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三防漆和紫外光荧光剂
三防漆根据各种各样实际操作自然环境为印刷线路板（PCB）和相近电气设备部件给予优异的维护，维护其有机化学，电气设备和/或物理性能。
镀层的稳定性依据静电喷涂原材料和应用标准而转变。假如要将PCB立即裸露在紫外光下，大部分三防漆都必须专业的生产加工和检测程序流程。人眼看不到，紫外线辐射的光波长在100-400纳米技术（nm）中间。向镀层中加上UV通常荧光剂用以液态保形建筑涂料中以用以查验目地，可是针对聚对二甲苯应用具备明显的缺陷。
Parylene一再主要表现出非凡的应用性，超过了大部分竞争建筑涂料（包含亚克力，环氧树脂胶，有机硅树脂和聚氨酯材料）做为生物体，日用品，工业生产，诊疗和国防系统软件板材的特性，包含：纳米防水网：http://www.wateroff.cn/
·对构件样子的适应能力，
·体积电阻率，
·经久耐用，灵便的构件维护，
·绝缘性能能，
·无针眼匀称镀层，
·耐化工品和有机溶剂。
除此之外，与竞争者对比，聚对二甲苯镀层可以以超层析增加，在最后商品上通常不容易检验到薄厚水准的明显维护。
聚对二甲苯和紫外光
虽然其做为保形镀层具备很多软件和特点，但大部分聚对二甲苯种类对UV辐射源的整体耐受力是有局限的。尽管在房间内长期保持，但大部分聚对二甲苯秘方不建议在照射阳光底下长期性实际操作自然环境下应用。
换句话说，聚对二甲苯C和N的UV可靠性非常少达到100钟头; 聚对二甲苯AF-4在这方面是优异的，当依照现行标准的ASTM G 154规范开展检测时，给予2,000钟头或更长期的紫外光安全防护。这类能力水准还超出了由亚克力，环氧树脂胶，有机硅树脂和聚氨酯材料做成的竞争保形镀层。
紫外光荧光剂和聚对二甲苯
在大部分液态保形镀层解决的查验环节应用UV荧光剂。可是，在聚对二甲苯镀层的情形下，务必留意下列缘故：
·UV少量添加物并不是聚对二甲苯二聚体的一部分，务必在涂敷前添加。
·紫外光莹光原材料的分子式超过聚对二甲苯分子结构。
·Parylene原材料保存了渗入掩蔽的工作能力，三十UV荧光剂不可以渗入。
·因而，粗略地查验很有可能没法检验无镀层地区内的UV原材料。
·该部件可以进行查验，受权和消除其制定的作用，即使这种缺点未被检验到。
常包含匀称的荧光剂，可是聚对二甲苯不具备。在UV光检验期内，UR，AR和SR镀层传出光亮而清楚的莹光。他们清晰地表明了印痕在镀层中的准确部位，在镀层中早已存有而且并未运用。
在这种状况下，假设向聚对二甲苯二聚体中加上UV莹光恰当地标示镀层是不是渗入一切无镀层地区是不正确的。
·在堆积全过程中，UV荧光剂通常会任意溅到PCB或别的部件上。
·在某种情形下，UV荧光剂的不匀称付款很有可能造成原材料随便刮伤。
·不管是不是采取一定的有效措施解决这种概率，别的PCB都很有可能彻底沒有紫外光荧光剂。
根据根据这种不靠谱結果的查验来根据部件不但会致使部件常见故障，并且还会继续造成潜在性的风险結果，在其中根据经久耐用或相近的技术专业实际操作标准来依靠部件以获取靠谱的特性。
紫外光干固和聚对二甲苯
用以维护保形建筑涂料，黏合剂和印刷油墨的光化学反应加工工艺，与基本干固技术性对比，UV固化造成各种各样升值特性。将高韧性紫外线照射到干躁（干固）镀层或别的成分上，紫外光干固可以给予及时实际效果，提升生产制造速率，与此同时降低对典型性设定和清除全过程的市场需求和总数。减少的实际操作成本费和提升的生产量是很多建筑涂料和加工工艺的UV固化的进一步优势。
在这种状况下，镀层和板材中间的出色黏合是节能环保的，节约能源而不用排出操纵。全过程/商品回绝的发病率减少给予了一些附加的益处：
·更强的附着性和黏合抗压强度，
·经久耐用而有延展性的镀层表层,
·提高耐磨性能/表层刮伤性，
·具备更强的避免触碰化工品和有机溶剂的维护。
在程序流程上，UV固化全过程中不可或缺的光化学反应将液态单个和低聚物与少量痕量元素的光稳定剂混和，光稳定剂接着曝露于UV动能。在紫外光线干固全过程中，紫外光与独特成份的化合物相互影响，比传统式方式迅速地干固镀层。光稳定剂消化吸收来源于解决灯源的紫外光动能，不论是电光或是激光器。所取得的化学变化在几秒内将液态涂料配方转换为平稳的干固膜。
在堆积聚对二甲苯以后，假如存有一切掩蔽地区，则除去掩蔽原材料。去掩蔽地区周边的聚对二甲苯塑料薄膜根据去掩蔽全过程最少水平地毁坏是非常广泛的。这将会造成聚对二甲苯的“手指头”或乃至大的撕破。有时候，建立的边沿务必密封性，以避免一切体内湿气或别的化合物渗透到侧面的概率。
可以根据增加液态保形镀层来修补这种边沿或别的缺点。大家常常应用聚氨酯材料保形建筑涂料，因为它最贴近地表明聚对二甲苯的特性。有时候大家的用户会需要大家应用UV固化液态装饰原材料。可是，因为以上缘故，大家不建议应用一切与聚对二甲苯镀层相互配合应用的UV固化机制，因为它会比较严重减少塑料薄膜的特性。
虽然合理用以其目地，但这类方式与聚对二甲苯的化学气相沉积（CVD）加工工艺非常大水平上不兼容，比较严重受限了其与聚对二甲苯的适用范围。
总 结
不建议应用UV荧光剂和UV固化原材料做为LED器材的聚对二甲苯敷形建筑涂料的成分。
最重要的是要掌握UV荧光剂并不是初始聚对二甲苯二聚体的一部分。因为这类实际，组成这2种原材料更改了堆积的保形镀层的构成，环境污染了聚对二甲苯的纯净度。接着的聚对二甲苯-UV荧光剂成键物可以进行查验，但通常不容易比其他状况下更耐UV光。与此同时，因为引进了UV荧光剂污染物质，因而应用聚对二甲苯保形镀层的基本上导电性，绝缘层和维护特性可能减少。
肯定沒有数据信息适用这类混和塑料薄膜的一切改善特性，而且因为污染物质的引进，UV荧光剂很可能最后会比较严重减少聚对二甲苯的特性。即便如此，现阶段的直接证据表明，虽然大部分聚对二甲苯种类（C，D，N）的容积比较有限，没法为曝露于紫外线源的LED给予靠谱的长久维护，但已设计方案出可用以外界LED应用的聚对二甲苯镀层。与UV荧光剂一样，针对聚对二甲苯是甄选的保形镀层原材料的诸多运用中的一切一种，UV可干固镀层是组成的欠佳挑选; 因而，它不应该用以擦抹聚对二甲苯。
