Bottom filling adhesive for FCBGA packaging and preparation method thereof

Abstract

The invention discloses an underfill adhesive for FCBGA packaging and a preparation method of the underfill adhesive. The underfill adhesive is prepared from the following components: silanol modified epoxy resin, alicyclic epoxy resin, silicon dioxide, a curing agent, a coloring agent, an adhesion promoter and a diluent. The epoxy resin is modified by using triethyl silanol, a triethyl silanol segment is introduced into bisphenol A type epoxy resin, so that the bisphenol A type epoxy resin has high flexibility, the bisphenol A type epoxy resin is endowed with high flexibility, the atomic radius of silicon atoms is larger than that of carbon atoms, chemical bonds around the silicon atoms can rotate within a large angle range, and therefore the flexibility of the epoxy resin is improved. Therefore, the molecular chain has better flexibility. Meanwhile, through the synergistic effect of the silanol modified epoxy resin and the alicyclic epoxy resin, the overall expansion coefficient, curing speed and other properties of the bottom filling adhesive are optimized, and the filling requirement of a bottom gap between a bare chip and a packaging substrate is met.

Description

Technical Field

[0001] The invention relates to the technical field of chip packaging, and in particular to a bottom filling glue for FCBGA packaging and a preparation method thereof. Background Art

[0002] FCBGA is mainly used in the field of high-density, high-speed, and multifunctional large-scale integrated circuit chip packaging by pasting the chip on the substrate in the form of flip-chip and using spherical solder as the electrical connection point. FCBGA packaging technology began in the 1960s and was originally developed by IBM for the assembly of large computers. Later, it gradually developed into an important packaging technology. The FCBGA packaging process is as follows: 1. Cut the wafer into bare chips (also called Dies); 2. Apply solder paste to the corresponding position of the packaging substrate through the steel mesh solder paste printing process, paste the bare chip on the packaging substrate and then heat it for reflow soldering; 3. Use FCBGA's bottom filler as an adhesive to fill between the bare chip and the packaging substrate. The function of FCBGA's bottom filler is to enhance the mechanical connection strength between the bare chip and the packaging substrate, disperse the stress generated by the bare chip and the packaging substrate when the temperature changes due to the different thermal expansion coefficients, thereby improving the reliability and stability of the package. The bottom filling glue of this FCBGA uses chemical glue (the main component is epoxy resin) and uses the capillary principle to make the bottom filling glue penetrate into the bottom gap of the FCBGA, thereby filling the bottom and using heating to cure to achieve the purpose of reinforcement, thereby enhancing the drop resistance between the bare chip and the packaging substrate of the FCBGA packaging mode.

[0003] At present, the bottom filler is mainly composed of epoxy resin. Epoxy resin has the advantages of good adhesion and low curing shrinkage, which makes it widely used in the field of electronic packaging. At present, this kind of FCBGA bottom filler is imported from Japan or the United States. There is still a blank in China, which limits the use of FCBGA bottom filler by domestic enterprises. Moreover, with the further development of electronic technology, the performance requirements for FCBGA bottom filler are becoming increasingly stringent. The bottom filler made of epoxy resin has gradually shown its limitations, such as its poor flexibility. When the electronic equipment is subjected to greater mechanical stress, the bottom filler is difficult to fully adapt to the stress change, and it is easy to crack and lose the protective effect on the solder joints; in addition, the thermal expansion coefficient of the bottom filler of FCBGA is relatively high, which causes the package to crack and the solder joints to fail.

[0004] Therefore, in view of the shortcomings of the prior art, it is necessary to provide a bottom filling glue for FCBGA packaging and a preparation method thereof to solve the shortcomings of the prior art. Summary of the invention

[0005] The first purpose of the present invention is to avoid the shortcomings of the prior art and provide a bottom filler for FCBGA packaging. The bottom filler for FCBGA packaging has good impact resistance and a low thermal expansion coefficient.

[0006] The above-mentioned purpose of the present invention is achieved by the following technical measures:

[0007] Provided is a bottom filling glue for FCBGA packaging, the bottom filling glue consists of the following components: silanol modified epoxy resin, alicyclic epoxy resin, silicon dioxide, a curing agent, a dye, an adhesion promoter, and a diluent.

[0008] The preparation method of the silanol-modified epoxy resin is that bisphenol A epoxy resin and triethylsilanol are reacted with triethylamine to obtain the silanol-modified epoxy resin.

[0009] The bottom filling glue for FCBGA packaging of the present invention is calculated by weight.

