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are programmed into the computer system, controlling the applicator so that the desired coating thickness is maintained. This method is effective for large volumes, provided that the PCBs are designed for the method. There are limitations in the select coat process, such as capillary effects around
321:
Spray coating can be completed with a spray aerosol or spray gun and is suitable for low and medium-volume processing. The coating application may be limited due to 3D effects. The masking requirements have less penetration. This method can be done in spray booths for medium-scale production.
442:
Wet film measurements are for conformal coatings where the dry film thickness can only be measured destructively or through the over-application of conformal coating. The wet film gauges are applied to the wet conformal coating; the teeth indicate the coating thickness.
423:) should have a thickness of 30–130 μm (0.0012–0.0051 in) when using acrylic resin, epoxy resin, or urethane resin. For silicone resin, the coating thickness recommended by the IPC standards is 50–210 μm (0.0020–0.0083 in).
463:
When liquid water is present, a pinhole can form in the coating. This is considered a defect and can be eliminated with appropriate steps and training. These techniques effectively "pot" or "conform" to components by completely covering them.
358:
Selective coating by machine uses a needle and an atomized spray applicator, a non-atomized spray, or an ultrasonic valve technology that can move above the circuit board and spray the coating material in select areas. Flow rates and material
367:
The process quality of dip or dam-and-fill coating and non-atomized spray technology can be improved by applying and then releasing a vacuum while the assembly is submerged in the liquid resin. This forces the liquid resin into all crevices.
345:
An issue of thin tip coverage, where the material slumps around sharp edges can be a problem, especially in a condensing atmosphere. This tip coverage effect can be addressed by either double dipping the PCB or using several thin layers of
180:
Conformal coatings are used to protect electronic components from possible environmental exposure: they allow moisture to escape but protect from contamination. More recently, conformal coatings are being used to reduce the formation of
488:
Traditionally, conformal coating inspection has been done manually. An inspector usually examines each PCB under a high-intensity, long-wave UV lamp. The inspector checks for standards. Recent developments in conformal coating
459:
An alternative to wet film measurement is by using eddy currents. The system works by placing the test head on the surface of the conformal coating. The measurement provides a repeatable result for thickness measurement.
410:
In moisture curing, the applied resin coating is reactive to moisture in the atmosphere and polymerizes with exposure, creating a homogenized coating. The curing process can take up to a few days to complete.
519:
process at ambient temperature. Film coatings ranging from 0.100 to 76 μm can be applied in a single operation. The coating thickness is uniform, even on irregular surfaces. Desired contact points, such as
524:
contacts or connectors, must be covered with an air-tight mask to prevent the parylene from coating the contacts. Applying perylene is a batch process that does not lend itself to high-volume processing.
389:
287:
The coating material can be applied by brushing, spraying, dipping, or selective coating by robots. Nearly all modern conformal coatings contain a fluorescent dye to aid in vapour coverage inspection.
263:, most organic coatings are easily penetrated by water molecules. A coating preserves the performance of electronics primarily by preventing contaminants that can ionize, such as salts, from reaching
342:(PCB) is designed appropriately, it can be the highest volume technique. However, the coating penetrates everywhere including beneath devices, so many PCB designs are unsuitable for dipping.
504:
The most common standards for conformal coating are IPC A-610 and IPC-CC-830. These standards list indications of good and bad coverage and describe various failure mechanisms such as
313:
533:
Different materials offer unique properties that make them suitable for various applications. Below is a comparison of the properties of different conformal coating chemistries.
295:
Brush coating works by coating the material onto the board and is suitable for low-volume application. The finish is thick and tends to be subject to defects such as bubbles.
388:
41:
Please remove or replace such wording and instead of making proclamations about a subject's importance, use facts and attribution to demonstrate that importance.
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film. The coating is more effective if all surface contamination is removed first, using a highly repeatable industrial process such as
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248:. This prevents accidental contact from damaging the wires or the chip. Another use of conformal coating is to increase the
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Incorrect selection can affect long-term reliability of the circuit board as well as cause processing and cost problems.
399:
of conformal coatings is becoming important for high-volume users in fields such as automotive and consumer electronics.
490:
376:
For standard solvent-based acrylics, air drying (film formation) is the normal process except where speed is essential.
173:. Many circuit board assembly firms coat assemblies with a layer of transparent conformal coating as an alternative to
472:
426:
There are several methods for measuring coating thickness, and they fall into two categories: wet film and dry film.
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wire. The chip and the wire are delicate, so they are encapsulated in a version of the conformal coating called a
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964:"Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies"
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can then be used, using batch or inline ovens with conveyors and using typical cure profiles.
218:
493:(AOI) have begun to use Automated Inspection Systems, which can be camera- or scanner-based.
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157:. Many materials can be used as conformal coatings depending on manufacturer needs, such as
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279:. Pinholes would make contact with circuit nodes and form undesired conductive paths.
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rating of a dense circuit assembly. An insulation coating can withstand a stronger
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166:
153:
Coatings can be applied in many ways including brushing, spraying, dispensing, and
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and vibrations on the circuit and its ability to perform in extreme temperatures.
217:
in higher humidity. A suitably chosen material coating can reduce the effects of
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Stable over a wide temperature range (in general, −40 to 200 °C; −40 to 392 °F)
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may suffer degraded accuracy if insulating surfaces become contaminated with
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to protect against moisture and other potentially damaging conditions.
