It may seem odd to think about the screws and bolts used in printed circuit boards. PCB isn’t automotive manufacturing, where great numbers of screws, bolts, and rivets hold everything together. The boards, after all, are printed; there aren’t that many screws, and these screws don’t hold the board together.
Yet the screws in PCB manufacturing are nonetheless essential. Screws mount your PCB to the object it powers. Critical hardware components, such as heat sinks, are likewise mounted to your board with screws. If these screws fall out or break, your board will drop off its mount or fall apart.
To keep your screws from coming loose or breaking, you need to apply a specific amount of torque. Without a set of tools which can reliably provide specified amounts of torque, you won’t be able to guarantee your products won’t go to pieces. To control the rate of your product loss, you need both proper equipment and an oversight procedure to assure the quality of your products. Fortunately, effective and reliable torque solutions exist for the specific needs of the PCB manufacturing process.
Why Torque Solutions Matter in PCB Manufacturing
Many critical applications rely on printed circuit boards. If a mounting inside a jet engine, pacemaker, or natural gas turbine loses its screw, the results can be catastrophic. While one screw hardly seems terrifying, as one part of a system fails, it increases the load on every other part—potentially beyond tolerance. If these parts fail, the cycle repeats, gaining strength and trending towards total system failure. This is known as a cascading failure.
Even for boards designed for more pedestrian usage, like those in digital clocks, screw failure is a potentially costly issue. If procedures are not in place to ensure each fastener is torqued correctly, the failure rate of your products will increase.
Reducing your failure rate is a key strategy for improving the profitability of your manufacturing operation. Lengthening the lifespan of your products lifts customer satisfaction rates, which can increase your sales volume and, ultimately, your revenue. As such, torque control should be a core function of your manufacturing process.
How Torque Holds PCB Together
In order to know how to keep things together, you must understand how things fall apart. So, what is torque? And how does it hold the screws in your circuit board in place?
Torque is radial force. When you turn a screw or bolt to hold two objects together, you are applying radial force to two inclined planes—the threads of the fastener and socket. The radial force drives the planes together. As the screw compresses the two objects it is holding together, they push back, exerting an opposite force on the screw—tension force.
A screw can only take so much tension force. As they reach the limits of their strength, screws begin to warp and deform along the paths caused by the tension. If subjected to increased tension force, particularly sharp, sudden applications, they become increasingly likely to break. Hypertension also leaves screws susceptible to shear force, which is force perpendicular to the axis of tension and compression. Increasing continuous or sudden applications of shear force can buckle the screw or cut it in half.
If, in contrast, a screw does not receive enough torque when it’s being fastened, it will suffer from a dearth of tension and compression. This can cause things to shift as the force moves through the screw and its substrates, which further diffuses tension. When enough tension is diffused, the screw will no longer hold the objects it fastens together and can fall from its socket.
Choosing Torque Tools for PCB Manufacturing
There are many which can precisely limit the amount of torque their operator applies. Automatic tools can event limit torque without the need for an operator using a variety of mechanisms, including clutches and deflection points. However, not all these tools are suitable for PCB manufacturing.
In addition to torque control, PCB manufacturing demands tools with the following abilities:
- Deliver torque within the right range
- Work rapidly
- Prevent electrostatic discharge
To be certain your tools are functioning properly, fastener quality assurance programs should also be implemented. These programs benefit from the implementation of screw counters and DC control systems.
Electric Screwdrivers and Automated Systems Aid PCB Manufacturing
Not all screws can take the same amount of torque. A wrench used to tighten lug nuts on a dump truck won’t work on the bolt holding your heat sink to your circuit board. PCB manufacturing usually requires minute amounts of torque, measured in inch-ounces or gram-force centimeters. When selecting tools for your operation, be sure they’re capable of delivering the torque ranges detailed in the design specifications of your anticipated products.
In addition to proper torque control, many PCB manufacturing operations produce boards in large volume. For these operations, fastening speed is essential. Electric torque screwdrivers allow manual tool operators to significantly increase production speed compared to using hand tools. Fully automated electric screwdrivers can further up production speed while maintaining accurate torque control.
Preventing Electrostatic Discharge
PCB is highly sensitive electronic material, making it vulnerable to damage from electrostatic discharge. Very small amounts of static electricity passed incidentally from operator or tool through your circuit board can cause irreparable damage. Even electrostatic discharge below 200v can damage semiconductors.
To prevent ESD, use tools specifically rated for work with sensitive electronics. It’s also important to remove environmental factors that accumulate static electricity, such as carpets, rugs, plastics, and synthetic materials like styrofoam.
Quality Assurance Programs for Fastener Oversight
Quality assurance programs to reduce product loss depend greatly on their ability to observe and record a plant’s operations. Whether using manual, electric, or fully automatic screwdrivers, investing in control tools and screw counting systems significantly enhances your oversight capabilities.
DC control tools and screw counting systems allow you to view, track, and record your fastening operations in real-time. You’ll be notified of any omissions, unfinished rundowns, or cross-threads as they happen. This visibility allows you to correct problems right away and identify tools which require maintenance, thereby reducing your product failure rate.
Fasteners are essential components of printed circuit boards, and each fastener must receive the right amount of torque in order to hold its position. Properly torquing screws and bolts with torque control tools will lower product failure rates and reduce exposure to critical failures in zero-tolerance applications. Augmenting your quality assurance program with screw counters and automatic tools will give you the oversight you need to detect fastening issues and correct them.
