Single Sided Flex Solutions
A dual access flex circuit is a single sided flex circuit that is manufactured so that the conductive material can be accessed from both sides of the circuit. Flexible Circuit is a front runner in this technology utilizing specialized lasers and processing to skive open the polyimide layer of the base material to allow for dual access to the single copper layer.
Benefits
Reduced Errors & Faster Assembly
Precision design and automated manufacturing eliminate the variability of hand-built wire harnesses—ensuring circuits are routed exactly as intended while reducing assembly time, labor, and overall cost.
Lower Production Costs
By removing the need for manual routing, wrapping, and soldering, flexible circuits streamline production, minimize errors, and deliver cost savings in both low- and high-volume applications.
Unlimited Design Freedom
Unlike rigid boards, flexible circuits enable true three-dimensional design. They can be formed into complex shapes and configurations, allowing engineers to solve challenging layouts and perform reliably—even in demanding environments.
Applications
Static Applications
An application where flexible circuits are flexed only to install the circuit and fit it into its application (also known as flex-to-install).
Dynamic Flexing Applications
A situation where the flexible circuit itself is dynamically (repeatedly) flexed during the actual use of the final product. Common examples include flip-type cell phones, laptops, printer heads and robotic arms. A dynamic application will require a very symmetrical material stack up and fully annealed copper conductors.
Materials
Conductors
Copper is the most widely used conductor and comes in various thicknesses to meet each customer’s requirements.
Adhesives
Adhesive selection depends on customer needs and conductor thickness. Common adhesives include:
Insulators
Flexible substrate (base) and coverlay materials are available in a variety of thicknesses and from several manufacturers.
Supplemental Information
The following chart provides a sample of the our manufacturing capabilities.
| Product | Standard Flex Capabilities | Advanced Flex Capabilities | Rigid Flex Capabilities | Printed Electronics | |
|---|---|---|---|---|---|
| Standard Panel Size | 9.85" (250mm) x 15.75" (400mm) | 3.94" (100mm) x 3.94" (100mm) | 9.85" (250mm) x 15.75" (400mm) | 9.85" (250mm) x 15.75" (400mm) |
|
| Line Width and Spacing | 1/4 oz. Cu 1/3 oz. Cu 1/2 oz. Cu 1 oz. Cu 2 oz. Cu | .002" (50µm) .002" (50µm) .003" (76µm) .004" (102µm) .005" (127µm) | .001" (25µm) .0014" (35µm) .002" (50µm) .003" (76µm) .004" (102µm) | .002" (50µm) .002" (50µm) .003" (76µm) .004" (102µm) .005" (127µm) | .010" (254µm) |
| Copper Thickness | 1/4 oz. Cu (9µm) 2oz. Cu (71µm) | 1/4 oz. (9µm) to 1/2 oz. (18µm) | 1/4 oz. (9 µm) and higher | .0005" (12.7µm) to .0010" (25µm) |
|
| Layer Count | 10 | 2 typical, Max of 4 | 12 (To Date) | Up to 4 | |
| VIA / DRILL SIZE | |||||
| Minimum Drill (Mechanical) Hole Diameter | .006" (152µm) | .004" (102µm) | .006" (152µm) | .010" (254µm) | |
| Minimum Micro Via (Laser) size | .004" (102µm) | .002" (50µm) | .004" (102µm) | N/A | |
| SOLDER MASK | |||||
| Solder Mask Dam (Web) | .003" (76µm) | .002" (50µm) | .003" (76µm) | .010" (254µm) | |
| Solder Mask Registration Tolerance | .003" (76µm) | .001" (25µm) | .003" (76µm) | .005" (127µm) | |
| SHIELDING MATERIALS | Copper / Silver Ink / Shielding film / Carbon | Copper / Silver Ink / Shielding film Carbon | Silver Foil | ||
| STIFFENER | |||||
| Stiffener Material | Polyimide / FR4 / Metal | FR-4 / Polyimide | PET/Metal/FR-4 | ||
| PI Stiffener | |||||
| Stiffener Registration | .008" (203µm) | .004" (102µm) | .008" (203µm) | .010" (254µm) | |
| FR4 Stiffener | |||||
| Stiffener Registration | .006" (152µm) | .004" (102µm) | .006" (152µm) | .010" (254µm) | |
| LEGEND | |||||
| Minimum Height | .032" (813µm) | .020" (508µm) | .032" (813µm) | Graphic Overlay | |
| Minimum Width | .006" (152µm) | .0032" (81µm) | .006" (152µm) | ||
| Registration | +/-.005" (127µm) | +/-.005" (127µm) | +/-.005" (127µm) | ||
| IMPEDENCE | +/- 10% | +/- 10% | +/- 10% | N/A | |
| TOOLING | |||||
| Hard Tooling Tolerance | .002" (50µm) | .002" (50µm) | .002" (50µm) | .005" (127µm) | |
| Zif Tolerance (Hard Tool, CMD, or Laser) | .002" (50µm) | .002" (50µm) | .002" (50µm) | .005" (127µm) | |
| CMD Tolerance (Chem Mill Die) | .004" (102µm) | .004" (102µm) | .004" (102µm) | .005" (127µm) | |
NOTE: FCT's capabilities Chart provides general capabilities for review; capabilities related to any specific circuit are dependent on various factors including circuit size, layer count, materials, design, and other considerations. We encourage customers to get our Application Engineers involved early in the design process.
