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  1. nigelt

    Thermal Interface Materials in outdoor applications

    Does anyone have experiences of using gap filler pads in applications where they may be exposed to (sheltered) outdoor environment conditions. So they can expect to see some dampness/moisture, minus 40C to +60C env. Life approx. 5 yr. Should be a dry assembly process. Typically these gap...
  2. nigelt

    structural reliability of PCB mounting a SMT style RJ45 pcb receptacle

    thread820-398618 Following up on this RJ45 receptacle issue. We knew that style with snap in pins cannot be used because they are incompatible with pick-&-place, so it had to be pure SMT. Not too thrilled with our final choice so as we are now going to full production I will be closely watching...
  3. nigelt

    structural reliability of PCB mounting a SMT style RJ45 pcb receptacle

    Given a choice between thro' hole RJ45 board mounted connector and SMT style of same I would prefer the thro' hole. For long term physical reliability risks due to stresses from Cat5 cable installation in the field, and fatigue on the solder joints from thermal cycling with cable load. In my...
  4. nigelt

    any user experience of 3M embossed tape/sheet?

    Hi Forum, I am curious if anyone has practical experience in use of any of the range of 3M embossed tapes/sheets? Looking at die-cutting a 2" x 3" sheet to sandwich between two die-cast Alum (chromated) components that are lightly bolted together. Surfaces are to be 'as-cast', and are typical...
  5. nigelt

    silicone oils weeping from thermal interface pads

    Any thoughts on the possible risks about the observation that silicone oils weep out of what are often called thermal gap pads? Is this normal/typical? Result is light oily film on top of the device and on mating surface of the pad. The compression is 15-25% of the nominal thickness - which is...
  6. nigelt

    Mitigation of radiated EMI from SD Card slot?

    Anyone have suggestions for physical design of slot that have proven successful in reducing EMI? Assuming that a small grounded door is not an option. We have experimented with slotted metal fascia plates and with metallized plastic fascia plates that recess the SD Card into a throat. Neither...
  7. nigelt

    Insights about UL pov on non-FR components in a rated pkg.

    First, sorry for the cryptic subject line. We design and manufacture enterprise IP imaging products the materials for which "need" to be UL94 HB as a minimum. You will know that in the case of resins, their FR rating is qualified with a specimen thickness. In essence UL/CSA requires that the...
  8. nigelt

    "Switching relay design" by Robert Lee Peek, Harold Nicholson Wagar

    I bought this book (publ. 1955) while on my continuing hunt for info and context on stamped metal cantilever contact springs. The book provides a treasure trove of useful resources on this topic - maybe 25 - 30% of the contents. Exactly what I was looking for & well worth the modest...
  9. nigelt

    Corner forming for sheet-metal enclosures

    thread820-326262 This may be of interest to folks trying to form tidy sealed corners. http://www.acf.at/lang/en/applications.html A local vendor has this machine, the only drawback is that each corner shape (that is radius and wall height) requires a specific rolling tool. So, unless your...
  10. nigelt

    RoHS compliant plating queries - take two!

    Perhaps I just have really poor resources, but hands up anyone else who is struggling with finding clarity on issues surrounding plating finishes and RoHS compliance? We are looking at it from the design & specifying side & we hear so many myths about what is & isn't compliant. I have queries...
  11. nigelt

    wire bundles traversing a cabinet door hinge

    It's so many years ago that I cannot remember, but what is the guideline for the correct orientation of a wire bundle that must cross a hinge axis. * Typical example, switches on a front panel that is hinged to front of a rack mount shelf. * The wire bundle can approach the hinge at 90deg (wires...
  12. nigelt

    role of plenum in forced air cooling of electronics

    I need to understand the role of the plenum in forced air cooling of electronics, please. I have observed two quite different types of structures being called plenums, though they may operate on the same principle. First is a fan fed box (typically a scroll type fan) from which air goes to an...
  13. nigelt

    silicone outgassing 101 required, please!

    I have noted concerns vis-a-vis outgassing in space/vacuum apps, when silicone based materials are used in enclosure components. I have some questions on this w.r.t. "sealed" enclosures, let's say IP'X'6 & above in the typical -20 +60 degC env... 1 - what, in the bigger picture is the...
  14. nigelt

    Infra Red bandpass filter window - matl search

    Hi all, I am looking please for some leads on inj moulding resins to use for small IR window. I know these are often molded in polycarbonate with a deep blue or deep purple dye. I wonder........ - is there a better descriptive term for this type of colorising so that I can describe it for the...
  15. nigelt

    RoHS compliant plating queries

    Thanks in advance for any reponses..... First: I am interested on any comments on RoHS compliance of Electroless Nickel plating. I'm generally thinking of metal substrates, typically Copper alloys. I am vaguely aware that there are different varieties of electroless nickel process, are some...
  16. nigelt

    Seeking source of low cost shock mounts for CD type drives

    If you have ever had cause to open a ghetto blaster or similar, you will observe that the CD drive is suspended on posts or standoffs with what appear to be moulded shock mounts. They are often like little convoluted bellows, moulded in a soft elastomeric. I'm sure these are available, in qty...
  17. nigelt

    ABS characteristics in low temp service

    We have an issue with failure of inj mld'd ABS parts due to stresses from a co-eff of thermal expansion event - actually not an event, more of a sustained load. The failure is occuring at low temps (-10, -20 deg C : still awaiting info). The assembly is an ABS holder for a disc made of...
  18. nigelt

    power cord strain relief design

    Anyone got any rules of thumb on this topic, please? I am interested in typical pull forces to spec too for portable equipment ( might it be: drop from height 'H' and restrain with cable - any typical height 'H'? ) I've seen clients complain that the cord moves when they whip the unit over...
  19. nigelt

    Minimum deflection of beam - posn of supports calc

    I know this is a trivial question, but I vaguely remember noting a ratio for the quick positioning of a pair of supports under a uniformly loaded uniform beam such that deflection of the centre and equal overhanging ends is minimum. Am I dreaming this, or can anybody recall it, please? Oh, I...
  20. nigelt

    thin strip metal springs

    I posted this in Electromech Design forum some weeks back but nobody took up the gauntlet. Any clues from this group, please? ....A recurring issue is doing the engineering calculations for cantilever or beam type leaf springs, where the "width" of the spring cross section is large...

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