CN112280244B

CN112280244B - Low-warpage epoxy resin composition and preparation method thereof

Info

Publication number: CN112280244B
Application number: CN202011174107.XA
Authority: CN
Inventors: 宋江林
Original assignee: Shanghai Kufu New Material Co ltd
Current assignee: Shanghai Kufu New Material Co ltd
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2023-11-03
Anticipated expiration: 2040-10-28
Also published as: CN112280244A

Abstract

The application relates to the technical field of adhesives, in particular to an epoxy resin composition and a preparation method thereof. The raw materials comprise, by weight: 5-30 parts of epoxy resin, 5-15 parts of nano epoxy resin, 1-10 parts of reactive diluent, 20-35 parts of curing agent, 1-5 parts of curing accelerator, 40-60 parts of inorganic filling material and 1-5 parts of thickener. The epoxy resin composition prepared by the application can be rapidly cured under the low-temperature condition and has extremely low warping tendency. The product has simple preparation process and excellent dimensional stability, has very wide application prospect, and is particularly suitable for packaging the sensor chip of the mobile phone camera.

Description

Low-warpage epoxy resin composition and preparation method thereof

Technical Field

The application relates to the technical field of adhesives, in particular to an epoxy resin composition and a preparation method thereof.

Background

Epoxy resins are a type of high molecular polymer, and refer to a generic term for polymers containing two or more epoxy groups in the molecule. Due to the chemical activity of epoxy group, it can be opened by using various compounds containing active hydrogen, solidified and crosslinked to form net structure, and can be made into coating material, composite material, casting material, adhesive, mould-pressing material and injection moulding material, so that it can be extensively used in various fields of national economy. Because of the many unique advantages of high insulating property, high structural strength, good sealing property and the like, the epoxy resin has been widely applied to the insulation and encapsulation of high and low voltage electrical appliances, motors and electronic components, and has rapid development.

Along with the increasingly lighter and thinner packaging forms, the sensitivity requirements of the sensor are also higher, the thickness of the epoxy resin composition on the surface of the chip is smaller and smaller in the injection molding process of the epoxy resin composition, and the problems of chip mark, air holes, warpage and the like are easy to occur in the packaging process. The problem is solved, and the dielectric property and the reliability of the plastic package product are ensured, so that the plastic package product becomes a hot spot for pursuing the industry. Manufacturers of epoxy resin compositions at home and abroad are actively developing, and no clear solution exists at present. Cn201710408369.X discloses a high dielectric constant epoxy resin, which provides a high dielectric constant epoxy resin composition with low porosity, low warpage and high reliability in an acceptable range by optimizing the kind of the epoxy resin composition and the kind of the stress absorber and the adding method thereof. But the epoxy resin composition prepared by the application is mainly applied to fingerprint module packaging.

Along with the rapid development of mobile phone photographing technology, the requirements of the market on mobile phone camera modules are higher and higher, wherein the packaging of a sensor chip in the camera module is an important ring, and how to solve the technical problem that the problem of low warpage is to be solved in the field is urgent.

Disclosure of Invention

The epoxy resin composition capable of being rapidly cured under the low-temperature condition is good in dimensional stability, low in warping value and simple in preparation process, and is particularly suitable for packaging of a mobile phone camera sensor chip.

The first aspect of the present application provides a low-warpage epoxy resin composition, which comprises the following raw materials in parts by weight: 5-30 parts of epoxy resin, 5-15 parts of nano epoxy resin, 1-10 parts of reactive diluent, 20-35 parts of curing agent, 1-5 parts of curing accelerator, 40-60 parts of inorganic filling material and 1-5 parts of thickener.

In a preferred embodiment, the nano-sized epoxy resin is a nano-silica modified epoxy resin.

In a preferred embodiment, the weight ratio of the epoxy resin to the nano-epoxy resin is (0.8-4): 1.

in a preferred embodiment, the curing agent is a thiol curing agent.

