PENCOM designed its new series of captive screws specifically for SMT processes.
SAN CARLOS, Calif.—PENCOM, a fastener manufacturer with a global manufacturing footprint, recently introduced what the company called “a smarter fastening solution for surface-mount PCB assemblies.”
The company’s newly released CMU Surface-Mount Captive Screws, described by the company as “an innovative addition to our line of precision fastening solutions,” are designed specifically for surface mount technology (SMT) processes.
“The CMU series enables engineers to install captive screws directly onto printed circuit boards (PCBs) using the same automated soldering techniques as other surface-mount components,” the company said in a release. “This development marks a significant step forward in simplifying assembly operations and improving the reliability of mechanical fastening in high-density electronic systems.”
Each CMU features a polyimide film patch on the top surface to facilitate vacuum pickup during automated placement. (Image courtesy PENCOM)
How they work
According to PENCOM, the CMU captive screw is a threaded fastener permanently retained within a low-profile housing that is soldered to a printed circuit board (PCB). During assembly, the fastener is placed and soldered into position using automated pick-and-place equipment and reflow soldering, in the same way as resistors or capacitors.
“Each CMU features a polyimide film patch on the top surface to facilitate vacuum pickup during automated placement,” the release stated. “Once installed, the fastener remains captive in the board—meaning it cannot be misplaced or dropped during use.”
The company said that after the reflow process, the screw is ready to secure the PCB to other components. This integration of mechanical fastening into the SMT process eliminates secondary operations, reduces handling, and improves overall assembly efficiency.
Key features and construction
PENCOM’s CMU Surface-Mount Captive Screws offer several practical features that are said to suit them well for demanding electronic applications.
SMT-compatible design. The CMU captive screw installs on PCBs at the same time and by the same method as other SMT components.
Permanent retention. The screw remains attached to the assembly, minimizing the risk of loose hardware.
Efficient packaging. Screws are supplied on tape-and-reel for seamless integration into automated “pick-and-place” production lines.
Precision materials. The retainer is carbon steel with an electroplated matte tin finish; the screw, heat-treated carbon steel with zinc and clear chromate coating. The spring: passivated stainless steel for strength.
Thread options. Screws are available in inch (4-40, 6-32) and metric (M3, M3.5) sizes.
Ease of installation. A solder-only attachment method is used, with no mechanical press-fitting required.
Advantages
PENCOM said the CMU series provides several important advantages for design engineers, manufacturing specialists, and maintenance teams.
Streamlined production. By integrating into SMT assembly lines, CMU captive screws eliminate secondary installation steps. They are soldered in place during the same reflow cycle as other electronic components, reducing production time and handling.
Reduced hardware management. Because the screw remains permanently retained, there is no risk of dropped or lost fasteners during service or assembly. This ensures clean, organized, and repeatable maintenance in field applications.
Space-efficient and reliable. The low-profile design conserves valuable space in compact assemblies—an essential benefit for consumer electronics, telecommunications, and instrumentation devices where real estate is at a premium.
Damage-free installation. SMT mounting removes the need for traditional press-fitting, minimizing potential damage to the PCB and simplifying board design.
Consistent quality and performance. Each CMU is manufactured to precise tolerances and finished per ASTM standards, ensuring consistent mechanical performance and corrosion resistance over time.
Applications
The CMU Surface-Mount Captive Screws are said to be particularly well-suited for applications such as communications and networking printed circuit boards; medical and laboratory devices; aerospace and defense electronics; and industrial control systems and instrumentation.
“By combining mechanical fastening and SMT automation, PENCOM’s CMU series redefines how captive screws are integrated into PCB assemblies,” the company said in the release. “The result is a solution that reduces labor, improves consistency, and enhances reliability—all while supporting the ongoing trend toward miniaturization and automated manufacturing.”