Importance

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Abstract

An electronic device includes electronic components, such as 'flip chip' semiconductor devices, chip resistors, capacitors and other electronic components, mounted to and interconnected to a substrate by a flexible adhesive membrane having contact pads that have substantially the same pattern as those of the corresponding electronic components. The flexible adhesive membrane includes an insulating matrix and conductive pads therein that employ thermoplastic and thermosetting adhesives, and combinations thereof, each having a low modulus of elasticity. The flexible conductive adhesive employed for the conductive pads or features preferably has a lower flow index than does the flexible adhesive employed for the insulating matrix, whereby the conductive features penetrate the insulating adhesive during bonding to assure reliable interconnection. Preferably, the higher flow index of the insulating adhesive facilitates it forming a fillet around the flip chip devices to provide a moisture barrier and additional mechanical strength to an assembled electronic device. Adhesives having flexibility and a low glass transition temperature are employed in the membrane to reduce internal stresses and enhance long-term bonding and contact reliability. The combination of adhesives may be selected to accommodate specific bonding and operating conditions. Such flexible membranes may also be employed for probing and testing semiconductor wafers and individual dies, as well as other small or delicate electronic components. Preferably, the contact pad features on the side of the flexible membrane that is to be probed have a sufficient area and pitch to facilitate probing, which area and pitch may be substantially greater than that on the side of the flexible membrane that is attached to the electronic component being tested.

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First Claim