Simplifying How a Press Fit PCB Works for Beginners

Press-Fit technology provides a reliable, solderless, lead-free, and user-friendly automation approach that provides both the high current capacity and design flexibility required for applications in various environments and industries.

Many modern electronic devices use push-fit component technology to provide additional functionality to their products. Press-fit technology provides a compatible interface between the PCB and the padded panel with a single pin or interface that eliminates the need for PCB soldering.

What Is a Press Hole?

Press-fit is a solderless technology that allows an electromechanical connection between the PCB and the component. During pressing, a machine or technician presses a pin into the PCB’s transparent through-hole lining.

The press hole is inserted into the hole with a tighter-than-standard tolerance of +/-0.10mm. The tolerances are very specific and tighter than standard, so the results and holes match up exactly. The size of the interference mounting hole corresponds to the lead wire that is not soldered and pressed into the hole.

The average PTH tolerance depends on the connection type specified by the manufacturer. Therefore, it is important that these tolerances are accurately described in your PCB design and that the “Press-fit” parameter is checked on the order.

Does Press-Fit Last?

As with soldering, we can use press fit to create a permanent connection. However, we need to make sure our measurements are correct by inserting the pin into the hole of the hole. This process mainly depends on pressure and friction.

As their name suggests, press-fit contacts are pressed into appropriately dimensioned plated-through holes on the PCB with gas-tight intrusion between the contact and the hole. A press-fit connector’s terminals (press-fit parts) are inserted into through-holes in the printed circuit board, where force is applied due to the twist of the press-fit sections, causing contact connecting the holes and the terminals to pass electric current.

If the fit is tight enough, the pin should be able to form a permanent bond. However, if there is insufficient friction or tension between the plug and the hole wall, the nail may need to withstand enough pressure to sit straight or maintain a strong bond.

This is achieved by introducing a specially-stamped terminal into a plated through hole (PTH) of a printed circuit board (PCB). Let’s take a look at this technology thoroughly. A Closer Look Press-Fit interconnects function like the ever-present blade and socket pair in a connector, except the genders are reversed. In a traditional blade and socket pair, the socket has elastic beams that provide the necessary normal force for an electrical connection, and the blade is firm.

Some key driving factors towards the growing adoption of press-fit include: Eliminating the risk of dry joints, cracking, and other solder formation problems with strong, solder-free, repeatable, and highly reliable interfaces.

What Are the Challenges of Using Press Fit on PCB?

Press-fit technology offers high-quality electrical equipment without soldering. This connection method is used to press single-pin components or entire assemblies with press-in areas into metal holes on printed circuit boards.

As the name suggests, interface bonding contacts are pressed into coated holes on a circuit board with hydrogen interference between the interface and the hole.

The push-pin joints on both sides of the PCB are adaptable and can be used for flexible double-sided pinhole assembly and PCB SMT. In addition, when the module size is reduced, compression pins can protect critical components and save critical space in narrow pin designs.

Mechanical systems and processors generate a lot of heat in the engine or server rooms. Interference mounting studs provide a reliable interface for thermal heat dissipation with a higher thermal barrier and lower failure rate than solder joints.

Advantages of Press-Fit Technology

Although press-fit eradicates the risks associated with soldering, it is not without its challenges. Manufacturers must choose from a range of products that offer press-fit terminations of different designs made from materials with different performance levels.

These key advantages have made press-fit technology a favored solution for the design of many new products. It has also encouraged large and better design upgrades of press-fit technologies.

  1. Very high capacity, suitable for high and strong DC currents
  2. Push-fit connectors are very stable in the environment
  3. Low resistance connections (< 200 μ) result in low self-heating, so the system has to dissipate less heat.
  4. No heat is generated in pressure areas, and there is no thermal load on the printed circuit board
  5. High reliability of the connection with extremely low FIT value
  6. Mechanically very stable
  7. Don’t worry about cold joints
  8. High mechanical holding power
  9. The circuit board can be double-sided
  10. Long-term reliability is much better than solder joints
  11. Safer than solder and screws
  12. No adjustments are required in printed circuit board manufacturing

Thermal compatibility is another advantage of socket connections over soldered waves. If secondary soldering is required, heat is introduced, which can damage the circuit board and attached devices. The press-fit technique eliminates excessive thermal cycling and makes secondary connections easy to repair, environmentally friendly, and cost-effective using only press-fit connectors.

