the thermoplastic resin can be used in combination as long as they can withstand the embedding property.

Examples of the reactive functional group of the thermosetting resin include a carboxyl group, a hydroxyl group, and an epoxy group. When having a carboxyl group, the acid value of the thermosetting resin is preferably 3 to 30 (mgKOH / g), preferably 4 to 20 (mgKOH / g), from the viewpoint of embedding property in step iv and migration resistance after curing. ), More preferably 5 to 15 (mgKOH / g).
When the acid value of the thermosetting resin is within the above range, the curing rate in the step iv can be moderately slowed down, so that the embedding property is not impaired and a sufficient cross-linking density can be secured, so that good migration resistance can be exhibited.

The weight average molecular weight Mw of the thermosetting resin is preferably 20,000 to 200,000. By setting the value to 20,000 or more, the release property and the temporary tension property can be effectively enhanced. Further, when the content is 200,000 or less, the effect of improving the embedding property can be obtained.

[Curing agent]
In order to accelerate the curing of the thermosetting resin, it is preferable to use a curing agent. The curing agent heat-melts and deforms the electronic component protective sheet, comes into contact with the base material and the electronic component, and then thermally crosslinks with the reactive functional group of the thermosetting resin to further strengthen the adhesiveness to the substrate and the electronic component. And migration resistance is improved.
The curing agent has a plurality of functional groups capable of reacting with the functional groups of the thermosetting resin. Examples of the curing 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 epoxy compounds and aziridine compounds are preferable, and both are used in combination. It is particularly preferable to do so.

The epoxy compound is a compound having two or more epoxy groups in one molecule. As for the properties of the epoxy compound, the Young's modulus can be lowered by using a liquid. On the other hand, Young's modulus can be increased by using the solid state. It is preferable to use an epoxy compound liquid at 23 ° C. for the first insulating resin layer to reduce Young's modulus and impart tackiness.
As the epoxy compound, for example, a glycisyl ether type epoxy compound, a glycisylamine type epoxy compound, a glycidyl ester type epoxy compound, a cyclic aliphatic (alicyclic) 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, and α-naphthol novolac. Type epoxy compound, bisphenol A type novolak type epoxy compound, dicyclopentadiene type epoxy compound, tetrabrom bisphenol A type epoxy compound, brominated phenol novolac type epoxy compound, tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) ethane And so on.

Examples of the glycidylamine type epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, triglycidylmethaminophenol, tetraglycidylmethoxylylenediamine and the like.

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

Examples of the cyclic aliphatic (alicyclic) epoxy compound include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate and bis (epoxycyclohexyl) adipate.

Examples of the aziridine compound include trimethylolpropane-tri-β-aziridinyl propionate, tetramethylolmethane-tri-β-aziridinyl propionate, and N, N'-diphenylmethane-4,4'-bis. (1-Aziridinecarboxyamide), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxyamide) and the like can be mentioned.

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. Examples thereof include a latent curing accelerator having improved storage stability, such as a type in which an epoxy resin is reacted with an epoxy resin and insolubilized in a solvent, or a type in which an imidazole compound is encapsulated in microcapsules.

The blending amount of the curing agent is preferably 3 to 100 parts by mass, more preferably 5 to 60 parts by mass, and 5 to 40 parts by mass with respect to 100 parts by mass of the total thermosetting resin. Is more preferable. With the above blending amount, the adhesive strength, Young's modulus at 23 ° C., and storage elastic modulus can be adjusted to suitable values.

Further, it is preferable to use a tackifier resin or a thermoplastic resin for the first insulating resin layer in addition to the thermosetting resin from the viewpoint of improving the adhesive strength.
Examples of the tackifier resin include rosin-based resin, terpene-based resin, alicyclic petroleum resin, and aromatic petroleum resin. Suitable examples of thermoplastic resins are polyolefin resins, vinyl resins, styrene / acrylic resins, diene resins, terpene resins, petroleum resins, cellulose resins, polyamide resins, polyurethane resins, polyester resins. , Polycarbonate resin, fluororesin and the like.

[Inorganic filler]
The first insulating resin layer preferably further contains an inorganic filler. By containing the inorganic filler, the adhesive strength, Young's modulus at 23 ° C. and storage elastic modulus can be appropriately increased, and migration resistance, embedding property and release property are improved.

Examples of the inorganic filler 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, bentonite, boron nitride, aluminum nitride and magnesium oxide (hereinafter referred to as inorganic filler in a narrow sense) and an ion collecting agent described later.
Among these, silica, talc, mica, kaolinite, or montmorillonite is preferable, and silica and talc are more preferable, from the viewpoint of further improving migration resistance and embedding property.

