Sealing sheets and electronic component devices

Abstract

To provide a sealing sheet and an electronic element device which can reduce unreacted materials in a sealing body sheet that is a cured product while suppressing a percentage of variation of adhesive force.SOLUTION: A sealing sheet contains an epoxy resin, a phenol resin, an urea-based curing accelerator, and an inorganic filler. A percentage (([A0-A1] / A0×100) of variation (A0-A1) to adhesive force A1 of the sealing sheet after the elapse of 24 hours at 23°C and 50% RH from adhesive force A0 of the sealing sheet immediately after production in the adhesive force A0 is 10% or less. A ratio of a calorific value determined by differential scan calorimetry of the sealing sheet after heating at 150°C for 20 minutes to a calorific value determined by differential scan calorimetry of the sealing sheet immediately after production is 0.10 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sealing sheet and an electronic device.

Background Art

[0002] It is known to manufacture an electronic device by sealing an electronic element using a sealing sheet (see, for example, Patent Document 1 below).

[0003] The sealing sheet described in Patent Document 1 contains an epoxy resin, a phenolic resin (hardening agent), and an imidazole-based curing accelerator. After embedding the electronic element, the sealing sheet is thermally cured to form a sealed body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The sealing sheet may be attached to one surface of an electronic element and then wait for a long time (for example, about 24 hours) in that attached state. However, the sealing sheet described in Patent Document 1 has a problem that the adhesive force significantly decreases during a long waiting time. Then, there is a problem that the positional accuracy of the sealing sheet with respect to the electronic element decreases. Therefore, it is required that the sealing sheet suppress the percentage of variation in the adhesive force.

[0006] Furthermore, it is also required that the sealed body sheet, which is a cured product of the sealing sheet, has few unreacted substances.

[0007] The present invention provides a sealing sheet and an electronic device that can suppress the percentage of variation in the adhesive force and reduce unreacted substances in the sealed body sheet, which is a cured product. [Means for solving the problem]

[0008] The present invention (1) includes a sealing sheet containing an epoxy resin, a phenolic resin, a urea-based curing accelerator, and an inorganic filler, wherein the percentage of the change (A0-A1) from the adhesive strength A0 of the sealing sheet immediately after manufacture to the adhesive strength A1 of the sealing sheet after 24 hours at 23°C and 50% RH ([A0-A1] / A0×100) is 10% or less, and the ratio of the heat generated by differential scanning calorimetry of the sealing sheet after heating at 150°C for 20 minutes to the heat generated by differential scanning calorimetry of the sealing sheet immediately after manufacture is 0.10 or less.

[0009] In this sealing sheet, the percentage change in adhesive strength from A0 to A1 after 24 hours at 23°C and 50% RH (A0-A1) ([A0-A1] / A0×100) is 10% or less. Therefore, even when the sealing sheet is exposed to low temperatures for extended periods, the percentage change in adhesive strength can be suppressed.

[0010] Furthermore, the ratio of the amount of heat generated by differential scanning calorimetry of the sealing sheet after heating it at 150°C for 20 minutes to the amount of heat generated by differential scanning calorimetry of the sealing sheet immediately after manufacturing is 0.10 or less, indicating that the amount of unreacted material in the sealing sheet is small.

[0011] The present invention (2) includes the sealing sheet described in (1), wherein the urea-based curing accelerator is an aliphatic urea compound.

[0012] Aliphatic urea compounds exhibit low reactivity in low-temperature ranges, resulting in a high degree of reduction in the percentage variation of penetration length in gaps between mounting substrates and electronic elements.

[0013] The present invention (3) includes a sealing sheet according to (1) or (2), wherein the percentage of variation (L1-L2) from the first penetration length L1 to the second penetration length L2 determined by test Y, at the first penetration length L1 determined by test X, is 90% or less ([L1-L2] / L1×100).

[0014] <Test X> Follow the steps below from 1 to 5 in order.

[0015] Step 1: Prepare a sample with a thickness of 200 μm from the sealing sheet immediately after manufacturing. Separately, prepare a mounting substrate comprising a glass substrate and nine dummy chips, each measuring 1 mm × 1 mm × 200 μm thick and arranged in a line with a spacing of 300 μm between them, which are mounted on the upper surface of the glass substrate via bumps.

[0016] Step 2: Using a vacuum plate press, the sample is pressed toward the glass substrate at a temperature of 65°C, a vacuum of 1.6 kPa or less, a pressing pressure of 0.2 MPa, and for 60 seconds.

