Insulating sealant coating

Abstract

The embodiment of the present application relates to the technical field of insulating glue, and discloses an insulating sealing coating glue, which comprises 60-80 parts of modified styrene-butadiene-styrene block copolymer, 0.3-1 part of ketone imine curing agent, 2-8 parts of aromatic amine curing agent, 3-8 parts of methyl silicone oil and 12-26 parts of petroleum ether, wherein the modified styrene-butadiene-styrene block copolymer is obtained by epoxidation of styrene-butadiene-styrene block copolymer (SBS), the molecular weight of the styrene-butadiene-styrene block copolymer is 7000-11000, the amount-of-substance fraction of PB end (polybutadiene segment) is 70-85%, and the branch structure:linear structure in the PB end is 1:2-1:3. The insulating sealing coating glue has the characteristics of high reliability, uniform glue hanging in multiple axial directions, especially in the vertical direction (i.e. z-axis direction), and is convenient to spray, and is beneficial to application on precision components.

Description

Technical Field

[0001] This application relates to the technical field of insulating adhesives, and in particular to an insulating and sealing coating adhesive. Background Technology

[0002] PCBA, or Printed Circuit Board Assembly, is a circuit board assembly with specific functions formed by soldering electronic components onto a PCB. Through the collaborative work of its components, it achieves the circuit board's preset functions, thus becoming a core component of electronic devices. The integrity and durability of the PCBA's structure and function play a decisive role in the performance and functionality of electronic products. To avoid the negative impact of environmental factors such as moisture on the operational stability and lifespan of components, protective materials are typically applied after the precision components are mounted on the PCBA, encapsulating and protecting the pin locations or the entire component.

[0003] As onboard components become increasingly dense and the reliability requirements of electronic components rise, traditional protective materials are gradually revealing new problems in practical applications. For example, traditional conformal coatings, due to their low viscosity and poor thixotropy, struggle to achieve uniform coverage for components with large dimensions in the Z-axis direction (or vertical direction), especially on the vertical surfaces of the components, leading to a decrease in protective effectiveness. However, increasing the viscosity of the protective material makes it unsuitable for spraying methods, further complicating the coating process. Furthermore, traditional protective materials have limited reliability, typically failing tests under harsh environmental conditions such as uHAST or PCT, and only maintaining their performance for 200 to 300 hours in SIR tests under double 85 conditions.

[0004] Therefore, in order to meet the current trends in component manufacturing, how to provide a protective material with high reliability, high adhesion and easy coating is a technical problem that urgently needs to be solved by those in the field. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide an insulating and sealing coating adhesive. This adhesive achieves high reliability and, in particular, coating uniformity in the Z-axis direction through a blend of modified styrene-butadiene-styrene block copolymer, ketimine curing agent, and aromatic amine curing agent. It is also easy to spray, facilitating application to PCBs and precision electronic components.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An insulating and sealing coating adhesive, characterized in that it comprises components in the following parts by mass ratio:

[0008]

[0009] The modified styrene-butadiene-styrene block copolymer has the structural formula as shown in formula (I):

[0010]

[0011] Preferably, the styrene-butadiene-styrene block copolymer has a molecular weight of 7000-11000, wherein the molar fraction of the PB end (polybutadiene segment) is 70-85%, and the molar ratio of the branched structure to the straight structure in the PB end is (1:2)-(1:3).

[0012] Preferably, it also includes 3-5 parts of fumed silica.

[0013] Preferably, the modified styrene-butadiene-styrene block copolymer is obtained by heating styrene-butadiene-styrene block copolymer (SBS) and H2O2 under the action of formic acid and a catalyst, wherein the molar ratio of H2O2 to SBS is (300:1)-(600:1).

[0014] Preferably, the molar ratio of formic acid to H2O2 is (1:0.9)-(2:1).

[0015] Preferably, the heating temperature is 65℃-85℃.

[0016] Preferably, the preparation method of the modified styrene-butadiene-styrene block copolymer includes: dissolving SBS and formic acid in an alkane solution, adding the catalyst, heating and slowly adding H2O2 while stirring;

[0017] The concentration of SBS in the alkane solvent is 80-105 g / L. The alkane solvent can be cyclohexane or other saturated hydrocarbons with boiling points above the reaction temperature that can dissolve SBS.

[0018] Preferably, in the step of adding the H2O2, the H2O2 solution is used, and the concentration of the H2O2 solution is not less than 25%.

[0019] Preferably, the aromatic amine curing agent is one or more of diaminophenylmethane, diaminodiphenyl sulfone, phenylenediamine trimer and its derivatives.

[0020] Preferably, the ketimine curing agent is prepared by condensation of methyl isopropyl ketone / methyl isobutyl ketone with a triamine.

