A cyanate ester composition containing BMI resin and its application

Abstract

The present invention provides a cyanate ester composition containing BMI resin and its application. A liquid BMI resin with maleimide end groups is used as a toughening agent, which is combined with cyanate ester resin, cashew shell oil-based phenolic resin, peroxide initiator, curing accelerator and other additives. After being fully and uniformly dispersed, the obtained composition can achieve a lower volume resistivity, higher bonding strength, higher room-temperature mechanical strength and high-temperature mechanical strength, good reliability, good moisture and heat resistance, resistance to reflow soldering and no delamination. In addition, a conductive adhesive can be prepared by adding silver powder, which can be applied to semiconductor device packaging, especially IC chip mounting.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor packaging or microelectronic device packaging, and particularly relates to a cyanate ester composition containing BMI resin and its application. Background Art

[0002] In the preparation and assembly of semiconductor packages and microelectronic devices, adhesives perform many functions, including: bonding, fixing, sealing and protecting, gap filling, grounding, insulation, flame retardancy, etc. The most traditional method in the process of fixing a chip to a frame or a substrate is to transfer an adhesive to the frame or a plastic substrate by means of dispensing or painting, and then attach the chip to the position with the adhesive through a fine nozzle on a robotic arm. After the adhesive is cured by baking in an oven and then undergoes wire bonding and subsequent encapsulation processes such as epoxy molding compound (EMC) encapsulation, the chip encapsulation is completed. The encapsulated chip will become part of a printed circuit board after undergoing high-temperature reflow soldering when transferred to the printed circuit board and perform its functions. The adhesive for die bonding and chip attachment needs to have appropriate rheological properties to cope with the construction methods of various application scenarios; in addition, after the adhesive is cured, it should have good bonding strength, certain heat resistance, be able to withstand the high temperature of the reflow soldering process multiple times, and have an appropriate coefficient of thermal expansion (CTE) relative to substrates, molding compounds, etc. to reduce thermal mismatch.

[0003] The main body of the adhesive for die bonding and chip attachment is based on thermosetting resins, such as: epoxy resin, acrylic resin, cyanate ester resin and other systems. Bismaleimide resin (BMI resin) is a class of advanced resin materials with good mechanical strength and excellent heat resistance. The combination of BMI resin and cyanate ester resin is an important raw material for the preparation and processing of PCB substrates (US4456712A, US4749760A, etc.), but the melting point of this type of resin is high and the processing performance is poor, which limits its application in electronic packaging adhesives. Summary of the Invention

[0004] The first object of the present invention is to provide a cyanate ester composition containing BMI resin.

[0005] To achieve the above object, the following technical solutions are adopted in the present invention:

[0006] A cyanate ester composition containing BMI resin, comprising:

[0007] a parts of cyanate ester resin, b parts of BMI-PPG polymer, c parts of cashew shell oil phenolic resin, d parts of accelerator, and e parts of peroxide;

[0008] Wherein: b / a = 1 / 3 to 1 / 2;

[0009] c / a = 1 / 6 to 1 / 3.

[0010] While adopting the above technical solutions, the present invention can also adopt or combine the following technical solutions:

[0011] As a preferred technical solution of the present invention: The monomer of the cyanate resin contains a diphenol derivative with 2 or more cyanate groups in its molecular structure, and can undergo a cyclotrimerization reaction upon heating to form a three-dimensional network with a high crosslinking density having a triazine ring;

[0012] The monomer of the cyanate resin is selected from at least one of bisphenol A cyanate, bisphenol B cyanate, bisphenol E cyanate, bisphenol F cyanate, bisphenol M cyanate, bisphenol AF cyanate, bisphenol AP cyanate, bisphenol BP cyanate, phenolic cyanate, and dicyclopentadiene-based cyanate.

[0013] As a preferred technical solution of the present invention: The cyanate resin is selected from at least one of L-10, M-10, B-10 of Ciba Geigy; Primaset PT30, PT30 S75, PT60, PT60S of LONZA, and the L-10 cyanate resin of Hubei Jiahui Xingcheng Biotechnology Co., Ltd.

