Applications Guide

Introduction

All Electromagnetic Compatibility (EMC) topics can be associated with either the process of producing or receiving Electromagnetic Interference (EMI). EMI produced by electrical equipment is classified according to its dominant mode of propagation, either as radiated emissions of energy through space (similar to television and radio signal transmission) or conducted emissions of energy along wires (similar to telephone signals and AC power transmission).

Besides producing potential interference, electrical products are exposed to ambient EMI from other pre-existing sources; a device that malfunctions in the presence of such EMI is said to be susceptible or lacking in immunity to perturbation by external EMI sources. Immunity is gradually replacing susceptibility as a preferred term, since quantitative descriptions of greater performance become more logical if one speaks of greater immunity rather than lower susceptibility. EMI immunity topics are also classified by their mode of propagation, either radiated or conducted.

Public awareness of the consequences of EMI issues greatly increased during the early 1970's. At the peak of the Citizen's Band (CB) radio fad, hundreds of thousands of CB's began transmitting radio frequency energy in every neighborhood. Church congregations experienced radiated EMI as they overheard the CB transmissions picked up by the susceptible antenna-like wires of chapel public address systems. During the same period, new microprocessor circuits began appearing in electronic cash registers and video arcade games. Unknown to their designers, the fast electronic devices in these new smart products generated intense radiated EMI. Radio wave noise from these products began to jam police and fire radio channels, threatening public safety.

As complaints of identified and unidentified radio interference increased, the Federal Communications Commission (FCC) accelerated its investigation of EMI problems and potential legislative solutions. In 1979, the FCC imposed legal limits on the strength of radiated and conducted EMI that may be generated by devices that use timing circuits operating at frequencies above 9 kilohertz. In the rest of the world, most countries now require that imported products comply with the EMI laws of the U.S., Germany, or the limits recommended by the International CISPR 22 committee. Until recently, most legal EMI requirements focused only on regulating the noise generated by a product. However, The European Community (EC) will soon enact EMI immunity standards that will require manufacturers to design and test their products so that they will not malfunction when subject to external EMI sources. In the United States, however, the FCC has not proposed similar immunity requirements for products intended only for the U.S. marketplace.

 

Precautions on the use of Ferrite Chip Beads, Chip Inductors, High Frequency Chip Inductors and Low Profile Surface Mount Common Mode Chokes.

The electronic components contained in this catalog are designed and produced chiefly for such general electronic equipment as audio equipment, visual equipment, white goods, office equipment, and information/communication equipment.

Therefore, if you wish to employ them in medical equipment, aircraft, space equipment, security systems, or other similar equipment that requires high safety, you are requested to confirm fitness after your own testing.

Regardless of the intended application, if high safety is required it is recommended that you establish a protective or redundant circuit and conduct a safety test.

Regardless of the intended application, we suggest that you ask for a technical specification describing the details and then make sure that it is the proper component for the equipment conforming to it.

Technical information in this catalogue is intended to convey examples of typical performances and/or applications and is not intended to convey patent rights, if any.

For the products which are controlled items subject to the Foreign Exchange and Foreign Trade Law, the export permission according to the Law is necessary.

The information provided here may be changed or revised without prior notice. Therefore, please be sure to
reconfirm the information shown in this catalogue before your designing and/or purchasing activities.

1. Circuit Design. The operating current for the components must always be less than or equal to their rated currents. Application of current in excess of the rated value at any time could affect the electrical performance of the components.

2. PCB Design.

• Design of Land Patterns. The solder mounting of components on a PCB can affect the performance of the component and the following items should be considered.
  1. The ability of the component to withstand various mechanical stresses can be affected by the volume of solder in the solder fillet. The size and layout of the land patterns must be considered to insure appropriate fillet formation.
  2. All components should have isolated soldering pads to insure adequate solder fillets for each component. If more than one component is to be soldered onto a land pad, the pad should be separated with solder resist.
• Layout on Panelized PCB. After solder mounting of components on boards, later manufacturing processes could introduce mechanical stresses on the components. Stresses on the components should be minimized by proper pattern configurations and positioning.
  1. Position the component perpendicular to the direction of the anticipated mechanical stress.
  2. The amount of mechanical stress will also vary with the component layout. In general, the further the component is mounted from the perforation, the less mechanical stress will be involved. It is also possible to place the component adjacent to a slit in the board although this is not as good as moving the component away from the breakaway altogether.
  3. The method used to break PC boards will cause the mechanical stress on the components to vary.

3. Soldering. The methods and materials used in the soldering process could present problems for the components if the methods and materials are not properly selected and controlled.

• Flux.
  1. The halogenated content of the flux must be kept to a minimum. In the presence of large amounts of a halogenated substance or a strong acidic content, corrosion of the terminations or degradation of insulation resistance may result.

  2. Special care must be taken to clean the boards when using water-soluble flux. If not, high humidity conditions may cause a degradation of insulation resistance and consequently affect the long term reliability of the component.

• Soldering
  1. The temperature and solder profile are specified in the respective component product drawing. Excessive dwell time can negatively affect the solderability so the dwell time should be kept in accordance with recommended times.
  2. The components should be preheated to within 100°C of the soldering temperature. The components are susceptible to thermal shock during rapid heating or cooling. The solder process must be carefully controlled to insure the components are not damaged due to thermal shock.
  3. The ideal solder fillet should be ½ to 1/3 of the thickness of the component.

4. Cleaning.

• Cleaning conditions and methods should be determined after verification that the desired process does not affect the component's mechanical or electrical properties.
• The use of ultrasonic cleaning can cause excess vibration of the board which can damage the solder joint or decrease the adhesion of the termination to the component body. The use of ultrasonic cleaning should be carefully determined and controlled.

5. Handling.

• Separation of Panelized PCB.
  1. Care is required during the separation of the PCB after mounting of components to prevent any stresses, deflection or twisting of the board.
  2. An appropriate device should be used to separate the PCB. The separation of the PCB should not be done manually.
• General Handling
  1. Care should be taken when handling the components to avoid excessive mechanical shock.
  2. The components should be kept away from all magnets and magnetic objects.
  3. Only non-magnetic tweezers should be used when handling the components.
  4. Always wear static control bands to protect against ESD.
  5. Properly ground all devices used with the components.

6. Storage.

• To maintain the solderability of the component terminals care must be taken to control the temperature and humidity in the storage area.
• The recommended maximum storage conditions are 40°C and 60% relative humidity.
• The recommended maximum storage time for an unopened bag with the tape and reel enclosed is 12 months.
• If the components are stored in a high temperature and humidity environment or if the bag containing the components is opened, problems such as reduced solderability caused by oxidation of the solderable component terminals may take place.