by Martin Houlroyd
Here are some general guidelines I use each day to help MEs and EEs with the PCB interconnect requirements. I hope you will find these helpful in your applications.
1. Press-Fit Barb – Specifically for non-plated through holes. This is the easiest and most cost-effective retention feature to machine. Like a fishhook, when the barb is set into a thermoplastic or FR-4 epoxy insulator, the pin will not walk out.
2. Press-Fit Knurl – A gear shaped feature, intended for non-plated through holes.
This is specifically for any application that requires anti-rotation. Such as a long
right angle pin or a wire-wrap pin, you do not want either to spin in place when
pushed or torqued.
3. Press-Fit Polygon – a technique of designing a low profile pin with a multi-facet barrel
such, that when it is press-fit into a multi-layer PCB, only the points of the polygon
achieve a gas-tight mechanical and electrical connection with the copper wall.
This technique is used for hard-to-solder thick PCBs.
4. Gull Wing – Is a method to achieve stronger solder joints by increasing the PCB land
surface area vs. a SMT component that has in-line circular pads. Since the gull-wing
leads are bent outward, it makes solderjoint inspection and access much easier.
5. Pin-in-Paste – This is an ideal technique for mechanically strengthening connector
components mounted on SMT PCBs. The lead is specifically designed not to protrude
beneath the PCB, and the pin shoulder is reflowed on the top PCB pad.
6. Solder Tail – If the engineer can live with the above board height, pins and sockets with
soldertails are beneficial because they require a minimum diameter plated through hole
inside the PCB. This allows for more signal routing channels between pins, which
effectively minimizes the required amount of PCB layers, saving cost.
7. Floating Shoulder – Floating shoulder is designing a feature onto the pin body that allows it to
float in a vertical direction. This is ideal for applications involving uneven surfaces or
SMT assembly over a very large area, where coplanarity is a concern. A surface mount
socket assembled with floating pins can compensate for peaks and valleys caused by
warp, twist or uneven solderpaste.
8. Surface Mount – The benefit of SMT attachment is it allows the designer to optimize both
sides of his PCB for component attachment. Double density packaging.
9. Swaging – Swaging is act of riveting, mechanically fastening a pin into
a hole. A very old and reliable technology, ideal for engineers may want to
solder heavy gauge wires to a PCB. The benefit of swaging is the swage
pin is not solely relying on a solderjoint, but rather the mechanical fastening.
This prevents the pin from reflowing and falling out of the hole during soldering
of heavy gauge wires.