The shape of the inorganic filler in the narrow sense is preferably scaly (flakes). By making the shape of the inorganic filler scaly, it is possible to suppress the warp of the electronic component protective sheet at the time of cooling and further improve the embedding property. Here, the scaly shape includes a flaky shape and a plate shape. The inorganic filler may be scaly as a whole particle, and may have an elliptical shape, a circular shape, or a notch or the like around the fine particles.

The average particle size D50 of the inorganic filler in the narrow sense is preferably 0.5 to 10 μm, and more preferably 0.7 to 7 μm. Embedding property is improved by setting the average particle size to 0.5 or more. By setting the average particle diameter D50 to 10 μm or less, migration resistance can be further improved.
The average particle size is a D50 average obtained by measuring an inorganic filler in a narrow sense with a tornado dry powder sample module using a laser diffraction / scattering method particle size distribution measuring device LS 13320 (manufactured by Beckman Coulter). It is a particle size, and the cumulative value in the particle size cumulative distribution is 50%. At the time of measurement, the refractive index of the inorganic filler in the narrow sense was set to 1.6.

The content of the inorganic filler in the narrow sense of the first insulating resin layer is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and 10 to 35 parts by mass with respect to 100 parts by mass of the thermosetting resin. More preferred. By setting the content of the inorganic filler in the narrow sense to the above range, the Young's modulus is adjusted to a suitable range and migration resistance and embedding property are improved.

[Ion collector]
As the inorganic filler, an ion collecting agent is also preferable. Ion scavengers include cation scavengers, anion scavengers, and both ion scavengers. The ion collecting agents may be used alone or in combination of two or more. Among these, it is preferable to use a cation collecting agent and a biion collecting agent in terms of improving migration resistance. Particularly preferred is a cation collector.
The ion collecting agent can be contained in the first insulating resin layer, can also include a second insulating resin layer described later, and can be contained in both layers.

The cation collector includes, for example, manganese compounds (hydrous manganese dioxide, etc.), antimony compounds (crystalline antimonic acid, hydrous antimonium pentoxide, etc.), zirconium compounds (zirconium hydroxide, zirconium phosphate, zirconium molybdate, zirconium tungstate, etc.). Etc.), silicate compounds (aluminosilicates, synthetic aluminosilicates, etc.), phosphate compounds (titanium phosphate, tin phosphate, etc.), cerium oxalate (III), ammonium molybdrinate, iron hexacyanoferrate (III). Examples thereof include cobalt (II) potassium, natural green sand, stabilized green sand, and Mn2 + type green sand, which can be used alone or in combination of two or more. Among these, antimony compounds and zirconium compounds have a high ability to collect cations, so that migration resistance can be enhanced.
As the cation collecting agent, known products such as IXE-100 and IXE-300 (manufactured by Toagosei Co., Ltd.) can be used.

Further, an anion collecting agent can also be used. Examples of the anion collecting agent include bismuth compounds (bismuth-containing hydroxide, bismuth hydrated nitrate, etc.), magnesium-aluminum composite oxides (magnesium-aluminum hydrotalcite, etc.), phosphate compounds (lead hydroxide phosphate, etc.), etc. Can be used alone or in combination of two or more. Among these, magnesium-aluminum composite oxide is preferable because it has a high ability to collect anions.
As the anion collecting agent, known products such as IXE-500, IXE-530, IXE-550, IXE-700F, IXE-700D, and IXE-800 (manufactured by Toagosei) can be used.

The amphoteric collecting agent includes a cation collecting agent and an anion collecting agent. The two ion collecting agents are, for example, a cation collecting agent appropriately selected from the zirconium compound, an antimony compound, a phosphate compound and the like already described, and an anion collecting agent appropriately selected from a bismuth compound, a magnesium / aluminum compound and the like. A mixture with and is preferred.

As the amphoteric agent, known products such as IXEPLAS-A1, IXEPLAS-A2, IXEPLAS-B1, IXE-600, IXE-633, IXE-6107, and IXE-6136 (manufactured by Toagosei) can be used.

The average particle size D50 of the ion collecting agent is preferably 0.1 to 10 μm, more preferably 0.1 to 3 μm. Embedding property is improved by setting the average particle size to 0.1 or more. By setting the average particle diameter D50 to 10 μm or less, migration resistance can be further improved.
The average particle size is obtained in the same manner as the above-mentioned inorganic filler in the narrow sense.

The ion collecting agent is preferably blended in an amount of 0.1 to 20 parts by mass, more preferably 0.3 to 10 parts by mass, based on 100 parts by mass of the thermosetting resin. By blending 0.1 to 20 parts by mass, it becomes easy to obtain a substrate for mounting an electronic component group with a coating protective layer having further improved migration resistance.