[0014] As a preferred technical solution of the present invention: The chemical structural formula of the BMI-PPG polymer is as follows:

[0015]

[0016] Wherein, n is 5 to 20;

[0017] The end group of the BMI-PPG polymer is a maleimide group, and the main chain has propylene oxide repeating units;

[0018] At room temperature, for example: at 25°C, it is a reddish-brown viscous and flowable liquid, and the viscosity is 5 to 40 kcps@10 rpm.

[0019] As a preferred technical solution of the present invention: The cashew nut shell oil-based phenolic resin is preferably a phenolic resin modified with cardanol, and the molecular structural formula of the phenolic resin modified with cardanol is as follows:

[0020]

[0021] In the above formula, the number of repeating units n is 2 to 10, and R is C 15 H 31-2m , where m is 0 or 1.

[0022] As a preferred technical solution of the present invention: the cardanol-modified phenolic resin is preferably NX4001, NX4004, NX4005 of Cardolite Corporation, with a hydroxyl equivalent of 316; more preferably NX4004.

[0023] As a preferred technical solution of the present invention: the accelerator is an imidazole accelerator, and the imidazole accelerator is at least one of 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole.

[0024] As a preferred technical solution of the present invention: the peroxide is at least one of benzoyl peroxide (BPO), tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyneodecanoate, tert-amyl peroxy-2-ethylhexanoate (Arkema Luperox 575), cumene hydroperoxide (CHPO), di-tert-butyl peroxide (DTBP), dicumyl peroxide (DCPD), tert-amyl peroxyneodecanoate, diisopropyl peroxydicarbonate.

[0025] The second object of the present invention is to provide an application of the cyanate ester composition containing BMI resin described above in the encapsulation of semiconductor devices

[0026] The application of the cyanate ester composition containing BMI resin described above in the encapsulation of semiconductor devices includes: adding conductive silver powder to the cyanate ester composition containing BMI resin to obtain a conductive adhesive, and applying the conductive adhesive to the encapsulation of semiconductor devices.

[0027] While adopting the above technical solutions, the present invention can also adopt or combine the following technical solutions:

[0028] As a preferred technical solution of the present invention: the conductive silver powder is spherical, flaky or a mixture of both;

[0029] The conductive silver powder is preferably micron-scale flaky conductive silver powder, with an average particle size of 0.3 - 30 μm, and the average particle size is preferably 1 - 15 μm.

[0030] As a preferred technical solution of the present invention: the conductive silver powder is f parts, where: f / (a + b + c + d + e) ≥ 3.

[0031] As a preferred technical solution of the present invention: the conductive silver powder is selected from at least one of silver powder Technic-077 of Technic Company, silver powder AA3462, AA-192N, P543-14, EA-0295 of Metalor Company, and silver powder KP84, KP74 of Ames Goldsmith Company.

[0032] It should be noted that in this field, resins include small molecule monomers, small molecule polymers, macromolecule polymers, etc.

[0033] The present invention provides a cyanate ester composition containing BMI resin and its application. Using a liquid BMI resin with maleimide end groups as a toughening agent, in combination with cyanate ester resin, cashew shell oil type phenolic resin, peroxide initiator, curing accelerator and other additives, the composition obtained after being fully and uniformly dispersed can achieve a lower volume resistivity, higher bonding strength, higher room temperature mechanical strength and high temperature mechanical strength, good reliability, good moisture and heat resistance, resistance to reflow soldering and no delamination. In addition, a conductive adhesive can be prepared by adding silver powder, which can be applied to semiconductor device packaging, especially IC chip mounting. Specific embodiments

[0034] The present invention will be further described in detail with reference to specific embodiments.

[0035] 1. Test preparation

[0036] 1.1 Test materials

[0037]

[0038] 1.2 Performance testing

[0039] Bonding strength test: The test method refers to "HG / T 5912-2021 Conductive Adhesive".

[0040] The size of the silicon wafer is: 2mm×2mm; the substrate is a silver-plated copper sheet, and the curing condition is 175°C×60min on a hot stage; the test equipment is a DAGE-4000P multi-functional push-pull force machine (Nordson DAGE Precision Industries LTD, USA), with a temperature-controlled heating stage, and the shear strength is the magnitude of the thrust (unit: kgF, kilogram-force); 5 specimens are taken for each glue sample, and the arithmetic mean is taken.

