Conductive Polymer Damping for THT Solder Joints
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Solution Overview
Problem
Soldering points in the THT manufacturing process face damage due to thermomechanically induced loads from temperature changes, affecting both electrical conductivity and mechanical hold, particularly in applications like the automotive sector where components undergo significant thermal stress.
Innovation Solution
Applying a conductive polymer layer to the contact wires or contact pins at the soldering tips to cushion thermally induced mechanical loads, allowing for flexible damping of bending, twisting, and tensile forces during temperature changes, thereby extending the damage-free period of electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid soldering connection is used in THT manufacturing, then mechanical strength is improved, but susceptibility to thermomechanical damage increases
Solution Approach 1:
The patent changes the mechanical parameters of the soldering connection by introducing a conductive polymer layer with specific viscoelastic properties. This polymer layer has a modulus of elasticity between 1 MPa and 100 MPa, which is significantly lower than the modulus of the rigid solder joint, allowing it to deform and absorb thermomechanical stresses while maintaining electrical conductivity and mechanical bonding.
Solution Approach 2:
The patent creates a composite structure consisting of multiple layers: the rigid solder joint, the conductive polymer layer, and the contact wire. This composite configuration combines the high strength of the rigid solder connection with the stress-absorbing properties of the viscoelastic polymer, resulting in a connection that is both strong and resistant to thermomechanical damage.
2Strength
If the contact wire is rigid to maintain structural integrity, then mechanical hold is improved, but ability to cushion thermal stress is reduced
Solution Approach 1:
The conductive polymer layer acts as an intermediary element between the rigid contact wire and the rigid solder joint. This intermediate layer with viscoelastic properties absorbs and distributes thermomechanical stresses, preventing direct transmission of thermal stress to the contact wire and solder joint, thereby protecting the overall connection from thermal damage.
3Ease of manufacture
If a thin conductive polymer layer is applied, then ease of manufacture is improved, but damping capacity is reduced
Solution Approach 1:
The patent optimizes the thickness parameter of the conductive polymer layer to a specific range between 1 μm and 100 μm. This thickness range provides sufficient damping capacity to absorb thermomechanical stresses while maintaining ease of application through standard coating or lamination processes. The viscoelastic properties of the polymer ensure effective stress damping even at these relatively thin thicknesses.
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 conductive polymer layer significantly reduces the risk of failure in electrical through-connections, enabling a longer service life and allowing for larger soldering process tolerances, thus enhancing the reliability and durability of electrical contacts between printed circuit boards and components.
Implementation Method 1
The conductive polymer layer used can be, for example, a highly filled conductive adhesive connection. The electrically conductive polymer layer is partially and/or fully applied to the soldering tips of the contact wires or contact pins to be contacted, so that in the subsequent selective soldering process, which represents a special case of the wave soldering process and enables the soldering of individual pins on complex printed circuit boards, they are formed into copper-plated vias to be soldered. Advantageously, thermally induced loads that occur as a result of the temperature changes mentioned above and that act on the contact wire or the contact leg in the form of bending, twisting and pulling are cushioned by the flexible polymer layer.
Implementation Method 2
the temperature changes cause thermomechanically induced loads in the soldering points, which can lead to damage to the soldering points. These loads are determined by geometry factors in relation to all components and are also dependent on transient thermal states (temperature-time profile).
Data Source
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AI summary
The invention relates to a method for producing an electrical via between one or more electrical or electronic components (10) and a circuit board (16). First, a conductive polymer layer (42) is applied to soldering tips (46) of connecting wires (12) over part of the surface or over the full surface thereof. At least one electrical or electronic component is joined to the circuit board (16) in a THT process. At least one solder connection is produced between the circuit board (16) and connecting wires (12) of the at least one electrical or electronic component (10) by means of selective soldering or a solder wave (28).