The thickness of the first insulating resin layer in the protective sheet of the present invention is preferably 10 to 150 μm, more preferably 50 to 130 μm. By setting the thickness as described above, both temporary tensioning property and embedding property can be achieved.

<Second insulating resin layer>
In the electronic component protective sheet of the present invention, the second insulating resin layer is located farthest from the electronic component group, and the adhesive strength by the probe tack test is 1N or less. In addition, the Young's modulus at 23 ° C. (hereinafter abbreviated as Young's modulus (2)) is preferably 30 MPa to 1000 MPa, more preferably 50 MPa to 800 MPa, and even more preferably 70 MPa to 500 MPa. By setting the adhesive strength to 1N or less, the release property is improved. Furthermore, by setting the Young's modulus (2) to 30 MPa or more, breakage of the electronic component protective sheet (hereinafter referred to as crack resistance) at the corners of the electronic component is suppressed, and by setting it to 1000 MPa or less, the followability to the groove between the electronic components is suppressed. Is improved.
The method of obtaining Young's modulus (2) is the same as that of the above-mentioned first insulating resin layer.

The second insulating resin layer preferably has a storage elastic modulus at 23 ° C. (hereinafter abbreviated as the storage elastic modulus (2)) of 1.0 + E06Pa to 1.0 + E10Pa. When the storage elastic modulus (2) is 1.0 + E06Pa or more, the release property is improved, and when it is 1.0 + E10Pa or less, the migration resistance is improved.
The method of obtaining the storage elastic modulus (2) is the same as that of the above-mentioned first insulating resin layer.

The second insulating resin layer can be formed of a thermosetting resin composition containing a thermosetting resin, similarly to the first insulating resin layer.
Further, the thermosetting resin composition preferably contains a curing agent, an inorganic filler in a narrow sense, an ion collecting agent, a flame retardant and the like. By using these, the Young's modulus and the storage elastic modulus at 23 ° C. described above can be adjusted in a suitable range, so that the release property, the implantability, and the like can be improved.

As the thermosetting resin, the same as in the case of the above-mentioned first insulating resin layer can be exemplified, and the same applies to the acid value, weight average molecular weight and the like.

As the curing agent, the same as in the case of the first insulating resin layer described above can be exemplified, and it is preferable to use the epoxy compound and the aziridine compound in combination, and the epoxy compound is a solid epoxy compound at 23 ° C. Can increase the young rate.
The blending amount of the curing agent is preferably 3 to 100 parts by mass, more preferably 5 to 60 parts by mass, and 5 to 40 parts by mass with respect to 100 parts by mass of the total thermosetting resin. Is more preferable. By setting the blending amount as described above, Young's modulus and storage elastic modulus at 23 ° C. can be adjusted to suitable values.

Examples of the inorganic filler and the ion collecting agent in the narrow sense are the same as in the case of the above-mentioned first insulating resin layer.
From the viewpoint of improving releaseability, the blending amount of the inorganic filler in a narrow sense is preferably 5 to 70 parts by mass, and more preferably 7 to 55 parts by mass with respect to 100 parts by mass of the total thermosetting resin. , 10 to 35 parts by mass, more preferably.
From the viewpoint of improving migration resistance, the blending amount of the ion collecting agent is preferably 5 to 40 parts by mass, and more preferably 7 to 30 parts by mass with respect to 100 parts by mass of the total thermosetting resin. , 10 to 25 parts by mass is more preferable.

The second insulating resin layer may further contain a colorant, a silane coupling agent, an antioxidant, a plasticizer, an ultraviolet absorber, a leveling adjuster and the like, if necessary.

The thickness of the second insulating resin layer in the protective sheet of the present invention is preferably 1 to 75 μm, more preferably 5 to 50 μm. By setting the thickness as described above, the embedding property between electronic components can be improved.

<Middle layer>
The protective sheet of the present invention may further have an insulating resin layer containing a thermosetting resin as an intermediate layer between the first insulating resin layer and the second insulating resin layer. The Young's modulus of the intermediate layer at 23 ° C. (hereinafter, also referred to as Young's modulus (3)) preferably satisfies the following formula. By satisfying the following formula, the temporary tension and migration resistance are improved, the intermediate layer relaxes the pressure in the hot pressing process, and a coating protective film in which cracks are less likely to occur can be obtained.
Young's modulus (2)>Young's modulus (3)>Young's modulus (1) ... (Equation 1)

The breaking elongation at 23 ° C. of each of the first insulating resin layer, the second insulating resin layer, and the intermediate layer that can be provided as needed, which constitute the protective sheet of the present invention, is preferably 50 to 1500%. , 100-1400%, more preferred. By setting the above range, it is possible to improve the followability to the uneven shape in the process iv and appropriately cover and protect a plurality of electronic components having different heights.
In the present invention, the elongation rate when a sample having a length of 100 mm is stretched and broken at 200 mm is set to 100%. The method of measuring the elongation rate will be described in detail in Examples.