[0017] Step 3: The sample is brought into contact with the upper surface of the dummy chip and left for 30 minutes at 23°C and 50% RH.

[0018] Step 4: The sample is heat-cured by heating it at 150°C for 1 hour under atmospheric pressure.

[0019] Step 5: Measure the length L1 of the sample entering the gap between the lower surface of the dummy chip located in the center and the upper surface of the glass substrate.

[0020] <Test Y> Steps 1 through 5 described above are carried out. However, the standing time in step 3 is changed from 30 minutes to 24 hours. In step 5, the second insertion length L2 of the sample is measured.

[0021] In this sealing sheet, since the percentage of the variation from the first penetration length L1 to the second penetration length L2 is 90% or less, the variation in the penetration length of the sealing body sheet can be suppressed when a long time has passed in the low temperature region. Therefore, the sealing stability is excellent.

[0022] The present invention (4) includes an electronic device including a sealing body sheet formed from the sealing sheet according to any one of (1) to (3), and an electronic element sealed by the sealing body sheet.

[0023] Since this electronic device includes a sealing body sheet formed from the above-described sealing sheet, it has excellent sealing reliability and a small amount of unreacted substances.

Effect of the Invention

[0024] The sealing sheet and the electronic device of the present invention can suppress the percentage of the variation in the adhesive force and reduce the unreacted substances in the sealing body sheet which is a cured product.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1A is each first step of Test X and Test Y. FIG. 1B is each second step to fifth step of Test X and Test Y. [Figure 2] It is a cross-sectional view of an electronic device.

Mode for Carrying Out the Invention

[0026] 1. Sealing Sheet An embodiment of the sealing sheet of the present invention will be described.

[0027] The sealing sheet is used for sealing an electronic element. The sealing sheet has a thickness. The sealing sheet extends in a plane direction. The plane direction is orthogonal to the thickness direction. The sealing sheet has a substantially plate shape (film shape).

[0028] 1.1 Components of the Sealing Sheet The sealing sheet contains an epoxy resin, a phenolic resin, a urea-based curing accelerator, and an inorganic filler. Specifically, the sealing sheet is formed in sheet form from a thermosetting composition containing the above-mentioned components. The thermosetting composition also contains a resin component and a filler component. The blending ratio of the resin component in the thermosetting composition is, for example, 1% by mass or more, preferably 5% by mass or more, and also, for example, 25% by mass or more, preferably 15% by mass or less. The blending ratio of the filler component in the thermosetting composition is, for example, 75% by mass or more, preferably 85% by mass or more, and also, for example, 99% by mass or more, preferably 90% by mass or less. The blending ratio of the filler component to 100 parts by mass of the resin component is, for example, 300 parts by mass or more, preferably 700 parts by mass or more, and also, for example, 3000 parts by mass or less, preferably 1500 parts by mass or less.

[0029] The resin component contains the epoxy resin, phenolic resin, and urea-based curing accelerator mentioned above. The filler component contains an inorganic filler.

[0030] 1.1.1 Epoxy resin Epoxy resin is the main component in thermosetting compositions. The type of epoxy resin is not limited. Examples of epoxy resins include difunctional epoxy resins and polyfunctional epoxy resins with three or more functions. Examples of difunctional epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, modified bisphenol A type epoxy resin, modified bisphenol F type epoxy resin, and biphenyl type epoxy resin. Examples of polyfunctional epoxy resins include phenol novolac type epoxy resin, cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenyloleethane type epoxy resin, and dicyclopentadiene type epoxy resin. Epoxy resins can be used alone or in combination of two or more types. Preferably, the epoxy resin is a difunctional epoxy resin, and more preferably, bisphenol F type epoxy resin and modified bisphenol A type epoxy resin. Bisphenol F type epoxy resin is preferred from the viewpoint of suppressing the percentage variation in adhesive strength (described later) and reducing the percentage variation in penetration length (described later). On the other hand, modified bisphenol A type epoxy resin is preferred from the viewpoint of reducing the ratio related to the amount of heat generated (described later).

[0031] The proportion of epoxy resin in the sealing sheet is not limited. The proportion of epoxy resin in the sealing sheet is, for example, 1% by mass or more, preferably 2% by mass or more, and also, for example, 25% by mass or less, preferably 10% by mass or less. The proportion of epoxy resin in the resin component is, for example, 5% by mass or more, preferably 15% by mass or more, and also, for example, 50% by mass or less, preferably 25% by mass or less.

