7.5.3 Soldering Surface Mount Gull Wing Components, Hot Gas Method

Outline

This procedure covers the general guidelines for soldering surface mount Gull Wing components. There is basically only one type of Gull Wing component. Whether leads are on two sides or four sides, or whether the component is large or small, the soldering principles are the same.

Minimum Skill Level - Intermediate
Recommended for technicians with skills in basic soldering and component rework, but may be inexperienced in general repair/rework procedures.

Conformance Level - High
This procedure most closely duplicates the physical characteristics of the original, and most probably complies with all the functional, environmental and serviceability factors.

Acceptability References
IPC-A-610 12.0	Surface Mount Assemblies


Procedure References
1.0	Foreword
2.1	Handling Electronic Assemblies
2.2	Cleaning
2.5	Baking And Preheating
7.1.1	Soldering Basics
7.1.2	Preparation For Soldering And Component Removal
7.1.3	Solder Joint Acceptability Criteria

Kits and Systems ▼

Additional Items and Supplies ▼

Images and Figures

Surface Mount Gull Wing Component

Figure 1: Add a small bead of solder paste along the row of pads.

Figure 2: Move the tool back and forth to heat all the solder joints until complete solder melt is observed.

Procedure

Procedure

Add a small bead of solder paste along the row of pads. (See Figure 1)
Place the component in position.
Adjust the pressure and temperature output of the hot air tool.
Direct the hot air over the component with the hot air tool tip approximately 2.50 cm (1.00") from the solder joint. This initial heating will pre-dry the solder paste.
Note: Solder paste has a dull flat appearance when dried.
When the solder paste has dried, move the hot air tooltip to approximately 0.50 cm (0.20") above the component. Move the tool back and forth to heat all the solder joints until complete solder melt is observed. (See Figure 2)
Remove the tool. Wait a moment for the solder to solidify.
Clean, if required, and inspect.

Solder Joint Acceptable Criteria - Gull Wing Components

Feature	Dim	Class 1	Class 2	Class 3
Maximum Lead Side Overhang	1	No more than 50% of the lead width or 0.50 mm (.020") whichever is less.	No more than 50% of the lead width or 0.50 mm (.020") whichever is less.	No more than 25% of the lead width or 0.50 mm (.020") whichever is less.
Maximum Toe Overhang	2	Does not violate minimum electrical clearance.	Not acceptable.	Not acceptable.
Minimum End Joint Width	3	50% of the lead width.	50% of the lead width.	75% of the lead width.
Minimum Side Joint Length: Lead thickness greater than 3X lead width	4	Equal to the lead width or 0.50 mm (.020") whichever is less.	3 times the formed foot length or 75% of the formed foot length, whichever is longer.	3 times the formed foot length or 75% of the formed foot length, whichever is longer.
Minimum Side Joint Length: Lead thickness less than 3X lead width	4	Equal to the lead width or 0.50 mm (.020") whichever is less.	Equal to 100% of formed foot length.	Equal to 100% of formed foot length.
Maximum Heel Fillet Height	5	No maximum, but solder must not touch the component package body.	No maximum, but solder must not touch the component package body.	No maximum, but solder must not touch the component package body.
Minimum Heel Fillet Height	6	Evidence of proper wetting.	Equal to the solder thickness plus 50% of lead thickness.	Equal to the solder thickness plus 100% of lead thickness.
Solder Thickness	7	Evidence of proper wetting.	Evidence of proper wetting.	Evidence of proper wetting.