That fits – press-fit technology

Basic technology

A press-fit connection is made by pressing a pin into a plated-through hole in the printed circuit board. The main feature is the fact that the crosssection of the pin has a larger diameter than the plated-through hole in the printed circuit board. When the pin is pressed into the hole, the excess material must be taken up either by deformation of the hole in the printed circuit board or of the pin.

There are two types of press-fit zones:

• the solid zone, which is not deformed. (solid pin)
• the flexible zone which is deformed. (compliant pin)

Especially the flexible zone has become established in the market for press-fit connectors. The flexible technology has many advantages over the solid technology:

• Flexible response of the press-fit zone on the pin, little strain on the plated-through hole
• A larger hole tolerance of the plated-through drill holes is permissible in the printed circuit boards
• Less press-fit forces are required, thus undesired side effects are reduced
• Multiple press-fitting of contacts into the same PCB drill hole is possible

Comparison: Solder technology – press-fit technology

The press-fit technology has a number of advantages compared to the conventional solder technology:

• No thermal load on the printed circuit board since no soldering is required
• No solder vapours and welding flux residues that impair the contact stability of the connector
• No "cold" soldering joints
• No short circuits due to solder bridges
• Mechanical fixing of the connector direct via the press-fit pins (no screws are required)
• Long connector pins remain free of brazing solder and, if they are gold plated, they can be used as rear mating connection
• Defined impedance of the connection due to a defined geometry (good HF properties)
• Can be repaired without problems
• Connectors and/or contacts can be replaced without problem
• Environmentally compatible, since printed circuit boards with press-fit components do not have to be washed
• Easy to recycle; the connector is disassembled by means of purely mechanical extrusion

An important and often underestimated advantage of the press-fit technology over soldering technology is the cost advantage when the PCB‘s are assembled. Studies in different companies have shown that costs due to soldering problems are considerably underestimated. A substantiated cost effectiveness study shows that press-fit technology is much more cost-effective than conventional soldering technology.

Press-fit technology and SMT

SMT and press-fit technology are the basis for an effi cient, cost-effective and high-quality assembly of modern modules. After assembling the module PCBs with SMT components and reflow soldering, the connector, base, pins, sockets, etc. are pressed into the plated-through PCB holes, which were not affected due to the reflow soldering process.

Press-fit zone requirements

The ept press-fit zones meet the requirements of DIN 41611 Part 5 or IEC 60352-5.

Tcom press® Press-fit zones for any applications

A modern press-fit zone can be adapted to most application-related requirements. This includes:

• Tin swarf on printed circuit boards is avoided with hot air leveling
• Sagging of backplanes is avoided (banana effect)
• Hole diameters can vary
• Functionality is ensured for various PCB surfaces