Led coatings

SPLFreak808

Well-Known Member
Plastic coating? Only two things really come to mind here, those screw on LED bulbs with the plastic diffuser or phosphor free LED with a phosphor diffuser, but maybe I'm not hearing you right.
 

SPLFreak808

Well-Known Member
You might be talking about conformal coating, I use polyurethane CC with circuit boards but I'm not sure exactly what the LED companies use, probably silicone based. All this does is add a layer of protection from moisture.
 

SDS_GR

Well-Known Member
It’s actually called conformal coating.
There are few different types of it,depending on the coating material used,like Parylene,acrylic,polyurethane,silicone and more .

Many of them can be found in spray can format .
Electrolube AFA is one of them ,
very well suited for LED applications.

 

canope

Well-Known Member
It’s actually called conformal coating.
There are few different types of it,depending on the coating material used,like Parylene,acrylic,polyurethane,silicone and more .

Many of them can be found in spray can format .
Electrolube AFA is one of them ,
very well suited for LED applications.

Awesome stuff, do you know if you lose alot of umol?
 

SDS_GR

Well-Known Member
Yes,I think that acrylic is better than silicone.
Silicone coat has to be very thick to be protective enough .
Furthermore ,acrylic is much more transparent and colourless ,than silicone .
And won't yellow under UV radiation .
Here you can read a quite informative article about conformal coatings and their application to LED devices .


Edit :
Some more info on conformal coatings and their application at LED devices .




 
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SDS_GR

Well-Known Member
Read carefully when this condition stands ...

1507ledsf6f6


FIG. 6. Different coating types can suffer varying degradation in optical efficiency when exposed to corrosive gases.



Environmental exposure
Comparing the performance of various products in harsh environments can also highlight preferential product choice based on the end-use conditions. For example, Fig. 6 illustrates the effect of corrosive gas environments on an acrylic conformal coating, a polyurethane resin, and a silicone resin by examining the percentage reduction in luminous flux of the LED after exposure to a mixed-gas environment. These results clearly illustrate the importance of choosing the correct product for the environment. Although the conformal coating does not deteriorate in terms of its surface insulation resistance in a corrosive gas environment, it is not an adequate protection for LEDs as it allows the gas to pass through the thin coating and penetrate the LED, thus degrading its performance over time.
A similar effect is also seen with the silicone resin; however, in this case, despite the protection layer being considerably thicker (2 mm versus 50 μm) the gas is still able to pass through the resin and affect the LED. When you compare the result of the silicone resin to the polyurethane material, it is evident that there is a difference in performance exhibited by these two chemistry types as the silicone resin is permeable to the gas whereas the polyurethane resin, at the same thickness, is not. In such cases, an optically clear polyurethane resin, such as Electrolube UR5634, would be the most suitable protection media to prevent the corrosive gases from adversely affecting the LED.



Such environments will not occur in an artificial horticulture facility of any size ( from a server tower case to a vast greenhouse ) ,under normal circumstances .
PU coatings are used in really harsh enviroments ( metal /petrol /gas industries ,mining ,etc ) and
are quite thick ( 0.5 to 2.5 mm ).
 
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SDS_GR

Well-Known Member
And here are some common ( to EU countries ) conformal coatings :

(acrylic,solventless )

(acrylic,solvent-based)


( Caution : Plastik 70 SUPER and not the Plastik 70 which has a max oper. temp. of 60°C ) ( acrylic ,solvent based )


( polyvinyl butyral -solvent based )
 

SDS_GR

Well-Known Member
All this does is add a layer of protection from moisture.
.....
“This elastic & transparent conformal coating ,as long as is applied and cured properly ,will protect the LEDs from :
-humidity, but also from water splashes ,sprays & mist.
- various hazardous to LEDs gasses ( like oxygen ,H2S , SOx ) and atmospheric pollution.
- dust ,fibers and other airborne solid particles .
- UV radiation
- VOCs
and from few other hazards that may
develop on an unprotected pcb ,even like “tin whiskers”.

They also protect you and others from
high voltage ,if present .“.....





 
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canope

Well-Known Member
.....
“This elastic & transparent conformal coating ,as long as is applied and cured properly ,will protect the LEDs from :
-humidity, but also from water splashes ,sprays & mist.
- various hazardous to LEDs gasses ( like oxygen ,H2S , SOx ) and atmospheric pollution.
- dust ,fibers and other airborne solid particles .
- UV radiation
- VOCs
and from few other hazards that may
develop on an unprotected pcb ,even like “tin whiskers”.

They also protect you and others from
high voltage ,if present .“.....
Exactly, and moisture lowers your output after a while
 

SPLFreak808

Well-Known Member
.....
“This elastic & transparent conformal coating ,as long as is applied and cured properly ,will protect the LEDs from :
-humidity, but also from water splashes ,sprays & mist.
- various hazardous to LEDs gasses ( like oxygen ,H2S , SOx ) and atmospheric pollution.
- dust ,fibers and other airborne solid particles .
- UV radiation
- VOCs
and from few other hazards that may
develop on an unprotected pcb ,even like “tin whiskers”.

They also protect you and others from
high voltage ,if present .“.....





I actually didn't even think of dust/particles etc, Excess build up of dust can be conductive, some environments more than others.
 
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wietefras

Well-Known Member
Read carefully when this condition stands ...
Why? It doesn't really explain that the chart is after any effect? Or is that on a clean surface?

You might not "need"PU coating since the environment isn't that harsh, but if it's not losing 15% of the light it would seem a much better material for coating our leds. If we could pry off the original silicon coating that is.
 
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