[0032] 1.1.2 Phenolic resin The phenolic resin is a latent phenolic resin that cures the epoxy resin. The type of phenolic resin is not limited. Examples of phenolic resins include novolac-type phenolic resins and phenol-aralkyl resins. The phenolic resin can be used alone or in combination of two or more types. From the viewpoint of reducing the percentage of variation in adhesive strength (described later), phenol-aralkyl resin is preferred as the phenolic resin. Also, from the viewpoint of reducing the ratio related to DSC (described later), novolac-type phenolic resin is preferred as the phenolic resin.

[0033] The blending ratio of phenolic resin to 100 parts by mass of epoxy resin is, for example, 10 parts by mass or more and 150 parts by mass or less. The blending ratio of phenolic resin in the sealing sheet is, for example, 0.5% by mass or more, preferably 2% by mass or more, and also, for example, 5% by mass or less, preferably 2.5% by mass or less. The blending ratio of phenolic resin in the resin component is, for example, 3% by mass or more, preferably 10% by mass or more, and also, for example, 40% by mass or less, preferably 15% by mass or less.

[0034] 1.1.3 Urea-based curing accelerators Urea-based curing accelerators do not promote the curing reaction in sealing adhesive sheets in the low-temperature range, but promote the curing reaction in the high-temperature range. Specifically, in the low-temperature range, thermal dissociation of the urea-based curing accelerator is less likely to proceed (the isocyanate portion blocks the dissociation of the amino portion), while in the high-temperature range, thermal dissociation occurs to produce isocyanate compounds and amine compounds, and the amine compound promotes the curing reaction. The low-temperature range is, for example, 100°C or less, and even 90°C or less, and the lower limit of the low temperature is not limited. The high-temperature range is, for example, above 100°C, and even 110°C or more, 120°C or more, 130°C or more, and 140°C or more, and the high-temperature range is, for example, 210°C or less, and even 200°C or less, 190°C or less, and 180°C or less.

[0035] Examples of urea-based curing accelerators include urea compounds containing a dialkylamino group. Examples of dialkylamino groups include dimethylamino. Since urea-based curing accelerators contain the above-mentioned dimethylamino, dimethylamine can be produced by thermal dissociation.

[0036] Examples of urea-based curing accelerators include aromatic urea compounds and aliphatic urea compounds. These can be used alone or in combination.

[0037] Aromatic urea compounds, for example, contain the dialkylamino group and aromatic group described above. Examples of aromatic urea compounds include dimethylamino group-containing aromatic urea compounds represented by the following formula (1).

[0038] [ka]

[0039] Examples of aliphatic urea compounds include those containing the dialkylamino group and aliphatic group described above. Examples of aliphatic urea compounds include dimethylamino group-containing aliphatic urea compounds represented by the following formula (2).

[0040] [ka]

[0041] Preferably, aliphatic urea compounds are used as urea-based curing accelerators. Aliphatic urea compounds have lower reactivity in the low-temperature range compared to aromatic urea compounds, thus providing a greater reduction in the percentage variation in penetration length (described later). On the other hand, aliphatic urea compounds can achieve a curing acceleration effect equivalent to that of aromatic urea compounds in the high-temperature range.

[0042] The blending ratio of the urea-based curing accelerator per 100 parts by mass of epoxy resin is, for example, 0.1 parts by mass or more, preferably 1 part by mass or more, more preferably 2 parts by mass or more, and also, for example, 10 parts by mass or less, preferably 5 parts by mass or less, preferably 3 parts by mass or less. The blending ratio of the urea-based curing accelerator in the sealing sheet is, for example, 0.01% by mass or more, preferably 0.02% by mass or more, and also, for example, 1% by mass or less, preferably 0.2% by mass or less. The blending ratio of the urea-based curing accelerator in the resin component is, for example, 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and also, for example, 1.5% by mass or less, preferably 1.0% by mass or less, preferably 0.7% by mass or less. If the blending ratio of the urea-based curing accelerator is above the lower limit and below the upper limit as described above, a high curing acceleration effect can be achieved while reducing the percentage variation in penetration length.

[0043] 1.1.4 Inorganic fillers Examples of inorganic fillers include silicate compounds and silicon compounds. Silicate compounds and silicon compounds are described in Japanese Patent Publication No. 2021-097206, respectively.