[0041] When measuring the high-temperature thrust, set the temperature of the temperature-controlled heating stage, wait for 5 minutes to stabilize after reaching the target temperature, and then start measuring the thrust.

[0042] Volume resistivity test: Refer to the four-probe method in the industry standard "HG / T 5912-2021 Conductive Adhesive".

[0043] Preparation of conductive film: On a glass substrate, a conductive adhesive with a thickness of 25 μm, a width of 9 mm, and a length of 50 mm was prepared by the method of scraping the film with a thickness control tape; baked and cured at 175 °C for 60 min;

[0044] The resistance tester is the TH2516 DC resistance tester of Changzhou Tonghui Electronics Co., Ltd.

[0045] Evaluation of the damaged surface: Observe the residual adhesive on the substrate after the thrust damage through an optical microscope, evaluate the area ratio (percentage relative to the chip area) of the part with residual adhesive, adopt a 10-point system, 100% residual adhesive corresponds to 10; 90% residual adhesive corresponds to 9, and so on, 10% residual adhesive corresponds to 1; 0% residual adhesive corresponds to 0; The arithmetic mean of 10 samples is taken.

[0046] Chip warpage test: A silver-plated frame was used, the chip size was 9 mm × 9 mm, and the chip / frame was baked and cured at 175 °C × 60 min after dispensing and pasting. The warpage was measured along the diagonal direction of the chip by a surface roughness measuring instrument, and the unit was μm. If it was less than 20 μm, it was considered to pass the test; if it exceeded 20 μm, it was considered unqualified.

[0047] Reflow soldering resistance (anti-delamination) test: The die-bonded chip / frame was molded and encapsulated with a molding compound (Sumikon EME-7026, Sumitomo Bakelite Co., Ltd., Japan), 20 in a group, cured at "double 85" (85% relative humidity and 85 °C) for 8 days, and after 3 reflow soldering operations (260 °C, 10 s each time), ultrasonic microscopy SAT ultrasonic scanning (T-Scan mode) was used to observe the delamination situation. If any chip delamination occurred, the test was considered unqualified.

[0048] 2. Test procedure

[0049] 2.1 Preparation of BMI-PPG

[0050] (1) Preparation of BMI-PPG400

[0051] Dissolve 253.5 g (1.5 mol) of maleimide propionic acid in 2500 ml of dichloromethane. Then dissolve 309 g (1.5 mol) of dicyclohexylcarbodiimide (DCC) powder in 300 ml of dichloromethane. Under stirring, slowly add the DCC solution dropwise to the maleimide propionic acid solution. After complete addition, continue stirring and reacting for 10 min. Then add 200 g (0.5 mol) of PPG-400 to the system. Finally, slowly add 6.1 g (0.05 mol) of 4-dimethylaminopyridine (DMAP) powder and stop the reaction after 8 h. Filter to remove the insoluble substances. Take the filtrate and extract it with water in a separatory funnel. Combine the organic layers, dry over anhydrous Na2SO4, rotary evaporate the filtrate to obtain a red viscous liquid. After standing and cooling, a small amount of solid precipitates. Filter again to obtain the final product, yield: 98%.

[0052] The NMR spectrum data are as follows:

[0053] 1 H NMR (600 MHz, Chloroform-d) δ 6.66 (s, 4H), 3.76 (p, J = 7.9, 7.3 Hz, 4H), 3.63–3.32 (m, 21H), 2.58 (t, J = 7.2 Hz, 4H), 1.46–0.83 (m, 18H).

[0054] The viscosity at 25 °C is 25–30 kcps @ 10 rpm. The viscosity test refers to the national standard GB / T 22314-2008 "Determination Method for Viscosity of Plastic Epoxy Resin". Viscometer model: Anton Paar Rheolab QC, Z5 rotor.

