Cerafil SFECF/SFECD series products. Electric characteristics of type SFECF10M7FA00-R0 series filter. SMD Cerafil SFECF/SFECD series ceramic filters

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urata Manufacturing Co.,

Ltd.’s ceramic filter, Cerafil, is a band pass filter that utilizes the piezoelectric effect of ceramics. Cerafil has a long history as the company’s flagship product. It is used mainly as a band pass filter for the intermediate frequency (IF) stage of superheterodyne reception circuits. Under this designation, Murata has commercialized kHz and MHz band pass filters. Cerafil covers the kHz band around 450kHz, the 4.5 to 6.5MHz bands and the band whose center frequency is 10.7MHz.

Cerafil SFECF/SFECD series products,

which meet the requirements for higher reliability. These products are small and have a low profile (photo). This report outlines the general features of the SFECF/SFECD series products with a perspective over the company’s future development activities.

Geometry

SFECF series — “standard types” (Fig. 2):

Dimensions: 3.45 × 3.1 × 1.4mm

Weight: 65mg

SFECD series — “thin types” (Fig. 3):

Dimensions: 3.45 × 3.1 × 1.0 mm

Weight: 40mg

This product is used mainly as the IF band pass filter for audio-video systems (AM/FM radios, TVs, etc.) and communication equipment (cordless telephone, mobile phones, etc.). Cerafil is extending its application fields. The products for 1015MHz have been used in FM radio, cordless telephone and PHS phone. They are recently used in communication equipment such as automatic counter reader, watch-shape communication terminal, and SMD Cerafil SFECF/SFECD series ceramic filters

card reader/writer). They are even applied to vehicle-mountable equipment including VICS, color TV, remote keyless entry (RKE), and tire pressure monitoring system (TPMS). In these applications to vehicle-mountable equipment, the requirements for reliability are becoming more and more demanding.

Murata has now commercialized SMD

Fig. 1: Electric characteristics of type SFECF10M7FA00-R0 series filter

Technical Data of SFECF/SFECD

Features of SFECF and SFECD Series

I) Low-profile and lightweight

An SFECF series product is small and light with its external dimensions of 3.45 × 3.1 × 1.4mm. It weighs 65mg. It is 7 percent thinner and 7 percent lighter than the Cerafil SFECS series, the company’s previous series.

With the SFECD series, the company has achieved further reduction of the product’s dimensions and weight: 3.45 × 3.1 × 1.0 mm and 40mg. It is 33 percent thinner and 43 percent lighter than the SFECS series. This great reduction in dimensions and weight of the device has been achieved by the use of a new unique material for the sheathing substrate as compared to the conventional device utilizing ceramic sheathing substrates.

II) High reliability

The SFECF and SFECD series products have excellent weatherability achieved by the company’s improved material, structure and processing technologies/techniques.

Like the existing SFECS series, the new series filter has a laminated “sandwich” structure composed of two piezoelectric ceramic elements squeezed by ceramic sheathing substrates. For the

SFECF/SFECD series, a newly developed bonding process was utilized and the technique for jointing the internal electrodes

Fig. 3: External dimensions of an SFECD series filter

on the ceramic element with the external electrodes on the sheathing substrates was improved.

These efforts allowed the company to greatly enhance the weatherability of the device and guarantee 1,000 cycles of thermal shock test between –55°C and +85°C. In response to the worldwide trend for lead-free products, Murata adopted an SnAg-Cu soldering process that does not utilize lead.

III) Compatibility of electrode land pat-tern with existing products

The SFECF/SFECD series products have been designed to be mounted in the same electrode land patterns as those of the existing Cerafil SFECS series. Therefore, SFECF/SFECD series devices can be easily substituted for SFECS series devices without modifying the electrode land pattern.

IV) SFECF/SFECD’s targets

With the low-profile feature and enhanced weatherability as compared to the existing Cerafil SFECS series, the newly released SFECF/SFECD series products are most suitable for small and thin and vehicle-mountable equipment sets that require high reliability in certain expected heavy operating conditions:

• PHS

• RKE (Fig. 4)

• TPMS

• VICS

• RFID (non-contact IC card reader/writer) • Card module

• etc.

Future Tasks and Development

Murata intensifies its development activities for new products to be able to respond to changes in market requirements. The Cerafil SFECF/SFECD series devices, with their small profile and enhanced weatherability, can potentially be used in any suitable applications in addition to those in the consumer markets described above.

To meet more demanding market requirements, the company will continue to pursue product features such as “smallness and low profile,” “high reliability,” and “higher frequencies” and endeavor to propose series products.

About This Article

The author, Hidetsugu Yoshida, is an Engineer at the Product Engineering Service Section II, Planning and Market Promotion Department, Piezoelectric Components Group, Murata Manufacturing Co., Ltd.

Note: The devices referred to as “***** series” in this diagram are products of Murata Manufacturing Co., Ltd. Fig. 4: An application of remote keyless entry (RKE)