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Gullwing Lead Deformation

Question: Does the IPC impose limits, or publish a standard on the amount of 160 CPLD lead bending that’s acceptable before restoring to original specifications? I have a surplus of obsolescent components that were damaged during packaging.

Answer: Here is the information from the IPC J-STD-001 specification and the 001 Handbook relative to reforming the leads.

J-STD-001, Para 7.1.1 Lead Deformation Limits states “…parts or components shall not [D1, D2, D3] be mounted if the part or component lead has nicks or deformation exceeding 10% of the diameter, width, or thickness of the lead except as allow for flattened leads. Exposed basis metal is acceptable is deformation does not exceed 10% of the diameter, width, or thickness of the lead.”

So if the leads are damaged or bent more than 10% of the diameter, width, or thickness of the lead, they cannot be used.

The 001 Handbook states on page 58, section 7.1.1 Lead Deformation: “After forming, component leads may be deformed up to 10% of the diameter, width, or thickness, and still be acceptable for use. Lead deformation beyond 10%, with or without exposed basis metal, may required review and improvement of the lead forming process. Such damage may compromise component performance or reliability. When damage is found to this extent, the electrical parameters of the component with the lead forming irregularity should be examined to determine if the performance has been compromised.”

So can you reform the leads? I would say yes, but the component has to be retested to verify the lead-to-body seal of the component has not been damaged. Secondly, reforming the leads beyond their modulus of elasticity will impact the grain structure of the basis metal, weakening or work hardening, which could cause catastrophic failures in the field.

Although I cannot find any specifics of this in the 001 document, we did mention this topic at the interim meeting last weekend and the Class 3 people were saying reforming the leads is not acceptable for Class 3 products.