Lap Solder Joint Calculation Formulas

Allowable stress

Joint shear stress

Minimum overlap length

Strength check

τ τ A

Design of optimum overlap length

Anticipates that any breakage occurs in the joint itself, and not in the basic material.

L opt = max {L min , L 1 }

where:

Meaning of used variables for metric units:

S US

Joint strength in shear [MPa]

k S

Shear safety factor

F

Transferred force [N]

b

Width of connected parts [mm]

s

Thickness of connected parts [mm]

S Ub

Tensile strength of basic material [MPa]

L

Length of overlap [mm].

Meaning of used variables for English units:

S US

Joint strength in shear [psi]

k S

Shear safety factor

F

Transferred force [lb]

b

Width of connected parts [in]

s

Thickness of connected parts [in]

S Ub

Tensile strength of basic material [psi]

L

Length of overlap [in]

Guiding values for solder joint strength

Soft solder alloys

Brazing filler metals