Reading time ( words)
As SMT matures and its end products continue to shrink in size but grow in capability, manufacturers are constantly in need of components that satisfy demanding footprint, reliability and placement require-ments. Modern manufacturing techniques are useless if a board's components are out of date, perform poorly or fail to satisfy end-user requirements. To assist manufacturers in this search, SMT Magazine presents Component Specifier, a new product section designed to spotlight state-of-the-art active, passive, odd-form and interconnect components.
ActiveDevices capable by themselves of controlling voltages and currents to produce gain or switching actions in analog or digital circuits, i.e., reacting to an applied signal, they can change their basic charater.
PassiveDevices that do not change their character when electrical impulses are applied, i.e., they provide a single, repeatable reaction.
InterconnectDevices that provide mechanical and electrical union/disconnection and consist of mating plugs and receptacles (sockets) to join PCBs with cables, racks, chassis or other PCBs (stacking); actual connection to the board, however, must be via surface mount-type contacts.
Odd-FormDevices whose geometrical form factors are singular but not necessarily unique such that they must be manually mounted. Their housings (as opposed to their basic functions) are nonstandard as to shape. Examples include many transformers, hybrid circuit structures, fans/blowers, mechanical switching blocks, etc.
SOIC/SSOP PackagesExposedPad (ePad) technology is now available in two new package types the eight-lead, 0.105" SOIC and the 16-lead, 0.150" SSOP. These packages are said to offer increased thermal efficiency and better loop inductance when the exposed pad is attached directly to the motherboard. Mounted using standard SMT techniques, the technology also reportedly allows for higher clock speeds. Applications include RF power amplifiers, audio amplifiers, voltage regulators and signal amplifiers. Amkor Technology, Chandler, Ariz.
Enhanced PBGADesigned to provide excellent electrical performance in complex designs, including systems on chips and ASICs, this enhanced PBGA (EPBGA) is said to deliver high performance and accommodate high frequency levels for devices with medium- to high-I/O counts. The fine-pitch wire-bonded package utilizes a four-layer substrate with power and ground planes for thermal and electrical performance. Pin counts of 300 and 800, and package sizes of 35 to 45 mm, are available. Staggered bond pads of 45 to 90 μm are also offered. ChipPAC, Santa Clara, Calif.
Q101-compliant SOT-223sThis SOT-223 series of HEXFET power MOSFETs is said to be qualified to the Q101 automotive industry quality standard for up to 150°C. Breakdown voltage is reportedly as high as 250 V, while RDS(on) is as low as 40 mΩ. Thirteen N- and P-channel devices are qualified for production. International Rectifier, El Segundo, Calif.
DC/DC ConvertersIntended for use in telecommunications applications, the SM Series of surface mountable DC/DC converters features single-, dual- and triple-output configurations in 10 and 20 W versions. A low-profile (0.4" high) package facilitates tight card pitch requirements, while a 1.830 sq. in. design ensures compatibility with existing pick-and-place equipment. Other features include a 10 ms startup for hot-plug conditions, remote on/off for complex system timing requirements, and 24 or 48 V nominal inputs for wireless and central office telecom applications. Lambda Electronics Inc., Melville, N.Y.
Epoxy-based CrystalsFeaturing a height of 4 mm, the EC3SM and EC4SM series of epoxy-based surface mount crystals are suited for high-volume applications where coplanarity is critical. The devices are available in frequencies from 3.579545 to 60.000 MHz. Performance options include ±15/±30 ppm tolerance stability, -40° to 85°C operating temperature and multiple pin configurations. Tape-and-reel packaging is standard is 1,000-piece increment. Ecliptek Corp., Costa Mesa, Calif.
SMT VCXOThe CMV3 surface mount VCXO is designed to provide high performance combined with 3.3 V operation. Its low-profile CLCC package offers a 7.5 x 5.08 x 1.8 mm size. As with other products in the series, the CMV3 produces a TTL/CMOS-compatible output on frequencies ranging from 2 to 52 MHz. Temperature range is from -40° to 85°C. Applications include phase-locked loop uses, such as cellular base stations and microwave radios, as well as clock recovery circuits, local reference clocking and signal tracking schemes. Champion Technologies Inc., Franklin Park, Ill.
Miniature OscillatorsThese low-profile, surface mountable, digitally temperature-compensated, voltage-controlled crystal oscillators (DTCVCXO) are intended primarily for use in PDC, CDMA, GSM and other mobile communication devices. The IQDTCVCXO-91 range is said to offer frequency stability to ±1.0 ppm over a -30° to 80°C temperature range. An automatic frequency control (AFC) function reportedly allows the output frequency to be trimmed by at least ±5 ppm through a voltage input of 1.5 ±1.0 V. Both functions are integrated within a ceramic package measuring 7.0 x 9.0 x 2.0 mm. A range of standard frequencies is offered. C-MAC Frequency Products (CFP), Durham, N.C.
