Thyristor Semiconductor Products Page 41 Thyristor

2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors AN1004 is available, depending upon the thickness of the heat sink material. Use an appropriate grip range to securely anchor the device, yet not deform the mounting tab. The recommended rivet tool has a protruding nipple that will allow easy insertion of the rivet and keep the tool clear of the plastic case of the device. Figure AN1004.9 Pop Riveting Technique A Milford #511 (Milford Group, Milford, CT) semi-tubular machine similar to a Milford S256 is also acceptable. Contact the rivet machine manufacturer for exact details on application and set-up for optimum results. Pneumatic or other impact riveting devices are not recommended due to the shock they may apply to the device. Under no circumstance should any tool or hardware come into contact with the case. The case should not be used as a brace for any rotation or shearing force during mounting or in use. Non-standard size screws, nuts, and rivets are easily obtainable to avoid clearance problems. Always use an accurate torque wrench to mount devices. No gain is achieved by overtorquing devices. In fact, overtorquing may cause the tab and case to deform or rupture, seriously damaging the device. The curve shown in Figure AN1004.10 illustrates the effect of proper torque. 1/2 Rated Torque Rated Torque Torque - inch-lbs C/Watt C-S Effect of Torque on Case to Sink Thermal Resistance Figure AN1004.10 Effect of Torque to Sink Thermal Resistance With proper care, the mounting tab of a device can be soldered to a surface. However, the heat required to accomplish this operation can damage or destroy the semiconductor chip or internal assembly. See "Surface catalog. Spring-steel clips can be used to replace torqued hardware in assembling Thyristors to heat sinks. Clips snap into heat sink slots to hold the device in place for PC board insertion. Clips are available in several sizes for various heat sink thicknesses and Thyristor case styles from Aavid Thermalloy is shown in Figure AN1004.11 Figure AN1004.11 Typical Heat Sink Using Clips Soldering Of Leads A prime consideration in soldering leads is the soldering of device leads into PC boards, heat sinks, and so on. Significant damage can be done to the device through improper soldering. In any soldering process, do not exceed the data sheet lead solder temperature of +280 C This application note presents details about the following three types of soldering: Hand Soldering This method is mostly used in prototype breadboarding applications and production of small modules. It has the greatest potential for misuse. The following recommendations apply to Littelfuse TO-92, TO-220, and TO-218 packages. Select a small- to medium-duty electric soldering iron of 25 W to 45 W designed for electrical assembly application. C to 425 C). The iron should have sufficient heat capacity to heat the joint quickly and efficiently in order to minimize contact time to the part. Pencil tip probes work very well. Neither heavy-duty electrical irons of greater than 45 W nor flame-heated irons and large heavy tips are recommended, as the tip temperatures are far too high and uncontrollable and can easily exceed the time-temperature limit of the part. Littelfuse Fastpak devices require a different soldering technique. Circuit connection can be done by either quick- connect terminals or solder. Mounting and Handling of Semiconductor Devices (continued)

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