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Aerospace Soldering & Electronic Assembly Techniques

Randall Pearl

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• Ground Systems Manufacturing

• Flight Systems Manufacturing

• Battery/Solar Engineering

RCA/GE Astro Space 1981-1989

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Basic Tools, Materials and Procedure of Hand Soldering

• Temperature controlled Soldering Iron with stand and sponge

• Solder Material

Basic Elements of Hand Soldering

• Flux • Flux removal solvent such as Isopropyl Alcohol• Brush to use with solvent

Basic Additional Materials

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Basic Tools, Materials and Procedure of Hand Soldering

• Put two target objects (to be soldered) together

Basic Procedure

• 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

• Clean the surfaces to be soldered (dirt free, grease free and oxide-free)

• Wet the joint area with flux, if needed

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Cleaning, Wetting and Pre-heating, Solder Flow

Cleaning

Iron tip cleaning Component lead cleaning Circuit board cleaning

Wetting (Tinning)

Iron tip wetting with molten solder Contact wetting with molten solder

Preheating

Pre-heat the contacts before soldering

Solder Flow

Allowing molten solder to flow freely

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Contact Area Between Iron and Work

Incorrect: Very Small contact Area

Correct: Sufficient Contact Area

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Size of Solder Fillet

a) Minimum amount of solderb) Optimalc) Excessive solder

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Basic Safety Procedures and Practices

• Hot Iron (temperature as high as 430oC)• Fumes• High Voltage • Loose Clothing and Hair• Lead of the solder

• Put the hot iron in its holder when not used

Basic Safety Procedures and Practice

Safety Hazards

• 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

• Work in a ventilated place, or use fume extractor

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Other materials

• DuPont 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

Kapton Tape

• 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.

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Other materials

Lacing Tape (or cord)

•Harnesses are usually fabricated on a harness jig or forming board.

•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.

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Resources

NASA-STD 8739.3 Soldered Electrical Connections:

NASA Training Program - Student Workbook for Hand Soldering:

•http://www.protostack.com/download/NASA%20Student%20Handbook%20for%20Hand

%20Soldering.pdf

•http://www.protostack.com/download/NASA-STD-8739.3%20including%20Change

%203.pdf

Wiring and Cabling:

•http://en.wikipedia.org/wiki/Cable_lacing