IC with special pads

I would like to know what is the name of those special pads designed to catch excessive solder and where can I find more information on them.

  • \$\begingroup\$ What are you talking about? There aren't any pads to catch "excessive" solder. There are some unused pads on that board (parts that weren't installed) and what might be test pads (for connecting test equipment to test the boards after assembly.) \$\endgroup\$
    – JRE
    Feb 4 '17 at 22:43
  • 3
    \$\begingroup\$ @JRE: on the IC at the rightmost pins, the pads are bigger to catch solder in the case of wave soldering. \$\endgroup\$
    – PlasmaHH
    Feb 4 '17 at 22:46

This is a mixed through-hole/SMT board and it was wave soldered (so all of the visible parts in your photo were literally immersed in molten solder).

enter image description here

The only thing I see related to excess solder are the extended pads for "solder thieving" on the right-hand side of the '324 quad op-amp chip. The board was sent through the wave from left to right and the extended pads help prevent bridging between pins. Sometimes you will see QFP packages mounted diagonally with similar extensions at the corner pins.

(Edit: arrow shows direction of wave flowing as board moves, not board direction).

enter image description here

Here is a quote from an excellent NXP/Philips app note "SMD Mounting Methods" (above illustration also from this app note):

The figures on the following pages show footprints for most of our IC packages. There are also details on some figures that are specific to wave soldering such as the indicated transport direction of the PC board and the location of solder thieves. The use of solder thieves (areas of metallization in addition to, or attached to, the downstream pair of solder lands of the IC footprint) is recommended for wave soldering as they reduce the likelihood of solder bridging on these lands.

If you are designing the board for reflow soldering, part orientation and solder theiving usually isn't a consideration.

  • \$\begingroup\$ Thank you for your answer, you took way more time to explain it than I thought someone would. \$\endgroup\$
    – Iouraxos
    Feb 6 '17 at 4:55
  • \$\begingroup\$ I assume these SMD devices have ("red") adhesive underneath them? \$\endgroup\$
    – Toybuilder
    Dec 12 '20 at 1:11
  • 2
    \$\begingroup\$ I think your arrow is the wrong way around. The solder wave would travel left to right (board stationary) to hit the thief pads last, but the board would travel right to left (wave stationary) \$\endgroup\$
    – Nick T
    Dec 17 '20 at 15:42
  • 1
    \$\begingroup\$ @NickT I think you're right. \$\endgroup\$ Dec 18 '20 at 2:39

I have mostly seen them being called "[solder] Thieving pad" or rarely "[solder] robber pad"


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.