EYE on NPI - TE Board-Mount Reflow Terminal Blocks #EyeOnNPI #DigiKey @DigiKey @TEConnectivity
Channel: Adafruit Industries
Date: 27/01/2022

This week's EYE ON NPI is gonna be a hit for anyone who has ever had to add terminal blocks to a design, then dealt with the frustrations and costs of having a mixed SMT/THM process. Presenting... TE Connectivity Board-Mount Surface Mount Reflow Terminal Blocks (https://www.digikey.com/en/product-highlight/t/te-connectivity-amp/board-mount-reflow-terminal-blocks). Yes! Almost everyone has created a design that had a raw-wire to board connection. And a super popular way to make a flexible but durable connection with a range of wire thicknesses is to use the tried-and-true Terminal Block (https://www.digikey.com/en/products/filter/terminal-blocks-wire-to-board/371).

Digi-Key carries thousands of different terminal blocks in all sizes, pitches and configuration. Multiple rows! Plug type! But they all tend to be through-hole type. Not surprising, because there's a lot of mechanical torque on the connector when twisting, and also a lot of current passes through these connectors - they're often used for power supplies, and motors, that can draw amps. Given that they are through hole, a selective, manual or wave-soldering step is required for manufacture. (https://blog.adafruit.com/2014/03/26/ace-production-selective-solder-kiss-102il-apex-expo-adafruitapex-ipcshow-ipcshow-apexexpo/) And believe us, while these machines are totally awesome - they also require a lot of maintenance and time to run. (https://blog.adafruit.com/2018/07/02/programming-the-crickit-for-selective-soldering-a-deep-dive-part-3-adafruit-crickit-manufacturing-selectivesoldering/)  So we try very hard to go with SMT-only processes: it's a lot faster and cheaper to only use one machine than to use two machines where boards have to move through two machines.

We've used some "SMT Terminal blocks" before in products like on our buckaroo bonsai (https://www.adafruit.com/product/4534), which only needs 2 wires connected, and low power ones at that. Since hauling all the PCBs to the selective for just two pins is a total pain, we figured its better to go with this 'side insert' type. It works fairly well but doesn't have the adjustability we love with the cage-type terminal blocks.

Which is why we are diggin' this series from TE, available in various pitches (3.5mm, 3.81mm or 5mm) and pin counts, from 2 to 7 pins. They look just like your everyday terminal blocks, but with flat rectangular pads that are bend 90 degrees to the back of the package, and mechanical shear/locating dots that will keep the connector from lifting up. They're even packaged in a chunky tape and reel, ready for use in your machine line. Note that even with the locator posts and large pads, you'll still want to make sure that you don't have a lot of force coming in from the front: The posts will protect against torque from the top but probably can't help much if they are lifted up from the front.

If you only need a couple terminal blocks in your design and want to save process costs - or if there's a reason you can't go with a through-hole block - these TE Board-Mount Reflow Terminal Blocks (https://www.digikey.com/en/product-highlight/t/te-connectivity-amp/board-mount-reflow-terminal-blocks) will do great. And, they're available and in stock at Digi-Key right now! Order today for immediate delivery, so you can be twistin' and terminatin' by tomorrow afternoon.