[0010] Silicon alcohol modified epoxy resin: 30 to 40 parts;

[0011] Alicyclic epoxy resin: 20 to 30 parts;

[0012] Silicon dioxide: 20 to 25 parts;

[0013] Curing agent: 5 to 10 parts;

[0014] Dye: 0.5 to 2 parts;

[0015] Adhesion promoter: 0.05 to 0.2 parts;

[0016] Diluent: 10 to 20 parts.

[0017] The bottom filling glue for FCBGA packaging of the present invention is calculated by weight.

[0018] Silicon alcohol modified epoxy resin: 35 parts;

[0019] Alicyclic epoxy resin: 28 parts;

[0020] Silicon dioxide: 22 parts;

[0021] Curing agent: 7 parts;

[0022] Coloring agent: 1.3 parts;

[0023] Adhesion promoter: 0.1 part;

[0024] Diluent: 15 parts.

[0025] In the silanol-modified epoxy resin, the molar ratio of bisphenol A epoxy resin, triethylsilanol and triethylamine is 1:5-8:0.01-0.05.

[0026] In the silanol-modified epoxy resin, the molar ratio of bisphenol A epoxy resin, triethylsilanol and triethylamine is 1:6.4:0.02.

[0027] Preferably, the alicyclic epoxy resins are MF-3285 and CER-170, and the weight ratio of MF-3285 to CER-170 is 1:1.5.

[0028] Preferably, the silanol-modified epoxy resin is prepared by the following steps:

[0029] S1, bisphenol A epoxy resin and triethylsilanol are mixed for 25 min to 40 min, and heated to 60° C. to 80° C. to obtain a mixture;

[0030] S2. Add triethylamine to the mixture obtained in S1, raise the temperature to 110° C. to 115° C., and react for 60 min to 100 min to obtain the silanol-modified epoxy resin.

[0031] Preferably, the silanol-modified epoxy resin is prepared by the following steps:

[0032] S1, bisphenol A epoxy resin and triethylsilanol were mixed for 36 minutes and heated to 73° C. to obtain a mixture;

[0033] S2. Add triethylamine to the mixture obtained in S1, raise the temperature to 113° C., and react for 80 minutes to obtain the silanol-modified epoxy resin.

[0034] Preferably, the adhesion promoter is NXH-635.

[0035] Preferably, the curing agent is an anhydride oligomer with a molecular weight of 1500-1600 Da.

[0036] Preferably, the above-mentioned coloring agent includes carbon black.

[0037] Preferably, the diluent is butyl glycidyl ether, dodecyl glycidyl ether, or 4-tert-butylphenyl glycidyl ether.

[0038] The second purpose of the present invention is to avoid the shortcomings of the prior art and provide a method for preparing a bottom filler for FCBGA packaging. The bottom filler for FCBGA packaging prepared by the method has good impact resistance and low thermal expansion coefficient.

[0039] The above-mentioned purpose of the present invention is achieved by the following technical measures:

[0040] A method for preparing the bottom filling glue for FCBGA packaging as described above is provided, which is prepared by the following steps:

[0041] A1. Put the silanol modified epoxy resin, alicyclic epoxy resin and dye into a stirring device, and stir and disperse them evenly under a vacuum environment;

[0042] A2. Put silicon dioxide, diluent and adhesion promoter into a stirring device and stir and disperse them evenly under a vacuum environment;

[0043] A3. Put the curing agent into a stirring device, stir and disperse it evenly under a vacuum environment to obtain the bottom filling glue.

[0044] The present invention discloses a bottom filling glue for FCBGA packaging and a preparation method thereof, wherein the bottom filling glue is composed of the following components: a silanol-modified epoxy resin, an alicyclic epoxy resin, silicon dioxide, a curing agent, a dye, an adhesion promoter, and a diluent; the preparation method of the silanol-modified epoxy resin is to obtain the silanol-modified epoxy resin by using a bisphenol A type epoxy resin and triethylsilanol under the catalysis of triethylamine. The beneficial effects of the present invention are as follows: the present invention uses triethylsilanol to modify the epoxy resin, and introduces a triethylsilanol segment into the bisphenol A type epoxy resin to have greater flexibility, thereby giving the bisphenol A type epoxy resin greater flexibility, and the atomic radius of silicon atoms is larger than that of carbon atoms, and the chemical bonds around them can rotate within a larger angle range, so that the molecular chain has better flexibility. At the same time, through the synergistic effect of the silanol-modified epoxy resin and the alicyclic epoxy resin, the overall expansion coefficient, curing speed and other properties of the bottom filling glue can be optimized to meet the bottom gap filling requirements between the bare chip and the packaging substrate. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described in conjunction with the following examples. Unless otherwise specified, the raw materials used in the following examples are all commercially available products.

