Target – Class 1,2,3 • The entire body length of the component is in contact with
the board surface. • Components required to be mounted off the board are at
minimum 1.5 mm [0.06 in] from the board surface; e.g., high heat dissipating.
• Components required to be mounted off the board are pro- vided with lead forms at the board surface or other
mechanical support to prevent lifting of solder land.
Defect – Class 1,2,3 • Components required to be mounted off the board are not
provided with lead forms at the board surface or other mechanical support to prevent lifting of solder land.
• Components required to be mounted above the board sur- face are less than 1.5 mm [0.06 in].
• Component height exceeds user-determined dimension. 1
2
Figure 7-121
1. No plating in barrel 2. Clinch required for Class 3, see 7.4.4
Figure 7-122
1. Lead form
Figure 7-123
Figure 7-124
7.4 Unsupported Holes
7-58 IPC-A-610F
July 2014
7.4.1 Unsupported Holes – Axial Leads – Horizontal
Target – Class 1,2,3 • Components that are mounted above the board surface in
unsupported holes are provided with lead forms or other mechanical support to prevent lifting of solder land.
Defect – Class 1,2,3 • Components mounted above the board in unsupported
holes are mounted without lead form at the board surface or other mechanical support.
Figure 7-125
Figure 7-126
7.4.2 Unsupported Holes – Axial Leads – Vertical
7-59 IPC-A-610F
July 2014
Note: High frequency applications may require more precise control of lead extensions to prevent violation of functional design considerations.
Acceptable – Class 1,2,3 • The leads protrude beyond the land within the specified
minimum and maximum L of Table 7-6, provided there is no danger of violating minimum electrical clearance.
Table 7-6 Protrusion of Leads in Unsupported Holes
Class 1 Class 2
Class 3
L Min. End is discernible in solder
Sufficient to clinch
L Max. Does not violate minimum electrical clearance
Note 1. Lead protrusion should not exceed 2.5 mm [0.1 in] if there is a possi- bility of violation of minimum electrical spacing, damage to soldered connec-
tions due to lead deflection or penetration of static protective packaging during subsequent handling or operating environments.
Defect – Class 1,2,3 • Lead protrusion does not meet Table 7-6 requirements.
• Lead protrusion violates minimum electrical clearance. • Lead protrusion exceeds maximum design height require-
ments.
L L
Figure 7-127
L L Min
L Max
Figure 7-128
7.4.3 Unsupported Holes – WireLead Protrusion
7-60 IPC-A-610F
July 2014
This section applies to terminations with a clinching requirement. Other requirements may be specified on relevant specifications or drawings. Partially clinched leads for part retention are considered as unclenched leads and need to meet protrusion require-
ments.
The clinch should be sufficient to provide mechanical restraint during the soldering process. The orientation of the clinch relative to any conductor is optional. DIP leads should have at least 2 diagonally opposing leads partially bent outward. Tempered leads
and leads greater than 1.3 mm [0.05 in] should not be bent nor formed for mounting purposes. Tempered leads are not termi- nated with a full-clinched configuration.
The lead meets the requirements of Table 7-6 when measured vertically from the land surface and does not violate minimum elec- trical clearance requirements.
Target – Class 1,2,3 • Lead end is parallel to the board and direction of the clinch
is along the connecting conductor.
Figure 7-129
7.4.4 Unsupported Holes – WireLead Clinches
7-61 IPC-A-610F
July 2014
Acceptable – Class 1,2,3 • The clinched lead does not violate the minimum electrical
clearance C between noncommon conductors. • The protrusion L beyond the land is not greater than the
similar length allowed for straight-through leads. • The leads protrude beyond the land within the specified
minimum and maximum L of Table 7-6, provided there is no violation of minimum electrical clearance.
Acceptable – Class 3 • Lead in unsupported hole is clinched a minimum of 45°.
Defect – Class 1,2,3 • The lead is clinched toward an electrically noncommon con-
ductor and violates minimum electrical clearance C. • Lead protrusion is insufficient for clinch, if required.
Defect – Class 3 • Lead in unsupported hole is not clinched a minimum of 45°
not shown.
C C
L
Figure 7-130
C C
1
Figure 7-131
1. Noncommon conductor