103:. Statements consisting only of original research should be removed.
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UV-curable conformal coatings have thermal cycling resistance.
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low profile connectors that suck up the coating accidentally.
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substances, such as fingerprint residues, that become mildly
224:
For example, in a chip-on-board assembly process, a silicon
142:(PCBs). Conformal coatings are typically applied at 25–250
89:. Many places that should have sources are missing sources.
438:
Wet film gauge for conformal coating thickness measurement
267:
and combining with water to form a microscopically thin
92:
627:Flexible, provides dampening and impact protection
232:process, and then it is electrically connected by
648:Excellent uniformity regardless of part geometry
455:Dry film conformal coating thickness measurement
447:Dry film conformal coating thickness measurement
392:UV Inline Conveyor for curing conformal coatings
870:International Journal of Adhesion and Adhesives
338:Dipping is a highly repeatable process. If the
201:Conformal coatings of PCBA where it is UV-cured
802:
800:
8:
228:is mounted on the board with an adhesive or
134:is a protective, breathable coating of thin
35:promotes the subject in a subjective manner
372:Solvent and water-based conformal coatings
256:than air, particularly at high altitudes.
866:"Moisture cure of adhesives and sealants"
119:Learn how and when to remove this message
57:Learn how and when to remove this message
941:"Acceptability of Electronic Assemblies"
535:
698:
189:between closely positioned components.
654:Minimal added mass and low out-gassing
430:Wet film conformal coating measurement
636:Low surface energy for better wetting
579:Harder durometer, abrasion resistance
7:
993:Printed circuit board manufacturing
787:"How do I apply Conformal Coating?"
32:This article contains wording that
847:"Conformal Coating Curing Methods"
829:"Conformal Coating Curing Methods"
738:"Whisker Resistant Metal Coatings"
484:Conformal Coating Inspection Booth
236:, typically with 25.4 μm diameter
37:without imparting real information
14:
675:High glass transition temperature
582:CTE closer to epoxy PCB substrate
657:Low environmental impact process
73:
23:
808:"Conformal Coating Application"
763:"SMT007 Magazine - SMT-May2018"
576:Useful to about 150 °C (302 °F)
511:Another type of coating called
1:
917:. Electrolube. Archived from
911:"Selection and Best Practice"
882:10.1016/s0143-7496(97)00031-6
643:Poly-Para-Xylylene (Parylene)
317:Conformal coating spray booth
707:"What is Conformal Coating?"
585:Higher Tg (Glass transition)
564:Ease of viscosity adjustment
491:automated optical inspection
354:Selective coating by machine
334:Conformal coating dip system
99:the claims made and adding
1014:
600:Good dielectric properties
588:Good dielectric properties
302:
864:Comyn, J. (August 1998).
415:Thickness and measurement
326:Conformal coating dipping
305:chemical vapor deposition
299:Spray application coating
767:iconnect007.uberflip.com
633:High dielectric strength
630:Good moisture resistance
609:Less reversion potential
603:Good moisture resistance
558:Good moisture resistance
419:Coating material (after
736:Lyudmyla Panashchenko.
672:Low dielectric constant
667:Amorphous fluoropolymer
660:Low dielectric constant
561:High fluorescence level
309:atomic layer deposition
485:
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456:
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140:printed circuit boards
810:. www.electrolube.com
555:Simple drying process
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476:Conformal Coating AOI
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391:
384:UV conformal coatings
340:printed circuit board
333:
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711:www. electrolyte.com
681:Low water absorption
148:electronic circuitry
16:Coating used on PCBs
915:www.electrolube.com
851:www.electrolube.com
833:www.electrolube.com
791:www.electrolube.com
612:Abrasion resistance
921:on 24 October 2017
684:Solvent resistance
678:Low surface energy
651:Chemical inertness
606:Solvent resistance
515:is applied with a
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207:analogue circuitry
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84:possibly contains
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529:Coating chemistry
517:vacuum deposition
348:atomized spraying
219:mechanical stress
132:Conformal coating
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275:or semi-aqueous
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47:November 2023
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970:. Retrieved
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947:. Retrieved
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919:the original
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812:. Retrieved
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770:. Retrieved
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745:. Retrieved
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719:. Retrieved
715:the original
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595:Polyurethane
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234:wire bonding
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193:Applications
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743:. NEPP NASA
542:Properties
378:Heat curing
269:electrolyte
155:dip coating
109:August 2024
987:Categories
972:2010-07-26
949:2010-08-27
814:2015-06-11
772:2018-09-05
747:23 October
693:References
468:Inspection
303:See also:
259:Excluding
215:conductive
205:Precision
93:improve it
890:0143-7496
506:dewetting
497:Selection
397:UV curing
361:viscosity
242:aluminium
230:soldering
167:urethanes
163:silicones
136:polymeric
97:verifying
998:Coatings
619:Silicone
539:Material
513:parylene
261:parylene
246:blob top
183:whiskers
171:parylene
159:acrylics
925:11 June
895:12 July
721:11 June
547:Acrylic
522:battery
283:Methods
277:washing
250:voltage
175:potting
91:Please
888:
421:curing
169:, and
967:(PDF)
944:(PDF)
741:(PDF)
571:Epoxy
211:ionic
927:2015
897:2024
886:ISSN
749:2013
723:2015
307:and
238:gold
878:doi
240:or
226:die
95:by
989::
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874:18
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799:^
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