[0046] The underfill, underfill, underfill composition and underfill material mentioned in the present invention are used interchangeably and refer to an adhesive with resin as the main material, which is usually used to fill the gap between a semiconductor component (such as a semiconductor chip) and a substrate. Underfill refers to the process of applying the underfill to the interface between the semiconductor component and the substrate to fill the gap between the underfill and the substrate.

[0047] Example 1

[0048] A bottom filling glue for FCBGA packaging, the bottom filling glue is composed of the following components: silanol modified epoxy resin, alicyclic epoxy resin, silicon dioxide, curing agent, dye, adhesion promoter, diluent. Among them, the adhesion promoter is NXH-635;

[0049] The curing agent is an anhydride oligomer with a molecular weight of 1500-1600Da. The alicyclic epoxy resins are MF-3285 and CER-170, and the weight ratio of MF-3285 to CER-170 is 1:1.5. The CER-170 alicyclic epoxy resin is Senmao brand, and the MF-32850 alicyclic epoxy resin is purchased from Hubei Zhenzhengfeng New Materials Co., Ltd.

[0050] The preparation method of the silanol modified epoxy resin is that bisphenol A epoxy resin and triethylsilanol are catalyzed by triethylamine to obtain the silanol modified epoxy resin, wherein the bisphenol A epoxy resin of the present invention is 828 epoxy resin of Shell Company.

[0051] The silanol-modified epoxy resin is carried out by the following steps:

[0052] S1, bisphenol A epoxy resin and triethylsilanol were mixed for 40 minutes and heated to 80° C. to obtain a mixture;

[0053] S2. Add triethylamine to the mixture obtained in S1, raise the temperature to 115° C., and react for 100 minutes to obtain a silanol-modified epoxy resin.

[0054] The method for preparing the bottom filling glue is characterized by comprising the following steps:

[0055] A1. Put the silanol modified epoxy resin, alicyclic epoxy resin and dye into a stirring device, and stir and disperse them evenly under a vacuum environment;

[0056] A2. Put silicon dioxide, diluent and adhesion promoter into a stirring device and stir and disperse them evenly under a vacuum environment;

[0057] A3. Add the curing agent into the stirring device, stir and disperse it evenly under a vacuum environment to obtain the bottom filling glue.

[0058] Wherein, the weight parts of each component are shown in Table 1:

[0059] Table 1. Weight parts of each component of Example 1

[0060]

[0061] Example 2

[0062] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 1, except that:

[0063] The silanol-modified epoxy resin is carried out by the following steps:

[0064] S1, bisphenol A epoxy resin and triethylsilanol were mixed for 25 minutes and heated to 60° C. to obtain a mixture;

[0065] S2. Add triethylamine to the mixture obtained in S1, raise the temperature to 110° C., and react for 60 minutes to obtain a silanol-modified epoxy resin.

[0066] Wherein, the weight parts of each component are shown in Table 2:

[0067] Table 2. Weight parts of each component of Example 2

[0068]

[0069] Example 3

[0070] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 1, except that:

[0071] The silanol-modified epoxy resin is carried out by the following steps:

[0072] S1, bisphenol A epoxy resin and triethylsilanol were mixed for 36 minutes and heated to 73° C. to obtain a mixture;

[0073] S2. Add triethylamine to the mixture obtained in S1, raise the temperature to 113° C., and react for 80 minutes to obtain a silanol-modified epoxy resin.

[0074] Wherein, the weight parts of each component are shown in Table 3:

[0075] Table 3. Weight parts of each component of Example 3

[0076]

[0077] Comparative Example 1

[0078] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 3, except that:

[0079] Table 4. Weight parts of each component of Comparative Example 1

[0080]

[0081] Comparative Example 2

[0082] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 3, except that:

[0083] Table 5. Weight parts of each component of Comparative Example 2

[0084]

[0085] Comparative Example 3

[0086] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 3, except that:

[0087] Table 6. Weight parts of each component of Comparative Example 3

[0088]

[0089] The method for preparing the bottom filling glue is characterized by comprising the following steps:

[0090] A1. Put alicyclic epoxy resin and dye into a stirring device, and stir and disperse them evenly under vacuum;

[0091] A2. Put silicon dioxide, diluent and adhesion promoter into a stirring device and stir and disperse them evenly under a vacuum environment;

[0092] A3. Add the curing agent into the stirring device, stir and disperse it evenly under a vacuum environment to obtain the bottom filling glue.

