The date was January 1, 1968, and on this day, America passed its first seat belt (fastener) law. The legal name for it was Title 49 of the United States Code, Chapter 301, Motor Vehicle Safety Standard. It required that all vehicles (except buses) have seat belts in all designated seating positions.
Even back then, it was apparent that securing that in which you value was an essential step in preserving it. However, it took a little more than a decade before the individual states begain to strictly enforce the use of seat belts. Now fast-forward to the present day, and little has changed in regards to the use of seat belts. Unless you include the slight advancement in the technology and the increased focus on advertising.
We have all seen the commercials regarding seat belts (fasteners), and some of us may even know of someone who’s life was spared due to wearing one. I, for one, have seen the life-saving miracle of seat belts, and I can attest that they do work. Well, this same logic applies to PCBs as well. Fasteners are, in a way, life-saving tools that help preserve the PCBs. Industrial engineering fasteners are a vital part of the overall PCB manufacturing process.
Industrial Engineering Fasteners Defined
By definition, a hardware device that mechanically joins two or more objects is called a fastener. Overall, fasteners, including industrial ones, are used to create non-permanent joints (able to be dismantled or removed). Examples of fasteners include clips, bolts, pins, latches, screws, nuts, washers, nails, and sockets, to name a few. Materials such as plastic, steel, stainless steel, bronze, brass, and nylon are used to make fasteners.
As I am sure you are aware, the types of fasteners, as well as the variety of materials used to create fasteners, are as vast as their applicational uses. Also, when you consider their level of importance (PCBs), the subject of industrial engineering fasteners is not as straightforward as one might think.
The right fastener, made from the correct material for the application, is the difference between a PCB performing optimally or not at all in some cases. Securing your well-designed PCB is as essential as the design itself. This conceptual approach also includes components on the PCB as well.
While a considerably simple part of the manufacturing process, it is still good to understand the roles fasteners play.
Importance of Industrial Fasteners in PCB Manufacturing
As I eluded to earlier, there are many different types of fasteners. However, I will limit my discussion to those aimed explicitly at the PCB market.
Regardless of the level of sophistication of the design or how advanced the components you use in the design, there is a need for secure and reliable attachment to achieve optimal performance. The electrical environment of PCBs is a delicate and fragile ecosystem that contends with EMI, ESD, and thermal threats. The last thing you want to be worrying about is the physical mount causing your well-designed PCB to fail.
The fact remains that many of us discount the importance of industrial fasteners to the overall PCB manufacturing process. The effects of a PCB not securely attached to the chassis is not a thing of beauty, but rather a nightmare. With that in mind, I will discuss in the next few paragraphs, some of the common causes of fastener failures so that you can avoid these common pitfalls.
Three Types of Industrial Engineering Fasteners in PCBs
There are three categories or types of industrial fasteners that provide reliable and secure attachment for an array of PCB applications. Contingent on type and style, these industrial engineering fastener solutions can accommodate board-to-board, component-to-board, board-to-chassis, or even stacking or spacing attachment challenges.
The three types or categories are:
Surface mount fasteners: They generally include unthreaded or threaded nuts and standoffs, captive panel screws, and uniquely provide durable reusable threads at right angles to boards.
Broaching fasteners: In general, they include threaded, or unthreaded standoffs, threaded nuts, panel fastener assemblies, threaded studs, and standoffs with a spring action to hold boards securely without screws or threaded hardware.
Broach/flare-mount standoffs: As the name implies, these are the hybrids of the group. They are for spacing applications or stacking and integrate a combination of a broach+flare feature promoting superior pullout performance upon installation in board materials.
Common Causes of Industrial Engineering Fastener Failure
Regardless of the quality of the design or the final build quality, everything eventually fails. This includes components bolstering the most precise designs executed with proven manufacturing techniques. This unavoidable truth also applies to industrial engineering fasteners. If you ask any engineer, they will tell you that it is not so much the failure, but rather when the failure occurs.
Think of it this way, if your Xbox One X fails after making sounds indicative of an impending hard drive failure, it might be unpleasant but expected. However, if you just purchased your new Xbox One X along with several games and accessories and then it suddenly stops working, well, you get the idea.
So, what are the usual causes of untimely failures of industrial fasteners? More so, what can be done to minimize the risks and maximize the life expectancy of the fasteners? Well, according to designers, manufacturers, and marketing research data on failure analysis, the primary cause of failures are as follows:
Over-tightening: The applying of too much force leads to tensile failures and damage to the PCB itself.
Under-tightening: Not applying enough force leads to improper installation which places too much stress on the fasteners. This, of course, leads to fatigue failures. Joints and fasteners can become loose due to insufficient clamping force as well.
Improperly designed joint: Improper design refers to improper loads placed on a fastener, which will cause premature failure. Also, fasteners and joints can become loose after the installation, or the fasteners can detach from the parent material.
Fastener quality: Materials used to make the fasteners dictate their performance. So, inferior materials mean poor performance and early failures.
Assembly equipment: The improper use of the assembling machine often leads to improperly installed fasteners and early failures.
Hydrogen embrittlement: In high-tensile steels above a specific hardness range, the tensile load applied to the fastener can cause hydrogen characteristically in the component, plating, or environment to flow to the area of stress, gradually causing micro-cracks as well as delayed failure in the fasteners.
We cannot rely on the specifications sheet alone. Simply because they do not and cannot tell PCB designers everything they need to know. Therefore, I encourage actual real-world tests to identify fastener issues before they make it to the production line.
This is especially true today as we continuously see an increase in the variety of the types of electronic devices in the marketplace. Furthermore, the PCB is still the most common component found in any electronic device, and the industrial engineering fasteners are their unsung heroes.
Cadence’s suite of design and analysis tools will enable you to barely bat an eyelash at fasteners in your production process. When preparing your design for production, OrCAD PCB Designer is the layout tool capable of organizing your workflow, streamlining communication, and offering clear documentation for any manufacturing necessities.
If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.