JPS6411074B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is applicable to electronic components that are overloaded or self-heating,
In other words, it relates to nonflammable paints for electronic parts used as coating materials for resistors, film capacitors, ceramic capacitors, coils, various heaters, etc. Construction of conventional examples and their problems Common paints for electronic parts are mainly organic, and epoxy-based, phenol-based, and silicon-based paints with excellent flame retardancy are known and put into practical use. However, in both cases, the curing and baking time of the paint is long (30 minutes to 2 hours).
In addition, silicon-based materials with excellent flame retardancy must be baked at high temperatures (over 180°C), and are not suitable for mass production in the manufacturing process of electronic components, and are considered unsuitable from an energy-saving perspective, but are often used. The current situation is that Particularly in recent years, from the standpoint of safety in the manufacturing process of electronic components, there has been a strong desire to develop nonflammable paints made of inorganic materials that are odorless, smokeless, and non-flammable and explosive. Purpose of the Invention The present invention has been made in view of the above points, and enables baking hardening at low temperatures (approximately 160°C) and in a short time (approximately 10 minutes), is non-flammable, is safe from a security standpoint, It is odorless and does not ignite due to self-heating due to overload or external flames, and has quality characteristics such as moisture resistance that are equal to or better than conventional products, and does not cause abnormal overload. The object of the present invention is to provide a nonflammable paint for electronic parts that is suitable as a coating material for electronic parts that are subject to load or self-heating. Structure of the Invention To achieve this object, the nonflammable paint for electronic components of the present invention comprises 1 part to 30 parts of aqueous colloidal silica having a silica solid content of 1% to 40% and 1 part to 5 parts of ethyl silicate monomer. is hydrolyzed using 1 to 2 parts of a titanate coupling agent as a catalyst and used as a binder component, and 50 parts to 50 parts of an inorganic filler such as silica powder, alumina powder, mica chips, etc.
70 parts and an inorganic pigment as necessary are mixed to form a uniform liquid slurry into a paint. According to this configuration, in the binder component, the silanol and titanium compound in the hydrolysis product are easily combined to form a thin and uniform film with a high crosslinking density. In particular, it is thought that the part of the titanium compound that binds to an inorganic substance and the part that has an affinity for ethersilicate due to silanol are crosslinked synergistically. Therefore, the present coating material has good mechanical adhesion to the metal or glass surface constituting the element body of the electronic component to be coated. Paints made by mixing such binder components with inorganic fillers and, if necessary, inorganic pigments, have a baking temperature of 150°C or more.
A hardening process at 170°C and a baking time of 10 to 15 minutes results in dehydration and condensation, producing ceramic-like siloxane and forming a dense coating film without generating harmful gases. Description of Examples Examples of the present invention will be described below. First, as shown in Table 1 below, a binder was prepared by hydrolyzing 25 parts of aqueous colloidal silica (silica solid content 20%) and 5 parts of ethyl silicate monomer using 1 part and 2 parts of a titanate coupling agent as a catalyst. As components, 70 parts of an inorganic filler and 1 part of an inorganic pigment were mixed therewith to form a uniform liquid slurry into a paint. Table 1 also shows a comparative example in which the titanate coupling agent was 0 parts and the other proportions were the same as above. The coating film properties as a paint at this time are shown in Table 2 below.

【table】

【table】

[Table] The performance (electrical performance and mechanical performance) of the coating paint as an electronic component in the above three types of paint is shown in Table 3 below.

