Flexible PCBs

	The 4B37803Q flexible PCB from Shenzhen Fastprint has four layers.

Low-end and midrange models target mobile phones, entry-level laptops and handheld devices, while upscale units eye the automotive, medical and industrial segments.

China suppliers of flexible and rigid-flex PCBs are raising their export ratio by up to 60 percent this year. Demand from the telecom, computer and consumer electronics sectors has picked up and makers are expanding capacity to make the most of the boom.

Applications in white-box mobile phones, low-priced laptops and digital handheld devices continue to sustain production of low-end and midrange models. The high-end line, meanwhile, is getting a boost from the automotive, medical and industrial segments.

Companies target Asia and Eastern Europe to veer away from the US and the EU, which are hardest hit by the current financial slump. Many are likewise beefing up output for the domestic market.

To strengthen their position, makers are widening selections and boosting R&D and QC capability. They are also shortening delivery time and lowering minimum order requirements to attract more buyers.

Product development efforts for flexible PCBs are geared toward enhancing control over the contraposition tolerance between layers and lamination parameters. Rigid-flex board suppliers, meanwhile, are working at better managing the size without compromising the varied thermal expansion coefficients between the insulation material and copper foil. Some companies have achieved this goal by tweaking the etching on the FR-4 dielectrics.

Future R&D thrusts for both types include using liquid crystal polymer, or LCP, and PI to prevent minute deformation resulting from changes in temperature or exposure to moisture.

Output and shipments dipped in the previous year, threatening to dislodge China from its status as one of the world’s top manufacturing hubs for flexible and rigid PCBs. More than 27 million square meters of flexible boards worth $2.6 billion were produced in 2007, according to the China Electronic Components Association or CECA. The turnout, however, dived by about
10 percent in 2008. A 15 percent increase in 2009 is nonetheless expected for both volume and value.

Rigid-flex PCB output climbed nearly 31 percent last year from 29 percent in 2007, according to media sources. Makers are optimistic that supply will stay at current levels, at best, this year.

Exports of both PCB types likewise tumbled by about 5 percent YoY due to decreased orders from the US and the EU. But because China-made boards are significantly less expensive than those from Japan, overseas demand peaked in the last six months.

Shenzhen Fastprint Circuit Tech Co. Ltd, for instance, experienced 100 percent growth in annual production value. It has invested more than $1.5 million in an ongoing expansion project.

Leveraging their price advantage has allowed suppliers to push the utilization rate higher. Zhuhai All-Winner FPC Co. Ltd is running at 75 percent of its capacity and turning out up to 20,000sqm flexible PCBs per month.

Zhiboxin Printed Circuit Board Co. Ltd is now making 500sqm more than last year. The bigger monthly output is attributed to increased demand for devices used in CD drives and storage systems.

	Suiwa's FPC001 military-grade rigid-flex PCB has green liquid photoimageable solder mask with ENIG finishing.

Still recovering from their losses, most suppliers are streamlining operations. Multiple models are being made in fewer manufacturing lines. Other companies, including Xiamen G&P Electronics Co. Ltd, conduct productivity training.

Small-quantity orders are now accommodated by enterprises such as Fasto (Zhangzhou) Electronic Co. Ltd. Kingsum Electronics Co. Ltd is implementing the roll-to-roll process to cut delivery time. The standard five to seven days for mainstream models is now down to two. Double-sided multilayer boards are completed within three days instead of about 10. Blind and buried vias are drilled in half the time.

The biggest challenge for suppliers is the lack of locally made equipment and materials. Most machines are from major brand names in Japan, South Korea and Germany. Whatever is available from domestic companies can process only single- and double-sided boards for the low-end market.

Large suppliers typically use CNC drills and roll-to-roll exposure units from Hitachi, and automatic target punches from Yamaha. They also import precision X-ray, OGP 3D smartscopes, CMI900 gold and nickel testers, and RoHS screening devices. Humidity and temperature chambers, and flexural-endurance, thermal-shock, solderability- and peeling-strength testers are usually from Taiwan.

More than 80 percent of makers conduct the entire manufacturing process in-house. The rest subcontracts plating and SMT.