[0044] The inorganic filler includes a layered silicate compound. The layered silicate compound is a curing flow reducer that reduces the fluidity of the cured sheet when the sealing sheet is heated to form a cured sheet. Examples of layered silicate compounds include montmorillonite. The surface of the layered silicate compound may be modified with an organic component. Examples of organic components include alkylammonium. Examples of alkylammonium include dimethyldistearylammonium. The above-mentioned layered silicate compound is described, for example, in Japanese Patent Publication No. 2021-097206.

[0045] The blending ratio of inorganic filler in the sealing sheet (thermosetting resin composition) is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 65% ​​by mass or more, and also 80% by mass or less, preferably 70% by mass or less. The blending ratio of inorganic filler to 100 parts by mass of resin component is, for example, 200 parts by mass or more, preferably 200 parts by mass or more, and also, for example, 1500 parts by mass or less, preferably 500 parts by mass or less. Details of the blending ratio of the inorganic filler are described, for example, in Japanese Patent Publication No. 2021-097206.

[0046] In this embodiment, the resin component preferably does not contain any curing accelerators other than the urea-based curing accelerator described above. Examples of curing accelerators other than urea-based curing accelerators include imidazole-based curing accelerators and phosphorus-based curing accelerators. In particular, the resin component more preferably does not contain imidazole-based curing accelerators. Imidazole-based curing accelerators are unsuitable for this invention because their amino groups easily accelerate the curing reaction in the low-temperature range. On the other hand, phosphorus-based curing accelerators have low curing acceleration properties, so the curing reaction takes time, and the manufacturing efficiency of the electronic device (see Figure 2) described later decreases, but trace amounts of phosphorus-based curing accelerators in the resin component are acceptable.

[0047] 1.1.5 Additives For example, additives may be added to the thermosetting resin composition. Examples of additives include thermoplastic resins and silane coupling agents as resin components, and pigments as filler components. The types and proportions of other additives are not limited. The types and proportions of other additives are described in Japanese Patent Application Publication No. 2021-097206.

[0048] 1.1.6 Manufacturing of sealing sheets To obtain a sealing sheet, a thermosetting resin composition is prepared by blending the above-mentioned components in the above-mentioned proportions. Preferably, the above-mentioned components are thoroughly stirred. If necessary, a solvent (such as a ketone such as methyl ethyl ketone) is further added to prepare a varnish. The varnish is then applied to a release liner (not shown), and then dried by heating to produce a sealing sheet having a sheet shape as a coating film. Alternatively, a sealing sheet (coating film) can be formed from the thermosetting resin composition by kneading and extruding without preparing a varnish.

[0049] Furthermore, to manufacture a thick sealing sheet, multiple of the above-mentioned coating films can be laminated (bonded together).

[0050] The sealing sheet is in the B stage (semi-cured state), specifically, it is the sealing sheet before the C stage. In other words, it is the sealing sheet before complete curing. The sealing sheet is formed from the A stage thermosetting resin composition into a B stage sheet by heating during the drying process and heating during the extrusion kneading process as described above.

[0051] The lower limit of the thickness of the sealing sheet is, for example, 10 μm, preferably 25 μm, and more preferably 50 μm. The upper limit of the thickness of the sealing sheet is, for example, 3000 μm, preferably 1000 μm, more preferably 500 μm, and even more preferably 300 μm.

[0052] 1.2 Percentage of variation in adhesive strength The percentage change (A0-A1) from the adhesive strength A0 of the sealing sheet immediately after manufacturing to the adhesive strength A1 of the sealing sheet after 24 hours at 23°C and 50% RH ([A0-A1] / A0×100) is 10% or less.

[0053] If the percentage change in adhesive strength from A0 to A1 exceeds 10%, the adhesive strength of the sealing sheet will decrease significantly when exposed to low temperatures for an extended period.

[0054] On the other hand, with this sealing sheet, the percentage of the above-mentioned fluctuation is 10% or less, so even when the sealing sheet is exposed to low temperatures for a long period of time, the percentage of the fluctuation in adhesive strength can be suppressed as much as possible.

[0055] On the other hand, the percentage of the change from adhesive strength A0 to adhesive strength A1 of the sealing sheet after 24 hours at 23°C and 50% RH immediately after manufacturing (A0-A1) ([A0-A1] / A0×100) is preferably 9% or less, more preferably 7% or less, even more preferably 5% or less, and particularly preferably 3% or less. The percentage of the change in adhesive strength described above is, for example, 0.001% or more, even more preferably 0.01% or more, or 0.1% or more.

[0056] "Immediately after manufacture" means, for example, within 10 minutes, or even within 5 minutes, or even within 3 minutes, after manufacture.