【table】

[Table] Here, properties such as hardness were measured using the test resistor shown in FIG. 1, except for the coating film strength test. That is, in FIG. 1, 1 is an alumina substrate of 10 mm x 5 mm x 0.8 mm, 2 is a RuO ₂ -based resistor provided between electrodes 3 and 3 of the substrate 1, and 4 is a coating film made of the above-mentioned paint. In addition, Fig. 2 shows a diagram during a coating film strength test, where 5 is a 1 mm thick iron plate, 6 is a coating film made of the above paint (2 mm coating thickness), and 7 is a line buried in the above coating film 6. It is a terminal with a diameter of 0.6mm. In the coating film strength test, the terminal 7 was pulled in the direction of arrow F, and the resistance strength until the coating film 6 was destroyed was measured. In addition, the boiling test is the resistance change rate after immersing in boiling water for 30 minutes, and the pressurized steam test (steam cutter test) is the resistance value change rate after immersing the resistor in boiling water for 30 minutes. It is expressed as the rate of change in resistance value after standing for a period of time. Furthermore, the solvent resistance was measured by immersing the test resistor in a chlorocene solvent and cleaning it with ultrasonic waves for 30 minutes, and measuring the pencil hardness of the coating film. In addition, nonflammability was observed by instantaneously applying an overload power of 20 W to the resistor under test and conducting the current until the resistor 2 became open. Furthermore, the humidity resistance load was measured by continuously applying 1W to the resistor under test in an atmosphere of 60°C and 95% (relative humidity), and measuring the rate of change in resistance value after 1000 hours. The heat resistance load was measured by continuously applying 1W to the resistor under test in an atmosphere of 85°C, and measuring the rate of change in resistance value after 1000°C. As shown in Tables 2 and 3, the baked coating films of Examples 1 and 2 using the paints of the present invention can be cured by baking at low temperatures in a short time, are not attacked by solvents, and have excellent resistance to hygroscopicity. It can be seen that it has excellent moisture resistance and also shows better performance than conventional products in boiling and pressurized steam tests.
In particular, this nonflammable paint forms a coating film made mostly of inorganic materials after baking, so it does not cause flames or ignition when overloaded, and has excellent heat resistance, ensuring sufficient safety as an electronic component. It can be said that
Furthermore, since the solvent of this paint is water, it has good storage and workability, and paint adhesion and stains during handling of the paint can be easily wiped off with water. That is, the present invention provides a pollution-free, non-toxic, and odorless paint that does not use organic solvents. Here, the coating material of the present invention is not limited to the above examples, but includes 1 part to 30 parts of aqueous colloidal silica having a silica solid content of 1% to 40%, 1 part to 5 parts of ethyl silicate monomer, and an inorganic filler. 50 copies~
The desired purpose and effect can be achieved within the range of 70 copies. In other words, if the amount of water-based colloidal silica exceeds 30 parts, the colloidal liquid may gel, or cracks may occur in the coating film, resulting in poor stability, and water-based colloidal silica is not effective at more than 1 part. . Next, if the silica solid component of aqueous colloidal silica is 0% (no silica), it is impossible to form colloidal silica, and if it is less than 1%, the strength of the coating after baking will deteriorate, while on the other hand, if the silica solid component is 40% If it exceeds it, the colloidal liquid will begin to gel, which is not preferable. Further, the reason for limiting the amount of ethylsilicate monomer is that ethylsilicate is an aqueous silicone solution, and if it is less than 1 part, it will lose its binding strength, and if it exceeds 5 parts, it will gel and cause cracks in the coating film. Furthermore, if the amount of the inorganic filler exceeds 70 parts, the coating film loses its flexibility and its strength deteriorates, and in particular it cannot withstand boiling, resulting in a significantly high water absorption rate. On the other hand, if the amount of inorganic filler is less than 50 parts, the coating loses stickiness and the strength of the coating deteriorates. The titanate coupling agent is limited because if it is less than 1 part, it has no catalytic effect, and if it exceeds 3 parts, it will gel and cause cracks in the coating film. Note that it is not necessary to separately add inorganic pigments, but if it is 0 parts, the color will be white and stains will be more noticeable on the exterior, so it is better to add inorganic pigments as appropriate for practical use in electronic parts. This is particularly preferable. Effects of the Invention As described above, the nonflammable paint for electronic parts according to the present invention is constructed and can be baked and cured at low temperatures and in a short time, making it suitable for mass production and advantageous in terms of energy saving. It is something. Also,
It has good mechanical adhesion when coated on electronic parts, has excellent solvent resistance, does not cause flames or ignition under overload, and has excellent heat resistance, making it suitable as a coating material for electronic parts. It is possible to sufficiently ensure safety. Moreover, the present invention provides a pollution-free, non-toxic, and odor-free paint that has good quality characteristics such as moisture resistance, and does not use organic solvents, and has great industrial potential.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing a sample coated with the paint of the present invention, respectively. 4, 6...Paint film.

Claims (1)

[Claims] 1. 1 to 30 parts of aqueous colloidal silica having a silica solid content of 1% to 40% and 1 to 5 parts of ethyl silicate monomer are hydrolyzed using 1 to 2 parts of a titanate coupling agent as a catalyst to inorganic A nonflammable paint for electronic parts made by mixing 50 to 70 parts of filler.