[0021] Based on the above technical solution, the present invention has the following technical effects:

[0022] 1. This invention provides an insulating and sealing coating adhesive. This adhesive achieves high reliability and uniform multi-axial, especially Z-axis, coating through the modification of the styrene-butadiene-styrene block copolymer's inherent structural characteristics and its compounding with ketimine and aromatic amine curing agents. It is also easy to spray onto PCBs and precision electronic components. Due to its low viscosity, this insulating and sealing coating adhesive can be sprayed through a nozzle and adheres to the component surface. Upon contact with moisture in the air, the adhesive rapidly undergoes initial curing, thus adhering well to the vertical direction of the component. Subsequent heating achieves secondary curing, further enhancing the properties of the formed insulating layer and resulting in high reliability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the rating of the "excellent" level in the uniformity test of insulating adhesive coating of the present invention.

[0024] Figure 2 This is a schematic diagram illustrating the rating of the "good" level in the uniformity test of insulating adhesive coating of the present invention.

[0025] Figure 3 This is a schematic diagram illustrating the medium-level rating in the uniformity test of insulating adhesive coating of the present invention.

[0026] Figure 4 This is a schematic diagram illustrating the rating of poor grades in the uniformity test of insulating adhesive coating according to the present invention. Detailed Implementation

[0027] To facilitate understanding of the present invention, a more comprehensive description will be provided below with reference to specific embodiments. Preferred embodiments are given herein. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0028] Before further describing in more detail the various embodiments of the compounds / compositions and methods of this disclosure through exemplary descriptions, examples, and results, it should be understood that the embodiments of this disclosure are not limited in application to the details of the methods and compositions described below. The descriptions provided herein are for illustrative purposes only and are not intended to be interpreted in a limiting sense. The inventive concept of this disclosure can have other embodiments or can be practiced or implemented in various ways. Therefore, the language used herein is intended to give the broadest scope and meaning; and the embodiments are intended to be exemplary, not exhaustive, and are not intended to limit this disclosure to these particular embodiments. Moreover, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting unless otherwise stated. Furthermore, numerous specific details are set forth in the following detailed description to provide a more thorough understanding of this disclosure.

[0029] However, it will be apparent to those skilled in the art that embodiments of this disclosure can be practiced without these specific details. In other instances, features well-known to those skilled in the art have not been described in detail to avoid unnecessary complexity. It is intended that all substitutions, replacements, modifications, and equivalents that are apparent to those skilled in the art are included within the scope of this disclosure. Based on this disclosure, all compounds / compositions disclosed herein, their preparation methods, applications, and uses can be prepared and implemented without excessive experimentation.

[0030] Therefore, although the compounds / compositions and methods of this disclosure have been described with reference to specific embodiments, it will be apparent to those skilled in the art that variations may be made to the formulations, compounds or compositions and / or methods, as well as the steps or sequence of steps of the methods described herein, without departing from the spirit and scope of the inventive concept of this disclosure.

[0031] As used herein, any reference to "an embodiment" or "an embodiment" means that a particular element, feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. The phrase "in an embodiment" appearing in multiple places throughout the specification does not necessarily refer to the same embodiment.

[0032] Unless otherwise defined herein, scientific and technical terms used in connection with this disclosure shall have the meanings commonly understood by one of ordinary skill in the art. Furthermore, unless the context requires otherwise, singular terms shall include plural forms, and plural terms shall include singular forms.

[0033] Example 1

[0034] Preparation of modified styrene-butadiene-styrene block copolymers

[0035] 1 mol of styrene-butadiene-styrene (SBS) and 315 mol of formic acid were added to cyclohexane, along with approximately 0.02 mol of cyclodextrin as a phase transfer catalyst. The mixture was heated to a certain temperature, and 30% hydrogen peroxide containing 450 mol of H2O2 was added uniformly over 210 min with vigorous stirring. After the addition was complete, stirring was continued for more than 3 hours. The phases were then separated, and the organic phase was washed with weakly alkaline water until neutral. The solvent was then removed by vacuum distillation to obtain the modified styrene-butadiene-styrene block copolymer.

[0036] The modified styrene-butadiene-styrene block copolymer has the structural formula described in formula (I):

[0037]

[0038] In this process, the SBS material undergoes epoxidation through a process shown in formula (II).

[0039]

[0040] In this embodiment, the raw material SBS has a molecular weight of 9000, with a polybutadiene segment (PB end) molar fraction of 80%, a branched structure to linear structure molar ratio of 1:2.5 in the PB end, a molar ratio of H2O2 to SBS of 450:1, a molar ratio of formic acid to H2O2 of 1:0.7, a stirring time of 180 minutes, and a SBS concentration of 95 g / L in cyclohexane to obtain a modified styrene-butadiene-styrene block copolymer with a H2O2 concentration of 25%.