Although press fit does not involve soldering issues, it has its challenges. Manufacturers are competing with various connected devices that provide different design complexities from different performance levels of materials when pressed.

Changing to Press-Fit Technology

Press-Fit connections have proven to be highly effective in various applications that benefit from the ability to provide a durable solderless connection while streamlining the installation process.

However, it is important to point out a few key considerations that should be taken into account to ensure a successful conversion. These include PCB hole size, plating control, Press-Fit pin lengths, and Press-Fit assembly forces.

The configuration of Press-Fit technology also makes it a simple process to upgrade from solder joints, which are part of most routine product upgrade processes. Manufacturers can improve reliability and reduce costs throughout the product life cycle by incorporating Press-Fit modifications during product updates.

As more and more manufacturers consider converting existing designs to use Press-Fit during refresh or retrofit cycles, several key factors are also being considered:

  1. Are there any changes or updates planned that could open up mod possibilities?
  2. Does the secondary welding process negatively affect the product outcome?
  3. What is the experience of quality and reliability in this area?
  4. Is the product exposed to other environmental temperatures and pressure cycles?
  5. Do solder joint failures cause quality problems in this area?
  6. Can the product benefit from cost reduction for the remainder of its life cycle?

Press Assembly Technology

Using environmentally hazardous materials or lead-free solder can significantly reduce the reliability of soldering. In addition, various problems have arisen, such as the need to avoid thermal shock to chip components due to soldering heat and the need for automatic assembly.

Reflecting this situation, for example, press-fit technology is used for connections between automotive control system circuits, such as onboard equipment, anti-lock braking systems, vehicle stability control, and navigation systems. The press fit technology allows easy removal of connectors and similar components and is also beneficial in compliance with the European Waste Electrical and Electronic Equipment Directive (WEEE Directive).

As a result, the application of this technology has expanded to mainstream consumer products, including personal computers, servers, and multifunction printers.

Things to Look For In a Press-Fit Expert

Press-Fit technology has become a powerful solution to eliminate welding, avoid complex secondary manufacturing processes, increase reliability and reduce costs. However, Press-Fit components are not off-the-shelf items that can be plated through holes.

The main things that a Press-Fit Interconnect specialist needs to deal with when press fitting are:

  • Test design and standards
  • Application documentation and support
  • Raw material selection and coating process control
  • Global tooling standards, inspection criteria, and production control plans
  • Test global functionality and application support capabilities

For optimal results, customers should turn to Press-Fit experts who are familiar with the design, testing, documentation, and careful manufacturing processes.

How Does a Press Hole Work?

Understanding how press-fit pins and press fit connectors work is very essential. Without this understanding of how press fit pins work, achieving press fitting may be difficult or impossible. Since these press fit pin connections support both mechanical and electrical loads, pin strength and long-term stability are important, depending on PCB bonding and distortion (PTH).

However, compared to ball grid arrays (BGAs), push-pin joints still have some unknowns about the degradation process. This study analyzed critical pins with similar structures but different initial microstructures and revealed highly deformed plastic regions.

Electron segment, sub-examination, and backscatter diffraction (EBSD) were used to evaluate and analyze the bond strength, microstructure evolution, and the effect of thermomechanical cycling.

Advanced thermocycling tests were performed with cycles from -40°C to 125°C to determine potential damage due to mechanical heat. The results show that the initial microstructure significantly affects stress development, percent strain, grain expansion, local distress, hardness, and bond strength.

In other words, the press-fit part of each terminal forms a tight fit with a through-hole in the printed circuit board due to the restoring force generated due to the flexible deformation at the time of press-fitting. A press-fit pin provides reliability that prevents thermal heat and can withhold higher heat threshold.

Conclusion

The above guide covers the technology of PCB pressing. In addition, he discusses whether it is a viable alternative to traditional assembly technologies such as SMT and THT. The press has many advantages; therefore, it is here to stay. However, choose a reputable PCB manufacturer like Hilman Curtis to get the best of your press-fit connection and enjoy a seamless assembly process for all your press-fit contacts