Tight supplies of some components including voice coil motors and ITO films may put a brake on the growing sales of HTC's high-end smartphones, including the HTC One X+, Windows Phone (WP) 8X and HTC Butterfly, according to industry sources.

Sales of the WP8X have been extremely strong in the US, while the HTC Butterfly has become one of the hot-selling models in Japan, Taiwan and China, the sources indicated.

HTC has been placing additional orders for PCBs and flexible PCBs since December in order to satisfy strong demand for the HTC Butterfly, which is reportedly in short supply in Japan and Taiwan at the moment, the sources revealed.

Additional PCB/FPCB supplies to HTC are believed to have been limited, since the capacity utilization rates of PCB/FPCB lines at makers have already been high, said the sources.

But the short supply of the Butterfly phones in Japan and Taiwan might have been caused by shortages of other components rather than PCBs/FPCBs, suggested sources in the PCB industry.

HTC is currently sourcing PCBs from Unimicron Technology, Unitech Printed Circuit Board and Multek, while buying FPCBs from Career Technology, Foxlink and M-Flex, revealed the sources.