[0093] Comparative Example 4

[0094] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 3, except that:

[0095] Table 7. Weight parts of each component of Comparative Example 4

[0096]

[0097]

[0098] The method for preparing the bottom filling glue is characterized by comprising the following steps:

[0099] A1. Put the silanol-modified epoxy resin and dye into a stirring device and stir and disperse them evenly under a vacuum environment;

[0100] A2. Put silicon dioxide, diluent and adhesion promoter into a stirring device and stir and disperse them evenly under a vacuum environment;

[0101] A3. Add the curing agent into the stirring device, stir and disperse it evenly under a vacuum environment to obtain the bottom filling glue.

[0102] Comparative Example 5

[0103] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 3, except that:

[0104] Table 8. Weight parts of each component of Comparative Example 5

[0105]

[0106] Comparative Example 6

[0107] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 3, except that:

[0108] Table 9. Weight parts of each component of Comparative Example 6

[0109]

[0110] Comparative Example 7

[0111] A bottom filling glue for FCBGA packaging, the other features are the same as those of embodiment 3, except that:

[0112] Table 10. Weight parts of each component of Comparative Example 7

[0113]

[0114] Effect example

[0115] 1. Flexibility and impact resistance test

[0116] The elongation at break, breaking strength and shear strength of the bottom filling glue prepared in Examples 1-3 and Comparative Examples 1-7 were tested. The test results are shown in Table 11.

[0117] Table 11. Elongation at break, breaking strength and shear strength data

[0118] Elongation at break (%) Breaking strength(MPa) Shear strength(MPa) Example 1 18.6 20.5 15.6 Example 2 19.8 21.5 16.2 Example 3 19.3 20.5 15.7 Comparative Example 1 12.4 15.5 11.3 Comparative Example 2 10.9 14.7 12.5 Comparative Example 3 8.7 13.6 10.4 Comparative Example 4 7.8 12.8 11.6 Comparative Example 5 10.5 14.2 12.9 Comparative Example 6 12.5 15.0 13.5 Comparative Example 7 15.7 18.6 14.3

[0119] It can be seen from the data in Table 11 that the elongation at break, breaking strength and shear strength of the bottom filling glue prepared in Examples 1-3 provided by the present invention are significantly higher than those of the bottom filling glue prepared in Comparative Examples 1-7, indicating that the bottom filling glue prepared by the preparation method provided by the present invention has excellent flexibility and impact resistance.

[0120] 2. Curing time test

[0121] The bottom filling glue prepared in Examples 1-3 and Comparative Examples 1-7 was subjected to curing tests at different temperatures to test the curing time at different temperatures. The curing time is shown in Table 12.

[0122] Table 12. Curing time data

[0123]

[0124]

[0125] It can be seen from the data in Table 12 that the curing time of the bottom filling glue prepared by Examples 1-3 provided by the present invention is lower than that of the bottom filling glue prepared by Comparative Examples 1-7. Therefore, it can be proved that the present invention has better low-temperature curing performance, thereby improving packaging efficiency.

[0126] 3. Thermal expansion coefficient test

[0127] According to the standard ASTME831-2019, take a sample that is completely cured at 165°C for 2h, and prepare a test sample with a size of 4mm×4mm×8mm. The thermal expansion coefficient of the sample is tested using thermomechanical analysis, and the heating rate is 5°C / min from 0°C to 260°C. The thermal expansion coefficient CTE1 between 25°C and 75°C, the thermal expansion coefficient CTE2 between 190°C and 240°C, and the thermal expansion coefficient CTE1 and thermal expansion coefficient CTE2 data are shown in Table 13.

[0128] Table 13. Data of thermal expansion coefficient CTE1 and thermal expansion coefficient CTE2

[0129] CTE1(ppm / ℃) CTE2(ppm / ℃) Example 1 28 147 Example 2 26 146 Example 3 24 142 Comparative Example 1 32 175 Comparative Example 2 34 178 Comparative Example 3 38 185 Comparative Example 4 42 183 Comparative Example 5 29 168 Comparative Example 6 31 171 Comparative Example 7 30 170

[0130] It can be seen from the data in Table 13 that the linear thermal expansion coefficient CTE1 and thermal expansion coefficient CTE2 of the bottom filling glue prepared in Examples 1-3 are lower than those of the comparative examples, among which the single silanol-modified epoxy resin or alicyclic epoxy resin in Comparative Examples 3 and 4 are significantly lower than the composite epoxy resin of the silanol-modified epoxy resin and alicyclic epoxy resin of the present invention.

