Lead Finger Locking Structure Mitigates Thermal Stress
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Solution Overview
Problem
Integrated circuit packaging faces issues with thermal stress causing structural problems, such as solder connection failures between lead fingers and bond wires due to thermal expansion and contraction, leading to premature failure.
Innovation Solution
Incorporating a locking structure on each lead finger that secures it to the substrate, mitigating thermal expansion and contraction by using a cavity or adhesive to lock the lead finger in place, thereby reducing stress on solder connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead fingers are used to connect terminals to the integrated circuit die, then electrical connectivity is achieved, but thermal expansion and contraction cause stress on solder connections leading to premature failure
Solution Approach 1:
The lead finger is divided into multiple segments that can move relative to each other, allowing the structure to accommodate thermal expansion and contraction without transmitting excessive stress to the solder connections
Solution Approach 2:
The lead finger structure incorporates elements with different thermal expansion coefficients or flexible joints that change their mechanical properties with temperature, allowing the connection to absorb thermal stress while maintaining electrical connectivity
2Stability of the object's composition
If lead fingers are secured rigidly to the substrate, then structural stability is improved, but thermal expansion and contraction cause solder connection failures
Solution Approach 1:
The lead finger structure transitions from a rigid fixed connection to a dynamic structure with controlled flexibility, allowing it to maintain stability while accommodating thermal movements through elastic deformation or articulated joints
Solution Approach 2:
The design incorporates stress-absorbing elements or compliance features in advance of the thermal stress application, such as flexible sections or damping structures that preemptively accommodate expansion and contraction forces
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The locking structure effectively reduces thermal stress on solder connections by up to 30%, preventing premature failure and ensuring proper operation of the integrated circuit.
Implementation Method 1
During use, the lead fingers of the integrated circuit package may experience thermal expansion and contraction, which can cause stress on connected components
Data Source
AI summary
Various aspects are directed to apparatuses, systems and related methods involving the mitigation of issues relating to thermal expansion and contraction of lead fingers of an integrated circuit package. Consistent with one or more embodiments, lead fingers on a leadframe substrate each have a locking structure that secures the lead finger in place relative to the substrate. The lead fingers provide a location to attach a bond wire to an integrated circuit, and connect the bond wire to terminals at a perimeter of the leadframe. The locking structure and arrangement of the lead fingers mitigate issues such as cracking or breaking of a solder connection of the bond wire to the leadframe, which can occur due to thermal expansion and contraction.