Tanaka Precious Metals has announced it will commence the provision of samples of gold-tin alloy bonding material (AuSn alloy lid) which is able to seal ultra-compact crystal oscillators with a mounting area of 1.2 mm x 1.0 mm at half the material cost of conventional products from March 22.
This AuSn alloy lid is a component to manufacture the so-called 1210-size crystal oscillators with a mounting area of 1.2 mm x 1.0 mm. The conventional 1210-size AuSn alloy lid Tanaka Kikinzoku Kogyo has provided as a prototype had a washer frame width of 0.15 mm and thickness of 0.015 mm. By combining high-precision press technology and precise rolling technology, the new product is able to provide the same air tightness and bond ability as the conventional product with a frame width of 0.10 mm and thickness of 0.010 mm. With the general composition of AuSn21.5 (78.5% Au, 21.5% Sn), it is possible to reduce material cost by approximately 53% compared to conventional products.
With the development of high-density mounting of electronics, sealing methods using AuSn alloy are now widely used
Lid is a component for vacuum sealing crystal oscillators used to control the electronic signals in mobile phones, smartphones, PCs and car-mounted devices. The miniaturization demand of the devices is required which associated with high-density mounting of electronic equipment has accelerated in recent years. The crystal oscillators mass-produced currently are generally 1.6 mm x 1.2 mm (1612-size), but the 1210-size is scheduled to be mass producted as the next-generation crystal oscillator in 2014.
There are various methods for air-tight sealing of ceramic packages, and until now, methods using cheap lid materials, such as seam welding and direct seam method were the mainstream. However, because such methods have low productivity and there are space restrictions on roller electrodes used for welding, it has become difficult to seal compact size items (2.0 mm x 1.6 mm or less) as it has become necessary to be more compact and have a lower profile. Because of this, many manufacturers begin to adopt sealing methods using "furnace brazing" where the materials being welded are heated in a furnace. Sealing using furnace brazing enables sealing of compact items because electrodes are not used, and has the advantage of being able to provide high productivity due to the ability to perform sealing in batches. However, because AuSn alloy is used as the bonding material, the high cost of Au has been indicated to be an issue.
Successful development of a lid able to seal 1210-size items at half of the material cost
In order to resolve these issues, Tanaka Kikinzoku Kogyo has established manufacturing technology which is able to accurately position a 0.010 mm-thick AuSn alloy washer with a 0.10 mm frame width on a small 1.2 mm x 1.0 mm kovar base material and control the binding shape as a lid. Thus, this enables the same sealing reliability as conventional products while having a narrower frame width (0.15 mm->0.10 mm), and thinner (0.015 mm->0.010 mm) than conventional products. Because of the following features of this AuSn lid, it can demonstrate a high level of sealing reliability at a low material cost.
Features of the new 1210-size AuSn alloy lid
- Material cost is reduced by half while maintaining the same sealing reliability as conventional products
- AuSn alloy possesses excellent wettability and sealing reliability with less problems such as the occurrence of voids
- The alloy composition can be adjusted to match the conditions of use
- Due to the use of a design that prevents AuSn alloy flowing into the package, it provides a high level of sealing reliability with only the minimum necessary amount of alloy.
Tanaka Kikinzoku Kogyo will supply these 1210-size AuSn alloy lids to crystal oscillator manufacturers in Japan and overseas, and is aiming for 30 million yen in monthly sales as processing fee when mass production in 2014. Development will continue to improve sealing performance and support even more compact sizes such as 1008 and 0806 size in the future.