In a preferred embodiment, the thiol curing agent comprises at least one of pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), 1,3, 5-tris (3-mercaptobutyryloxyethyl) -1,3, 5-triazine-2, 4,6 (1H, 3H, 5H) -trione.

In a preferred embodiment, the thickener is nanoscale fumed silica.

In a preferred embodiment, the cure accelerator is prepared from a starting material comprising an epoxy resin binder and an alkyl imidazole.

In a preferred embodiment, the particle size of the inorganic filler material is 0.2-2 μm.

The second aspect of the present application provides a method for preparing a low warpage epoxy resin composition, comprising the steps of:

s1, weighing 5-30 parts of epoxy resin, 5-15 parts of nano epoxy resin, 1-10 parts of reactive diluent, 20-35 parts of curing agent, 1-5 parts of curing accelerator, 40-60 parts of inorganic filling material and 1-5 parts of thickener according to parts by weight;

s2, sequentially adding the epoxy resin, the nano epoxy resin, the reactive diluent, the curing agent, the curing accelerator, the inorganic filling material and the thickener into a material cylinder of a double-planetary dispersing instrument, and stirring for 10-20min at a first stirring speed; setting the vacuum degree of the material cylinder to be-0.08 MPa, and stirring for 80-100min at a second stirring speed.

In a preferred embodiment, the first stirring speed is 50-200r/min and the second stirring speed is 750-1200r/min.

The beneficial effects are that:

the epoxy resin composition with low warpage is prepared by the method, can be rapidly cured under the low-temperature condition, and has extremely low warpage tendency. The product has simple preparation process and excellent dimensional stability, has very wide application prospect, and is particularly suitable for packaging the sensor chip of the mobile phone camera.

Detailed Description

The disclosure of the present application will be further understood in conjunction with the following detailed description of the preferred embodiments of the application, including examples. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. If the definition of a particular term disclosed in the prior art is inconsistent with any definition provided in the present application, the definition of the term provided in the present application controls.

As used herein, unless the context clearly indicates otherwise, the absence of a limitation to a plurality of features is also intended to include the plurality of features. It will be further understood that the terms "made of …" and "comprising," "including," "having," "including," and/or "containing," as used herein, are synonymous with "including," "having," "containing," and/or "containing," and when used in this specification, mean the stated composition, step, method, article, or apparatus, but do not preclude the presence or addition of one or more other compositions, steps, methods, articles, or apparatus. Furthermore, when describing embodiments of the present application, the use of "preferred," "more preferred," etc. refers to embodiments of the present application that may provide certain benefits in some instances. However, other embodiments may be preferred under the same or other circumstances. In addition, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the application. In addition, the raw materials used in the present application are commercially available unless otherwise specified.

In order to solve the above problems, a first aspect of the present application provides a low warpage epoxy resin composition comprising, in parts by weight: 5-30 parts of epoxy resin, 5-15 parts of nano epoxy resin, 1-10 parts of reactive diluent, 20-35 parts of curing agent, 1-5 parts of curing accelerator, 40-60 parts of inorganic filling material and 1-5 parts of thickener.

In some preferred embodiments, the epoxy resin is at least one of a bisphenol a type epoxy resin, a bisphenol F type epoxy resin, and a phenolic type epoxy resin.

In some preferred embodiments, the nano-sized epoxy is a nano-silica modified epoxy. The nanosilica modified epoxy resins may be commercially available, for example, from the winning industry group.

The present inventors found that when a nano-type epoxy resin is added to the system, the warp tendency of the cured product is suppressed. The reason is probably that spherical silica nano particles are uniformly distributed in the epoxy resin matrix in the structure of the nano epoxy resin, so that the dispersibility and uniformity of a system are improved when the epoxy resin is cured, the defect of poor product flowing property of the epoxy resin on the premise of not improving the viscosity is overcome, unstable aggregation among polymer molecular chains in the curing process is inhibited, the dimensional stability of a cured product is improved, and the warping degree of the cured material is reduced; but a decrease in the glass transition temperature of the material after curing is initiated.

