From dome optical lens to liquid silicone materials for encapsulation and adhesion, on the booth’s panel, noted LED package material manufacturer Dow Corning, now a wholly owned subsidiary of the Dow Chemical Company, showcased a myriad of advanced silicone products for various package types. At GILE 2017, LEDinside had an interview with Mr. Takuhiro Tsuchiya, Global Segment Leader at Dow Corning, on current trends and the company’s role in the LED package industry.

LED package concepts are growing both in number and sophistication to meet an increasingly diverse list of lighting designs. These include such as ceramic substrate-based surface mount device (SMD), chip-on-board (CoB) and plastic leaded chip carrier (PLCC) packaging. LED packagers used to encapsulate LEDs with conventional materials, such as epoxy, which, despite lower cost, discolor easily and have temperature restrictions. As aforementioned, when LED penetrated to more applications including street lights, displays, horticultural lighting, UV LED and vehicle interior and exterior lighting, the quality of LED packages and their efficiency became important and were required to upgrade. In this case, traditional encapsulants are no longer able to fully meet the stringent requirements of those critical designs; however, silicones, especially quality ones, can.

Dow Corning at GILE 2017 (Image: LEDinside)

Considering the emergence of chip scale packages (CSP), we see the LED package industry is marching to a direction that companies want to downsize the components (chips and packages) but at the same time require the same or higher light output from the chip, hence more thermal density in ever smaller form factors. ‘Dow Corning has noticed the trend and been working on improving our silicone encapsulants to meet or even exceed our customers’ needs, capturing future needs for them,’ said Tsuchiya. Dow Corning supports LED packagers with its deep knowledge in chemistry, total solutions and intellectual properties, he added.

Solid Background in Chemistry

With the knowledge that in the package industry more and more emphasis is being placed on raising luminous flux within smaller chip areas, the silicone expert pointed out two issues cannot be ignored – increased photothermal density and improved mechanical stability. Tsuchiya explained, Dow Corning’s advanced NRI (Normal RI) silicone encapsulants, compared with its equivalents, after a series of development and testing by the professional team, are more photo and thermal stable. For instance, Dow Corning’s OE-7340 Optical Encapsulant, launched in 2016, possess a superior thermal stability and flexibility that when tested at 250℃ maintained it properties longer than 200 hours. It is also highly crack-resistant. It features an elongation of 170% and thus is especially suited for high power CoB packages.

Dow Corning's OE-7340 Optical Encapsulant (Image: LEDinside)

In terms of mid power PLCC packages, to sustain longer light output from decay is to prevent the discoloration of silver reflectors within lead frames. Dow Corning’s OE-7662 Optical Encapsulant receives a lot of market attention because of its higher gas barrier property. Dow Corning launched OE-7840 optical encapsulant and others, a new family of MRI (Middle RI) products in early 2017 which address higher photo –thermal resistance for mid power PLCC packages run at ever harsher conditions. Dow Corning is working on advancing HRI (High RI) silicone encapsulant with upgraded properties in photo-thermal resistance and mechanical stability that will be launched soon targeting mid and high power LED packages, according to Tsuchiya.

Dow Corning listed out its quality silicone encapsulants for different LED packages. (Image: LEDinside)

Dow Corning's OE-7840 Optical Encapsulant possesses superior properties to prevent packages from sulfur corrosion. (Image: LEDinside)

Total Solutions Tailored to Customers’ Needs

Apart from the capability to design and manufacture new silicone chemistry, as an international corporation with a distinguished share in the global market, Dow Corning has a tradition of collaborating closely with LED designers and manufacturers along with the entire value LED chain to bring new innovations that help its customers to attain their goals.

Tsuchiya proved to LEDinside that Dow Corning is always working in tandem with its customers to seize market trends by introducing the Dow Corning CL-1000 Optical Silicone Binder- a new, photothermally stable HRI material formulated to enable more design options for chip scale packages. This binder, launched first to the China market, outperforms other high RI materials, showing when exposed at high temperatures over 180℃ for 2000 hours its excellent thermal stability and minimum degradation. It consequently spans the lifetime of a package and enhance its efficiency, considered an optimized solution for molding and liquid-based processes during the manufacture.

The WR series reflective materials (Image: LEDinside)

For CSP LED, the company also offered the WR series reflective materials: the WR-3001, WR-3100 and WR-3120. These silicones share remarkable reflectivity when made into a thin layer and deliver noticeable photometric properties at sustained high heat in other cases might crack regular resins. They are also intended for LEDs packing several emitting chips densely as high power CoB packages. Manufacture would coat the sides of a chip with these high RI reflective materials as a way to control beam emission and improve light extraction.  

The CL-1000 Optical Silicone Binder and the WR series therefore come as a total solution Dow Corning offers to Chinese LED makers developing innovative CSP LEDs, explained Tsuchiya.

He further leaked that Dow is also working on new silicone technology that can contribute to the film process of CSP production. 

Takuhiro Tsuchiya, Global Segment Leader of Dow Corning, received LEDinside's interview to talk about trends in the LED package industry. (Image: LEDinside)

IPs Strengthen Product Differentiation

Fierce Competitions in the package industry have been driving companies to advance their production and attempts to differentiate their products from others. To secure their innovations, LED manufacturers stirred up the war of intellectual property. ‘Our materials are all covered with patents. Companies using our products can truly differentiate themselves from their contenders and avoid possible patent infringements,’ told Tsuchiya.

As a highly collaborative advanced encapsulant provider, Dow Corning will continue to develop new reliable materials for the burgeoning package market and support LED packagers to realize more efficient LED lighting, concluded Tsuchiya.

(Written by Evangeline Huang, Editor, LEDinside)