Method for attaching an electronic device
AssigneeMotorola, Inc.
InventorVernon L. Brown
Life of this patent
Estimating the term…
Abstract
A method for attaching a flip chip or other microelectronic device to a circuit board or other substrate. The method entails the forming of recesses having precise volumes above and surrounding each terminal pad so as to enable the deposition on each pad of a controlled volume of conductive material, such that reduced spacing between terminals can be enabled. If a conductive adhesive is used as the conductive material, the method drastically reduces the likelihood that an inadequate amount of adhesive will be deposited, while excess adhesive can be accommodated without causing shorting between adjacent terminals. If flip chip attachment is achieved with a solder composition, the method eliminates the prior art requirement for circuit board terminal bumping and bump flattening.
Claims18
A method for attaching a microelectronic device having a terminal to a substrate, the method comprising the steps of:
- forming a metal region and a dielectric layer on the substrate, the metal region having a surface lying in a first plane, said dielectric layer having a surrounding dielectric surface region about the metal region and lying in a second plane above the first plane, such that a first recess is delineated by and between the first and second planes;
- depositing a dielectric material on the surrounding dielectric surface region and the metal region, the dielectric material having a surface in a third plane above the first plane and the second plane;
- forming an opening in the dielectric material so as to expose at least a portion of the metal region and a portion of the surrounding dielectric surface region, the opening forming a second recess having a volume delineated by and between the second and third planes, the opening forming a wall in the dielectric material that surrounds the portion of the metal region and the portion of the surrounding dielectric surface region;
- depositing a conductive material on the metal region and within at least a portion of the first recess;
- and
- positioning the microelectronic device on the substrate such that the terminal of the microelectronic device is received in at least the second recess and contacts the conductive material so as to be electrically interconnected with the metal region.
A method for reflow soldering a flip chip having a terminal to a substrate, the method comprising the steps of:
- depositing a first photodefinable resin on the substrate so as to form a first dielectric layer, the first dielectric layer having an upper surface in a first plane;
- photoimaging and developing an opening in the first dielectric layer;
- forming a metal region on the substrate within the opening in the first dielectric layer, the metal region having an upper surface lying in a second plane below the first plane containing the upper surface of the first dielectric layer, the opening in the first dielectric layer forming a first recess having a volume delineated by and between the first and second planes;
- depositing a second photodefinable resin on the first dielectric layer and the metal region so as to form a second dielectric layer, the second dielectric layer having an upper surface in a third plane above the first plane containing the upper surface of the first dielectric layer and above the second plane containing the upper surface of the metal region;
- photoimaging and developing an opening in the second dielectric layer so as to expose the metal region and an annular surface region of the first dielectric layer surrounding the metal region, the opening forming a second recess having a volume delineated by and between the first and third planes, the opening forming a wall in the second dielectric layer that surrounds the metal region and the surface region of the first dielectric layer;
- depositing a solder material on the metal region;
- and
- positioning the flip chip on the substrate such that the terminal of the flip chip is received in the first and second recesses and contacts the solder material.
A method for attaching a flip chip having a terminal to a substrate, the method comprising the steps of:
- depositing a first photodefinable resin on the substrate so as to form a first dielectric layer, the first dielectric layer having an upper surface in a first plane;
- photoimaging and developing an opening in the first dielectric layer;
- forming a metal region on the substrate within the opening in the first dielectric layer, the metal region having an upper surface lying in a second plane below the first plane containing the upper surface of the first dielectric layer, the opening in the first dielectric layer forming a first recess having a volume delineated by and between the first and second planes;
- depositing a second photodefinable resin on the first dielectric layer and the metal region so as to form a second dielectric layer, the second dielectric layer having an upper surface in a third plane above the first plane containing the upper surface of the first dielectric layer and above the second plane containing the upper surface of the metal region;
- photoimaging and developing an opening in the second dielectric layer so as to expose the metal region and an annular surface region of the first dielectric layer surrounding the metal region, the opening forming a second recess having a volume delineated by and between the second and third planes, the opening forming a wall in the second dielectric layer that surrounds the metal region and the surface region of the first dielectric layer;
- depositing a conductive adhesive in the first recess such that the conductive adhesive contacts the metal region;
- positioning the flip chip on the substrate such that the terminal of the flip chip contacts the conductive adhesive so as to be electrically interconnected with the metal region;
- and
- forcing the terminal into the first and second recesses.
Dependencies are inferred from the claim text.