[0131] In summary, the present invention can significantly improve flexibility and impact resistance by combining silanol-modified epoxy resin and alicyclic epoxy resin, and has excellent expansion coefficient, curing speed and other properties, so as to meet the bottom gap filling requirements between the bare chip and the packaging substrate. Moreover, the above data show that the present invention can further improve the above properties through the reasonable ratio of each component and appropriate preparation conditions.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A bottom filling glue for FCBGA packaging, characterized in that: The bottom filling glue is composed of the following components: silanol modified epoxy resin, alicyclic epoxy resin, silicon dioxide, curing agent, dye, adhesion promoter, and diluent; The preparation method of the silanol-modified epoxy resin is that bisphenol A epoxy resin and triethylsilanol are reacted with triethylamine to obtain the silanol-modified epoxy resin.

2. The bottom filler for FCBGA packaging according to claim 1, characterized in that: In parts by weight, Silicon alcohol modified epoxy resin: 30 to 40 parts; Alicyclic epoxy resin: 20 to 30 parts; Silicon dioxide: 20 to 25 parts; Curing agent: 5 to 10 parts; Dye: 0.5 to 2 parts; Adhesion promoter: 0.05 to 0.2 parts; Diluent: 10 to 20 parts.

3. The bottom filler for FCBGA packaging according to claim 2, characterized in that: In parts by weight, Silicon alcohol modified epoxy resin: 35 parts; Alicyclic epoxy resin: 28 parts; Silicon dioxide: 22 parts; Curing agent: 7 parts; Coloring agent: 1.3 parts; Adhesion promoter: 0.1 part; Diluent: 15 parts.

4. The bottom filler for FCBGA packaging according to any one of claims 1 to 3, characterized in that: In the silanol-modified epoxy resin, the molar ratio of bisphenol A epoxy resin, triethylsilanol and triethylamine is 1:5-8:0.01-0.

05.

5. The bottom filling glue for FCBGA packaging according to claim 4, characterized in that: In the silanol-modified epoxy resin, the molar ratio of bisphenol A epoxy resin, triethylsilanol and triethylamine is 1:6.4:0.02; The alicyclic epoxy resins are MF-3285 and CER-170, and the weight ratio of MF-3285 to CER-170 is 1:1.

5.

6. The bottom filling glue for FCBGA packaging according to claim 4, characterized in that: The silanol-modified epoxy resin is prepared by the following steps: S1, bisphenol A epoxy resin and triethylsilanol are mixed for 25 min to 40 min, and heated to 60° C. to 80° C. to obtain a mixture; S2. Add triethylamine to the mixture obtained in S1, raise the temperature to 110° C. to 115° C., and react for 60 min to 100 min to obtain the silanol-modified epoxy resin.

7. The bottom filling glue for FCBGA packaging according to claim 6, characterized in that: The silanol-modified epoxy resin is prepared by the following steps: S1, bisphenol A epoxy resin and triethylsilanol were mixed for 36 minutes and heated to 73° C. to obtain a mixture; S2. Add triethylamine to the mixture obtained in S1, raise the temperature to 113° C., and react for 80 minutes to obtain the silanol-modified epoxy resin.

8. The bottom filling glue for FCBGA packaging according to claim 7, characterized in that: The adhesion promoter is NXH-635; The curing agent is an anhydride oligomer with a molecular weight of 1500-1600 Da.

9. The bottom filler for FCBGA packaging according to claim 4, characterized in that: The diluent is butyl glycidyl ether, dodecyl glycidyl ether, or 4-tert-butylphenyl glycidyl ether.

10. A method for preparing the bottom filling glue for FCBGA packaging according to any one of claims 1 to 9, characterized in that: Prepared by the following steps: A1. Put the silanol modified epoxy resin, alicyclic epoxy resin and dye into a stirring device, and stir and disperse them evenly under a vacuum environment; A2. Put silicon dioxide, diluent and adhesion promoter into a stirring device and stir and disperse them evenly under a vacuum environment; A3. Put the curing agent into a stirring device, stir and disperse it evenly under a vacuum environment to obtain the bottom filling glue.

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