Method and composition for mounting an electronic component and device formed therewith

Abstract

A method of mounting a component on a substrate includes applying a conductive adhesive on a contact pad joined to a substrate, aligning a component with the substrate such that at least one lead of the component is juxtaposed with the conductive adhesive, performing a partial cure of the conductive adhesive, testing performance of the component, and performing a full cure of the conductive adhesive. Another method includes the additional steps of applying a tacky film to the substrate and juxtaposing the component with the tacky film. When the testing in either embodiment shows a defective or misaligned component, the component may be replaced or repositioned by cold separation of the at least one component lead from the partially cured conductive adhesive. Optionally, additional conductive adhesive may be applied, when needed, before replacement or repositioning of a component. A composition for mounting a component on a circuit board includes a conductive adhesive screened on a contact pad, the conductive adhesive being partially cured, wherein the composition allows cold separation of the component from the substrate and may be fully cured by heat exposure. An apparatus is also provided including a component, a substrate, and a means for temporarily mounting and electrically connecting the component on the substrate.

Description

[0001] 1. Technical Field[0002] This invention relates to the field of mounting an electronic component on a substrate, particularly on circuit boards. More specifically the invention relates to a method and composition for mounting an electronic component on a substrate and the device formed by using such a method and composition.[0003] 2. Background Art[0004] An increasing need exists in the electronics and / or computer industry to provide electronic packages of components and substrates, wherein multiple components are joined to a single substrate, such as a circuit board, particularly a printed circuit board (PCB). In fabricating such packages, the components and substrate are typically tested individually prior to assembly. However, once the package is fully assembled, defective devices may still be discovered in subsequent testing of the overall package due to problems at the system level, that is, problems only apparent when certain components and the substrate operate togethe...

AI Technical Summary

Benefits of technology

"The present invention provides a method for mounting a component on a substrate using a conductive adhesive. The method involves applying a conductive adhesive on a contact pad joined to the substrate, aligning the component with the substrate such that at least one lead of the component is juxtaposed with the conductive adhesive, performing a partial cure of the conductive adhesive, testing the performance of the component, and performing a full cure of the conductive adhesive. The method may also include applying a tacky film to the substrate and aligning the component with the tacky film. The invention also provides a composition for mounting a component on a substrate, which allows cold separation of the component from the substrate and may selectively be fully cured to permanently mount the component. The method and composition may be used in electronic packaging and other applications where temporary mounting and testing of components is necessary."

Problems solved by technology

However, once the package is fully assembled, defective devices may still be discovered in subsequent testing of the overall package due to problems at the system level, that is, problems only apparent when certain components and the substrate operate together in their respective systems.

Also, problems may become apparent due to improper alignment or orientation of a component on the substrate.

The rework process is time consuming and can introduce new defects into the package, other components, and / or the substrate.

The soldered connections that result from the soldering process are conductive and durable, as desired, however, they are also difficult to rework.

Nevertheless, whenever a soldering iron, hot gas tools, or other heated tools are used it is extremely difficult to avoid exposing neighboring components to the heat as well.

The heat exposure may damage a component, the substrate, or a solder connection or otherwise introduce another defect into the package.

The ability to later reflow the solder allows reworking of soldered components, however, existing technology does not provide a process for reworking cured conductive epoxy.

Accordingly, even if subsequent testing showed that an epoxied package was defective, current practices would not allow for the replacement or repositioning of selected components.

For this reason, the inability to rework conductive epoxy is presently considered a disadvantage of such technology.

Attempts have been made to remedy the problems discussed above, however, they have met only limited success.

Accordingly, the removal process does not require heat and the attachment process allows reworking, but the electrical connection has proven unreliable.

Because the conductive resin does not provide a mechanical bond of the leads to the contact pads, the electrical connection may be easily compromised.

The adhesive tape might be sufficient to bond the component to the substrate, but it is not sufficient to keep the leads electrically connected to the contact pads.

For example, it would be impractical to use the process with a component having for its leads an array of conductive bumps between the component and the substrate, providing both an electrical and a mechanical connection.

The difficulty of applying adhesive tape amongst an array of contact pads on a substrate is typically sufficient to discourage use of the tape and resin process.

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