International Business Machines Corporation

Lawrence P Lehman

Donald W Henderson

David V Caletka

George Henry Thiel

Krishna Darbha

Raymond Thomas Galasco

Robert D Topa

William Louis Brodsky

Roy H Magnuson

Madhav Datta

Robin A Susko

Francis Joseph Downes, Jr

Daniel C Van Hart

Daniel C Webster, Deceased

Edward J Burke

Solder balls, such as, low melt C4 solder balls undergo volume expansion during reflow. Where the solder balls are encapsulated, expansion pressure can cause damage to device integrity. A volume expansion region in the semiconductor chip substrate beneath each of the solder balls accommodates volume expansion. Air-cushioned diaphgrams, deformable materials and non-wettable surfaces may be used to permit return of the solder during cooling to its original site. A porous medium with voids sufficient to accommodate expansion may also be used.

Method to accommodate increase in volume expansion during solder reflow

Solder balls such as, low melt C4 solder balls, undergo volume expansion during reflow, such as may occur during attachment of chip modules to a PCB. Where the solder balls are encapsulated, expansion pressure can cause damage to device integrity. A volume expansion region in the semiconductor chip substrate beneath each of the solder balls accommodated this volume expansion. Air-cushioned diaphgrams, deformable materials and non-wettable surfaces may be used to permit return of the solder during cooling to its original site. A porous medium with voids sufficient to accommodate expansion may also be used.

Method of accommodating in volume expansion during solder reflow

Structure to accommodate increase in volume expansion during solder reflow

An electronic package is provided including a substrate, a device mounted on the substrate, and a solder member electrically coupling the device to the substrate. The package includes a dielectric material positioned substantially around the solder member which forms a physical connection between the substrate and the device. The volume of the solder member contracts during melting thereof to prevent failure of the physical connection and/or the electrical coupling between the substrate and the device.

Negative volume expansion lead-free electrical connection

A congruence between the element that provides an electrical conductive path in a component of micron dimensions and an imaging of that element provides a basis for predicting the effectiveness and the consistency in the functioning of the element in an actual operating environment. The element is formed first into a sandwich whereby the operating end is deformed against a light transparent surface. By directing a beam of light into the end of that light transparent surface, the asperity of the operating end produces a light scattering effect that is imaged by microscopic optics that is located facing the operating end.

Technique for imaging electrical contacts

An arrangement and method for the degassing small high-aspect ratio drilled holes or vias which are present in panels such as printed circuit boards prior to wet chemical processing, including copper plating of the vias, in order to remove any air or gas bubbles from the vias tending to inhibit the reliable plating thereof. This is carried out through the utilization of an ultrasonic prewetting in a liquid bath preceding cleaning for the electroless plating process, thereby enabling all of the vias or holes to be degassed; in effect, having air removed and the vias or holes filled with liquid; thereby allowing subsequent process cleansing solutions to easily flow into the respective holes or vias in order to facilitate the electroless copper plating process.

Arrangement and method for degassing small-high aspect ratio drilled holes prior to wet chemical processing

A method of removing a metal skin from a through-hole surface of a copper-Invar-copper (CIC) laminate without causing differential etchback of the laminate. The metal skin includes debris deposited on the through-hole surface as the through hole is being formed by laser or mechanical drilling of a substrate that includes the laminate as an inner plane. Removing the metal skin combines electrochemical polishing (ECP) with ultrasonics. ECP dissolves the metal skin in an acid solution, while ultrasonics agitates and circulates the acid solution to sweep the metal skin out of the through hole. ECP is activated when a pulse power supply is turned on and generates a periodic voltage pulse from a pulse power supply whose positive terminal is coupled to the laminate and whose negative terminal is coupled to a conductive cathode. After the metal skin is removed, the laminate is differentially etched such that the copper is etched at a faster rate than the Invar. To prevent the differential etching, a copper layer is formed on a surface of the substrate with an electrical resistance R,between the copper layer and the positive terminal of the pulse power supply. Additionally, an electrical resistance R,is formed between the laminate and the positive terminal of the pulse power supply. Adjustment of R,and R,controls the relative etch rates of the copper and the Invar.

Removal of metal skin from a copper-Invar-copper laminate

An anode container, electroplating system, method and object so plated. A feature of the invention is that an anode container has an interior cross-sectional area, at or near a lower end thereof, that is larger than an interior cross-sectional area of an upper end thereof. An anode-receiving container also has a body with a plurality of sides and a lower end having a larger cross-sectional interior area than an upper end. The container may also include punched out apertures positioned to provide strength to the container and an apparatus to vibrate the container coupled to a lower end of the container.

Anode container, electroplating system, method and plated object

A method for cleaning a copper-INVAR-copper laminate in an acid solution without inducing a galvanic etching of the INVAR. An initial step of the method forms a circuit element that includes a power supply, the laminate electrically coupled to a negative terminal of the power supply, and a conductive anode electrically coupled to a positive terminal of the power supply. The conductive anode may include a conductive material, such as titanium, that is preferably inert to an acid solution into which the laminate will be subsequently immersed. After turning on the power supply to a voltage between about 1 volts and about 10 volts, the laminate and conductive anode are immersed in the acid solution, so as to form a closed circuit with a voltage bias across acid copper-INVAR-copper interfaces. The voltage bias prevents galvanic action from occurring and therefore protects against galvanic etching of the INVAR. After the laminate has been cleaned by the acid solution, the laminate is removed from the acid solution and the power supply is turned off. The laminate may also exist as an internal layer of a dielectric substrate, wherein the substrate is immersed in the acid solution, and wherein a through hole passing through the substrate passes through the copper-INVAR-copper laminate.

Biased acid cleaning of a copper-invar-copper laminate

Apparatus and method for establishing a solder bond between a solder ball grid array and a circuit mounted on a substrate includes a bonding tool having a bonding tip for applying heat to the site of one or more of the solder balls in the solder ball grid array, a transducer for measuring displacement of the bonding tip during the bonding operation, and a signal generator responsive to the transducer for providing a signal indicative of tip displacement. The signal generated by the signal generator may be fed back to the bonding tool to optimize bonding parameters.

Growing community of inventors

Endicott, NY, United States of America

Lawrence P Lehman