PCBコンフォーマルコーティング: 初心者向けの包括的なガイド

Electronic devices play a vital role in our everyday lives. まだ, they’re extremely vulnerable to the external environment, which may affect their functionality. ここで PCB コンフォーマル コーティングが始まります。, working as a defensive barrier. 記事上で, we will focus on different types of conformal coatings and how to choose the right one for your projects.

Why Is Conformal Coating Important for PCBs?

A well-fabricated circuit board typically functions as intended. When it is exposed to the working environment, some external factors will affect its performance. Conformal coating is a thin film applied to the board to shield it from chemicals, ほこり, 水分, 温度変動, 等. It is like a “protective shield” that can extend the service life of the circuit board, especially under harsh conditions. そうでなければ, they tend to deteriorate in performance or even fail prematurely.

Different Types of PCB Conformal Coatings

回路基板の絶縁保護コーティングは、その化学組成によって区別されます。, それぞれが独自の特性と利点を提供します. ここに, 最も一般的に使用されている 5 つのタイプを見ていきます:

1. アクリル樹脂 (と)

Acrylic conformal coating is an economical choice. The coating is easy to apply and forms a light, flexible protective layer, typically applied at thicknesses of less than 100 μm. Acrylic resin coating cures quickly, especially acrylic resin with less solvent, which can dry on the surface in a few seconds to more than ten seconds, saving a lot of curing time. したがって、, it is suitable for UV curing and selective coating.

Acrylic PCB coating does not release heat during curing, which will not damage heat-sensitive components. Once cured, this conformal coating doesn’t shrink, どちらか. しかしながら, acrylic coatings are more susceptible to softening and warping than other coatings in high-temperature environments. It is also sensitive to solvents and can be repaired by dissolving part of the coating.

2. ウレタン樹脂 (あなたは)

Urethane conformal coating is wear-resistant and solvent-resistant, which is divided into single components (1K) and two components (2K). Single-component urethane material is easy to apply, but its curing time is long. Two-component urethane material can be cured in a short time and reach its best state. しかしながら, it demands a strict mixing ratio and process control.

They both have good moisture resistance, chemical stability, および電気絶縁性. Due to their good chemical stability, special stripping agents must be used when replacing components or repairing circuit boards. This results in high repair costs and difficulty. The polyurethane-coated surface can be soldered, but a brown residue will remain, affecting the appearance of the circuit board.

3. エポキシ Resin (IS)

Epoxy conformal coating can form a hard and smooth coating surface, offering good chemical resistance. Before coating, it is necessary to add a buffer around the fragile components to protect them from the large shrinkage stress during the coating curing process. It is typically a two-part material with a very fast cure time and needs to be mixed immediately before application.

Once the coating has cured, it is almost impossible to remove it chemically, so the repair process is more difficult. The only effective way to remove or repair the coating is to burn it with a soldering iron and scrape it off with a knife, which can damage the product.

4. シリコーン樹脂 (SR)

Silicone conformal coating can provide excellent protection at extreme temperatures (-100 ~ 200°C) and offer low dielectric loss. It is suitable for high-frequency circuit boards with high-power resistors. The coating is thicker (0.03 ～ 0.50 んん), so it can partially fix components or traces while providing protection. Silicone resin coatings are not wear-resistant but flexible and can cope with vibration or slight mechanical stress. They have good adhesion to PCB surfaces and are insoluble in polar solvents. さらに重要なことには, UV curing can be carried out efficiently even in humid environments.

5. パリレン (XY)

Parylene conformal coating needs to be applied by vapor deposition equipment, which can form a uniform, pinhole-free, and transparent film on the PCB surface. This conformal coating doesn’t require curing and will not cause internal stress to damage components, offering excellent electrical insulation properties. It is the most effective protective coating for high-frequency components, high-density components, and high-insulation components. しかしながら, it is a challenge to remove the coating for rework or repair.

Pros and Cons of Each Conformal Coating Type

How to Choose the Right Conformal Coating for Your PCB?

