| Dennis, thanks for your input. I myself can't remember having any caps fail due to thermal stress/cracking. But the guru's here says it happens and since the assembly is for space flight, it's a requirement to preheat. Also, your process is exactly what our's is for soldering assemblies for ground support, except the temperature range of the soldering iron is 600�F � 35� per NASA-STD-8739.3.
| | Hi Sherry: | | You know, we solder thousands of ceramic caps by hand daily. 1206 to 0402, on rigid and flexible circuits. We have never had a problem with cracking components. The most important item to consider here is to have a temperature controlled soldering iron. Normally you don't need more than 600 degrees F. We normally use 580 to 650 degrees F, depending on the size of the pad. Use a 63/37 type solder and add some liquid flux to help the temperature conduct. This will work faster and save you the time of preheating every board. We see a lot of damage at our facility caused by using the one temperature type of solder guns that range for 700 to 800 degrees F and more. With todays microsized technology, low temp soldering guns are the key. Does anyone know how to find NASA-STD-8739.2. Is it available on the net? I would like to read it.
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