[0057] "Long duration" means, for example, more than one hour and less than or equal to 50 hours.

[0058] To determine the adhesive strengths A0 and A1, prepare two plates facing each other, one above the other. Secure the sealing sheet to the lower plate, then press the upper plate against the sealing sheet. Next, raise the upper plate at 5 μm / second, and determine the load required to peel the upper plate away from the sealing sheet as the "adhesive strength of the sealing sheet immediately after manufacturing."

[0059] 1.3 Ratio of heat generation due to DSC The ratio of the amount of heat generated by differential scanning calorimetry (DSC) of the sealing sheet immediately after manufacture to the amount of heat generated by differential scanning calorimetry of the sealing sheet after heating it at 150°C for 20 minutes is 0.10 or less, preferably 0.09 or less, more preferably 0.07 or less, even more preferably 0.05 or less, and most preferably 0.03 or less.

[0060] The amount of heat generated by the sealing sheet is based on the reaction of unreacted substances in the sealing sheet. Furthermore, the heating to 150°C is intended to heat-cur the sealing sheet after sealing the electronic elements. Therefore, since it is preferable that the amount of unreacted substances in the heat-cured sealing sheet (described later) is small, it is preferable that the ratio of the amount of heat generated by the sealing sheet after heating at 150°C for 20 minutes to the amount of heat generated by the sealing sheet immediately after manufacturing is low.

[0061] In this embodiment, since the ratio of the amount of heat generated is 0.10 or less, the amount of unreacted material in the sealing sheet is small. Furthermore, if the ratio is below the preferred upper limit described above, the amount of unreacted material in the sealing sheet will be even smaller, which is preferable.

[0062] The heat generation of the sealing sheet is determined by obtaining a DSC curve of the sealing sheet. The heat generation (mJ / mg) is calculated from the integral of the peak area. Differential scanning calorimetry (DSC) will be described in a later example.

[0063] 1.4 Percentage of variation in entry length The percentage ([L1-L2] / L1×100) of the variation (L1-L2) from the first entry length L1 determined by test X to the second entry length L2 determined by test Y is, for example, 90% or less, preferably 70% or less, more preferably 65% ​​or less, even more preferably 59% or less, and also, for example, 10% or more, even more preferably 25% or more, or 45% or more.

[0064] The percentage of variation from the first penetration length L1 to the second penetration length L2 represents the degree of effectiveness in reducing variation in penetration length when a long period of time has elapsed in a low-temperature region. Therefore, a low percentage is preferable, which results in excellent sealing stability.

[0065] <Test X> In Test X, the following steps 1 through 5 will be performed in order. This will measure the entry length L1.

[0066] Step 1: As shown in Figure 1A, a sample 11 with a thickness of 200 μm is prepared from the sealing sheet 1 immediately after manufacturing. Separately, a glass substrate 2 and nine dummy chips 4 to be mounted on the upper surface of the glass substrate 2 via bumps 3 are prepared. Each of the nine dummy chips 4 measures 1 mm × 1 mm × 200 μm thick. The nine dummy chips 4 are arranged in a 3x3 grid with a spacing of 300 μm between them.

[0067] Step 2: As shown in Figure 1B, sample 11 is pressed toward the glass substrate 2 using a vacuum plate press at a temperature of 65°C, a vacuum of 1.6 kPa or less, a pressing pressure of 0.2 MPa, and for 60 seconds.

[0068] Step 3: Leave sample 11 at 23°C and 50% RH for 30 minutes.

[0069] Step 4: Thermocures sample 11 by heating it at 150°C for 1 hour under atmospheric pressure.

[0070] Step 5: Measure the length L1 of the sample entering the gap 10 that separates the lower surface of the dummy chip 4 located in the center from the upper surface of the glass substrate 2.

[0071] Although not shown in the diagram, if there is an unfilled space formed outside the aforementioned void 10, the length L1 of the unfilled space is determined as a negative value.

[0072] <Test Y> In separate experiment Y, steps 1 through 5 will be performed. However, the waiting time in step 3 will be changed from 30 minutes to 24 hours. In step 5, the second entry length L2 of sample 11 will be measured.

[0073] Calculate the percentage ([L1-L2] / L1×100) of the variation (L1-L2) from the first entry length L1 determined by test X to the second entry length L2 determined by test Y.

[0074] 2. Electronic Devices Referring to Figure 2, an embodiment of an electronic device comprising a sealing sheet molded from the sealing sheet described above will be described.

