IBM Inventors Seek PTH Adapter Patent PDF Print E-mail
Written by Mike Buetow   
Thursday, 02 January 2014 18:22

POUGHKEEPSIE, NY -- Several IBM inventors have filed a patent application for an adapter for plated through-hole mounting of surface mount components. The disclosure relates to printed circuit board assembly techniques, and more particularly, to the attachment of temperature sensitive components designed for surface mounting.

In the filing, the inventors write, "Many electronic components have a manufacturer-specified thermal processing limit that is not allowed to be exceeded during printed circuit board assembly. Violation of a component's thermal processing limit will degrade the reliability of the component and may void the manufacturer's warranty. Some surface mount assembly techniques require temperatures that are incompatible with certain classes of temperature sensitive components (TSCs). For example, the assembly of lead-free circuit boards will typically require a high temperature lead-free solder reflow process in an oven. TSCs that may be incompatible with such processing include polymer or aluminum capacitors.

"One known technique for avoiding TSC overheating during high temperature reflow processing is to solder the TSCs to the circuit board with a soldering iron following the reflow operation. Another known technique is to perform a second solder reflow process that attaches TSCs using a lower melting lead-free alloy. A further known technique is to attach the TSCs to the circuit board using conductive adhesive at room temperature. A still further known technique is to shield the TSCs in the reflow oven to prevent overheating. Yet another known technique is to solder or otherwise attach the TSCs to a plated through hole (PTH) daughter card that is attached to the main circuit board.

"Although the foregoing known techniques are all practical solutions that have been used in the past and currently to solve the TSC overheating problem, such solutions have various disadvantages. These include, but are not limited to, requirements for tight control of the heating source, unique circuit board designs or configuration changes to accommodate the processing, unique heat shield designs, qualification of low-melt lead-free alloy, and constraints on the rework capabilities of conductive adhesive. It is to improvements in the field of surface mount component attachment that the present disclosure is directed."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "A surface mount component adapter, assembly and related method are provided for attaching a surface mount component using a non-surface mount technique. The surface mount component adapter includes a substrate, a surface mount component holder on the substrate, and flexible leads on the surface mount component holder. The flexible leads each have a base end attached to the surface mount component holder and a free end configured to engage a plated through hole on a circuit board. The surface mount component holder is configured to engage electrical contacts of a surface mount component when mounted on the surface mount component adapter, and provides electrical pathways from the electrical contacts to the flexible leads. In the surface mount component assembly, a surface mount component is mounted on the surface mount component adapter. According to the surface mount component method, the surface mount component is mounted on the surface mount component adapter to form the surface mount component assembly, and the free ends of the flexible leads are attached to a corresponding number of the plated through holes on the circuit board.

"In an embodiment, the spring contacts each comprise a base attached to the substrate, a flexible arm, and a lead carrier. The spring contacts may be spaced from each other to define a component receiving area that is adapted to receive the surface mount component with the flexible arms engaging the electrical contacts thereof. The base ends of the flexible leads may be attached to the lead carriers. The free ends of the flexible leads may comprise compliant pins adapted to releasably engage the plated through holes on the circuit board. Alternatively, the free ends of the flexible leads may be configured for attachment to the plated through holes on the circuit board using soldering, ultrasonic welding, or an adhesive bonding agent. is ready for attachment to a circuit board."

Daniel J. Buschel, Wai Mon Ma, James E. Tersigni, Raymond D. Birchall made the filing on June 13, 2012, and it was made available online on Dec. 26, 2013. The patent's assignee is IBM.




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