Results 1 to 8 of 8

Thread: Removing & resoldering a can / shield?

  1. #1
    Join Date
    May 19, 2019
    Location
    Australia
    Posts
    26
    Thanks
    12
    Thanked 65 Times in 18 Posts
    Country: Australia

    Default Removing & resoldering a can / shield?

    Interested to hear the techniques used to remove a sealed shield or can like the one below, and then how they're reflowed back on to the PCB again? Hoping to be able to do this without a hot air reworking station or my very crude 'cut the top off with a Dremel and reseal it with a copper shim hat' method...


  2. #2
    Astro Spectra's Avatar
    Astro Spectra is offline T S - Moderator
    CS Forums $upporter
    Join Date
    Nov 22, 2012
    Posts
    836
    Thanks
    285
    Thanked 508 Times in 261 Posts
    Country: Great Britain

    Default

    With care you can use a hardware store hot air gun (commonly used for paint stripping). Practice on something you don't care about first and use a tin foil mask to avoid heating parts you don't want to unsolder. I use disposable oven liners as they're thicker than regular cooking foil.
    It is a fine thing to be honest, but it is also very important to be right

  3. The Following 3 Users Say Thank You to Astro Spectra For This Useful Post:

    jry (Jun 04, 2019),Mars (Jun 03, 2019),motorola_otaku (Jun 04, 2019)

  4. #3
    Join Date
    Jan 18, 2013
    Location
    In Your Network
    Posts
    2,606
    Thanks
    2,408
    Thanked 1,739 Times in 878 Posts
    Country: Holy See

    Default

    A hot air tool is less than a hundred dollars and works well.
    Apparently NOT a radio professional.

  5. #4
    Join Date
    May 19, 2019
    Location
    Australia
    Posts
    26
    Thanks
    12
    Thanked 65 Times in 18 Posts
    Country: Australia

    Default

    I ended up getting the can off by mechanical means - carefully running a scalpel blade along the solder join several times until it was thin enough to flex the shield off the board.
    After modding the VCO, I'll use the hot air rework tool that'll arrive next week to reflow the shield back on. Any tips or tricks on what you do to make a good job of that task would be gladly appreciated eg: Solder paste & reflow? Place the can and run a bead of Sn/Pb solder along like you would some silicone sealant on a window?

  6. #5
    Join Date
    Jan 18, 2013
    Location
    In Your Network
    Posts
    2,606
    Thanks
    2,408
    Thanked 1,739 Times in 878 Posts
    Country: Holy See

    Default

    There are SEVERAL good tutorials on YouTube if you search for them. Those should give you the basics on what other people are doing. IF you have a dead radio or other electronics around, wouldn't hurt to practice first.
    Apparently NOT a radio professional.

  7. The Following User Says Thank You to com501 For This Useful Post:

    motorola_otaku (Jun 17, 2019)

  8. #6
    Join Date
    Jul 21, 2019
    Location
    Keswick, Virginia
    Posts
    3
    Thanks
    0
    Thanked 1 Time in 1 Post
    Country: United States

    Default

    The choice of techniques I have used has depended on the style of shield, the side access and what makes sense to avoid damaging delicate parts around it.

    A method not mentioned yet is to apply heat locally to the shield, near the board, with a very hot soldering pencil while soaking up the solder with solder wick.

  9. #7
    Join Date
    Feb 04, 2012
    Posts
    1,874
    Thanks
    180
    Thanked 668 Times in 303 Posts

    Default

    A hot air tool is the way to go. I have removed a ton of them. My technique is to use a medium focused tip and work around the parameter of the shield and lift it suing a small pry tool in the vent hole. This avoids possibly desoldering components under or around the shield.

  10. The Following User Says Thank You to Notarola For This Useful Post:

    Bill_G (Jul 24, 2019)

  11. #8
    Join Date
    Jan 31, 2015
    Location
    Portland OR
    Posts
    652
    Thanks
    927
    Thanked 884 Times in 429 Posts
    Country: United States

    Default

    Same. I have a Weller heat gun with a stainless steel funnel tip to focus the air to about a one cm diameter. Though it's a gun shape, I put a glove on, and hold the barrel like a pencil for better control. Clean all the old solder off, and apply fresh in a light bead. It should not be a mound. It should be the lightest possible layer of fresh solder on the cleaned trace. ie: some fresh material, but not a lot. Otherwise the shield will spread the excess solder out like a smashed pie in all directions, and totally hose up your work. And you have to work fast, or you'll cook the crap out of the board. As already mentioned, practice on some dead boards first. It's all about finesse.
    Bow wow wow yippie yo yippie yay

  12. The Following User Says Thank You to Bill_G For This Useful Post:

    motorola_otaku (Jul 25, 2019)