Suppliers of aluminum-base PCBs adopt advanced processes and bolster R&D to enhance product features to match trends for miniaturization and multifunctionality.
China makers of aluminum-base PCBs are gearing R&D and production toward improved thermal conductivity and efficiency to meet requirements posed by the miniaturization and multifunctionality trends in electronic devices. To keep up with developments in target applications, enterprises are enhancing machining precision further and striving to reduce the appearance of cracks, scratches and burrs. Efforts are likewise aimed at elevating peeling strength, breakdown voltage, dielectric constant, flammability, and surface and thermal resistance.
Riding on growing demand for environment-friendly products, companies are also shifting their attention to the LED industry from the conventional power supply field. Aluminum-base types are preferred to FR-4 kinds because they have a lower thermal resistance of just 1 to 2 C/W compared with the latter’s 20 to 22 C/W. This makes the first suitable for high-power LED products and electronic equipment requiring strong heat dissipation such as audio devices, power supplies, computers and household appliances.
The HitekPCB0003 model by Hitek Technology (HK) Co. Ltd is used in LED modules, including single 3W and three 1W diodes. It utilizes 0.5 to 5oz copper foil and Teflon.
Despite the rising output of LED-targeted aluminum-base PCBs, mainland China manufacturers will trail Taiwan in this line. The latter currently leads production, especially of boards for LED TVs, with major players such as Tong Hsing, Gia Tzoong, PTTC and ICP.
There are more than 100 enterprises engaged in the line, most of them expanding product catalogs to include LED applications. More than 80 percent is located in Shenzhen, Guangdong province, and the rest can be found in Zhejiang and Jiangsu provinces. More players, however, are predicted to enter the sector as demand is forecast to surge by over 100 percent amid the thriving LED industry.
Also spurring orders are “green” initiatives such as the government’s 10,000 Lights in 10 Cities project, which is aimed at promoting the use of diode-based lighting across the country.
Although generally regarded as a side business and accounting for only 10 percent of total PCB supply in China, aluminum-base kinds currently lead the output of boards adopting metal. The production share is projected to increase to about 50 percent in the months ahead amid brisk demand. Compared with other types, particularly FR-4 variants, the former boasts high heat dissipation, electromagnetic shielding and mechanical strength. The lightweight construction and low cost are additional advantages.
Aluminum-base PCB selection
Hong Kong: Widening adoption of aluminum-base PCBs spurs output expansions
According to structure and performance, aluminum-base printed boards from China are divided into three categories, namely universal, high thermal dissipation and -frequency types. The insulating layer of the first is made of epoxy-glass fabric bonding sheet. The second consists of epoxy resin with strong heat conductivity, while models with elevated frequency have polyolefin or polyimide resin glass fabric adhesive tablets.
The selection includes single- and double-sided, and multilayer versions. The first two dominate output, taking up more than 95 percent of the total yield. The third is growing in popularity amid the expansion of the interconnect circuit technology. Makers of this variety offer 4, 6, 8, 10 and 12-level boards. Such types provide strong thermal dissipation and mechanical stability as they are fabricated directly on one or both sides of a metal base plate. The method used is sequential deposition of polymer insulator materials and conductors. The additive microvias can increase the integration of circuitry.
The copper foil is 0.5 to 6oz thick, and the base 0.5 to 3mm. The thickness of the dielectric layer, meanwhile, is from 3 to 6mil. The minimum line width and spacing may be 0.1, 0.15, 0.2, 0.25 and 0.3mm. The hole diameter measures 0.15 to 1mm.
Products adopt various surface finishes such as HASL, lead-free HAL, ENIG, immersion gold and OSP. The first two are the mainstream.
Shenzhen Zhiboxin Circuit Board Co. Ltd’s Zbx003 model is a single-sided aluminum-base PCB that boasts a 1.2 C/W thermal resistance, white solder mask and immersion gold surface finish.
The aluminum base, copper foil and thermal conductive electrical insulation or dielectric layer account for more than 80 percent of total outlay. The first two are sourced domestically, while the last is acquired from local and foreign partners such as Bergquist, Laird and several Taiwan companies.
To increase thermal conductivity and achieve better heat dissipation and reduced thermal resistance, makers use first-grade materials for the dielectric layer. The latter provides electrical isolation with minimum thermal resistance. It also bonds the aluminum substrate and copper foil together, and facilitates thermal transfer between the heat source and the base metal.
Suppliers likewise utilize insulating layers with good electrical isolation properties and low thermal impedance. Upscale models employ materials from Bergquist, Laird, NRK and Denka.
Currently, prices of single-sided variants range from $150 to $370 per square meter. Double-sided kinds go for $230 to $750, while upscale models with high thermal conductivity are 50 percent more expensive than their mainstream counterparts.
Quotes depend on the cost of materials. Spending on copper has climbed due to a weak US dollar and slumping inventories. LME copper, for instance, which was listed at$7,440 per ton in the beginning of 2010, rose to $8,400. Goldman Sachs forecasts the metal will trade at $11,000 per metric ton in a year because of increasing orders.
The outlay for aluminum, meanwhile, remained at $1,800 to $2,400 per metric ton. These, however, could climb with the devaluation of the dollar and a rosy economic outlook.
Increasing labor expenses and the appreciation of the yuan could likewise affect quotes.
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The growing number of products requiring high-power surface-mount components is driving many Hong Kong PCB suppliers to add aluminum-base PCBs to their lineups. The main applications are LED displays and streetlights, amplifiers, voltage regulators, transistor and resistor arrays, solar cell substrates, and other power and commercial lighting uses.
The selection from the territory includes single- and double-sided, and multilayer versions. The base sheet is typically 1.5mm thick. Custom sizes are also offered.
The surface finish can be OSP, lead-free HAL, tin plating and immersion gold. Some companies carry out advanced techniques, including heavy copper, micro, blind and buried via, hard gold plating and superthin core, and provide complementary assembly and chip-mounting services. These allow enterprises to release more compact products while reducing manufacturing time.
There are about 50 PCB suppliers in Hong Kong. Most have factories in mainland China, although some undertake operations in the territory. The majority conducts PCB layout, tool making and QC in-house.
Clients include major electronic companies in North America, Europe and Japan.
ANS Industrial Co. Ltd specializes in aluminum-core PCBs and high-precision double-sided rigid and rigid-flex types. It manufactures up to 30-layer boards with 0.15 to 6mm thickness, 0.15mm via hole size, 10:1 plating aspect ratio and 12oz heavy copper. Aside from traditional surface finishes, the supplier offers palladium gold, silver and tin, carbon print, gold fingers, flux coating, peelable mask and LPI.
Single- and double-sided kinds comprise the line of Advanced Electronic Technology HK Ltd. The company utilizes blind and buried vias, peelable mask/carbon ink printing, CNC V-cut/gold finger, flash/hard gold plating, lead-free HASL and other surface finishes for its rigid, flexible and rigid-flex variants.
Onpress Printed Circuits Ltd offers aluminum-base PCBs among its other products. The maker’s surface finish options are HAL, lead-free HAL, OSP, immersion gold, tin and silver, selective gold plating and OSP/HASL+gold finger, and flash and hard gold.
ANS Industrial Co. Ltd
Onpress Printed Circuits Ltd
Vitek Printing Circuit Board Co. Ltd
Note:This article 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.
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