ITAR/Military Flex and Rigid-Flex PCBs

At this point, it is common knowledge that rigid-flex printed circuit boards help customers reducing their PCB footprint, as well as allowing you to use fewer parts and interconnections and to take on more aggressive design challenges. However, the next level of flex and rigid-flex PCBs is being able to design and manufacture parts in the U.S. for ITAR, military, and aerospace applications.

These highly complex and high-reliability applications require a high level of experience in engineering and processing knowledge as well as a significant investment in the proper equipment to ensure that these designs can be produced repeatedly with a high level of accuracy and consistency. As the flex part of a rigid-flex PCB are manufactured from thin, high dielectric constant material such as polyimide, and the copper traces from a photo etching process, truly having the experience in this area will be the difference between a highly reliable PCB and a significant amount of scrap after assembly.

Our NetVia Group facility and highly dedicated staff in Dallas, Texas has more than 25 years of engineering and production experience in flex and rigid-flex PCBs for military, aerospace, and defense applications. Having extensive experience with both rigid and flexible polyimide PCB materials along with the traditional FR-4 products allowsus to ensure that our customers get the highest quality regardless of their design parameters.

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Design Challenges

With more than 70 years of design and manufacturing experience with printed circuit boards, Epec has developed a significant library and catalog of the challenges that we most often face when helping customers get their parts into production. In the military and aerospace industry where high reliability, size/weight restrictions, and electrical performance are of the utmost importance, there are several common challenges that we often see in flex/rigid-flex designs:

• Components only available in high-density ball-grid array packages, which require via in pad, which do not allow for Class 3 min. annular ring requirements.
• Mixed high current and controlled impedance designs requiring thicker copper, 1 oz or greater, and dielectrics, for the impedance lines, and the negative impact on flexibility / bend requirements.
• Min. trace width 0.005" (or greater) design rules combined with controlled impedance again requiring thicker dielectrics to achieve the impedance values and not meeting the bend requirements.
• Higher current carrying requirements, requiring copper thicknesses of greater than 2 oz, and the negative impact on flexibility/bend capability.
• Keeping plated trough holes at least 50 mils away from the flex and rigid PCB areas.Because of the uniqueness of rigid flex designs and because the coverlay portion of the flex circuit does NOT continue on through the rigid PCB, plated through holes need to avoid this transition area.

All these challenges typically have technical solutions that can be applied when the entire design and performance specifications are reviewed with our engineering team and the customer design team.

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Manufacturing Issues

Equipment Investment in Rigid-Flex PCB Equipment

In order to properly manufacture RF/microwave PCBs, significant investment in specialized equipment to meet the demanding tolerances required in high-frequency applications, including:

• Laser Direct Imaging: To ensure the high yield on sub 3 mil. lines and spaces along with proper adhesion of soldermask dams after developing.
• Plasma Etch: In order to properly prepare the through holes for plating on the flexible portion of the rigid-flex PCB.
• Laser Drilling/Routing: To be able to drill very small vias, to control depth drill blind and buried vias and to be used to rout out patterns on the coverlay portion of the flex circuit. Too many companies use their traditional mechanical equipment for these processes and in severely reduces yield.
• Autoclave Lamination: Computer-controlled accuracy and greater control over the heat levels used in the laminate resin system when using 2 or more different types of laminate (FR-4, Polyimide and PTFE) on RF microwave rigid-flex PCBs.
• X-Ray Drill: Optimizes the location of the drill pattern on laminated boards especially important when laminating polyimide and FR-4 on rigid-flex PCBs.
• CNC/Optical Machining: Traditional PCB CNC equipment works on a +/-0.005" as a tolerance and many high-technology rigid-flex PCB designs require much tighter tolerances than mechanical features. Epec’s investment in CNC equipment at our Metal Craft Machining facility in Southbridge, Mass.,allows us to perform all of these functions in house to further improve lead times and quality control.

Connector Assembly for Flex and Rigid-Flex PCBs

Engineering expertise and manufacturing capabilities under one roof streamlines turnkey process. Epec offers a complete range of miniaturized printed circuit board connectors with high-reliability in both through-hole and surface mount designs in every angle and mounting style for integration into single-sided, double-sided, and multilayered flex circuitry.

J-STD-001 and IPC Class III Certified

Exceptional facilities, equipment, and technicians who are J-STD-001 and IPC Class III certified ensure superior assemblies. Our turnkey flex circuit assemblies are designed and produced to exacting specifications, including the use of EMI shielding, polarization, strain-relief/stiffeners, and connector packaging technologies. Our experienced design and manufacturing team ensures that the final design will exceed the exact mechanical and electronic requirements of the target environment.

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Experience the Difference in Quality and Reliability

Make sure your flexible PCBs are manufactured to the highest standards for your military and aerospace applications. Consult our engineering experts today for customized, U.S.-manufactured rigid-flex pcb solutions.

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