最新コーティング方案を発信するShimada Appli(シマダアプリ)→High T.E. spray


最新基板防湿コーティング情報(An up-to-date conformal coating information)

2015-01-30 | 基板防湿コーティング


(New selective conformal coating method & valve to printed circuit board for VOC)

1.コンフォーマルコーティングの課題( Problem of conformal coating now)

 湿気や埃を嫌う実装回路基板には、防湿絶縁材料の被覆は信頼性を維持するためには必須であり、特に最近の実装回路基板は、ハンダ表面に発生するウィスパー防止にも防湿絶縁材料の被覆が効果的のため、防湿絶縁材料による被覆の採用が注目されております。この実装さたれ電子基板面に防湿絶縁材を薄く均一に塗布することはコンフォーマルコーティング(Conformal Coating)と呼ばれプリント基板製造業界にすでに普及されてます。その被覆に用いられる防湿絶縁材料には、合成樹脂に芳香族系溶剤やケトン系溶剤を半分以上含有した溶剤系防湿絶縁材料が使用されている。それらは従来技術である浸漬法や、刷毛塗り法及びスプレー法によるものが一般的ですが、すでに20年前から「エアレススプレイによるフィルムコーティング方法」を使用して、塗布したい個所への選択塗布が可能なフィルムコーティング方法が、すでにコンフォーマルコーティングで広く採用されているのが現状であります。

しかし昨今のVOC(volatile organic compounds)規制による溶剤使用を削減する傾向に際し、脱溶剤系のコンフォーマルコーティング材料であります無溶剤系材料の中高粘度防湿絶縁材料の使用や、水性型防湿絶縁材料も開発され販売もされていますが、思ったように使用されてないのがコンフォーマルコーティング市場の現状です。その原因としては、無溶剤系防湿絶縁材料が、粘度が200センチポイズ以上という中高粘度のため、上記の従来技術やフィルムコーティング法では見切りの良いパターン形成がされないことや、他スプレー工法を用いても発泡の問題、乾燥時間が長くなり、塗布された成膜が100ミクロン以上になるという必要以上の塗布膜厚を形成する等、品質、生産性、コスト面での諸問題があるためそれ程進展しておりません。また水性型防湿絶縁材料においても、材料の吐出後に、吐出時の泡の巻き込み発生や、回路基板中にある凹部での液たまり等の未乾燥の問題や、液粒子飛散の発生での飛散問題、均一膜が得られない欠点等で、なかなか広範囲に水性防湿絶縁材料も採用されてないのが現状です。 

(The mounting circuit boards which dislike humidity and dust are required because of maintenance of covering of a prevention-of-moisture insulating material of reliability. By the latest zisso circuit boards, also from whisker prevention, since the application of conformal coating is effective, adoption of the application of conformal coating attracts attention. It set to apply conformal coating material to this substrate side of circuit board uniformly thinly to Conformal Coating, and it is the printed circuit board manufacture industry and has already spread. The solvent system conformal coating material to which, as for conformal coating material, more than half contained the solvent in the synthetic resin is often used.        

As for them, what is depended on the dipping method, the brush applying method, and the spraying method of conventional technology is common as for them, "The film coating method by an airless spray" will already be used from 30 years before, and the curtain coating method by nozzle in which a selective coating in a part to coating is possible is already widely adopted by conformal coating.

However, the tendency which reduces the solvent use by VOC (volatile organic compounds) regulation of these days is faced, the present condition of a conformal coating market is use of the low-to-middle viscosity moisture-proof insulating material of the non-solvent type material which is the solvent les conformal coating material and not used as considered although used by developing a water based type material.)


(Selectable thinly coating machine used VOC type material)


(We developed selective coating machine without the splashes like these pictures. This is applicable to restrictive coating used water-based or solvent-lees type conformal coating material.Conformal Coating covers thin film of insulated transparent polymeric resin thinly to PCBA. The coating purpose is protection of PCBA from moisture, dirt, mechanical shocks, vibrations and etc. A uniform thin layer ensures security and reliability of the performance remarkably. There are mainly 3 types conformal coating materials. It is solvent type, solvent-less type and water-based type. In conformal coating market, a lot of solvent types are used now in Japan. The water based and solvent less type are not used too much because of some issues. As issue of using VOC type conformal coating material, The issues are film thickness becomes too thick and Bubbles are involved in film, Dryness is too slow. It needs masking to coat thinly. This is called FSCC06 spray coater we developed to solve these issues. It is characterized by good atomization.We improved our FS type micro spray gun to FSCC06 spray coater and coating system can be coated high viscosity material thinly. FSCC06 has special parts are caused tornado air to get fine atomization and no splashing.(Refer to following animation)