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Multilayer flexible PCBs breaching mainstream supply

Makers of flexible PCBs upgrade models to accommodate the growing popularity of thinner, smaller mobile gadgets.

China suppliers of flexible PCBs are gearing R&D toward increased density, additional layers, finer line width and spacing, smaller hole diameters and more complex layouts. The efforts are aimed to enable multilayer units to break into the mainstream as makers respond to strong demand from the LED backlight module, smartphone and touch panel markets. Most companies can provide up to 10-layer types. Single- and double-sided models, however, continue to be popular choices.


Xiamen G&P's model GPD-08657A doublesided flexible PCB with a gold immersion surface finish has 5.9mil line width/spacing.

In coming months, the general trend favors variants with a 2mil line width/spacing and a 0.15mm hole. Xiamen Hongxin Electron-Tech Co. Ltd can produce high-flex multilayer PCBs with a line width/spacing as fine as 2mil.

Driven by rising utilization among thinner and smaller mobile devices such as smartphones, tablet PCs and e-book readers, projections for China's flexible PCB industry are optimistic. Interviewed maker Xiamen G&P Electronics Co. Ltd, for instance, foresees sales jumping by as much as 25 percent valuewise throughout the year.

A typical e-book reader requires five to 12 flexible PCBs. An iPhone has 10 to 15, which means at least 20 to 30 for other handsets. An iPad employs about 16 units.

The automotive, industrial control, medical electronics and defense or aerospace industries are emerging segments. Monitors and displays, PCs and telecom devices currently account for 75 percent of demand.

Despite positive expectations, China suppliers of flexible PCBs are facing a range of challenges. Foremost of these is the increasing cost of raw materials, particularly copper. Rates for the metal have continued to climb, surging 140 percent in recent months due to keen demand and tightening resources. Resultantly, prices of flexible PCBs will stay on an upward trend this year.

Makers are also coping with increasing labor costs. Wage levels in China rose 15 to 20 percent on average in 2010, and major production hubs augmented salaries further in recent months.

Jiangsu province adjusted worker remuneration by 15 percent in February. In March, compensation in Guangdong province factories went up 19 percent.

The appreciation of the yuan poses particular risk to exporters. The exchange rate moved roughly 3 percent against the US dollar in 2010, with predictions of 3 to 6 percent for 2011.

Makers address these difficulties by strengthening production and R&D capability, and concentrating on midrange and high-end multilayer flexible PCBs that bring in more profit.

Xiamen Hongxin boosted monthly capacity with the opening of a new 18,000sqm factory in January 2011.

At Xiamen G&P, which offers one-stop solutions from flexible printed board construction to component SMT, an investment of $1.5 million has been put in place to purchase newequipment for additional SMT lines.

Flexible types constitute more than 15 percent of mainland China's total PCB output. There are about 250 makers domestically, accounting for 20 percent of global supply.

Manufacturers are located in the Pearl River and Yangtze River Delta regions, and Fujian province. The key hubs are Guangdong, especially Shenzhen, Zhuhai and Guangzhou, Kunshan and Suzhou in Jiangsu, and Xiamen in Fujian. Shenzhen Danbon, Zhuhai Topsun, AKM and Parlex are among the major industry players. The mainland also hosts manufacturing facilities of tier 1 multinationals from Japan, the US and Taiwan such as Nippon Mektron, Nitto Denko, Career, Foxconn, Sony and Kinwong. These were attracted by strong local demand and the mainland's cost advantage.

Meanwhile, global production of flexible PCBs from 2000 to 2009 increased about 90 percent. The industry improved further in 2010, spurred by the economic recovery of key markets. The annual growth rate will stay at 13 percent in coming years, with sales reaching $6.8 billion and $7.7 billion in 2011 and 2012, respectively, according to the Industrial Economics and Knowledge Center.

Product gallery


The model D90275 double-sided flexible PCB from Xiamen Hongxin has 3.5mil line width and 3mil line spacing.

Flexible PCB specifications

Of China's selection of flexible PCBs, single- and double-sided models are the mainstream, comprising 70 percent of output. These are used in PCs, telecom devices and consumer electronics.