[0041] Preparation of insulating and sealing coating adhesive

[0042] Weigh 70 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.6 parts of ketimine curing agent, 5 parts of aromatic amine curing agent, 5.4 parts of methyl silicone oil, and 19 parts of petroleum ether, and disperse them evenly in a homogenizer to obtain the insulating and sealing coating adhesive. Preferably, to maintain the properties of the insulating and sealing coating adhesive, it can be packaged in sealed nitrogen-filled packaging.

[0043] When applying, the sample is uniformly sprayed onto the circuit board using a spray gun under ambient humidity of 75% and temperature of 25°C. After standing for at least 15 minutes, it is cured in an oven at 120°C for 15 minutes.

[0044] Example 2

[0045] Unlike Example 1, the raw material SBS used had a molecular weight of 11,000, with a PB end content of 70%, a molar ratio of branched to straight-chain structures of PB end of 1:2, a molar ratio of H2O2 to SBS of 600:1, a molar ratio of formic acid to H2O2 of 2:1, a stirring time of 180 minutes, and a SBS concentration of 105 g / L in cyclohexane.

[0046] Example 3

[0047] Unlike Example 1, the raw material SBS used had a molecular weight of 7000, with a PB end content of 85%, a molar ratio of branched to straight-chain structures of PB end of 1:3, a molar ratio of H2O2 to SBS of 300:1, a molar ratio of formic acid to H2O2 of 1:0.9, a stirring time of 240 minutes, and a SBS concentration of 105 g / L in cyclohexane.

[0048] Example 4

[0049] Unlike Example 1, 80 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.3 parts of ketimine curing agent, 2 parts of aromatic amine curing agent, 5.7 parts of methyl silicone oil, and 12 parts of petroleum ether were weighed and dispersed evenly in a homogenizer to obtain the insulating and sealing coating adhesive.

[0050] Example 5

[0051] Unlike Example 1, in the preparation of the modified styrene-butadiene-styrene block copolymer, the concentration of SBS in cyclohexane was 80 g / L. 60 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 1 part of ketimine curing agent, 8 parts of aromatic amine curing agent, 5 parts of methyl silicone oil, and 26 parts of petroleum ether were weighed and dispersed evenly in a homogenizer to obtain the insulating sealant coating adhesive.

[0052] Example 6

[0053] Unlike Example 1, 66 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.6 parts of ketimine curing agent, 5 parts of aromatic amine curing agent, 8 parts of methyl silicone oil, 20.4 parts of petroleum ether, and 4 parts of fumed silica were weighed and dispersed evenly in a homogenizer to obtain the insulating and sealing coating adhesive.

[0054] Comparative Example 1

[0055] Unlike Example 1, the raw material SBS used has a molecular weight of 13,000.

[0056] Comparative Example 2

[0057] Unlike Example 1, the raw material SBS used has a molecular weight of 5000.

[0058] Comparative Example 3

[0059] Unlike Example 1, the molar fraction of the PB end in the raw material SBS is 60%.

[0060] Comparative Example 4

[0061] Unlike Example 1, the molar fraction of the PB end in the raw material SBS is 95%.

[0062] Comparative Example 5

[0063] Unlike Example 1, in the PB end of the raw material SBS, the molar ratio of branched structure to linear structure is 1:4.

[0064] Comparative Example 6

[0065] Unlike Example 1, in the PB end of the raw material SBS, the molar ratio of branched structure to linear structure is 1:1.

[0066] Comparative Example 7

[0067] Unlike Example 1, the molar ratio of H2O2 to SBS in the preparation process is 200:1.

[0068] Comparative Example 8

[0069] Unlike Example 1, the molar ratio of H2O2 to SBS in the preparation process is 800:1.

[0070] Comparative Example 9

[0071] Unlike Example 1, 74 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.6 parts of ketimine curing agent, 1 part of aromatic amine curing agent, 5.4 parts of methyl silicone oil and 19 parts of petroleum ether were weighed and dispersed evenly in a homogenizer to obtain the comparative coating adhesive.

[0072] Comparative Example 10

[0073] Unlike Example 1, 63 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.6 parts of ketimine curing agent, 12 parts of aromatic amine curing agent, 5.4 parts of methyl silicone oil and 19 parts of petroleum ether were weighed and placed in a homogenizer to disperse evenly, thus obtaining the coating adhesive of this example.

[0074] Comparative Example 11

[0075] Unlike Example 1, 70.5 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 0.1 parts of ketimine curing agent, 5 parts of aromatic amine curing agent, 5.4 parts of methyl silicone oil and 19 parts of petroleum ether were weighed and placed in a homogenizer to disperse evenly, thus obtaining the coating adhesive of this example.