英语全文
Conformal Coatings and UV Trace
Conformal coatings provide exceptional protection for printed circuit boards (PCBs) and similar electrical assemblies, through a wide variety of operating circumstances, safeguarding their chemical, electrical, and/or mechanical properties.
The reliability of coatings varies according to the coating material and conditions of use. Most conformal coatings require specialized processing and inspection procedures if PCBs are to be used in direct exposure to UV light. Invisible to the naked eye, UV radiation’s wave length registers between of 100-400 nanometers (nm). The addition of UV trace to coatings is commonly used in liquid conformal coatings for inspection purposes, but has significant drawbacks for parylene use.
Unsuitably of UV Treatments for Parylene Conformal Coatings
Parylene has repeatedly demonstrated superior utility in comparison to most competitive coatings – including acrylic, epoxy, silicone and urethane — surpassing their performance as a substrate covering for biological, consumer, industrial, medical and military systems, in terms of:
· adaptability to component shape,
· dielectric strength,
· durable, flexible component protection,
· insulating properties,
· pinhole-free uniform coating, and
· resistance to chemicals and solvents.
In addition, parylene coatings can be applied in ultra-thin layers, compared to competitors’, providing significant protection at thickness levels are generally undetected on the final product.
Parylene and UV Light
Despite its many applications and assets as a conformal coating, the overall resistance of most parylene varieties to UV radiation is limited. While it remains stable indoors, most formulations of parylene are not recommended for long term use outdoors where exposure to direct sunlight is a condition of the operating environment.
That is, the UV stability of parylenes C and N seldom exceeds 100 hours; parylene AF-4 is superior in this respect, providing UV-protection for 2,000 hours or more, when tested according to the prevailing ASTM G 154 standards. This level of performance also exceeds competing conformal coatings produced by acrylic, epoxy, silicone and urethane.
UV Trace and Parylene
UV trace is used during the inspection stage of most liquid conformal coating processing. However, in the case of parylene coatings, care must be taken for the following reasons:
· The UV trace additive is not part of the parylene dimer and must be added prior to coating.