Now that we understand the properties of different PCB conformal coatings, 次に、プロジェクトに最適なコーティングを選択するために考慮すべき要素は何ですか? 上手, 以下にいくつかの重要な考慮事項を示します:

動作環境

• Temperature Range – Consider the maximum and minimum operating temperature of the PCB. Acrylic resin can withstand -60~130℃, which is suitable for most common products. If you want a wider temperature range, choose silicone resin that can withstand -100~200℃.
• Humidity – If moisture resistance is critical, パリレンと一部のウレタンは、水蒸気の透過と吸収に対して最適な保護を提供します。.
• Chemical – For corrosive chemical environments, パリレンとウレタンは一般に最高の化学バリア特性を持っています.

電気的特性

• Dielectric Strength – This should exceed the maximum voltage the PCB traces will carry. パリレンとシリコーンは高い絶縁耐力を持っています.
• Insulation Resistance – A higher megohm value indicates better electrical insulation, which is important for avoiding leakage currents.
• Thermal Conductivity – It refers to the ability to dissipate heat, which is critical for power electronics. Silicone conformal coating could be a good option.

機械的性質

• Hardness – Harder coatings like epoxy and some polyurethane provide greater abrasion resistance.
• Flexibility – Silicone and parylene coatings provide flexibility, which is important for dynamic flexing circuits.
• Adhesion – This property determines how well a coating bonds to the PCB基板.

料金 考慮

Cost matters, which also need to be weighed against specific application requirements, including environmental conditions, temperature range, and level of protection needed. The acrylic conformal coating offers a budget-friendly option but only provides general protection. For demanding applications and harsher conditions, some expensive options such as silicone, エポキシ, ポリウレタン, and parylene coatings should be chosen.

Applications of Conformal Coating in PCB

この部分では, we outline some typical applications of conformal coating, and the factors that affect circuit board performance vary from industry to industry.

家電 – 家電, スマートフォンを含む, 家電, とタブレット, suffer mostly from moisture and dust exposure. PCB conformal coating can enhance their moisture and dust resistance, offering reliability and extending lifespan.

自動車産業 – Electronic devices in vehicles are susceptible to damage from vibration, ほこり, chemical exposure, and fluctuating temperatures. Conformal coating protects them from running stably throughout prolonged exposure to harsh conditions.

航空宇宙 and Defense – Due to their special working environments, electronic devices should meet high demands and withstand extreme conditions. PCB coatings can protect circuit boards in satellites, aircraft, and military equipment from extreme environmental conditions (such as high-altitude pressure).

Marine Electronics – Navigators are easily damaged due to salt spray and humidity. Conformal coating offers a protective barrier to avoid moisture and corrosion.

医療 – PCB conformal coatings can isolate medical electronics from external chemical agents or harsh environments. This successfully increases the longevity and dependability of medical devices, including wearable health monitoring devices and pacemakers.

Industrial Control – Industrial electronic equipment is subjected to chemicals, ほこり, そして極端な気温. Conformal coatings can improve their reliability in harsh environments and reduce failures.

結論

明らかに, it’s essential to weigh many factors when selecting the right conformal coating. Each coating provides distinct advantages and limitations. Some coatings may perform well in a moist environment, while others excel in high temperatures. まだ, there is no best conformal coating, only the one that matches your needs. If you are finding the right one for your project, reach us for expert advice.

FAQs about Conformal Coating

Can I use conformal coating for waterproofing?

Conformal coating helps protect electronics from moisture and humidity, but it is semi-permeable and not completely waterproof. To be completely waterproof (such as for outdoor or underwater applications), you need additional sealing.

Which conformal coating is the best?

There is no best type, it depends on your exact needs. Acrylic is low-cost and can be used for general electronics. Silicone is used for high-temperature applications and parylene can be used for medical implants. Industrial electronics often use polyurethane, which requires wear resistance.

How long does conformal coating take to cure?

Cure time depends on the curing method. UV curing is fast and usually completed in seconds. Heat can speed up the curing process, while air drying at ambient temperature takes longer.

What is the difference between potting and conformal coating?

Potting is completely immersing the components or PCBs in gel-like substances or liquid protective materials (such as silicone, ポリウレタン, and epoxy). The conformal coating is a thin protective film that coats objects.