[0075] The electronic device 5 has thickness. The electronic device 5 extends in the planar direction. The electronic device 5 comprises a sealing sheet 6 and an electronic element 7. The electronic device 5 further comprises a bump 8 and a mounting substrate 9.

[0076] 2.1 Sealing Sheet 6 The sealing sheet 6 seals the electronic element 7. The sealing sheet 6 is positioned at one end of the electronic element device 5 in the thickness direction. The sealing sheet 6 forms one side of the electronic element device 5 in the thickness direction. The sealing sheet 6 is a cured version of the sealing sheet 1 described above (see Figures 1A and 1B).

[0077] 2.2 Electronic Element 7 In this embodiment, a plurality of electronic elements 7 are provided in the electronic element device 5. The electronic elements 7 have a substantially rectangular cross-sectional shape. The plurality of electronic elements 7 are arranged apart from each other in the planar direction. Electrodes (not shown) are provided on the other surfaces of the electronic elements 7 in the thickness direction. In the present invention, a plurality of electrodes are provided for one electronic element 7. Examples of electronic elements 7 include semiconductor elements.

[0078] 2.3 Bump 8 The bump 8 electrically connects the electrodes (not shown) of the multiple electronic elements 7 to the electrodes of the mounting substrate 9. The bump 8 is positioned between the electrodes of the electronic elements 7 and the electrodes of the mounting substrate 9. The bump 8 has a shape that extends in the thickness direction. 2.4 Mounting board 9 The mounting substrate 9 is positioned at the other end of the electronic device 5 in the thickness direction. The mounting substrate 9 forms the other side of the electronic device 5 in the thickness direction. The mounting substrate 9 extends in the plane direction. The mounting substrate 9 has a sheet shape. One side of the mounting substrate 9 in the thickness direction faces the other side of the electronic device 7 in the thickness direction. An electrode (not shown) is provided on the aforementioned one side of the mounting substrate 9.

[0079] A gap 10 is provided between the region of the mounting substrate 9 facing the electronic element 7 and the other side of the electronic element 7. Part of the sealing sheet 6 is allowed to enter the peripheral edge of the gap 10.

[0080] 3. Effects of one embodiment In one embodiment, the percentage change (A0-A1) from the adhesive strength A0 of the sealing sheet immediately after manufacturing to the adhesive strength A1 of the sealing sheet after 24 hours at 23°C and 50% RH ([A0-A1] / A0×100) is 10% or less. Therefore, even when the sealing sheet is left in a low-temperature environment for a long period of time, the percentage change in adhesive strength can be suppressed as much as possible.

[0081] Furthermore, the ratio of the amount of heat generated by differential scanning calorimetry of the sealing sheet after heating it at 150°C for 20 minutes to the amount of heat generated by differential scanning calorimetry of the sealing sheet immediately after manufacturing is 0.10 or less, indicating that the amount of unreacted material in the sealing sheet 6 is small.

[0082] Sealing sheets equipped with urea-based curing accelerators, which are aliphatic urea compounds, exhibit a high degree of reduction in the percentage variation of penetration length in the gaps between the mounting substrate and electronic elements, due to the low reactivity of aliphatic urea compounds in the low-temperature range.

[0083] In this sealing sheet, the percentage of variation (L1-L2) from the first penetration length L1 determined by test X to the second penetration length L2 determined by test Y ([L1-L2] / L1×100) is 90% or less, thus providing excellent sealing stability even after prolonged periods in low-temperature environments.

[0084] Since this electronic device 5 is equipped with a sealing sheet 6 formed from the sealing sheet described above, it offers excellent sealing reliability and a small amount of unreacted material. [Examples]

[0085] The present invention will be further described below with reference to examples and comparative examples. However, the present invention is not limited in any way to the examples and comparative examples. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical properties, and parameters used in the following description may be replaced with the upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to" or "greater than or equal to") of the corresponding blending ratios (content ratios), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0086] The components used in the examples and comparative examples are shown below. Epoxy resin A: YSLV-80XY, bisphenol F type epoxy resin, manufactured by Nippon Steel Chemical Co., Ltd. Epoxy resin B: EPICLON EXA-4850-150, manufactured by ADIC, modified bisphenol A type epoxy resin. Phenolic resin A: LVR-8210DL, novolac-type phenolic resin, manufactured by Gun-ei Chemical Co., Ltd. Phenolic resin B: HME-7851SS, phenol-aralkyl resin, manufactured by Meiwa Kasei Co., Ltd.

