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We are considering implementing the SCS 51060HIC125-CF humidity indicator card for our long-term storage of assembled PCBs. We bought a can for experimentation and find it difficult to interpret that do the colors means, or more precisely subject to interpretation. I’ll provide examples below, but the key question is:
Does SCS provide baseline, or guidance on color ranges for what is considered yellow, tan, and brown?
Examples:
In the data sheet illustration, is the 10% considered “not brown”? (it is certainly not brown compared to how brown of the 60% indicator is).
The uploaded image is of a card photographed immediately when taken out of the can. Is the 10% indicator yellow? That is, according to the legend on the card, is it “not tan”? Is the 5% indicator yellow?
While waiting for further response, I would consider doing an actual test in a high humidity environment (boil water or similar in relatively closed environment) and actively observe the color change every few minutes to get an understanding of what they will actually look like before and after exposure to high humidity.
This would help to give a more intuitive understanding of expected color change which is not dependent on the vagaries of image color variations on monitor screens.
I can see a definite difference between the first and second, though, at least as it appears on my screen, it is still somewhat subtle.
I get the impression that the 51060HIC125 non-cobalt-free variant with blue and pink colors are a little less subtle, but if you can’t use that then the cobalt-free 51060HIC125-CF is the logical choice.
Color changes are visible, which is good. However, this also illustrates why manufacturer-defined color ranges are needed for field use that isn’t guesswork. The card instructions rely on terms such as “yellow,” “tan,” and “brown,” but those terms are visually ambiguous without reference ranges.
For example, in this photo, different users could reasonably disagree about whether the 60% indicator should be interpreted as brown. That distinction matters because the card instruction says: “Bake parts if 60% is NOT brown.”
Could SCS please provide objective color interpretation guidance for this card, such as:
Reference images showing in what rage an interpretation should be “brown,” “tan,” and “yellow” states for the 5%, 10%, and 60% indicators.
The intended color state of each indicator when fresh from the factory can. In other words, is a card valid for first use?
The expected color state at or above each RH threshold.
Without this guidance, interpretation becomes subjective guesswork, which voids the original intent of maintaining moisture-sensitive components under J-STD-033D.
· In the data sheet illustration, is the 10% considered “not brown”? (it is certainly not brown compared to how brown of the 60% indicator is).
The photo in the data sheet is incorrect.
· The uploaded image is of a card photographed immediately when taken out of the can. Is the 10% indicator yellow? That is, according to the legend on the card, is it “not tan”? Is the 5% indicator yellow?
