Self-heating circuit board
AssigneeCredence Systems Corporation
InventorPaul D. Wohlfarth
Life of this patent
Estimating the term…
Abstract
Separate heating elements are embedded in a printed circuit board near integrated circuit (IC) packages or other parts mounted on the circuit board. Each heating element supplies heat to the part residing near it in response to an input voltage pulse. The heating elements are used to selectively melt solder or adhesives attaching the parts to the circuit board so that they can be easily removed or to temporarily melt solder or cure adhesive when the parts are mounted on the circuit board. The heating elements are also used to supply heat to IC packages for regulating their operating temperatures.
Claims12
An apparatus for holding and regulating a temperature of a first integrated circuit (IC) package (36) and a second IC package (38), the apparatus comprising:
- a substrate (26,28,30) having an upper surface upon which said first IC package is mounted, said substrate comprising electrically insulating material;
- a first heating element (32) embedded in said substrate below said first IC package for generating first heat in response to a voltage applied to said first heating element, said first heat traveling through said substrate to said first IC package and warming said first IC package, and
- temperature regulation means (76, 78, 80) for monitoring a first temperature of said first IC package and for applying said voltage across said first heating element when said temperature falls below a first minimum level and for removing said voltage from said first heating element when said first temperature rises above a first maximum level, wherein said first maximum level is at least as high as said first minimum level.
A self-heating circuit board for holding a plurality of integrated circuit (IC) packages (50) board comprising:
- a substrate (44, 46) having an upper surface upon which said IC packages are mounted, said substrate comprising an electrically insulating material;
- a grid (49) of heating conductors (54) embedded in said substrate below said IC packages for generating substantial heat in response to a voltage applied to said grid, said heat traveling through said substrate to said integrated packages;
- a plurality of conductive contacts (56), wherein each conductive contact contacts the grid, and wherein separate areas (58) of said grid reside between corresponding pairs of said contacts and under corresponding ones of said IC packages;
- and
- means for delivering separate voltage pulses across each of said separate pairs of said contacts.
A method for mounting integrated circuit packages on corresponding areas of a surface of a circuit board and controlling their temperatures, comprising the steps of:
- embedding a separate heating element corresponding to each of said areas in the circuit board proximate to its corresponding area, each heating element being of a type which generates heat in response to an applied voltage pulse, said heat flowing through said circuit board to the corresponding area,
- positioning solder between each integrated circuit package and its corresponding area,
- applying a first voltage pulse to each heating element of sufficient magnitude and duration to cause each heating element to generate enough heat to temporarily melt the solder between its corresponding area and the area's corresponding integrated circuit package, and thereafter
- applying a second voltage pulse to each said heating element when a temperature near an integrated circuit package corresponding to the heating element's corresponding area falls below a predetermined minimum level.
Dependencies are inferred from the claim text.