TRT meeting Oct 2002

1
Capacitor Assembly

• K. McFarlane
• 9/30/02

2
Task

• Assemble 18,000 capacitor assemblies, consisting
  of socket, capacitor, bent pin
• Coat with protective coating

3
General Concept

• Batch process in two phases
• Phase 1 Solder reflow in jig
• Phase 2 Coating
• Number in batch 100 500
• Initial experiments on phase 1 promising phase 2
  not yet tried
• Note final choice of capacitor not made.

4
Phase 1 steps

1. Place capacitor and socket in jig
2. Apply solder paste to ends of capacitor
3. Add bent pin
4. Pass jig through reflow cycle
5. Ultrasonic clean with water
6. Dry in oven at 60 C

5
Initial Experiments

• Use clay jig (180C max temperature)
• Johanson 202S43W102KV4E capacitor
• Custom socket (Duke)
• Standard Mill-Max pin, bent
• EFD Sn42 or Sn43 solder paste
• Max reflow temperature 190 C
• Rate of change of temperature lt2 C/s

6
Assembly tooling
Oven with jig and thermocouple
Application of solder paste to capacitors in jig.
7
Finished products
8
Possible Fragility?
The design with the pin on the side seems
fragile. This geometry is intended to fit under
the electronics. With the pin on the side, the
overall height is 7mm. On top, it would be
7.5mm.
9
Production times

• 20 seconds per assembly to fill jig
• 25 minutes for reflow cycle
• 15 minutes for cleaning (inc. database)
• With 5 jigs and 100 per jig, 124 hours for 18,000
  assemblies. With a single jig, 220 hours.
• Coating time not estimated.

10
Plan for coating

• Plan to try Stycast 1266 first
• Find a batch coating process. May require
  release agent or peelable coating
• Would likely involve an oven cure, perhaps at
  100C
• Suggestions welcome for coating material

11

END