Thyristor Semiconductor Products Page 46 Thyristor

2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors AN1005 R e c o m e n d a t i o n s Gluing Recommendations Prior to wave soldering, surface mount devices (SMDs) must be fixed to the PCB or substrate by means of an appropriate adhesive. The adhesive (in most cases a multicomponent adhesive) has to fulfill the following demands: deteriorate component and PC board repair Low-temperature Solder for Reducing PC Board Damage In testing and troubleshooting surface-mounted components, changing parts can be time consuming. Moreover, desoldering and soldering cycles can loosen and damage circuit-board pads. Use low-temperature solder to minimize damage to the PC board and to quickly remove a component. One low-temperature alloy is indium-tin, in a 50/50 mixture. It melts between 118 C and 125 C, and tin- lead melts at 183 C. If a component needs replacement, holding the board upside down and heating the area with a heat gun will cause the component to fall off. Performing the operation quickly minimizes damage to the board and component. Proper surface preparation is necessary for the In-Sn alloy to wet the surface of the copper. The copper must be clean, and you must add flux to allow the alloy to flow freely.You can use rosin dissolved in alcohol. Perform the following steps: (1) Cut a small piece of solder and flow it onto one of the pads. (2) Place the surface-mount component on the pad and melt the soldered pad to its pin while aligning the part. (This operation places all the pins flat onto their pads.) (3) Cut small pieces of the alloy solder and flow each piece onto each of the other legs of the component. Indium-tin solder is available from ACI Alloys, San Jose, CA and Indium Corporation of America, Utica, NY. Multi-use Footprint Package soldering footprints can be designed to accommodate more than one package. Figure AN1005.8 shows a footprint design for using both the Compak and an SOT-223. Using the dual pad outline makes it possible to use more than one supplier source. Cleaning Recommendations Using solvents for PC board or substrate cleaning is permitted from approximately 70 C to 80 C. The soldered parts should be cleaned with azeotrope solvent followed by a solvent such as methol, ethyl, or isopropyl alcohol. Ultrasonic cleaning of surface mount components on PCBs or substrates is possible. The following guidelines are recommended when using ultrasonic cleaning: Cleaning of the parts is best accomplished using an ultrasonic cleaner which has approximately 20 W of output per one liter of solvent. Replace the solvent on a regular basis. MT2 / Anode Compak Footprint for either Compak or SOT-223 Dual Pad Outline Pad Outline 0.150 (3.8) 0.328 (8.33) 0.079 (2.0) 0.030 (.76) 0.040 (1.0) 0.019 (.48) 0.079 (2.0) 0.091 (2.31) 0.079 (2.0) .055 (1.4) 0.059 (1.5) TYP 0.079 (2.0) 0.079 (2.0) 0.079 (2.0) 0.110 (2.8) 0.030 (.76) 0.040 (1.0) Gate MT1 / Cathode MT1 Not used M T 2 SOT-223 Footprint Dimensions are in inches (and millimeters). MT2 / Anode MT1 / Cathode MT2 / Anode Figure AN10058 Dual Footprint for Compak Package Surface Mount Soldering Recommendations (continued)

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