Transparent PCB | translucent material | clear multilayer up to 6 layers

A transparent circuit board is the right choice when light needs to pass through the board or when the visible routing is part of the product design. Typical cases include backlit panels, signage, light surfaces and exhibits with exposed electronics. If light is only emitted forwards and the circuit board remains concealed, standard FR4 with white solder mask or an aluminium core circuit board is sufficient. Both are cheaper and available with flame retardancy to UL94 V-0 (flammability classification by Underwriters Laboratories).

Glass substrates are crystal clear but brittle, usually one or two layers, and require special processes. Film circuits on PET (polyethylene terephthalate) with ITO (indium tin oxide) are thin and partly flexible, but severely limited in current-carrying capacity and solderability. Leiton's transparent circuit board is a through-hole multilayer made from translucent laminate with up to six layers and runs through established circuit board processes including SMT assembly (Surface Mount Technology). Where optical clarity is more important than routing density, glass remains the better choice. Where multilayer routing with a visible circuit is required, the translucent multilayer is the appropriate solution.

Copper is opaque. Conductor tracks and copper areas appear as shadows when backlit. The routing is therefore deliberately planned in the layout — either as a visible design feature or with reduced copper areas in the light-active zones.

Yes. The solder heat resistance is 288°C over three cycles, and final finishes such as ENIG (Electroless Nickel Immersion Gold) are available. The glass transition temperature (Tg) starts at 105°C. The maximum continuous operating temperature is 75°C. Suitability for applications with permanently high operating temperatures must be assessed on a case-by-case basis.

UL94 HB is not flame retardant to V-0 or V-1. Whether this is sufficient is determined by the fire protection requirements of the application, not the material. For decorative lighting, trade fair construction and exhibits, HB is frequently sufficient. For devices with normative fire protection requirements, suitability must be demonstrated at assembly or device level.

No, it is low-halogen. The combined content of chlorine and bromine is below 1,500 ppm (parts per million). Low-halogen is not the same as halogen-free. RoHS (Restriction of Hazardous Substances) and REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) are separate topics and are verified independently.

With limitations. The maximum continuous operating temperature is 75°C. In shaded and ventilated installations, this is not critical outdoors. With direct sunlight, surface temperatures can quickly reach 60°C to 80°C depending on absorption and structure — in enclosed housings and behind glass even higher. Combined with the self-heating of LEDs (Light Emitting Diodes), this limit may then be exceeded. Such installations require thermal design measures, such as shading, ventilation or reduced power density, and temperature measurement on the actual assembly. For yellowing under UV light (ultraviolet), see the following question.

Under UV exposure, yes. The base material is an epoxy-based laminate, and epoxy resins yellow under UV through photo-oxidation. With direct sun exposure and no UV protection, visible yellowing can be expected within months. For outdoor applications with visual requirements, a UV-filtering cover should therefore be provided. Prolonged operation close to the temperature limit of 75°C can also cause the material to darken over its lifetime, independently of UV. In indoor applications with moderate operating temperatures, yellowing is generally not a concern, as white LED light contains virtually no UV component.

On the number of layers, format and panel utilisation, on the special material HT820 compared to standard FR4, as well as on the final finish, quantity and delivery time. Prototypes and small series bear the material costs more heavily; unit price decreases with series production. Reliable pricing results from the layout, not from blanket figures.

Common terms include translucent circuit board, light-permeable circuit board, transparent PCB (Printed Circuit Board) and clear PCB in English. Not included are glass PCBs on glass substrates and film circuits on PET (polyethylene terephthalate) or ITO (indium tin oxide). These are different technologies.