Further preferably, the weight ratio of the epoxy resin to the nano epoxy resin is (0.8-4): 1.

the present application has unexpectedly found that when the weight ratio of epoxy resin to nano-epoxy resin is (0.8-4): 1, not only the shrinkage of the cured material is reduced, but also the glass transition temperature Tg of the cured material is increased. The weight ratio of the epoxy resin to the nano epoxy resin is (0.8-4): in the step 1, the activity of the crosslinking reaction of the epoxy resin and the curing agent in the system is higher, and the stable crosslinking point density after the resin gel is high, so that the movement and rotation of polymer molecular chains during heating are inhibited, and the glass transition temperature Tg of the cured material is further improved.

In some preferred embodiments, the curing agent is a thiol curing agent.

The application discovers that when the curing agent in the system is a mercaptan curing agent, the epoxy resin composition can be cured at 70-80 ℃. Probably because the active hydrogen in the mercaptan curing agent can react with the oxidation byproducts in the curing process, new free radicals formed after mercaptan is deprived of hydrogen can continuously participate in the curing reaction of the epoxy resin, so that the problem of slow curing caused by the existence of oxygen byproducts in the system is restrained, and the effect that the epoxy resin and the curing agent can be rapidly cured at a lower temperature is achieved. On the other hand, although the addition of the thiol curing agent accelerates the occurrence of the curing reaction, the rapid occurrence of the curing reaction in a short period of time causes a problem that the degree of reaction is not easily controlled, entanglement and aggregation are easily generated between polymer molecular chains, the degree of disorder of the reaction system increases, and the tendency of warping of the cured product increases.

Further preferably, the thiol curing agent comprises at least one of pentaerythritol tetrakis (3-mercaptopropionic acid), pentaerythritol tetrakis (3-mercaptobutyrate), 1,3, 5-tris (3-mercaptobutyryloxyethyl) -1,3, 5-triazine-2, 4,6 (1H, 3H, 5H) -trione, and pentaerythritol tetrakis (3-mercaptobutyrate).

The present application has unexpectedly found that when the thiol curing agent comprises at least one of pentaerythritol tetrakis (3-mercaptopropionate), 1,3, 5-tris (3-mercaptobutyryloxyethyl) -1,3, 5-triazine-2, 4,6 (1H, 3H, 5H) -trione, pentaerythritol tetrakis (3-mercaptobutyrate), both the curing time and the degree of warpage of the product can be reduced. The reason is probably that pentaerythritol tetra (3-mercaptopropionic acid), 1,3, 5-tris (3-mercaptobutyryloxyethyl) -1,3, 5-triazine-2, 4,6 (1H, 3H, 5H) -trione, and pentaerythritol tetra (3-mercaptobutyric acid) can increase the stable crosslinking point density of a cured product, so that polymer molecular chain segments are closely packed, the stability of the system is improved, the shrinkage rate of the cured product is reduced, and the effect of reducing the warping degree of the product is achieved.

In some preferred embodiments, the reactive diluent is at least one of ethylene oxide benzene, octane oxide, glycidyl ether.

In some preferred embodiments, the thickener is nanoscale fumed silica. Further preferably, the nano-sized fumed silica is subjected to a silanized surface treatment.

The present application has found that when the thickener is nano-sized fumed silica, the warpage of the epoxy resin composition is reduced. The reason is probably that the nanoscale fumed silica has small specific surface area, strong surface adsorption capacity and high interface bonding strength with the epoxy resin, so that the structural stability of the mesh structure of the cured product is improved, and the warping tendency of the cured product is further restrained. The present application unexpectedly found that when nano-sized fumed silica is subjected to a silanized surface treatment, the curing reaction can be accelerated; the reason is hypothesized that the nano-scale fumed silica can inhibit the sedimentation and fluidity of the epoxy resin in the system after the silanization surface treatment, optimize the uniform dispersion degree of the system in the crosslinking curing reaction process, and promote the quick curing of the epoxy resin and the mercaptan curing agent in a stable environment.

