Thyristor Semiconductor Products Page 44 Thyristor

2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors AN1005 Surface Mount Soldering R e c o m e n d a t i o n s Reflow Soldering Zones Zone 1: Initial Pre-heating Stage (25 C to 150 C) Zone 2: Soak Stage (150 C to 180 C) the oxides on component leads and PCB pads. temperature at which solder bonding can occur. same temperature. Zone 3: Reflow Stage (180 C to 235 C) interface so metallurgical bonding occurs. Zone 4: Cool-down Stage (180 C to 25 C) Assembly is cooled evenly so thermal shock to the components or PCB is reduced. The surface tension of the liquid solder tends to draw the leads of the device towards the center of the soldering area and so has a correcting effect on slight mispositionings. However, if the layout is not optimized, the same effect can result in undesirable shifts, particularly if the soldering areas on the substrate and the components are not concentrically arranged. This problem can be solved by using a standard contact pattern which leaves sufficient scope for the self-positioning effect (Figure AN1005.3 and Figure AN1005.4) Figure AN1005.5 shows the reflow soldering procedure. 0.079 (2.0) 0.110 (2.8) 0.079 (2.0) Pad Outline Dimensions are in inches (and millimeters). Figure AN1005.3 Minimum Required Dimensions of Metal Connection of Typical DO-214 Pads on Hybrid Thick- and Thin-film Substrates 0.079 (2.0) 0.040 (1.0) 0.030 (0.76) 0.079 (2.0) 0.079 (2.0) 0.110 (2.8) Pad Outline Dimensions are in inches (and millimeters). Figure AN1005.4 Modified DO-214 Compak - Three-leaded Surface Mount Package 1. Screen print solder paste (or flux) 2. Place component (allow flux to dry) 3. Reflow solder Figure AN1005.5 Reflow Soldering Procedure After the solder is set and cooled, visually inspect the connections and, where necessary, correct with a soldering iron. Finally, the remnants of the flux must be removed carefully. Reflow Condition Pb - Free assembly Pre Heat - Temperature Min (T s(min) ) 150C - Temperature Max (T s(max) ) 200C - Time (min to max) (t s ) 60 - 180 secs Average ramp up rate (Liquidus Temp (T L ) to peak 5C/second max T S(max) to T L - Ramp-up Rate 5C/second max Reflow - Temperature (T L ) (Liquidus) 217C - Time (min to max) (t s ) 60 - 150 seconds Peak Temperature (T P ) 260 +0/-5 C Time within 5C of actual peak Temperature (t p ) 20 - 40 seconds Ramp-down Rate 5C/second max Time 25C to peak Temperature (T P ) 8 minutes Max. Do not exceed 280C Surface Mount Soldering Recommendations (continued)

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