Utilizing all pins on a custom breakout
So many options... SMDheader underneath was looking good but I saw it may may be prone to lifting or damage if swapping the MCU in and out frequently. Maybe a bit of love from a hot glue gun can make the connections underneath more like a single connection?
Mounting upside down would also have an advantage of being able to add later if needed but has the drawback of covering the reset button and making access to the SD card a bit tricky.
EXPERIMENT : Had a look at double male headers I have (ones that can break off to any size)... it seems the pins bend quite easily so it would be more than possible to join 33->3.3v, 34->47, 35->48 etc. This should solve issues with lining up pins, means the bottom can be facing the bottom and hopefully since each SMD connection will have a through hole to support it... it shouldn't be prone to damage. I'm going to give this a dry run on my Teensy 3.1 that still has no headers.
VERDICT : The bent male double header approach seems good... however as the pins that get bent do not sit flush the entire pin array is mounted up slightly which should not be a problem as there is still enough to solder on the opposite side and once soldered in place some hot glue could easily fill the small gaps if needed. As for the female headers on the breakout... would use the breakable single ones on board as needed as all connections on the breakout will be through hole.
I'm very happy with this project so can prob commit to backing $100ish to secure enough units for testing and eventual use.
The original breakout I had started had provisions for SD card and a RTC... guess they can go for starters.
One method that people use for breakout boards is to use a castellated design, such as this board for Teensy 3.1/2 from FrankB: https://oshpark.com/shared_projects/cYQjHdCu. His newer board is here (but the pictures don't show the castellation): https://pcbs.io/user/FrankB.
You might want to check out this thread from KurtE about a carrier board he is designing: https://forum.pjrc.com/threads/36244-Teensy-3-5-3-6-Breakout-board-to-test-things-with.
Here is a post from Jimmayhaug on a sturdier way to solder pins to the underneath pads: https://forum.pjrc.com/threads/26071-Using-all-Teensy3-x-pins-with-a-socket.
Note, in the 3.5/3.6 all of those pins are on the outside edges, so you might not need to solder to the pads underneath the Teensy.
So many options... SMDheader underneath was looking good but I saw it may may be prone to lifting or damage if swapping the MCU in and out frequently. Maybe a bit of love from a hot glue gun can make the connections underneath more like a single connection?
Mounting upside down would also have an advantage of being able to add later if needed but has the drawback of covering the reset button and making access to the SD card a bit tricky.
EXPERIMENT : Had a look at double male headers I have (ones that can break off to any size)... it seems the pins bend quite easily so it would be more than possible to join 33->3.3v, 34->47, 35->48 etc. This should solve issues with lining up pins, means the bottom can be facing the bottom and hopefully since each SMD connection will have a through hole to support it... it shouldn't be prone to damage. I'm going to give this a dry run on my Teensy 3.1 that still has no headers.
VERDICT : The bent male double header approach seems good... however as the pins that get bent do not sit flush the entire pin array is mounted up slightly which should not be a problem as there is still enough to solder on the opposite side and once soldered in place some hot glue could easily fill the small gaps if needed. As for the female headers on the breakout... would use the breakable single ones on board as needed as all connections on the breakout will be through hole.
I'm very happy with this project so can prob commit to backing $100ish to secure enough units for testing and eventual use.
The original breakout I had started had provisions for SD card and a RTC... guess they can go for starters.