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Original question:

the specsheet of 0.7 XGA 2LVDS 12deg DMD is for a type A DMD. IAre there other types? What are the differences?

DLP4500: 0.45 WXGA DMD package vacuum seal

Anton Travinsky
Prodigy 140 points
Part Number: DLP4500

Hello,

is the 0.45 WXGA DMD vacuum - sealed? I understand that a "TYPE A" DMD means a hermetically sealed package. The data sheet for this DMD does not specify a type so I assume this is not hermetically sealed. Am I correct? Is there a gas inside the package? I am considering epoxy in the immediate vicinity of a DMD in my application and I am worried about outgassing.

Thank you

Anton 

  • 0
    TI__Mastermind 23070 points
    Hi Anton,
    Could you please share details your use case ? Why and how are you using Epoxy? Any details about the environment will be helpful.

    regards,
    Vivek
  • 0 in reply to Vivek Thakur
    Prodigy 140 points
    Vivek,

    Thank you for your prompt responce. I would preffer to not discuss my application because I do no think it is relevant to my question. My question is if the package of 0.45 WXGA DMD vacuum sealed. I understand that "TYPE A" dmd means a vacuum sealed package. The datasheet for the 0.45 WXGA DMD does not say "TYPE A". Does this mean the 0.45 WXGA is not vacuum sealed? The mechanical drawing in the 0.45 WXGA data sheet states a presence of encapsulation. What is the material of the encapsulation?

    Thank you
    Anton
  • 0 in reply to Anton Travinsky
    TI__Mastermind 23070 points
    Hi Anton,
    The Type A DMDs and Automotive DMDs are hermetically sealed. The Pico class DMDs are not in hermetic package. The Pico DMDs are designed to operate for long period ( years) in environment (Humidity & temperature) as listed in Datasheet.

    Regarding your concern about epoxy and outgassing, I see a bigger concern about outgassing and condensing on windows of the DMD. Which will impact image quality. I see this more likely issue than it getting inside DMD.

    The term "vacuum sealed" is misnomer for DMD. There is no vacuum inside DMD.
    I hope this addressed your concern. Please let me know if you further question.

    regards,
    Vivek
  • 0 in reply to Vivek Thakur
    Prodigy 140 points

    Vivek,

    Thank you for you answer. Let me make sure I understand: although the 0.45'' WXGA DMD is not a "TYPE A" DMD its package is still hermetically sealed. Is this correct? If so what is the difference between a "TYPE A" DMD and not a "TYPE A" DMD? I was led to believe that this difference is the hermetic seal of the package of "TYPE A" DMDs.

  • 0 in reply to Anton Travinsky
    TI__Mastermind 23070 points
    Hi Anton,
    When a DMD is "Hermetically sealed" or "Hermetic package ", it implies that no moisture (even small traces -parts in million) gets inside the device even if it is operated in a high humidity and high temperature environment. The Type A package DMD and automotive DMDs are hermetically sealed.

    The DLP4500 DMD packages is not hermetically sealed. It is robust enough that it can operate in normal environment for long period. Moisture permeation in the device at such a low rate that it can operate for years. However, the moisture permeation does accelerate with high temperature and high humidity.

    Coming back to your concern about degassing inside the device. I don't think that should be a concern. If there is any degassing related issue, it will be epoxy condensing on the DMD window rather than getting inside.

    I hope this explains. Please let me know if you any further question.

    regards,
    Vivek
  • 0 in reply to Vivek Thakur
    Prodigy 140 points
    Vivek,

    Thank you for your answers. I understand it better now.

    Thank you again
    Anton