Further, on the electronic component protective sheet of the present invention, a hard coat layer or a fiber layer can be laminated on the outer side of the second insulating resin layer from the viewpoint of improving the protective property.

<Manufacturing method of electronic component protective sheet>
In the method of manufacturing an electronic component protective sheet, an insulating resin composition for a first insulating resin layer is applied onto a peelable sheet and dried to form a first insulating resin layer. Similarly, separately, the insulating resin composition for the insulating resin layer to be located farthest from the electronic component group is coated and dried on the peelable sheet, and the insulation to be located farthest from the electronic component group is applied. Form a sex resin layer. Next, it can be formed by superimposing both insulating resin layers.
Further, one of the insulating resin compositions is coated and dried on the peelable sheet to form one of the insulating resin layers, and the other insulating resin composition is placed on the resin layer. It may be formed by direct coating and drying.
In the case of the embodiment having the cushion material, the cushion material can be provided by peeling off the peelable sheet on the insulating resin layer side to be located farthest from the electronic component group and laminating the cushion material on the peelable sheet. .. Alternatively, the cushion material may be directly coated with the thermosetting resin composition to form an insulating resin layer to be located farthest from the electronic component group, and then a first insulating resin layer may be formed. good.

<Use of electronic component protective sheet>
The electronic component protective sheet of the present invention exhibits practically sufficient adhesion regardless of whether the substrate is metal, resin, fiber, ceramic, glass, or conductive silicon. As the metal, it can be used for aluminum, copper, brass, stainless steel, iron, chrome and the like. As the resin, it can be used for epoxy resin, polyethylene terephthalate, polyimide, polyamide, polyethylene, polypropylene, polyolefin-based graft polymer, polystyrene, polyvinyl chloride and the like. Therefore, the present electronic component protective sheet can be suitably used for adhesion between different materials having different polarities.
The electronic component protection 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.

It is preferable that the electronic component using the electronic component protection sheet of the present invention is provided in an electronic device such as a notebook PC, a mobile phone, a smartphone, a tablet terminal, etc., in addition to a liquid crystal display, a touch panel, and the like.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The following "parts" and "%" are values based on "parts by mass" and "% by mass", respectively.

The raw materials used in the examples are shown below.
<Thermosetting resin>
[Synthesis of thermosetting resin 1]
166 parts of terephthalic acid, 146 parts of adipic acid and 212 parts of 3-methyl-1,5-pentanediol and 25 parts of ethylene glycol were placed in a glass flask equipped with a stirrer, thermometer, reflux condenser, nitrogen introduction tube, and decompression equipment. The mixture was charged, stirred while passing through nitrogen gas, gradually heated under normal pressure, and reacted at 200 to 230 ° C. for about 8 hours to obtain a liquid substance having an acid value of 43. Next, 0.01 part of tetra-n-butoxytitanium was charged, and after nitrogen substitution, the mixture was stirred at 180 ° C. for 30 minutes under sealing. Then, the reaction was carried out at 230 ° C. and 5 mmHg for 2 hours to obtain a polyester diol having an acid value of 1.1, a hydroxyl value of 114.2, a molecular weight of 982 and a hue of 10 (APHA method, the same applies hereinafter).
Next, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 734 parts of the polyester diol, 23.9 parts of dimethylol propionic acid, 219 parts of toluene diisocyanate, and 242 parts of toluene were placed. It was charged and reacted at 50 ° C. for 8 hours under a nitrogen atmosphere. To this, 1200 parts of toluene was added to obtain a solution of urethane prepolymer having an isocyanate group at the terminal.
Next, while heating the obtained prepolymer solution to 70 ° C. and maintaining the temperature, 20.0 parts of 1,3-diaminopropane, 3.1 parts of benzylamine, 600 parts of 2-pronol, and 961 parts of toluene were used. Was added dropwise over 1 hour. By further reacting at 70 ° C. for 6 hours after the completion of the dropping, a polyurethane resin (A-1) having a molecular weight (Mw) of 130000, an acid value of 10 mgKOH / g, a Tg of 20 ° C. and a solid content of 25% was obtained. Obtained.

