Ceramic packaging for greater crystal oscillator miniaturization

by Vianie Li & Cecile de Veyra

Crystal oscillators are widely used in the mobile and consumer electronics, automotive, communications, industrial, aviation and military fields. To keep up with advancements in these applications with complex and dense circuitries, they need to deliver high performance in terms of frequency accuracy and stability with low phase noise even in ever smaller form factors.

These discrete components typically have a metal package, while glass, plastic and ceramic are less common alternatives. But because of its insulating property, ceramic is expected to gradually replace metal as the primary material, especially for high-density applications demanding tiny but robust and heat-resistant components. With a metal lid, ceramic packages offer a hermetically seam-sealed housing, ensuring a stable atmosphere against environmental changes for the crystal's optimum functioning.

As small as 1008 SMD crystal oscillators for wearable devices, smartphones and medical devices are available in the market. These come from key companies from Japan and the Taiwan region.

Chinese Manufacturers

Chinese manufacturers aim to catch up with these industry leaders. The Chinese mainland is a major crystal oscillator production base with a market share of 18 percent, according to QY Research, close behind Japan, North America and the Taiwan region.

QY Research projects the mainland will realize 10 percent CAGR from 2019 to 2026, outperforming the global market forecast to register a 7.3 percent increase during the same period. In value, this growth is from $3.1 billion in 2019 to $4.69 billion in 2026.

Mordor Intelligence's recent report offers a different vista, taking into account the category's 2020 market performance worldwide of $2.0557 billion. In its 2021 to 2026 estimate, value will reach a more modest $2.2812 billion and register a CAGR of 2.2 percent.

Both market research firms acknowledge the mainland's key role in the market for crystal oscillators, with Mordor Intelligence noting it is a major consumer of these components as well.

The key demand drivers for this category are mobile and consumer electronics, wearable devices, computers, communications equipment and the automotive industry. Smartphones and automotive applications are expected to lead in the near term. According to Sohu News, up to 3.52 billion crystal oscillators will be in handsets made by Chinese manufacturers alone in 2022, with a total value of $366 million. This upward trend will persist over the next two years.

Hundreds of manufacturers in the Chinese mainland offer crystal oscillators. Over two-thirds are domestic enterprises, led by Tangshan Jingyuan, Zhejiang East Crystal, Faith Long Crystal, China Electronics Panda Crystal, TKD and TROQ. Companies with investment from Japan include Seiko Epson, NDK and KCD, and from the Taiwan region, TXC, KDS, Siward and Harmony.

Most Chinese suppliers export their products, mainly to North America, Europe and the Asia-Pacific region. South America, the Middle East and Russia are destinations as well.

The key cities where many manufacturers congregate include Shenzhen in Guangdong, Yangzhou and Nanjing in Jiangsu, Jinhua in Zhejiang and Tangshan in Hebei.

DIP & SMD product range

Although Chinese companies have been pursuing the miniaturization trend, releasing more SMD crystal oscillators, they continue to offer through-hole versions.

In terms of types, their selections consist mostly of TCXO, VCXO, OCXO, SPXO and LPXO units.

By package, the DIP subcategory has HC-49U, HC-49U/S, HC-49USMD, UM-1 and UM-5. SMD crystal oscillators that are widely available come in sizes of 1612, 2012, 2016, 2025, 3225, 4025, 5032 and 6035.

Typical specifications are 0.5 to 800MHz operating frequency, ±20 to 100ppm frequency stability and 1.8 to 12V rated voltage. These can be modified according to customers' requirements. All companies ensure their products are RoHS-compliant.

Quartz blanks, coated electrodes, ceramic bases, solder pads, metal lids and adhesive are the main materials used in the production of crystal oscillators. These are sourced from domestic providers or foreign companies such as Kyocera and Sumitomo.

Suppliers interviewed by Global Sources Electronic Components say input costs may become steady toward the end of 2021 and put a lid on price increases.

1 to 150MHz crystal oscillator

In a four-pad SMD package, this 5032-4 crystal oscillator from Chequers Electronic (China) Ltd has 1 to 150MHz frequency range and ±25 to ±50ppm frequency stability. The supply voltage is 1.8, 2.5, 2.85, 3.3 or 5V with ±10 percent tolerance. The 5x3.2x1.3mm unit has 10ns maximum rise/fall time. Operating temperature is between -10 to 60 C and -40 to 85 C.

The 1,000-unit minimum order has a 28-day lead time.

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4 to 75MHz crystal oscillator

This RoHS-compliant 2N SMD 2520 Crystal Oscillator-5 from Shenzhen Crystal Technology Industrial Co. Ltd has 4 to 75MHz frequency range and ±25, ±50ppm or buyer-specified frequency stability. The supply voltage is 1.8 to 3.3V. The 2.5x2x0.8mm unit, with a tri-state function, suits WLAN, GPS and automotive applications. It operates in -40 to 85 C.

The supplier requires a 3,000-unit minimum order for delivery within 18 days.

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32.768kHz crystal oscillator

Strong Electronics & Technology Ltd markets this SOK2016-32.768K-20-1.8V crystal oscillator with 32.768kHz frequency, ±20ppm frequency stability and 45 to 55 percent output symmetry. The 2x1.6x0.8mm SMD unit has 1.8 to 5V and maximum 15mA supply voltage and current. It operates in -40 to 85 C.

The minimum order quantity is 1,000 units. Lead time is 14 days.

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16,000MHz crystal oscillator

The TX3 SMD 16MHz Quartz Crystal from WTL International Ltd is a 3.2x2.5x0.7mm crystal oscillator with 16,000MHz frequency, 10ppm frequency tolerance, 12pF capacitance, 3pF maximum shunt capacitance, 80ohm maximum equivalent series resistance and 50µW typical drive level. The fundamental-mode unit, with AT-cut crystals, ages at maximum ±3ppm per year at 25 C. Its operating temperature is -20 to 70 C.

An order of at least 3,000 units is required. Lead time is 15 days.

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