Aerospace Soldering Electronic Assembly Techniques Randall Pearl 1

Aerospace Soldering & Electronic Assembly Techniques Randall Pearl 1

RCA/GE Astro Space 1981 -1989 • Ground Systems Manufacturing • Flight Systems Manufacturing • Battery/Solar Engineering 2

Basic Tools, Materials and Procedure of Hand Soldering Basic Elements of Hand Soldering • Temperature controlled Soldering Iron with stand sponge • Solder Material Basic Additional Materials • Flux removal solvent such as Isopropyl Alcohol • Brush to use with solvent 3

Basic Tools, Materials and Procedure of Hand Soldering Basic Procedure • Clean the surfaces to be soldered (dirt free, grease free and oxide-free) • Put two target objects (to be soldered) together • Wet the joint area with flux, if needed • Pre-heat the joint area with soldering iron • Apply solder at the joint and remove when sufficient solder has flowed down to the joint • Remove solder wire and then soldering iron, and allow the joint to cool down 4

Cleaning, Wetting and Pre-heating, Solder Flow Cleaning ü Iron tip cleaning ü Component lead cleaning ü Circuit board cleaning Wetting (Tinning) ü Iron tip wetting with molten solder ü Contact wetting with molten solder Preheating ü Pre-heat the contacts before soldering Solder Flow ü Allowing molten solder to flow freely

Contact Area Between Iron and Work Incorrect: Very Small contact Area Correct: Sufficient Contact Area 6

Size of Solder Fillet a) Minimum amount of solder b) Optimal c) Excessive solder

Basic Safety Procedures and Practices Safety Hazards • • • Hot Iron (temperature as high as 430 o. C) Fumes High Voltage Loose Clothing and Hair Lead of the solder Basic Safety Procedures and Practice • Work in a ventilated place, or use fume extractor • Put the hot iron in its holder when not used • Avoid touching the metallic part of the iron while it is hot and/or connected with the power-line • Wear appropriate clothes and tie back long hair • No food or drink in the lab while working • Wear safety glasses • Keep flammable materials away from the hot soldering iron 8

Other materials Kapton Tape • Du. Pont Kapton™ HN general purpose film. It has been used in applications at temperatures as low as -269°C (-452°F) and as high as 400°C (752°F). Solder Sleeves • Solder sleeves are primarily used to attach a ground wire (lead) to the shielding braid of a shielded cable by means of a shrinkable tubing assembly having an integral solder pre-form. • Solder sleeves are also used to splice two or more conductors together. 9

Other materials Lacing Tape (or cord) • Cable lacing is a method for tying wiring harnesses and cable looms, traditionally used in telecommunication, naval, and aerospace applications. This cable management technique is still used in some modern applications since it does not create obstructions along the length of the cable, avoiding the handling problems of cables groomed by plastic or velcro cable ties. • Harnesses are usually fabricated on a harness jig or forming board. 10

Resources NASA Training Program - Student Workbook for Hand Soldering: • http: //www. protostack. com/download/NASA %20 Student%20 Handbook%20 for%20 Hand% 20 Soldering. pdf NASA-STD 8739. 3 Soldered Electrical Connections: • http: //www. protostack. com/download/NASASTD 8739. 3%20 including%20 Change%203. pdf Wiring and Cabling: • http: //en. wikipedia. org/wiki/Cable_lacing 11