[Synthesis of thermosetting resin 2]
A diol esterified with adipic acid, terephthalic acid and 3-methyl-1,5-pentanediol in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen introduction tube (number average molecular weight). (Hereinafter referred to as "Mn") = 1006) 414 parts, 8 parts of dimethylolbutanoic acid, 145 parts of isophorone diisocyanate, and 40 parts of toluene were charged and reacted at 90 ° C. for 3 hours under a nitrogen atmosphere. Then, 300 parts of toluene was added to obtain a solution of urethane prepolymer having an isocyanate group at the terminal.
Next, 816 parts of the obtained urethane prepolymer solution was added to a solution in which 27 parts of isophorone diamine, 3 parts of di-n-butylamine, 342 parts of 2-propanol, and 576 parts of toluene were separately mixed, and at 70 ° C. After reacting for 3 hours, cooling was performed. Further, 144 parts of toluene and 72 parts of 2-propanol were added and mixed to obtain a polyurethane resin (A-2) solution having a non-volatile content of 30%. The resin (A-2) had Mw = 54,000 and an acid value of 5 mgKOH / g.

<Curing agent>
Curing agent 1: Bisphenol A type epoxy compound "jER828" (epoxy equivalent = 189g / eq) Curing agent 2: Tetraphenol ethane type epoxy resin "jER1031s" (4 functional, epoxy equivalent = 200g / eq) Mitsubishi Chemical Co., Ltd. Hardener 3: Vinyl ether-modified bisphenol A type epoxy resin "EXA4850-150" (epoxy equivalent 450, molecular weight 900) DIC hardener 4: Aziridine compound, "Chemitite PZ-33" Japanese catalyst hardener 5: Hexamethylene diisocyanate-bullet body, "Duranate 24A-100" (solid content 100%, NCO 23.5% by mass) Hardener manufactured by Asahi Kasei Co., Ltd. 6: Polyvalent carbodiimide "Carbodilite V-03" manufactured by Nisshinbo Chemical Co., Ltd.

<Inorganic filler>
Inorganic filler 1: Microace P-2 (talc, average particle diameter D50 is 5.0 μm (manufactured by Japan Talc)
Inorganic filler 2: IXE PLUS-A1 (both ion collecting agent of a mixture of zirconia-based inorganic cation collecting agent and hydrotalcite-based inorganic anion collecting agent, average particle diameter D50 is 0.5 μm (manufactured by Toagosei Co., Ltd.) )))
Inorganic filler 3: IXE300 (antimony-based inorganic cation collector, average particle diameter D50 is 0.5 μm (manufactured by Toagosei Co., Ltd.))
Inorganic filler 4: SS50 (silica, average particle size D50 is 4.5 μm (Tosoh Silica Co., Ltd.))

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

[Creation of insulating resin layer 1]
100 parts of the thermosetting resin 1 (solid content), 20 parts of the curing agent 3, 0.5 part of the thermosetting agent 4 and 11.4 parts of the inorganic filler 1 are charged in a container, and the non-volatile content is charged. A thermosetting resin composition was obtained by adding a mixed solvent of toluene: isopropyl alcohol (mass ratio 2: 1) so as to have a concentration of 45% by mass and stirring with a disper for 10 minutes. This thermosetting resin composition was applied to a releasable substrate using a doctor blade so that the dry thickness was 40 μm. Then, it was dried at 100 ° C. for 2 minutes to obtain a laminated sheet in which the releasable base material and the resin layer 1 were laminated.

[Preparation of Insulating Resin Layers 2-22, 101-102]
Laminated sheets in which the insulating resin layers 2 to 22 and 101 to 102 were laminated on the peelable substrate were obtained by the same actions as those of the insulating resin layer-1 except that the blending amount in Table 1 was changed.

The following physical property values were measured for the obtained insulating resin layer. The results are shown in Table 1.

<Measurement of adhesive strength by probe tack test>
A stainless steel probe (200 g including a weight) having a diameter of 5 mmφ is brought into contact with the surface of the insulating resin layer of the laminated sheet in which the releasable base material and the insulating resin layer are laminated for 1 second, and then the probe is placed. The detected force was measured as the adhesive layer was separated from the surface at a rate of 10 mm / sec. The measurement was carried out 5 times, and the average value was calculated.

<Measurement of Young's modulus at 23 ° C>
A laminated sheet in which a releasable substrate and an insulating resin layer were laminated was allowed to stand at 23 ° C. and a relative humidity of 50% for 24 hours. After that, the insulating resin layer from which the releasable substrate was peeled off was placed in a constant temperature and humidity chamber at 23 ° C. and a relative humidity of 50% under the conditions of a tensile speed of 50 mm / min and a marked line spacing of 25 mm, and a tensile tester "EZ Tester" (Shimadzu Corporation). The stress-strain curve was measured by (manufactured by Shimadzu Corporation), and the linear regression (slope) in the region where the strain (elongation) was 0.1 to 0.3% was defined as the Young's modulus at 23 ° C.