[0087] Thermoplastic resin: HME-2006M manufactured by Negami Kogyo Co., Ltd., a carboxyl group-containing acrylic ester copolymer, and a methyl ethyl ketone solution with a solid content concentration of 80% by mass. Silane coupling agent: KBM-403, 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.

[0088] Curing accelerator A: U-CAT 3513N manufactured by Sunapro, a urea-based curing accelerator represented by formula (2) above, and an aliphatic urea compound. Curing accelerator B: U-CAT 3512T manufactured by Sunapro, a urea-based curing accelerator represented by the above formula (1), and an aromatic urea compound. Curing accelerator C: 2PHZ-PW, 2-phenyl-4,5-dihydroxymethylimidazole, manufactured by Shikoku Chemicals Co., Ltd. Curing accelerator D: TPP-K, tetraphenylphosphonium tetraphenylborate, manufactured by Hokko Chemical Industry Co., Ltd.

[0089] Inorganic filler A: FB-8SMFD, spherical fused silica powder, manufactured by Denka Co., Ltd., average particle size 7.0 μm Inorganic filler B: An inorganic filler made by surface-treating Admatex's SC220G-SMJ (average particle size 0.5 μm) with 3-methacryloxypropyltrimethoxysilane (product name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.). Inorganic particles surface-treated with 1 part by mass of silane coupling agent per 100 parts by mass of inorganic filler. Layered silicate compounds: Esben NX manufactured by Hojun, an organic bentonite with a surface modified with dimethyldistearylammonium. Pigment: Mitsubishi Chemical Corporation #20 carbon black, particle size 50nm Solvent: Methyl ethyl ketone

[0090] Example 1 A varnish was applied to the surface of a release liner made of polyethylene terephthalate film (PET film) with a silicone release treatment on its surface to form a coating. The varnish was prepared by compounding and mixing each component according to the formulation described in Table 1. The coating was then heated and dried at 120°C for 1.5 minutes to produce a 50 μm thick coating on the surface of the release liner. The coating was in the B stage. Next, four coatings were bonded together at 90°C to produce sample 11 with a thickness of 200 μm. This sample 11 was also in the B stage.

[0091] Examples 2 to 5 and Comparative Examples 1 and 2 Sample 11 of the sealing sheet was prepared in the same manner as in Example 1, except that the formulation was modified according to Table 1.

[0092] <<Rating>> The following items were evaluated for each of the 11 samples from Examples 1 to 5 and Comparative Examples 1 and 2. The results are shown in Table 1.

[0093] <Percentage variation of adhesive strength A0 and A1> Two 15mm diameter plates were mounted on a viscoelasticity measuring device (RSA-G2, manufactured by T.A. Instruments). Each of the upper and lower plates was disc-shaped, and sample 11 was fixed to the lower plate with double-sided tape. Then, under a 25°C atmosphere, the upper plate (probe) was lowered and pressed against sample 11 with a load of 1.74N for 60 seconds. After that, the upper plate was raised at 5μm / second, and the load required to peel the upper plate from sample 11 was determined as the "adhesive strength A0 of the sealing sheet immediately after manufacturing".

[0094] Separately, for sample 11 that had been left at 23°C and 50%RH for 24 hours immediately after manufacturing, the load required to peel the upper plate from sample 11 was measured in the same manner as above, and this was defined as "adhesive strength A1 of the sealing sheet after 24 hours at 23°C and 50%RH".

[0095] Then, the percentage ([A0-A1] / A0×100) of the change from the adhesive strength A0 of sample 11 immediately after manufacturing to the adhesive strength A1 of sample 11 after 24 hours at 23°C and 50% RH was calculated.

[0096] <Ratio of calorific value> The heat generation of sample 11 immediately after manufacturing was measured using differential scanning calorimetry (DSC). Specifically, the heat generation was determined from the DSC curve obtained by differential scanning calorimetry according to the following conditions.

[0097] Differential scanning calorimeter: Q2000 manufactured by TA Instruments Corporation Measurement temperature: -10℃~300℃, Heating rate: 10℃ / min Sample pan: Made of aluminum

[0098] Separately, differential scanning calorimetry (DSC) was used to measure the heat generated by heating sample 11 immediately after manufacturing at 150°C for 20 minutes.

[0099] Then, the ratio of the heat generation obtained by differential scanning calorimetry of sample 11 after heating sample 11 at 150°C for 20 minutes to the heat generation obtained by differential scanning calorimetry of sample 11 immediately after manufacturing was determined.