[0055] (2) Preparation of BMI-PPG1000

[0056] Dissolve 253.5 g (1.5 mol) of maleimide propionic acid in 2500 ml of dichloromethane. Then dissolve 309 g (1.5 mol) of dicyclohexylcarbodiimide (DCC) powder in 300 ml of dichloromethane. Under stirring, slowly add the DCC solution dropwise to the maleimide propionic acid solution. After complete addition, continue stirring and reacting for 10 min. Then add 500 g (0.5 mol) of PPG-1000 to the system. Finally, slowly add 6.1 g (0.05 mol) of 4-dimethylaminopyridine (DMAP) powder and stop the reaction after 8 h. Filter to remove the insoluble substances. Take the filtrate and extract it with water in a separatory funnel. Combine the organic layers, dry over anhydrous Na2SO4, rotary evaporate the filtrate to obtain a red viscous liquid. After standing and cooling, a small amount of solid precipitates. Filter again to obtain the final product, yield: 98%.

[0057] The NMR spectrum data are as follows:

[0058] 1 1H NMR (600 MHz, Chloroform-d) δ 6.67 (s, 4H), 3.78 (t, J = 7.2 Hz, 4H), 3.61–3.26 (m, 52H), 2.60 (t, J = 7.1 Hz, 4H), 1.29–0.98 (m, 51H).

[0059] The viscosity at 25 °C is 5 - 10 kcps @ 10 rpm. The viscosity test refers to the national standard GB / T 22314-2008 "Determination Method for Viscosity of Plastic Epoxy Resin". Viscometer model: Anton Paar Rheolab QC, Z5 rotor.

[0060] 2.2 Preparation of Conductive Adhesive (Taking Example 1 as an Example)

[0061] Weigh 12 parts of cyanate ester resin L10, 4 parts of BMI-PPG1000 (self-made), and 2 parts of cardanol phenolic resin NX4004, add them to a mixing kettle, and mix at 800 rpm for 15 min; then add 0.1 part of cumene hydroperoxide CHPO and 0.2 part of imidazole accelerator 2E4MZ-CN, mix at 800 rpm for 15 min, and finally add 3 times the amount of silver powder, 54.9 parts, disperse at 800 rpm for 15 min, and then carry out vacuum degassing for 10 min, with the vacuum degree < -0.095 MPa; discharge under normal pressure to obtain the conductive adhesive.

[0062] Table 1

[0063]

[0064] Table 2

[0065]

[0066] 3. Result Discussion:

[0067] For Comparative Examples 1 / 2 and Examples 1 / 2, when the amount of cyanate ester is 12 parts, the content of BMI-PPG400 resin gradually increases from 2 parts to 10 parts, and the volume resistivity of the cured product gradually increases, from 5×10 -4 Ω·cm to 12×10 -4Ω·cm indicates that the increase in the content of BMI-PPG resin is not conducive to the reduction of volume resistivity; correspondingly, the normal temperature thrust (chip thrust @ 23°C) gradually decreases, from 23 kgF to 16 kgF. In terms of high-temperature chip thrust (chip thrust @ 250°C), it experiences a process of first increasing and then decreasing. Examples 1-2 (Example 1 is 3.6 kgF, Example 2 is 3 kgF, both ≥ 3 kgF) are better than Comparative Examples 1-2 (Comparative Example 1 is 2.6 kgF, Comparative Example 2 is 1.5 kgF, both ≤ 3 kgF), and the residual glue rate on the fracture surface is significantly improved with the increase in the content of BMI-PPG400 resin, increasing from 2 to more than 5. Compared with Examples 1 / 2, Example 5 adjusts the contents of BMI-PPG400 and NX4004, with more balanced performance and better chip thrust and residual glue surface.

[0068] Compared with Examples 1 / 2 / 5, Examples 3 / 4 / 6 replace BMI-PPG400 resin with BMI-PPG1000 resin, resulting in a corresponding increase in volume resistivity and a decrease in chip thrust. For example: compared with Example 1, the volume resistivity of Example 3 increases from 6×10 -4 Ω·cm to 10×10 -4 Ω·cm, the corresponding normal temperature chip thrust (chip thrust @ 23°C) decreases from 22 kgF to 17 kgF, and the high-temperature chip thrust (chip thrust @ 250°C) decreases from 3.6 kgF to 2 kgF; while the change in the residual glue surface is not significant. Example 4 has a similar change pattern compared with Example 2. Observing the change in the volume resistivity of Examples 3 / 4 / 6 shows a pattern similar to that of Examples 1 / 2 / 5, that is, the increase in the content of BMI-PPG resin is not conducive to the reduction of volume resistivity. Generally speaking, Example 6 has more balanced performance compared with Examples 3-4.