<Storage modulus at 23 ° C>
A laminated sheet in which a releasable substrate and an insulating resin layer were laminated was allowed to stand at 23 ° C. and a relative humidity of 50% for 24 hours. After that, the insulating resin layer from which the releasable substrate was peeled off was deformed with respect to the insulating resin layer using a dynamic elastic modulus measuring device DVA-200 (manufactured by IT Measurement Control Co., Ltd.), and the frequency was 10 Hz. The temperature rise rate was 10 ° C./min, and the measurement was performed under the conditions of a measurement temperature range of −50 ° C. to 300 ° C. to determine the storage elastic modulus at 23 ° C. In addition, the storage elastic modulus at 120 ° C. and 170 ° C. was also measured.

<Measurement of elongation rate>
A laminated sheet in which a releasable base material and an insulating resin layer were laminated was cut into a size of 200 mm in width × 600 mm in length, and then the insulating resin layer was peeled off from the releasable base material to prepare a measurement sample. About the measurement sample Using a small tabletop tester EZ-TEST (manufactured by Shimadzu Corporation), a tensile test (test speed 50 mm / min) was conducted with an effective tensile size of 200 x 230 mm under the conditions of a temperature of 25 ° C and a relative humidity of 50%. Then, the elongation rate at the time of breakage was obtained.

[Example 1]
By laminating the insulating resin layer 8 and the insulating resin layer 1 with a thermal roll laminator, a releasable base material / a second insulating resin layer (resin layer 8) / a first insulating resin layer (resin layer). 1) / An electronic component protective sheet with a peelable base material, which was laminated in the order of a releasable base material, was obtained. The conditions for bonding were 70 ° C. and 3 kgf / cm ² .
Hereinafter, the "second insulating resin layer" is abbreviated as "outer insulating resin layer", and the "releaseable base material" covering the "outer insulating resin layer" is referred to as "outer releasable base material". May be abbreviated.

[Examples 2 to 22, Comparative Examples 1 to 2]
According to the same behavior as in Example 1 except that the combination of the insulating resin layers was changed as shown in Table 2, the electronic component protective sheets with the peelable substrate of Examples 2 to 22 and Comparative Examples 1 and 2 were used, respectively. Obtained.

[Example 23]
By laminating the insulating resin layer 1 and the insulating resin layer 14 with a thermal roll laminator, a releasable base material / an intermediate insulating resin layer (resin layer 14) / a first insulating resin layer (resin layer 1). ) / Releasable substrate was laminated in this order.
Next, the releasable base material on the insulating resin layer 14 side is peeled off, and the insulating resin layer 12 is attached to the exposed surface by a thermal roll laminator, whereby the outer releasable base material / insulating resin layer 12 / An electronic component protection sheet with a peelable base material was obtained by laminating the insulating resin layer 14 / insulating resin layer 1 / releasable base material in this order. The conditions for bonding were 70 ° C. and 3 kgf / cm ² .

[Example 24]
An electronic component protective sheet with a peelable base material of Example 24 was obtained by the same operation as in Example 23 except that the combination of the insulating resin layers in Table 3 was changed.

[Examples 25 to 30]
The electronic component protective sheets with the peelable substrate of Examples 25 to 30 were obtained by the same actions as in Example 1 except that the combination of the insulating resin layers was changed as shown in Table 4.

The electronic component protection sheets obtained in each Example and Comparative Example were evaluated for temporary tension, release, migration resistance, and embedding. The results are shown in Tables 2 and 3.

<Temporary tension>
The electronic component protection sheet with a peelable substrate is cut to a width of 25 mm and a length of 100 mm, and the releasable substrate on the first insulating resin layer side is peeled off to expose the exposed first insulating resin layer to a width of 30 mm. -It was roll-laminated and attached to a polyimide film having a length of 150 mm and a thickness of 125 μm at 23 ° C. and 3 kgf / cm ^2.
Next, the outer releasable base material was peeled off, and the exposed outer insulating resin layer surface was mediated by a double-sided acrylic adhesive tape "DF715" manufactured by Toyochem Co., Ltd. (thickness of the acrylic adhesive layer on each surface: 35 μm). A sample to which a 25 μm PET film was attached was used as a measurement sample.
A T-peel peeling test was performed at a tensile speed of 50 mm / min using a tensile tester, and the adhesive strength between the first insulating resin layer and the polyimide film was measured.
⊚: Adhesive strength is 0.5N or more. Very good result.
〇: Adhesive strength is 0.25 or more and less than 0.5. Good result.
Δ: Adhesive strength is 0.1 or more and less than 0.25. There is no problem in practical use.
X: Adhesive strength is less than 0.1. Not practical.