[0100] <Percentage of variation in entry lengths L1 and L2> <Test X> In Test X, the following steps 1 through 5 were performed in order. This allowed for the measurement of the entry length L1.

[0101] Step 1: As shown in Figure 1A, a sample 11 with a thickness of 200 μm was prepared from the sample 111 immediately after manufacturing. Separately, a glass substrate 2 and nine dummy chips 4 to be mounted on the upper surface of the glass substrate 2 via bumps 3 were prepared. Each of the nine dummy chips 4 had dimensions of 1 mm × 1 mm × 200 μm thickness. The nine dummy chips 4 were spaced 300 μm apart from each other. The nine dummy chips 4 were arranged in a 3x3 grid.

[0102] Step 2: As shown in Figure 1B, sample 11 was pressed toward the glass substrate 2 using a vacuum plate press at a temperature of 65°C, a vacuum of 1.6 kPa or less, a pressing pressure of 0.2 MPa, and for 60 seconds.

[0103] Step 3: Sample 11 was placed in contact with the top surface of dummy tip 4 and left for 30 minutes at 23°C and 50% RH.

[0104] Step 4: Sample 11 was thermocured by heating it at 150°C for 1 hour under atmospheric pressure.

[0105] Step 5: The insertion length L1 of the sample 11 into the gap 10 partitioned between the lower surface of the dummy chip 7 located in the center and the upper surface of the glass substrate 2 was measured.

[0106] <Test Y> In separate experiment Y, steps 1 through 5 were performed. However, the waiting time in step 3 was changed from 30 minutes to 24 hours. In step 5, the second entry length L2 of sample 11 was measured.

[0107] The percentage ([L1-L2] / L1×100) of the variation (L1-L2) from the first entry length L1 determined by test X to the second entry length L2 determined by test Y was calculated.

[0108] [Table 1] [Explanation of symbols]

[0109] 1. Sealing sheet 2 Glass substrate 3.8 Bump 4 Dummy Chips 5. Electronic component device 6. Sealing sheet 7 electronic buttons 9. Implemented circuit board 11 samples

Claims

1. This is a sealing sheet containing epoxy resin, phenolic resin, urea-based curing accelerator, inorganic filler, and thermoplastic resin. In the epoxy resin, phenolic resin, thermoplastic resin, and urea-based curing accelerator, the proportion of the epoxy resin is 50% by mass or less. The percentage change (A0-A1) from the adhesive strength A0 of the sealing sheet immediately after manufacturing to the adhesive strength A1 of the sealing sheet after 24 hours at 23°C and 50% RH ([A0-A1] / A0×100) is 10% or less. An sealing sheet in which the ratio of the amount of heat generated by differential scanning calorimetry of the sealing sheet after heating it at 150°C for 20 minutes to the amount of heat generated by differential scanning calorimetry of the sealing sheet immediately after manufacture is 0.10 or less.

2. The encapsulating sheet according to claim 1, wherein the urea-based curing accelerator is an aliphatic urea compound.

3. The sealing sheet according to claim 1 or claim 2, wherein the percentage of variation (L1-L2) from the first entry length L1 to the second entry length L2 determined by test Y, at the first entry length L1 determined by test X, is 90% or less ([L1-L2] / L1×100). <Exam X> Follow the steps below from 1 to 5 in order. Step 1: Prepare a sample with a thickness of 200 μm from the sealing sheet immediately after manufacturing. Separately, prepare a mounting substrate comprising a glass substrate and nine dummy chips, each measuring 1 mm × 1 mm × 200 μm thick and arranged in a line with a spacing of 300 μm between them, which are mounted on the upper surface of the glass substrate via bumps. Step 2: Using a vacuum plate press, the sample is pressed toward the glass substrate at a temperature of 65°C, a vacuum of 1.6 kPa or less, a pressing pressure of 0.2 MPa, and for 60 seconds. Step 3: The sample is brought into contact with the upper surface of the dummy chip and left for 30 minutes at 23°C and 50% RH. Step 4: The sample is heat-cured by heating it at 150°C for 1 hour under atmospheric pressure. Step 5: Measure the length L1 of the sample entering the gap between the lower surface of the dummy chip located in the center and the upper surface of the glass substrate. <Test Y> Steps 1 through 5 described above are carried out. However, the waiting time in step 3 is changed from 30 minutes to 24 hours. In step 5, the second entry length L2 of the sample is measured.

4. A sealing sheet molded from a sealing sheet according to any one of claims 1 to 3, An electronic element device comprising an electronic element sealed by the aforementioned sealing sheet.

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