What are the benefits of screw machine interconnects?

As Principal Engineer for a large connector manufacturer, each day I am challenged by electrical engineers and mechanical engineers to help bridge their leading edge technology from one module to another. I remember years ago, when the pin grid array went obsolete to the emerging QFP quad-flat pack, people said that “screw machine was a goner.” Compounded by the fact that the entire electronics industry was migrating to high-density, high-speed SMT assembly methods, that surely was to become the final nail.

But somehow, technology for screw machine interconnects evolved and survived. Even with advances in BGA and LGA packaging, we’re still standing! In fact, over my 35 years of experience—25 in the world of screw machine—the applications of screw machine technology continue to grow at an exponential rate. It’s not by accident that military, medical, aerospace, industrial, automation, robotics, telecommunication and every other industry involved in the design of the most leading edge technology continue to rely on screw machine interconnects for their most critical, “failure-is-not-an-option” applications. This technology traces back to Swiss pride and precision watch making many moons ago. A few thousand years from now, this discussion will continue. This proven technology is not ready to leave anytime soon. Nope, not yet

The image shows a variety of styles of screw machine technology for interconnect applications. Here are descriptions of each, from top row, left to right:

1. Swage rivet pin for wire attachment
2. Screw machine low profile receptacles can be packaged on tape and reel
3. BeCu contact clips integrated into shells for multiple points of electrical contact
4. Screw machine pins with polygon features (flats) for SMT assembly
5. Another example of screw machine pins with polygon features (flats) for SMT assembly
6. Horizontal SMT 26-AWG wire capture devices
7. Cross-cutting features to promote solder wicking
8. V-Groove features to promote solder wicking
9. Eye-of-needle compliant tail technology for solderless attachment to PCBs that are hard to solder
10. Polygon cutting (hexagon) for solderless press-fit in multi-layer PCBs
11. Socket receptacle technology using BeCu multi-finger contact clips
12. Spring-loaded contacts (SLC) used everywhere in modular design
13. Lead bending to create SMT connectors
14. Channeled grooves for solder wicking of power pins, high conductivity alloys
15. A press-fit barb: the simplest, most reliable feature for pin retention in thermoplastics and FR-4, but not intended for insertion into PTHs

Martin Houlroyd is Principal Engineer/Marketing Specialist at Preci-Dip. He has worked in the interconnect industry for 35 years. Email him at m.houlroyd@precidip.com.