Help me understand a phrase regarding acceptability of bubbles in a conformal coating

[cmyguo3o]

Hi all,

In a standard regarding conformal coatings, I cannot fully understand this phrase:

"Bubbles are generally acceptable when their size is less than 50% of the distance between conductors at the location and they do not expose conductor, bridge of lands, or adjacent conductor surfaces"

It may be because English is not my native language or because the phrase itself is not very clear. Specifically, I'm not sure about the meaning of "expose" and the part starting from "they do not expose...".

1) By exposure, do they mean that the coating is essentially absent in this place due to the bubble - or just that the bubble doesn't touch the items listed?
2) Is the word "surfaces" common for all list items so the phrase can be expanded as "they do not expose conductor surfaces, bridge of lands surfaces, or adjacent conductor surfaces"?
3) What is meant by "bridge of lands"?

P.S.: Sorry if this is the wrong subforum, I'm not sure where exactly this belongs to.

 

[crutschow]

1)I would say that "expose" means the coating is absent directly at the mentioned items due to a bubble.
2). Yes.
3) Land - The portion of the conductive pattern on printed circuits designated for the mounting or attachment of components. Also called Pad

 

[cmyguo3o]

Thank you crutschow!

I do know what "land" means, I just don't understand "bridge of lands". Googling it (with quotes) returns 3 results. Do they mean something like a jumper?

 

[KeepItSimpleStupid]

It's a basic grammer exercise:

Bubbles are generally acceptable when their size is less than 50% of the distance between conductors at the location and they do not expose conductor, bridge of lands, or adjacent conductor surfaces

Is this better?

"Bubbles are generally acceptable when their size is less than 50% of the distance between the PCB traces at the location of the bubbles. The bubbles should not expose the traces, bridge the lands/pads or the surrounding conductive land patterns."

There.

 

[cmyguo3o]

Here's a belated thank you to KeepItSimpleStupid. Going back to that part of text, it's clearer that way.

 

[Tony Stewart]

FYI, Use of vacuum pressure in enclosure reduces bubbles.