Most materials are purchased from foreign providers, including DuPont, Arlon and Taiflex. These are electrodeposited or ED and rolled-annealed or RA copper foil, FR2 and FR-4 prepreg, and PI and PET adhesives. RA is more flexible than ED but is 20 percent pricier, so it is limited to high-end printer heads and HDDs. The ED type is for standard keypress and static 3D circuits.

Single- and double-sided boards are prevalent as are multilayer PCBs. Not many offer the latter for low-end and midrange applications. Few make high-density devices because these are generally regarded as upscale.

Six-layer flexible units are the mainstream. Eight-layer versions target mobile phones and medical equipment.

The typical minimum line width and spacing is 2mil for the single-sided type and 3mil in double-sided units. Others have 1.5mil.

Most products feature a hole diameter of at least 0.15mm. More-complex flexible boards have 0.05 to 0.1mm.

Rigid-flex PCBs rarely come in more than 10 layers. These are primarily for high-end applications, including communication and military equipment. A handful of makers have released 20-layer
models. The hole sizes are 0.2 and 0.1mm for vias and blind vias, respectively.

Single-sided models in FR-1 and FR-4, and CEM-1 and CEM-3 prepreg range from $45 to $75 per square meter. These are 0.8 to 1.6mm thick and about 550x400mm. Plating options are standard or lead-free HASL, immersion gold, silver or tin, and OSP.

Double-sided units with the same specifications are $52 to $86 per square meter. Four- and six-layer versions list at $112 to $127, and $179 to $200 for each square meter.

Makers also offer models complying with RoHS and UL standards.

Quotes dropped 10 percent in April this year. A further reduction of 5 to 10 percent is expected in the next six months due to fierce competition. Price is usually determined by the board material, number of layers, board and hole dimensions, and surface treatment. Devices with international quality approval tend to be more expensive.

China has more than 200 flexible and rigid-flex PCB makers. Shenzhen and Zhuhai in Guangdong province, and Suzhou and Kunshan in Jiangsu province host the most number of suppliers. Others have factories in Fujian province, specifically Xiamen.

Mixed production is common, although more focus on flexible boards, which are easier to make. Between 20 and 30 percent offers rigid-flex types.

Companies usually employ 150 to 1,500 workers and have a monthly turnout of 2,000 to 40,000sqm.

Small and midsize enterprises serve local mobile phone makers. Their revenue is about $1.5 million per year and output is 1,000sqm each month.

Large companies are clustered in Suzhou and Kunshan. These have annual sales exceeding $8 million and monthly output of more than 10,000sqm. They cater to suppliers of LCD modules and netbooks.

Most have facilities certified to ISO 9001 and ISO 14001. Some have acquired TS16949 certification.

Xiamen takes advantage of its position as a manufacturing base for various electronics products, particularly LCD modules, to become a strong hub for PCBs. The city’s proximity to Taiwan, where most materials and components come from, ensures a steady supply of these inputs. Makers also procure from Japan and Hong Kong providers.

Xiamen is home to about five rigid-flex and 10 flexible PCB manufacturers. Collectively, they account for 10 percent of China’s total rigid/rigid-flex PCB output.

Major players include Xiamen G&P Electronics Co. Ltd, New Flexible Circuit Technologies (Xiamen) Co. Ltd and Suiwa High Technology Electronic Industries (Xiamen) Co. Ltd.

The selection consists of single- and double-sided and multilayer versions for various household appliances and telecom products. Single- and double-sided flexible PCBs dominate Xiamen’s output with an 80 percent share, followed by multilayer types with 15 percent.

In the rigid PCB line, low-end and midrange models with fewer than 10 layers lead supply.

Regarded as a high-end product, rigid-flex PCBs support high-density interconnects and are popular in mobile phones and other electronics and computer devices. Due to their more-complex manufacturing process and high material costs, rigid-flex PCBs only make up about 5 percent of Xiamen’s total output. They are also available in single- and double-sided and multilayer types.