Companies also offer multilayer flexible circuits, which are expected to become the structure of choice in future following the need for smaller, more complex and portable products.

The key component is the FCCL substrate, representing 30 to 50 percent of total costs. The typical base material is three-layer FCCL, although makers predict this will be replaced by two-layer types for their heat resistance, dimensional stability, deflection and low profile.

At present, two-layer FCCL flexible printed boards are found in upscale mobile phones, IC packaging and HDD products. The high price and complex processing are the main obstacles to large-scale development.

Other materials include the cover layer, stiffener and adhesive. Makers usually source these from local and Taiwan providers such as Taiflex, Aplus, Microcosm, ThinFlex, Grace, Shengyi and Haiso. Depending on requirements, companies also adopt varieties from DuPont and 3M, and Japan vendors. No supply issues are seen for this year.

The cover layer is usually 25 or 12.5µm-thick PI film. Models come with PI, PET, FR-4 and stainless steel stiffeners, depending on clients' specifications. The minimum line width and spacing are 0.05, 0.075, 0.1, 0.15 and 0.2mm, with 0.075 and 0.1mm the mainstream. The hole diameter is usually 0.2 or 0.25mm, but 0.15mm models are also available. The surface finish is mainly gold or tin plating, immersion gold or tin, and OSP.

To remain competitive, makers have increased prices by no more than 5 percent in the past six months, taking into consideration the cost of raw materials and labor, and the appreciating yuan. Suppliers will try to keep quotes stable the rest of 2011 despite mounting manufacturing outlay.

Taiwan: Flexible PCB makers target LED backlight, touchscreen markets

Driven by demand for LED backlighting in LCD units and touchscreens on smartphones and tablet PCs, R&D in Taiwan's flexible PCB industry is directed at the adoption of two-layer FCCL. The substrate boasts better heat resistance, flexibility and stability than the mainstream three-layer type.

Models meet the requirements of multifunction, slim solutions that fit the latest portable electronic devices.

Apart from mobile phones, the targeted applications are monitors and displays, laptops, optical disc drives, digital cameras and personal navigation devices such as GPS systems.

Another trend within Taiwan is the development of rigid-flex variants for handsets in slide, clamshell and other novelty configurations. This poses a challenge for flexible PCB makers, however, as they have less experience in design and production compared with foreign competitors such as those from South Korea. With the rise of cellular broadband accelerating shipments of rigid HDI boards, suppliers are also looking to progress in the manufacture of high-density flexible variants as a design option.

Companies are facing the lack of autonomy in key materials. Many of the inputs needed in manufacture, including RA copper, PI and BT epoxy, still depend on supply from abroad. The US and Japan are the major providers at present.

There are 40 to 50 companies in Taiwan producing flexible PCBs. Career, FLEXium, Ichia, Sunflex Tech Co. Ltd and ThinFlex are among the notable players.

Hong Kong: Simple, high-density flexible PCBs suit communications sector

Flexible PCBs from Hong Kong suppliers are available in single-, double-sided and multilayer versions. These utilize polyester and PI film or a copper base in 400x400, 500x800, 400x1,000mm and other sizes. The base material is 25 to 100µm thick, while copper conductor thickness ranges from 18 to 105µm.

Some makers are capable of 0.2mm minimum hole diameter, 3mil minimum line width/spacing and 0.1mm minimum annular ring. Buyers can specify punched and routed holes, and choose among nickel, gold and solder plating.

Suppliers usually cater to the communications sector, responding to strong global demand from mobile phones and smartphones, some of which even use multiple units.

Makers of portable electronic devices are also increasingly adopting flexible PCBs because they are pliable, lightweight, small and thin. Products have a high wiring density and are cost-competitive, thanks to the efficiency of the line's manufacturing process. In laptops and LED TVs, flexible printed boards are used to connect the LED backlight to the rigid main board.

Suppliers are also steadily making inroads into consumer electronics applications. Other major segments served are the military, medical, automotive, home appliance and industrial sectors.

Hong Kong has at least 10 companies that manufacture flexible PCBs. The supplier base consists of small and midsize operations with factories in the territory and in southern mainland China. Some enterprises offer value-added assembly services such as COB, SMT and though-hole component assembly, while others provide related rigid-flex PCBs, connectors, cables and wire harnesses. A few emphasize simpler flexible PCBs such as those for keyboards and calculators. Some suppliers specialize in finished products with subsidiaries that have surplus capacity.