The silanized surface-treated nanoscale fumed silica can be commercially available, for example, from cabot corporation.

In some preferred embodiments, the cure accelerator is prepared from a synthetic process, and the cure accelerator is prepared from raw materials including an epoxy resin base and an alkyl imidazole. Further preferably, the specific preparation steps of the curing accelerator include:

(1) 300-400g of epoxy resin base stock is diluted by 1-2 times by a first solvent, and the temperature is raised to 74-85 ℃ to obtain epoxy resin base stock diluent.

(2) 120-140g of alkyl imidazole is diluted 2-3 times by a second solvent to obtain 2-methylimidazole diluent. Slowly adding 2-methylimidazole diluent into the epoxy resin base stock diluent prepared in the step (1) in a dropwise manner for 3 hours, and slowly stirring in the dropwise manner.

(3) And after the dripping is finished, the temperature is raised to 74-85 ℃ again, the mixture is stirred and reacts for 4 hours, the temperature is raised to 142-155 ℃ continuously, and the crude material of the curing accelerator is obtained through reduced pressure distillation.

(4) Grinding and sieving coarse material of the curing accelerator to obtain powder with the particle size of 0.1-5 mu m, namely the curing accelerator.

The first solvent and the second solvent are methanol and toluene, and the mass ratio of the methanol to the toluene is 1:1 mixing the obtained solutions.

In some preferred embodiments, the alkyl imidazole is 2-methylimidazole and CAS number 693-98-1.

The application discovers that when the curing accelerator prepared by the self-synthesis method is added into a system, the epoxy resin composition can be cured at 70-80 ℃ for 24-35 min. The curing accelerator synthesized by the method is surmised to introduce more active hydrogen atoms, so that the reactivity of the epoxy resin and the curing agent is improved, and the crosslinked network structure of the cured product can better block the intervention of oxygen, so that the generation of oxidation byproducts is inhibited, and the effect of completing the curing at a lower temperature and in a shorter time is achieved.

The present application has unexpectedly found that the properties of the cured product are best when the epoxy equivalent weight of the epoxy resin binder is 156-170 g/equivalent. The reason is probably that the compatibility of the curing accelerator prepared when the epoxy equivalent of the epoxy resin base material is 156-170 g/equivalent with substances such as the first epoxy resin, the mercaptan curing agent, the inorganic filler and the like is optimal, the dispersibility and the stability of the system are strong, the crosslinking curing reaction can occur in a relatively stable environment, the compatibility among the components is more sufficient, the epoxy resin and the mercaptan curing agent are promoted to rapidly form a firm crosslinking product in a stable environment, the curing effect can be achieved at 70-80 ℃ for 24-35min, the warping degree of the obtained curing product is low, and the vitrification conversion temperature is slightly improved.

In some preferred embodiments, the inorganic filler material is silica and/or alumina, and the inorganic filler material has a particle size of 0.2-2 μm. The inorganic filler material having a particle size of 0.2 to 2 μm may be commercially available, for example, from the company of the trade (Shanghai) of the Utility model of ya Dou Ma.

In some preferred embodiments, the method for preparing the low warpage epoxy resin composition comprises the following specific steps:

In some preferred embodiments, the first agitation speed is 50-200r/min and the second agitation speed is 750-1200r/min.

In some preferred embodiments, the epoxy resin composition prepared by the application is particularly suitable for packaging a mobile phone camera sensor chip.

Examples

Example 1.

The present example provides a low warpage epoxy resin composition. The raw materials comprise, by weight: 19 parts of epoxy resin, 14 parts of nano epoxy resin, 3 parts of reactive diluent, 23 parts of curing agent, 2 parts of curing accelerator, 38 parts of inorganic filling material and 1 part of thickener.