Platinum Temperature Sensor ChipsThese surface mount platinum film resistive temperature sensor chips are geared toward automotive, industrial and instrumentation applications. Designated the PTS 1206 Series, they reportedly feature resistance values of 100 Ω with a tolerance of ±0.5 percent, TCRs of 3,750 ±100 ppm/°C, and operating temperature of -50° to 125°C. In addition, the platinum film sensing element is said to exhibit long-term stability of 0.1 percent (typical) and response times of 2.2 seconds in still air. IRC Inc., Corpus Christi, Texas.
Miniature Trimmer CapacitorThis 5 pF miniature, solid dielectric A4 Series trimmer capacitor reportedly tunes from 0.6 to 5 pF with five full turns for fine resolution. Measuring 0.325" long x 0.16" dia., the device has surface mount, leaded PC or strip line configuration. Voltage rating is 125 VDC, with a high-voltage option of 1,000 DC working volts and 2,000 DC withstanding volts. Q is said to be more than 2,000 at 100 MHz, with self-resonant frequency of 1.8 GHz at 5 pF. Voltronics Corp., Denville, N.J.
Surface Mount InductorsThe CM10 SMD chip inductor and the SRR0603 and SRR0604 SMD shielded power inductors are intended to simplify design in limited-space applications. At 1 mm in size, the CM 10 SMD is a sealed unit manufactured with laser-cut copper, making it resistant to heat, humidity, mechanical shock and pressure. Inductance is said to be as low as 1 nH, with an SRF minimum of 6 GHz. The power chokes offer low unit height, high maximum current of 2.3 A, and an inductance range of 3.3 to 1,000 μH. Bourns Inc., Riverside, Calif.
Shielded Power InductorsThe SHS Series of surface mount power inductors reportedly offers 100 percent ferrite shielding for high-density applications that must withstand current to 10,000 mA. The series is made up of coils in three size groups 0706, 1206 and 1208. Inductance levels in the 0706 Series range from 0.1 to 100 μH, with corresponding DCR maximums ranging from 0.004 to 0.140 Ω and DC current maximums from 5,000 to 800 mA. The 1206 types range from 10 to 680 μH, with 0.025 to 1.20 Ω DCR, 4,000 to 500 mA, and the 1208 versions range from 1.0 to 47.0 μH, with 0.007 to 0.10 Ω DCR, 10,000 to 2,500 mA. Associated Components Technology Inc. (ACT), Garden Grove, Calif.
Telecom TransformerDesignated the SPT-1103, this surface mount telecom transformer is intended for voice and most data applications. The 600 Ω:600 Ω dry model offers a low profile of 0.48" maximum, a 1,500 VAC dielectric strength (hipot) rating, a gull-wing-style lead frame and a length of 0.790" maximum. The component also conforms to FCC and DOC requirements. Prem Magnetics Inc., McHenry, Ill.
DC/DC ConvertersPD Series high-density DC/DC converters can now accommodate 12 V inputs for use in battery power systems architectures for portable equipment. Inputs of 24, 48, 150 and 300 are also possible. Both full-brick 300 W and half-brick 150 W low-profile (0.40") versions are available. Standard features include overvoltage and overcurrent protection, thermal shutdown and frequency synchronization. Powercube, Chatsworth, Calif.
SCSI Combo Connector Available in surface and straddle mount versions, this three-in-one SCSI connector incorporates data, control and power functions in one component. The Ultra SCSI Combo connector features four power, 12 control and 68 data contacts constructed of phosphor bronze, copper or brass. Power contacts are rated at 3 A and data contacts at 1 A. Mating contact faces are plated with gold flash over 50 μin palladium nickel, while solder connections areas are plated with 100 μin or more of tin/lead solder over nickel. Operating temperature is rated at -40° to 160°C. Ranoda Electronics Inc., Broomfield, Colo.
An Alternative to Plastic devices
Since the widespread adoption of SMT in the early 1980s, circuit designers have contended with a variety of package types. Many components are available in different packages. For example, there are more than 12 different packages offered for diodes; all are plastic with the exception of metal electrode face (MELF).
The MELF is hermetically sealed, offering immunity to moisture in humid environments. Plastic-encapsulated devices can fail in high-moisture environments because of the internal corrosion via interaction with the plastic package contaminants.
MELF is cost competitive with plastic packages and has a lower physical profile (less shadowing in wavesoldered printed circuit boards). The package is able to operate reliably at junction temperatures up to 175°C. Plastic devices can fail at temperatures higher than 150°C.
One of the more noticeable differences between plastic and MELF is that the MELF endcaps solder joint fillets. In a typical J lead, the fillet is obscured underneath the body of the device.
Outdated thinking has kept many design engineers from using MELF. The myth was that MELFs would roll off the board during placement. This myth is based on some fact. During the early days of SMT, most boards were wave soldered. To keep the parts on the board, they had to be glued with adhesive material, and in some cases, the glue did not always hold. Today, most surface mount boards use reflow soldering and the solder paste holds the parts down, making rolling a thing of the past. Microsemi, BKC Semiconductors, Lawrence, Mass.