Bluetooth module singlechip Development and design of PCBA

           Characteristics of different waterproofing schemes commonly used in electronic products

Structural waterproofing

Structural waterproofing is the most traditional waterproof mode of electronic products, which is effectively isolated from the internal electrical parts by hydrophobic, diversion, external packaging.

Key points: the mold design of the product and various plugging, of course, the more complex the mold cost is not cheap. For example, a few years ago, some waterproof mobile phones used waterproof cover when designing earphone hole and charging port, which is to block water from the outside, so as to achieve the purpose of waterproof.

Even if a lot of structural changes are made, it is still unable to prevent the immersion of moisture. Because electronic products, especially mobile phones and earphones, are frequently used, users' damage to the appearance (artificial or non-human) is always present. The appearance will also have the risk of deformation in the process of use, and the gap between the appearance joint will also deform and become a potential burden Worry.

Bluetooth headset structure waterproof

Sealing and waterproof

At present, epoxy resin pouring glue is often used for potting of electronic product modules, which can wrap the whole PCB board, so as to achieve waterproof, moisture-proof, salt fog proof, mold proof, anti-seismic, anti-shock, etc.

Advantages of epoxy resin potting adhesive: it has the characteristics of high bulk strength, strong adhesion, good weather resistance, low shrinkage, high insulation strength, non-toxic and environmental protection, and stable mechanical and electrical properties between - 45-120 ℃ after potting. It can protect the circuit board in all directions and greatly improve the service life of the circuit board.

Disadvantages: at the same time, there are some fatal problems. For example, the heat dissipation of PCB board will be greatly affected. The most troublesome problem is that the product is almost impossible to be repaired, or the repair cost is too high.

Sealing and waterproof

Surface coating waterproof

Three proofing paints

Three proofing paint is also called circuit board protection oil, coating oil, waterproof glue, insulating paint and moisture-proof paint. The waterproof effect of three proofing paint products is not good, mainly has the following shortcomings:

Generally thick, poor heat dissipation and high viscosity;

The cured film can only protect moisture and a small amount of water;

It is not resistant to fall and vibration, and easy to peel off under external impact;

At present, many three proofing paints still use volatile solvents, which is harmful to human body and environment.

However, if only play a basic role in protection, it is possible to choose three proofing paint for protection.

Surface coating waterproof

Nano coating for PCB

Nano waterproof coating for circuit board is a new nano material, also known as nano coating. At present, it is an ideal substitute of three proofing paint.

Its thickness is only 2-4 μ m, which can't be seen by naked eyes. It forms an extremely thin net on the PCB surface, effectively reduces the PCB surface energy, forms lotus leaf effect, has good heat dissipation performance, does not affect the normal conductivity of the connector, waterproof can reach ipx5, basically meets the domestic waterproof standard, also can be corrosion resistant, acid and alkali salt resistant.

Nano coating for PCB

Surface spray nano waterproofing coating

The surface of the mobile phone or computer can be used to form a nano film on the surface of the mobile phone or tablet computer, thus preventing the entry of water vapor from outside and achieving the effect of waterproofing.

Advantages: simple operation

Disadvantages: the anti-wear ability is weak. After all, the coating is in the shell part of the product, and the shell is the most closely contacted part of various articles. In the face of too many complex use environment, the damage rate will be greatly accelerated. Moreover, the appearance of the product may be deformed during the use process. Once it is deformed, the influence of moisture on the internal circuit board cannot be guaranteed.

Suggestion: it can be used in some short-term waterproof products

Vacuum sprayed waterproof coating for coating machine

This technology uses a vacuum coating machine to spray the waterproof agent into the interior of the product from the slot of the appearance of the product in the form of spray under vacuum. The purpose is to make the waterproof agent more widely touch the circuit part. However, due to the different appearance and sealing properties of various products, the coating formed by waterproofing agent after spraying is often incomplete.

Advantages: multiple devices can be operated at the same time to speed up efficiency

Disadvantages: the need to buy a certain number of equipment, the quality of the equipment will affect the quality of the coating, and some devices are far more effective than the actual application. Therefore, they will be largely subject to the performance of the equipment. According to their principle, different mobile phone will have different reactions to the spray effect of the product, and it will easily cause the overlay. The film is incomplete and the yield is not guaranteed.

Suggestion: to have better equipment, but also have good waterproof agent.

PCBA immersion nano coating

This technology is the current trend, that is to add a process in the production line after all components on the PCB are installed, that is, the circuit board is directly immersed in nano waterproof solution, the soaking time is only 3-5 seconds, and then it is taken out and naturally dried at room temperature for about 10 minutes, which is very convenient. There is no need to purchase equipment such as coating machine, and the film formation is also very complete.

The most important thing is that the quality of the nano liquid used must pass the standard, and can meet the requirements of the international market for product quality. The film thickness of this product is only 2-4 μ m, which is invisible to the naked eye. On the micro level, it is composed of very fine nano particles, but there is a gap between the nano particles. Using the principle of gas-phase precipitation, the surface energy of PCB board can be effectively reduced, so that the water droplets and the circuit board can be made The contact angle of the surface becomes larger, forming lotus leaf effect, supermarket hydrophobic, because the coating is very thin, so the heat dissipation performance