[0076] Comparative Example 12

[0077] Unlike Example 1, 68.6 parts of the modified styrene-butadiene-styrene block copolymer prepared above, 2 parts of ketimine curing agent, 5 parts of aromatic amine curing agent, 5.4 parts of methyl silicone oil and 19 parts of petroleum ether were weighed and placed in a homogenizer to disperse evenly, thus obtaining the coating adhesive of this example.

[0078] The insulating adhesives prepared in Examples 1-6 and Comparative Examples 1-12 were used to measure their viscosity using a cone-barrel viscometer (CP52) at 25°C and a rotation speed of 2 revolutions per minute (rpm). A weathering test was conducted under the following conditions: temperature 85°C and relative humidity 85%. The specific method for the weathering test was to place the sample in a double 85°C test chamber and time it. After a certain period, the sample was removed and its resistivity was measured using a high-resistivity meter at 250V. When the resistivity was higher than 10... 8 Ω / cm, return to the test chamber and continue timing; repeat the above operation until the resistivity is below 10 Ω / cm. 8 Ω / cm is considered as insulation failure, and the total time spent in the test chamber is recorded as weather resistance. The insulation is then applied to the PCBA samples using a spray coating method, and its uniformity is judged by the degree of coverage in the Z-axis direction (i.e., the vertical direction). Specific evaluation criteria are detailed below. Figures 1 to 4 The data results obtained after the above tests are shown in Table 1.

[0079] Table 1. Test results of insulating adhesive performance for each experimental group

[0080]

[0081]

[0082] As shown in Table 1, the viscosity of the insulating and sealing coating adhesives prepared in Examples 1 to 6 is between 9000 and 19000, and the uniformity of the Z-axis coating is excellent or above. This makes them suitable for spraying processes while also possessing excellent encapsulation properties, allowing for uniform coating and facilitating their application in precision components. Furthermore, the initial insulation of the insulating and sealing coating adhesives in Examples 1 to 6 can reach 10. 10 Ω / cm or higher, and can reach more than 500 hours and not less than 10 under double 85 test. 8The Ω / cm ratio balances insulation and reliability. Therefore, the insulating and sealing coating adhesive provided by this invention exhibits excellent overall performance, making it a highly reliable, highly adhesive, and easy-to-apply protective material.

[0083] The above description is merely an example and illustration of the structure of this invention, and while the description is specific and detailed, it should not be construed as limiting the scope of this invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention, and these obvious substitutions all fall within the protection scope of this invention.

Claims

1. An insulating and sealing coating adhesive, characterized in that, Includes components in the following parts by mass ratios: 60-80 parts of modified styrene-butadiene-styrene block copolymer Ketoimine curing agent 0.3-1 part 2-8 parts of aromatic amine curing agent 3-8 parts of methyl silicone oil 12-26 parts of petroleum ether The modified styrene-butadiene-styrene block copolymer has the structural formula as shown in formula (I): Equation (I); The styrene-butadiene-styrene block copolymer has a molecular weight of 7000-11000, wherein the molar fraction of the PB end (polybutadiene segment) is 70-85%, and the molar ratio of the branched structure to the straight structure in the PB end is (1:2)-(1:3). The modified styrene-butadiene-styrene block copolymer is obtained by heating styrene-butadiene-styrene block copolymer (SBS) and H2O2 under the action of formic acid and catalyst, with the molar ratio of H2O2 to SBS being (300:1)-(600:1). The structural formula of the styrene-butadiene-styrene block copolymer (SBS) is: 。 2. The insulating and sealing coating adhesive according to claim 1, characterized in that, It also includes 3-5 parts of fumed silica.

3. The insulating and sealing coating adhesive according to claim 1 or 2, characterized in that, The molar ratio of the formic acid to the H2O2 is (1:0.9)-(2:1).

4. The insulating and sealing coating adhesive according to claim 3, characterized in that, The heating temperature is 65℃-85℃.

5. The insulating and sealing coating adhesive according to claim 1 or 2, characterized in that, The preparation method of the modified styrene-butadiene-styrene block copolymer includes: dissolving SBS and formic acid in an alkane solution, adding the catalyst, heating and slowly adding H2O2 while stirring; The concentration of SBS in alkane solvents is 80-105 g / L.

6. The insulating and sealing coating adhesive according to claim 5, characterized in that, In the step of adding H2O2 dropwise, the H2O2 solution is used, and the concentration of the H2O2 solution is not less than 25%.

7. The insulating and sealing coating adhesive according to claim 1, characterized in that, The aromatic amine curing agent is one or more of diaminophenylmethane, diaminodiphenyl sulfone, phenylenediamine trimer and its derivatives.

8. The insulating and sealing coating adhesive according to claim 1, characterized in that, The ketimine curing agent is prepared by condensation of methyl isopropyl ketone / methyl isobutyl ketone with a triamine.

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