International Business Machines Corporation

Michael Vito Longo

Michael James Cummings

James Ralph Case

John Michael Griffin

Thomas R Miller

Ashwinkumar C Bhatt

Ross William Keesler

Michael Wozniak

Timothy Leroy Wells

Andrew Michael Seman

Curtis L Miller

Brant S Blomberg

Raymond C Tompkins

Eboney J N Smith

Robert J Lerner

A hybrid photolithography process for printed circuit board patterning combines two types of photoresist applications to achieve superior protection of printed circuit board (PCB) 'plated through holes' (PTH). In a first step, electro-deposited (ED) photoresist (also known as 'ED resist') is applied to a fully copper plated PCB including the 'plated through holes' to protect the outer layers and the &#x2018;plated through holes&#x2019; from copper etchant solution. In a second step, the electro-deposited photoresist is imaged (exposed) and patterned (developed). In a third step, after developing the circuit image, a layer of Dry Film resist is applied to the panel of the PCB on top of the developed electro-deposited (ED) photoresist. This Dry Film resist layer will &#x2018;tent&#x2019; the plated through holes by adding an extra layer of protection to the plated through holes. In a fourth step, the dry film resist is then exposed and developed. At this point, the PCB is etched as normal and all subsequent processing remains unchanged.

Electrodeposited photoresist and dry film photoresist photolithography process for printed circuit board patterning

A cutting apparatus and method wherein a blade holder includes two blades which are each designed for cutting web material (e.g., dry film photoresist) in a reverse manner prior to application of the material to a substrate (e.g., dielectric-conductor structure) designed for eventual usage as a printed circuit board or as part thereof (e.g., if laminated up with other, similarly formed substrate members).

Method for cutting movable web material

A method of making a circuitized substrate having plated through holes free of filler material is provided. The method includes the steps of providing a dielectric substrate having first and second opposite faces. At least one via hole is formed from one face to the other. A first electrically conductive layer is applied onto the top and bottom faces of the dielectric member and onto the side wall of the via. First layers of photoresist are applied to each layer of conductive material and entering at least partially into the via hole. The first layers of photoresist are selectively exposed and developed to remove all of the photoresist, except that photoresist which is disposed in the via holes. Thereafter, a portion of the faces of the metal coatings on the surfaces of dielectric material and any photoresist remaining in the holes extending above the layers of electrically conductive material are removed to form a planar surface thinner than the thickness of the metal in the through hole. Thereafter, a second layer of photoresist material is applied to both the surfaces of the metal on both faces of the dielectric material and exposed to a desired circuit pattern. Thereafter, the second layers of the photoresist material are developed to reveal the underlying metal which is then etched to form a circuit pattern in the metal layer on both faces. Thereafter, the second layers of the remaining photoresist are stripped and also the photoresist remaining in the hole is stripped, thereby to provide a circuitized substrate with plated through holes having an opening extending from the upper face of the substrate to the lower face of the substrate.

Fine pitch circuitization with unfilled plated through holes

A wiring board for mounting an electrical device, which has an array of connectors thereon arranged in a grid pattern, wherein the connectors have at least two levels of criticality of connection to the substrate. The substrate has a plurality of mounting structure or features arranged in the same grid pattern to connect with the array of connectors on the electrical device. The mounting structures or features are divided into a plurality of at least two groups, with each group corresponding to a level of criticality of the connectors on the device. Each group of mounting structures has a discernible feature differing from each other group, to thereby permit different levels of inspection criteria for each group. The invention also contemplates a method of forming a substrate having the features for connecting the connectors on the device that have different levels of criticality

Structure and method for forming the same of a printed wiring board having built-in inspection aids

A cutting apparatus wherein a blade holder includes two blades which are each designed for cutting web material (e.g., dry film photoresist) in a reverse manner prior to application of the material to a substrate (e.g., dielectric-conductor structure) designed for eventual usage as a printed circuit board or as part thereof (e.g., if laminated up with other, similarly formed substrate members).

System for making a printed circuit board

A method for reverse cutting with material wherein a blade holder includes two blades which are each designed for cutting web material (e.g., dry film photoresist) in a reverse manner prior to application of the material to a substrate (e.g., dielectric-conductor structure) designed for eventual usage as a printed circuit board or as part thereof (e.g., if laminated up with other, similarly formed substrate members).

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Glen Aubrey, NY, United States of America

Michael Vito Longo