The present invention is generally directed to an electronic module and, more specifically, to a surface mount axial leaded component for an electronic module.
In general, electronic assemblies that have implemented relatively large surface mount components have experienced limited thermal cycle life in automotive applications, due to the failure of solder joints, which have attached the large surface mount components to conductive traces formed on a substrate. Typically, large surface mount components have been implemented within an electronic module when the components have been expected to dissipate a significant amount of power, e.g., greater than 0.5 watts, and carry significant current. While axial leaded components are capable of handling relatively high power and current levels, while providing a relatively long thermal cycle life, axial leaded components have typically been mounted to substrates as through-hole mounted components.
Unfortunately, the use of through-hole mounted axial leaded components has generally required an additional soldering process, e.g., a wave soldering process, which has added additional cost to the electronic module. While some higher current axial leaded components are commercially available with surface mount lead form designs, the designs of such components have been top heavy and, as such, are prone to fall over during assembly processes, and have also required correct orientation during component placement. A number of techniques have been implemented to address the thermal cycle reliability problem associated with large surface mount components. In general, these techniques have required removal of substrate material and/or use of additional components to provide stress relief for solder joints associated with the large surface mounted components. However, such techniques have also resulted in additional cost to the electronic module.
What is needed is a technique that addresses the thermal cycle reliability problem associated with large surface components that allows axial leaded components to be readily surface mounted.
Various embodiments of the present invention are directed to a surface mountable axial leaded component that includes a component body, a first component lead and a second component lead. The first component lead extends from a first end of the component body and a second component lead extends from a second end of the component body that is opposite the first end. A portion of the first and second component leads is formed in a loop and a diameter of the loop is at least equal to a diameter of the component body. The loop may be formed as a circular loop, an elliptical loop, a polygon loop, a square loop or rectangular loop, among other loop configurations. When formed as a circular loop, the loop may include a flat segment. According to a different aspect of the present invention, the diameter of the loop is greater than the diameter of the component body and the loop may be formed in a plane that is substantially orthogonal to a main axis of the component body. It should be appreciated that configuring the leads into loops provides stress relief for the component body, which decreases the stress applied to solder joints that attach the leads to conductive traces of an associated substrate, during thermal cycling.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
The present invention is generally directed to an electronic module and, more specifically, an electronic module that includes one or more axial leaded components that have been modified and/or manufactured to be readily mounted as surface mount components. Advantageously, surface mount axial leaded components, configured according to the present invention, are lower in cost than standard surface mount components having the same current and power capabilities. In general, axial leaded components with leads configured according to the present invention are capable of handling higher power and current levels and have a longer thermal cycle life than traditional large surface mount components.
According to various embodiments of the present invention, the axial leads of a component may be formed in a variety of shapes, such as a circular, elliptical or segmented polygon configuration, that are symmetric to a component body. The leads of the component may be configured by wrapping an existing lead around a circular, elliptical or polygon-shaped mandrel. The diameter of a formed lead can be the same size or larger than a component body diameter to provide a desired stress relief and to achieve a desired footprint.
According to various embodiments of the present invention, a surface mount axial leaded component does not require specific rotational orientation and, as designed, provides substantially more stress relief during thermal cycles than standard surface mount components. As is mentioned above, the diameter of the leads can be increased to provide additional stress relief.
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Accordingly, a surface mountable axial leaded component has been described herein that includes a plurality of leads, each of which are configured in a loop to readily allow for surface mounting of the axial leaded component and advantageously provide stress relief for the component body and its associated solder joints.
The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the doctrine of equivalents.