<Release>
The electronic component protection sheet with a peelable substrate is cut to a width of 25 mm and a length of 100 mm, the outer releasable substrate is peeled off, and the exposed outer insulating resin layer surface is 30 mm wide and 150 mm long. It was roll-laminated and attached to a 125 μm polyimide film under the conditions of 23 ° C. and 3 kgf / cm ^2.
Next, the releasable base material on the first insulating resin layer side was peeled off, and the double-sided acrylic adhesive tape "DF715" manufactured by Toyochem Co., Ltd. (acrylic adhesive on each surface) was applied to the exposed first insulating resin layer surface. A 25 μm PET film attached via a layer thickness (35 μm) was used as a measurement sample.
A T-peel peeling test was performed at a tensile speed of 50 mm / min using a tensile tester, and the adhesive strength between the outer insulating resin layer and the polyimide film was measured.
⊚: Adhesive strength is 0.1 or less. Very good result.
〇: Adhesive strength exceeds 0.1 and is 0.25 or less. Good result.
Δ: Adhesive strength exceeds 0.25 and is 0.5 or less. There is no problem in practical use.
X: Adhesive strength exceeds 0.5N. Not practical.

<Migration resistance test>
The migration test will be described with reference to FIG. By etching a laminate of a copper foil having a thickness of 18 μm and a polyimide film having a thickness of 25 μm, as shown in the plan view of FIG. 4 (1), a line / space = 0.1 mm / 0. A 1 mm comb-shaped conductor patterns 200 and 300 and electrodes 200'and 300' continuous with both comb-shaped conductor patterns were formed.
The peelable base material on the first insulating resin layer side is peeled off from the electronic component protective sheet with the peelable base material, and both comb-shaped conductor patterns 200 and 300 are covered as shown in the plan view of FIG. 4 (2). The exposed first insulating resin layer is laminated on a size such that both electrodes 200'and 300'are exposed, and the temperature is 150 ° C., 2.0 MPa, 3 min. After hot pressing under the conditions of (1) to peel off the outer peelable substrate, the mixture was further heated in an electric oven at 160 ° C. at normal pressure for 60 min. Heat treatment is performed to cure the first insulating resin layer and the outer insulating resin layer, and as shown in FIGS. 4 (3) and 4 (4), both comb-shaped conductors are formed by the cured product 10'of the electronic component protective sheet. The pattern was coated and used as an evaluation sample.
A voltage of 50 V was applied between the comb-shaped conductors of the evaluation sample in an atmosphere of 85 ° C. and 85% RH (relative humidity), and the change in resistance value was continuously measured for 1000 hours. The following "leak touch" means that there is dielectric breakdown due to a short circuit, the resistance drops momentarily, and a current flows. If there is no leak touch, the insulation does not decrease. The evaluation criteria are as follows.
◎: resistance value after 1000 hours is 10 ⁸ Ω or more, no leak touch. Good result.
○: resistance after 1000 hours 10 ⁷ Omega above, no leakage touch. Good result.
△: resistance value after 1000 hours is 10 ⁷ Ω or more, there is a single leak touch. There is no problem in practical use.
×: There resistance after 1000 hours is less than 10 ^7, more leakage touch twice. Not practical.

<Embedability>
[Preparation of test board]
A test substrate was prepared in which two types of electronic components 2a and 2b were alternately mounted in a grid pattern at intervals of 0.5 mm on a substrate made of glass epoxy. The thickness of the substrate is 0.3 mm, the height of the electronic component 2a is 2 mm, the height of the electronic component 2b is 1 mm, and the size of the electronic components 2a and 2b in a plan view is 2 cm × 2 cm. A schematic cross-sectional view of the test substrate is shown in FIG.

The electronic component protective sheet with the peelable substrate is cut into a size of 10 cm × 10 cm, the releasable substrate on the first insulating resin layer side is peeled off, and the first insulating resin layer comes into contact with the electronic component 2a. It was placed on the test board as described above. After that, two types of films (TPX with a thickness of 0.05 mm (product name: Opulan X-44B) manufacturer: Mitsui Chemicals) were used as cushioning materials on the surface exposed by peeling off the peelable base material on the second insulating resin layer side. Tohcello Co., Ltd.), 2.0 mm PVC film (product name: Celebrity T maker: Okamoto)) were laminated in this order, and cardboard was further laminated to prevent sticking. From above, the substrate surface was heat-pressed at 5 MPa and 160 ° C. for 20 minutes. After hot pressing, it was cooled and the cushion material and cardboard were peeled off to prepare a sample for measurement.
The embedding property was evaluated by polishing the thickness direction of the sample for measurement, forming a cross section for observation, and observing 10 grooves between electronic components with an electron microscope. The evaluation criteria are as follows.
⊚: All grooves are embedded. Very good result.
〇: Nine grooves are embedded. Good result.
Δ: Eight grooves are embedded. There is no problem in practical use.
×: Not all grooves are embedded. Not practical.