The epoxy resin is bisphenol F type epoxy resin, and is purchased from Shanghai Kaijin chemical industry Co., ltd, and the model is Dow DER354.

The nano-epoxy is purchased from Yingchang Industrial group under the model number of NANOPOX E470.

The reactive diluent is p-di (epoxy ethyl) benzene, and the CAS number is 16803-58-9.

The curing agent is pentaerythritol tetra (3-mercaptopropionic acid) ester with CAS number of 7575-23-7.

The curing accelerator is prepared by a self-synthesis method, and comprises the following specific steps:

(1) 340g of epoxy resin base stock is diluted by 1.5 times by a first solvent, and the temperature is raised to 80 ℃ to obtain epoxy resin base stock diluent. The epoxy resin base was purchased from DIC under the model EXA-835LV.

(2) 130g of 2-methylimidazole was diluted 2.5-fold with a second solvent to give a 2-methylimidazole dilution. Slowly adding 2-methylimidazole diluent into the epoxy resin base stock diluent prepared in the step (1) in a dropwise manner for 3 hours, and slowly stirring in the dropwise manner.

(3) And after the dripping is finished, the temperature is raised to 80 ℃ again, the mixture is stirred and reacts for 4 hours, the temperature is continuously raised to 150 ℃ and the mixture is distilled under reduced pressure, so that the coarse material of the curing accelerator is obtained.

The inorganic filler material is silica with the particle size of 0.5 mu m, and is purchased from Yadu Ma commercial (Shanghai) Inc. under the model number SC2500-SQ.

The thickener is silanized surface treated nano-grade fumed silica, and is purchased from cabo-O-SIL TS720.

The preparation method of the epoxy resin composition comprises the following specific steps:

s1, weighing 19 parts of epoxy resin, 14 parts of nano epoxy resin, 3 parts of reactive diluent, 23 parts of curing agent, 2 parts of curing accelerator, 38 parts of inorganic filling material and 1 part of thickener according to parts by weight;

s2, sequentially adding the epoxy resin, the nano epoxy resin, the reactive diluent, the curing agent, the curing accelerator, the inorganic filling material and the thickener into a material cylinder of a double-planetary dispersing instrument, and stirring for 15min at a first stirring speed; the vacuum degree of the material cylinder is set to be-0.08 MPa, and the material cylinder is stirred for 90min at a second stirring speed.

The first stirring speed is 100r/min, and the second stirring speed is 1000r/min.

Example 2.

The present example provides a low warpage epoxy resin composition. The raw materials comprise, by weight: 27 parts of epoxy resin, 10 parts of nano epoxy resin, 5 parts of reactive diluent, 28 parts of curing agent, 2 parts of curing accelerator, 37 parts of inorganic filling material and 1 part of thickener.

The epoxy resin is phenolic epoxy resin, and is purchased from Shanghai Kaijin chemical industry Co., ltd, and the model is Dow DEN438.

The nano epoxy resin is purchased from Yingchang industrial group and has the model number of NANOPOX E500.

The reactive diluent is glycidyl carbonate E10P, and the CAS number is 26761-45-5.

The curing agent is 1,3, 5-tris (3-mercaptobutyryloxyethyl) -1,3, 5-triazine-2, 4,6 (1H, 3H, 5H) -trione, and the CAS number is 928339-75-7.

The inorganic filler material is silicon dioxide with the particle size of 1.1 mu m, and is purchased from Yadu Ma commercial (Shanghai) limited company, and the model is SC4500-SQ.

s1, weighing 27 parts of epoxy resin, 10 parts of nano epoxy resin, 5 parts of reactive diluent, 28 parts of curing agent, 2 parts of curing accelerator, 37 parts of inorganic filling material and 1 part of thickener according to parts by weight;

Example 3.

A low warpage epoxy resin composition, and a specific embodiment is as in example 1. Except that no nano-epoxy was added.