Companies typically use FR-2/4, PI and PET as stiffeners. PI is highly favored as it can withstand temperatures of 150 to 300 C, making it suitable for rigid-flex and multilayer PCBs. PI has a 0.02 to 0.04 mmC-1m-1 thermal expansion and 1.69MNm-2 tensile strength, and is compatible with conventional epoxy-glass laminates.

Suppliers also employ special materials such as aluminum- or copper-based, high-Tg, high-frequency board and halogen-free laminates. Many adopt blind or buried vias as well.

Almost 100 percent of orders come from OEMs. The major clients include Foxconn, Panasonic, Siemens, Sony, Sharp, Motorola and Fujian Newland Computer.

About 30 to 80 percent of products are exported. Suppliers are planning to expand to Taiwan, Japan, South Korea and Southeast Asia.

Xiamen-made flexible PCBs are priced 3 to 5 percent less than foreign counterparts.

Companies are optimistic that the local flexible PCB industry is on its way to recovery as demand picks up, albeit at a slower rate. In a bid to further generate market momentum, many are enhancing production efficiency by optimizing processes and manpower. To boost competitiveness, they are improving quality and shortening delivery time. Some are considering providing PCB assembly services and expanding into other lines such as terminals to augment slackening sales.

Under efforts to attract more orders, suppliers focus on complying with RoHS directives by adopting lead-free manufacturing. Most products already conform to UL and TS.

Order flexibility, fast delivery and low pricing are the current differentiation strategies adopted by Taiwan makers of flexible and rigid-flex PCBs. Companies there offer models with almost the same quality as those from Japan, the world’s leading PCB hub, at quotes comparable to those made in mainland China.

The maturing industry is composed of about 200 manufacturers, including publicly listed companies. Active players include Compeq, Unimicron, Unitech and Career Technology.

Units come in ever-smaller sizes as applications in compact electronics rise. Flexible and rigid-flex PCBs from Taiwan are typically used in mobile phones, display panels, driver ICs, PCs and CD players. Some suppliers have started catering to LED lights and laptops.

Others makers, including Finpo Electronic Co. Ltd, focus on customized production. Finpo delivers prototypes in about two days for flexible boards and seven for rigid-flex. It purchases some components from Japan.

Suppliers of flexible and rigid-flex PCBs in Hong Kong are targeting the high end. Because they cannot match the rock-bottom quotes of mainland China makers, many have sustained losses in recent years.

Companies are positioned as a one-stop sourcing service. They are shortening the prototype and mass production turnaround to entice more customers.

Hong Kong exported 148.3 million kilograms of PCBs worth $6.2 billion in 2008, according to customs statistics.

Flexible and rigid-flex types made up the bulk.

By releasing value-added devices, suppliers hope to expand export share and are therefore increasing spending on product development. Some maintain multiple R&D teams in different locations. Others are upgrading equipment and facilities.

The segment is composed of about 15 companies, many of which are small and midsize. Most maintain factories in the mainland to cut costs. Others are subsidiary operations.

The diverse range includes high-precision rigid-flex PCBs with up to 30 layers, such as those made by ANS Industrial Co. Ltd. Its 0.4 to 6mm-thick boards have 0.15mm vias and 10:1 aspect ratio. A combination of heavy and standard copper is used for multilayer models.

The company’s selection of finishing includes HASL or lead-free HASL, selective or immersion gold, and silver and tin. ANS also offers carbon print, gold fingers, Entek OSP and flux coating. Peelable mask and LPI complete the range. The supplier also offers aluminum-core PCBs.

A rising number of companies specialize in custom production. One of them is Advanced Electronic Technology HK Ltd, which rolls out 14-layer flexible boards and 16-layer rigid-flex units with blind and buried vias, and impedance control.
The supplier offers peelable mask and carbon-ink printing, selective plating in flash or hard gold, CNC V-cut or gold finger processing, and Entek, lead-free HASL and immersion tin/gold/silver coating. Its boards have a 3mil minimum line and spacing and 0.1mm finished hole size.

The bulk of suppliers are affiliated with the Hong Kong Printed Circuit Association Ltd, which promotes the industry by organizing seminars, trainings, conferences and exhibitions.