Onpress Printed Circuits Ltd has more than eight years of experience in the line. It has an annual production capacity of about 17,000sqm simple, single-sided conductive paths to complex, double-sided designs with high-density circuitry.

Compass Technology Co. Ltd supplies flexible PCBs for backlight wiring in small TFT-LCD screens and in cameras, calculators, measuring devices, smart cards and other applications. Its PI-based models are available with 18µm copper, 15µm minimum hole size, electrolytic nickel/gold plating, and optional OSP and immersion.

Flexible PCBs account for about 30 percent of Advanced Electronic Technology HK Ltd's output. It can manufacture models with up to 14 layers with ENIG, selective hard gold, immersion silver or tin, peelable or blue mask, carbon ink and other options.

 Double-Sided Flexible PCB

Product gallery

Advanced Electronic Technology HK Ltd
(Hong Kong)

Model: Double-Sided Flexible PCB
Description: Double-sided type; Teflon, FR-4 high Tg, halogen-free or aluminum core base; peelable mask or carbon ink printing, CNC V-cut or gold finger, selective plating or Entek coating, flash or hard gold plating, lead-free hot air solder leveling, or immersion tin, gold or silver surface finish; 3mil minimum line width/spacing; 0.25mm minimum hole diameter; blind and buried vias

Flexible PCB

Compass Technology Co. Ltd
(Hong Kong)

Model: Flexible PCB
Description: Strip type; 12.5, 25, 38, 50, 75, 100µm dielectric thickness; lead-, halogen-free; embedded, passive, rigid-flex, embedded-die technologies; for mobile phone SIM and credit card modules; UL, RoHS

Flexible PCB

Honlex Flexible PCB Industrial Co. Ltd(Taiwan)

Model: HL-40
Description: 0.5, 1, 2, 3 or 5mm polyamide or PC base; epoxy, acrylic or polyester adhesive; tin lead, nickel or gold surface finish; 4mil minimum line width/spacing; 0.3mm hole diameter

Flexible PCB

Onpress Printed Circuits Ltd
(Hong Kong)

Model: Flexible PCB
Description: Low-flow PP, PET special, PI bond ply buildup materials; OSP, select OSP, flash/thick gold surface finish; 1/3 to 2oz copper foil; 50µm minimum solder mask opening; 75µm hole location tolerance; 8:1 maximum aspect ratio through hole; ±10% impedance control

Flexible PCB

Xiamen Innov Electronics Tech. Co. Ltd
(mainland China)

Model: IVD-G-110114A
MOQ: 1,000 units
Delivery: 5 days
Description: Double-sided type; 0.5oz FCCL, polyimide and stainless steel stiffener; immersion gold surface finish; green solder mask; 4mil minimum line width; 3mil minimum line spacing; 0.2mm hole diameter

Flexible PCB

Xiamen Strong Flex Co. Ltd
(mainland China)

Model: D0133
Delivery: 7 days
Description: Double-sided type; 0.5mil polyimide base; FCCL; nickel or gold surface finish; green solder mask; 3.5mil minimum line width; 3mil line spacing; 0.2mm hole diameter; 0.5oz copper thickness; ±0.03mm conductor tolerance; RoHS, UL

Note: This article "Multilayer flexible PCBs breaching mainstream supply" was originally published by Global Sources, a leading business-to-business media company and a primary facilitator of trade with China manufacturers and India suppliers, providing essential sourcing information to volume buyers through our e-magazines, trade shows and industry research.

All price quotes in this report are in US dollars unless otherwise specified. FOB prices were provided by the companies interviewed only as reference prices at the time of interview and may have changed.

Disclaimer: All product images are provided by the companies interviewed and are for reference purposes only. Those product images featuring products with trademarks, brand names or logos are not intended for sale. We, our affiliates, and our affiliates' respective directors, officers, employees, representatives, agents or contractors, do not accept and will not have any responsibility or liability for product images (or any part thereof) which infringe on any intellectual property or other rights of a third party.

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