[0069] Compared with Example 1, the contents of phenolic resin NX4004 in Comparative Examples 3 / 4 are different (0 parts and 6 parts in Comparative Examples 3 and 4 respectively). In Comparative Example 3, due to insufficient curing, the volume resistivity is relatively large, reaching 20×10 -4 Ω·cm, the corresponding normal temperature and high-temperature chip thrusts decrease significantly, only 13 kgF and 2.5 kgF respectively, the residual glue surface is 4, and the chip warpage is relatively large; while compared with Example 1, the residual glue surface in Comparative Example 4 decreases significantly, only 2, but the other performance aspects are comparable.

[0070] The above specific embodiments are used to explain and illustrate the present invention, which are only the preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and scope of the protection of the present invention fall within the protection scope of the present invention.

Claims

1. A cyanate ester composition containing BMI resin, characterized in that: The cyanate ester composition containing BMI resin comprises: a parts of cyanate ester resin, b parts of BMI-PPG polymer, c parts of cashew shell oil modified phenolic resin, d parts of accelerator, and e parts of peroxide; wherein: b / a = 1 / 3 to 1 / 2; c / a = 1 / 6 to 1 / 3; The chemical structural formula of the BMI-PPG polymer is as follows: wherein, n is 5 to 20; The viscosity of the BMI-PPG polymer at room temperature is: 5 to 40 kcps @ 10 rpm.

2. The cyanate ester composition containing BMI resin according to claim 1, wherein: The monomer of the cyanate ester resin is selected from at least one of bisphenol A cyanate ester, bisphenol B cyanate ester, bisphenol E cyanate ester, bisphenol F cyanate ester, bisphenol M cyanate ester, bisphenol AF cyanate ester, bisphenol AP cyanate ester, bisphenol BP cyanate ester, phenolic cyanate ester, and dicyclopentadiene type cyanate ester.

3. The cyanate ester composition containing BMI resin according to claim 1, characterized in that: The cashew shell oil modified phenolic resin is a phenolic resin modified by cardanol, and the molecular structural formula of the cardanol modified phenolic resin is as follows: In the above formula, the number of repeating units n is 2 to 10, and R is C 15 H 31-2m , where m is 0 or 1.

4. The cyanate ester composition containing BMI resin according to claim 1, characterized in that: The accelerator is an imidazole type accelerator, and the imidazole type accelerator is at least one of 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole.

5. The cyanate ester composition containing BMI resin according to claim 1, characterized in that: The peroxide is at least one of benzoyl peroxide, tert-butyl 2-ethylhexanoate peroxide, di-tert-butyl peroxide, tert-butyl benzoate peroxide, tert-amyl neodecanoate peroxide, tert-amyl 2-ethylhexanoate peroxide, cumene hydroperoxide, diisopropylbenzene peroxide, tert-amyl neodecanoate peroxide; and diisopropyl diperoxy dicarbonate.

6. Use of the cyanate ester composition containing BMI resin according to any one of claims 1-5 in semiconductor device packaging, characterized in that: The application includes: adding conductive silver powder to the cyanate ester composition containing BMI resin to obtain a conductive adhesive, and applying the conductive adhesive to semiconductor device packaging.

7. The application according to claim 6, wherein: The conductive silver powder is spherical, flaky or a mixture of both.

8. The application according to claim 7, wherein: The conductive silver powder is micron-sized flaky conductive silver powder with an average particle size of 0.3 to 30 μm.

9. The application according to claim 8, wherein: The average particle size of the micron-sized flaky conductive silver powder is 1 to 15 μm.

10. The application according to claim 6 or 7 or 8 or 9, characterized in that: The conductive silver powder is f parts, wherein: f / (a + b + c + d + e) ≥ 3.

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