· The molecular structure of UV fluorescent materials is larger than that of parylene molecules.
· Parylene materials retain the ability to penetrate masking, even where those of UV fluorescents do not.
· Thus, cursory inspection may not detect UV material within the coating-free zone.
· The component may pass inspection, authorized and cleared for functions it is designed for, even as these flaws go undetected.
This is a problem for application of parylene coatings, in comparison to competitive conformal types, when a UV tracer is added. For instance, while urethane (UR), acrylic (AR) and silicone (SR) typically include a uniform fluorescing agent in their chemistry, parylene does not. During UV light inspection, UR, AR and SR coatings fluoresce brightly and clearly. They plainly indicate the precise location of the trace within the coating, where it has and has not been applied.
Under these circumstances, it is wrong to presume the addition of a UV florescent to the parylene dimer correctly indicates whether or not the coating has infiltrated any coating free zones.
· The UV trace tends to randomly splatter onto PCBs or other assemblies during its deposition process.
· Uneven disbursement of the UV trace can cause haphazard streaking of the material in some instances.
· Other PCBs may receive no UV trace at all, regardless of the care taken to alleviate these possibilities.
Passing the component through inspection based on these unreliable outcomes can not only lead to component malfunction, but also potentially dangerous outcomes, where the component is relied on for reliable performance through ruggedized, or similarly specialized, operating conditions.
UV Curing and Parylene
A photochemical process used to preserve conformal coatings, adhesives, and inks, UV curing generates a variety of value-added properties in comparison to conventional curing techniques. Applying high-intensity UV light to dry (cure) coatings or other substances, UV curing can provide instant results, increasing production speed while reducing the need for and number of typical set-up and clean-up processes. Lowered operating costs and increased production capacity are further advantages of UV curing for many coating materials and processes.
In these cases, the consequent superior bonding between coating and substrate is environmentally friendly, saving energy without need for emissions’ controls. The diminished incidence of process/product rejection offers the additional benefits of:
· better adhesion and bond strength,
· durable yet elastic coating surfaces, and
· enhanced resistance to abrasion/surface scratching,
· with improved protection against exposure to chemicals and solvents.
Procedurally, the photochemical reaction essential to the UV curing process mixes liquid monomers and oligomers with minute traces of photoinitiators, which are subsequently exposed to UV energy. In the UV curing process, ultraviolet light interacts with specially formulated chemistries to cure coatings more rapidly than possible with traditional methodologies. The photoinitiators absorb the UV energy from the process light source, either arc light or laser light. The resultant chemical reaction converts liquid coating formulation into a stable, cured film in a matter of seconds. 纳米防水网：http://www.wateroff.cn/
After parylene has been deposited, if there were any masking areas, the masking materials are removed. It is fairly common for the parylene film around the de-masking area to be minimally damaged by the de-masking process. This can result in “fingers” of parylene or even large tears. Sometimes, it is critical that the edges that were created be sealed to prevent any possibility of moisture or other chemicals penetrating the side edges.
These edges or other imperfections can be repaired via the application of a liquid conformal coating. We often use urethane conformal coating, as it most closely exhibits the properties of parylene. Sometimes our customers will request that we use a UV curable liquid touchup material. However, for the reasons outlined above, we do not recommend using any UV curing mechanism in concert with parylene coating, as it can severely degrade the film.
While efficient for its purposes, this approach is largely incompatible with parylene’s chemical vapor deposition (CVD) process, severely limiting its suitability for use with parylene.
Summary
Applying UV trace and touching up with UV cured material as components of parylene conformal coatings for LED appliances is not recommended.
Of paramount importance is understanding that the UV trace is not part of the original parylene dimer. Because of this reality, combining the two materials changes the composition of the deposited conformal coating, tainting the purity of the parylene. The consequent parylene-UV trace hybrid may pass inspection, but will typically not be any more resistant to UV light than it would otherwise have been. At the same time, the conductive, insulating and protective properties basic to the use of parylene conformal coatings will be diminished because of the introduction of UV trace contaminants.
Absolutely no data supports any improved properties of this hybrid film and, as a result of the introduction of the contaminant, it is highly likely that UV trace will ultimately degrade the parylene\’s performance, potentially in a serious way. Nevertheless, the current evidence shows that, despite the limited capacity of most parylene types – C, D, N – to provide dependable, longer-term protection for LEDs exposed to UV sources, parylene coatings have been devised that are useful for external LED use. As with UV trace, UV curable coating is a bad choice for combination for any of the numerous applications where parylene is the preferred conformal coating material; thus, it should not be used for touch up with parylene.
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