As the flex circuit market continues to expand, there have been many advances in technology including:
Heat Sinks – Heat sinks can be laminated to flex circuits to dissipate heat away from sensitive components such as LEDs.
Component Assembly –We offer through hole and surface mount capabilities, as well as in circuit testing, conformal coating, and electrostatic protective packaging.
InControlled Impedance – With increasing signal switching speeds, engineers need to understand and control the impedance of traces. With short signal transition times and high clock rates of modern digital circuitry, traces need to be considered transmission lines instead of simple interconnections. With today’s higher speed requirements, controlled impedance traces are designed to minimize electrical reflections and ensure an error free transition between the track and interconnections. If perfectly optimized, controlled impedance allows control of the physical dimensions and material of the cable. Controlled impedance signal transmission requires flexible circuit materials to be uniform in both thickness and electrical properties. At Flexible Circuit Technologies, we have extensive experience in designing and manufacturing flex circuits with controlled impedance.
Crimp Pins – Crimp Pins are mechanically attached a circuit to allow for soldered connections.
Graphic Overlays – Graphic Overlays can be placed over flexible circuits, rigid boards or membrane switches. The overlays provide the user interface with the underlying circuit and typically are used in conjunction with LEDs, LCD displays or dome switches mounted on thie circuits. The overlays are made from polycarbonate, polyester or acrylic materials.
Laser Skived Slots and Holes – Historically, X-acto knives or razor blades were utilized to cut intricate areas of a flex circuit, the successful yield of which depended on the skill of the operator. FCT has dramatically improved this process by utilizing a top-of-the-line laser beam with extremely precise depth control to accurately cut the underlying substrate of a flex circuit. Precise laser beams can skive circuit openings with the utmost precision.
Overmolding – Overmolding is the process by which FCT embeds electronics versus simply placing electronics on the circuit. As electronic devices and required interconnections become more compact, embedding electronic circuitry within the cable assembly is a cost effective alternative to on-board electronics. Most often referred to as smart cables or dongles, these embedded devices can solve many packaging challenges.
Pressure Sensitive Adhesives (PSAs) – PSAs with a release liner are used in applications where a portion(s) of the circuit needs to be secured to a specific location within the final product. During assembly, the release liner is peeled away and the exposed adhesive allows the assembler to press the circuit into place and keep it there.
Sculptured Flex Circuits – Sculptured flex circuits are special in that the copper conductors vary in depth and thickness in different places. The copper is thin at the most flexible part of the circuit and thick at the interconnection point. Sculptured flex circuits allow for bare metal connections (like a plug in) and remain strong at the solder joint formation. Sculptured fingers provide a more reliable alternative to mechanically fastened crimp pins.
Stiffeners – Stiffeners are applied to flex circuits where additional support is needed such as areas of component assembly or underneath exposed traces that will be plugged in for connection. Common stiffeners are FR4 and polyimide.
Wire Assembly – In certain applications a combination of flex or rigid circuit with traditional wire may be a more economical design that still meets the needs of the customer’s subassembly. At Flexible Circuit Technologies, we have the capabilities to design, source, manufacture and assemble the entire subassembly incorporating the circuit, wiring and components. This level of capabilities and commitment is what differentiates us from other flex circuit suppliers. It is also why our motto is “We Go Where Others Will Not”.
Flexible Heaters – Flexible heaters are thin, bendable heating elements, shaped to fit your unique heating equipment needs.
Hot Bar Solder – Hot bar solder connection is a way to eliminate a connector set between the hardboard and the flex circuit. This connection provides an efficient, durable and less expensive alternative to a standard connector set.
Dual Access – Laser skiving of single sided circuits ensures smooth, low profile, dual access.