In the results shown in Tables 2 to 4, the electronic component protective sheet of the present invention was excellent in all of temporary tensioning property, release property, migration resistance, and embedding property.
As a result, it was confirmed that the electronic component protection sheet can be applied to a small substrate having complicated shape irregularities.

1 Board 2 Electronic components 3 Solder 4 Electronic component mounting board 10 Electronic component protective sheet 10'Cured product of electronic component protective sheet 11 First insulating resin layer 12 Second insulating resin layer 13 Cushion material 14 Conventional electronic components Protective sheet 15 Covering protective layer 20 Heat crimping device 100 Polyimide film 200, 300 Comb-shaped conductor pattern 200', 300' Electrodes

Claims (10)

An electronic component protection sheet for covering and protecting a group of electronic components composed of a plurality of electronic components having different heights mounted on a substrate.
The electronic component protective sheet has an insulating resin layer containing a thermosetting resin, and has an insulating resin layer.
The adhesive strength of the surface in contact with the electronic component group by the probe tack test is 0.3 to 5N.
Adhesive strength by probe tack test on the opposite side is 1N or less,
An electronic component protection sheet characterized in that the adhesive force of the surface in contact with the electronic component group in the probe tack test is larger than that of the probe tack on the opposite surface. The electronic component protection sheet
The first insulating resin layer in contact with the electronic component group,
It has a second insulating resin layer located farthest from the electronic component group, and has.
The Young's modulus of the first insulating resin layer at 23 ° C. is 5 MPa to 200 MPa.
The Young's modulus of the second insulating resin layer at 23 ° C. is 30 MPa to 1000 MPa.
An electronic component protective sheet characterized in that the Young's modulus of the second insulating resin layer at 23 ° C. is higher than the Young's modulus of the first insulating resin layer at 23 ° C. by 8 MPa or more. The first insulating resin layer has a storage elastic modulus of 1.0 + E04Pa to 5.0 + E08Pa at 23 ° C.
The second insulating resin layer has a storage elastic modulus of 1.0 + E06Pa to 5.0 + E09Pa at 23 ° C.
The electronic component protective sheet according to claim 1, wherein the second insulating resin layer has a higher storage elastic modulus at 23 ° C. than the first insulating resin layer. The electronic component protection sheet according to claim 1 or 2, wherein the first insulating resin layer and the second insulating resin layer each contain an inorganic filler. The electronic component protection sheet according to claim 4, wherein the inorganic filler is at least one selected from the group consisting of silica, talc, and an ion collecting agent. The electronic component protection sheet according to claim 5, wherein the first insulating resin layer contains 5 to 20% by mass of silica, and the second insulating resin layer contains 5 to 40% by mass of silica. The first insulating resin layer and the second insulating resin layer each contain silica or talc, and at least one of the first insulating resin layer and the second insulating resin layer captures ions. The electronic component protection sheet according to claim 5, which comprises a collecting agent. An electronic component mounting substrate in which an electronic component group composed of a plurality of electronic components having different heights mounted on a substrate is covered with a cured product of the electronic component protective sheet according to any one of claims 1 to 7. The process of mounting an electronic component group consisting of multiple electronic components with different heights on a board,
The process of preparing the electronic component protection sheet according to claims 1 to 7.
A process of placing an electronic component protective sheet so that the tallest electronic component in the electronic component group and the first insulating resin layer in the electronic component protective sheet are in contact with each other.
A process of deforming an electronic component protective sheet to follow the shape of each electronic component by heating and pressurizing, and covering at least a part of the electronic component group and the substrate.
And, including the step of thermally curing the deformed electronic component protective sheet in a deformed state to form a covering protective layer.
How to protect the coating of the electronic component group mounting board. The process of mounting an electronic component group consisting of multiple electronic components with different heights on a board,
The process of preparing the electronic component protection sheet according to claims 1 to 7.
A process of placing an electronic component protective sheet so that the tallest electronic component in the electronic component group and the first insulating resin layer in the electronic component protective sheet are in contact with each other.
A step of deforming the electronic component protective sheet so as to follow the shape of each electronic component by heating and pressurizing, and covering at least a part of the electronic component group and the substrate.
And, including the step of thermally curing the deformed electronic component protective sheet in a deformed state to form a covering protective layer.
A method for manufacturing a board for mounting an electronic component group with a protective layer.

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