Example 4.

A low warpage epoxy resin composition, and a specific embodiment is as in example 1. The difference is that the particle size of the added filler is commercial large-particle silicon micropowder with the particle size of 12 mu m.

Example 5.

A low warpage epoxy resin composition, and a specific embodiment is as in example 1. The difference is that the curing accelerator is 2-methylimidazole, purchased from sigma aldrich (Shanghai) trade company, CAS number 693-98-1.

Performance test method

Warp value:

the obtained epoxy resin composition was used to attach a sensor chip of 0.5cm×0.5cm to a pcb board with a glue thickness of 30 μm, and the resultant was cured in an oven at 80℃for 30 minutes, and the warpage value of the material was measured using a Kihn's 3D meter.

Curing time:

the resulting epoxy resin composition was placed in an oven and heated at 80℃and the time required for curing was recorded. The same sample was repeated twice in the same manner, and the average value was obtained.

Performance test data

Table 1. Results of performance test of the epoxy resin compositions prepared in examples.

	Warp/μm	Curing time/s
			Example 1	8.9	26.4
Example 2	7.6	28.1
			Example 3	25.0	28.5 minutes
Example 4	36.1	28.9 minutes
			Example 5	\	> 30 minutes

Finally, it is pointed out that the foregoing examples are illustrative only and serve to explain some of the features of the method according to the application. The appended claims are intended to claim the broadest possible scope and the embodiments presented herein are merely illustrative of selected implementations based on combinations of all possible embodiments. It is, therefore, not the intention of the applicant that the appended claims be limited by the choice of examples illustrating the features of the application. Some numerical ranges used in the claims also include sub-ranges within which variations in these ranges should also be construed as being covered by the appended claims where possible.

Claims

1. The low-warpage epoxy resin composition is characterized by comprising the following raw materials in parts by weight: 19 parts of epoxy resin, 14 parts of nano epoxy resin, 3 parts of reactive diluent, 23 parts of curing agent, 2 parts of curing accelerator, 38 parts of inorganic filling material and 1 part of thickener;

the epoxy resin is bisphenol F type epoxy resin, and the model is Dow DER354;

the nano epoxy resin is purchased from Yingchang industrial group, and the model is NANOPOX E470;

the reactive diluent is p-di (epoxy ethyl) benzene;

the curing agent is pentaerythritol tetra (3-mercaptopropionic acid);

(1) Diluting 340g of epoxy resin base material with a first solvent for 1.5 times, and heating to 80 ℃ to obtain epoxy resin base material diluent; the model of the epoxy resin base material is EXA-835LV;

(2) Diluting 130g of 2-methylimidazole with a second solvent for 2.5 times to obtain a 2-methylimidazole diluent; slowly adding 2-methylimidazole diluent into the epoxy resin base stock diluent prepared in the step (1) in a dropwise manner for 3 hours, and slowly stirring in the dropwise manner;

(3) After the dripping is finished, the temperature is raised to 80 ℃ again, stirring is carried out for 4 hours, the temperature is continuously raised to 150 ℃ and the crude material of the curing accelerator is obtained through reduced pressure distillation;

(4) Grinding and sieving coarse materials of the curing accelerator to obtain powder with the particle size of 0.1-5 mu m, namely the curing accelerator;

the first solvent and the second solvent are methanol and toluene, and the mass ratio of the methanol to the toluene is 1:1 mixing the obtained solution;

the inorganic filling material is silicon dioxide with the particle size of 0.5 mu m;

the thickener is nano-scale fumed silica with silanized surface treatment;

s2, sequentially adding the epoxy resin, the nano epoxy resin, the reactive diluent, the curing agent, the curing accelerator, the inorganic filling material and the thickener into a material cylinder of a double-planetary dispersing instrument, and stirring for 15min at a first stirring speed; setting the vacuum degree of the material cylinder to be-0.08 MPa, and stirring for 90min at a second stirring speed;