Pitch-reducing solder interconnect for RF transitions

A system comprising:

• an integrated circuit device having a first pair of electrical interconnect pads with solderable surfaces, wherein the integrated circuit device comprises:
• a bare integrated circuit die;
• a polymer layer formed on the bare integrated circuit die, wherein the polymer layer includes a plurality of conductive traces to redistribute electrical connections from the bare integrated circuit die;
• and
• a metallization layer formed on the polymer layer, wherein the metallization layer includes the first pair of electrical interconnect pads having solderable surfaces;
• an interposer circuit board having a second pair of electrical interconnect pads with solderable surfaces, the second pair of electrical interconnect pads being configured to provide electrical coupling to the first pair of electrical interconnect pads through solder connections, and having a first pair of conductive paths spaced to create a radio frequency (RF) transmission line, wherein the first pair of conductive paths are electrically coupled to the second pair of electrical interconnect pads;
• wherein the first pair of electrical interconnect pads are noncircular and elongated on a common axis and are configured, during a solder reflow process, to cause solder to flow in a direction of the common axis to form an RF transition between the integrated circuit device and the interposer circuit board.

An interposer circuit board comprising:

• a first pair of conductive paths having a first spacing to create a radio frequency (RF) transmission line;
• and
• a first pair of electrical interconnect pads having solderable surfaces configured to be electrically coupled to an integrated circuit device using solder connections, wherein the first pair of electrical interconnect pads have a second spacing greater than the first spacing;
• an RF launcher electrically coupled to the RF transmission line;
• wherein the first pair of electrical interconnect pads are electrically coupled to the RF transmission line, the first pair of electrical interconnect pads being noncircular and elongated on a common axis and are configured, during a solder reflow process, to cause solder to flow in a direction of the common axis to form an RF transition between the integrated circuit device and the interposer circuit board.

An integrated circuit device comprising:

• a radio frequency (RF) circuit configured to produce RF energy;
• and
• a first pair of electrical interconnect pads with solderable surfaces configured to provide electrical coupling to a circuit board using solder connections;
• wherein the first pair of electrical interconnect pads are electrically coupled to the RF circuit to conduct the RF energy, the first pair of electrical interconnect pads being noncircular and elongated on a common axis and are configured, during a solder reflow process, to cause solder to flow in a direction of the common axis to form an RF transition between the integrated circuit device and the circuit board.

A method comprising:

• fabricating an interposer circuit board having a first pair of conductive paths spaced to form a radio frequency (RF) transmission line, and having a first pair of electrical interconnect pads with solderable surfaces being noncircular and elongated on a common axis, wherein the first pair of electrical interconnect pads are electrically coupled to the RF transmission line;
• and
• electrically coupling an integrated circuit device to the interposer circuit board, wherein the electrically coupling comprises performing a solder reflow operation to allow solder to flow in a direction of the common axis of the first pair of electrical interconnect pads;
• molding over an integrated circuit die to produce a molded integrated circuit device, wherein the integrated circuit die includes an RF circuit configured to produce RF energy;
• forming a polymer layer on the molded integrated circuit device, wherein the polymer layer includes a second plurality of conductive paths to redistribute interconnects on the molded integrated circuit device to a ball grid array pattern having a pitch compatible with the interposer circuit board, wherein a second pair of the second plurality of conductive paths are electrically coupled to conduct the RF energy;
• and
• forming a metallization layer on the polymer layer to form the integrated circuit device, wherein the metallization layer includes a second pair of electrical interconnect pads electrically coupled to the second pair of the second plurality of conductive paths on the polymer layer to conduct the RF energy, wherein the second pair of electrical interconnect pads are spaced to be electrically coupled to the first pair of electrical interconnect pads on the interposer circuit board during the solder reflow operation to form an RF transition between the integrated circuit device and the interposer circuit board.