VERTICALLY TAPERED TRANSMISSION LINE FOR OPTIMAL SIGNAL TRANSITION IN HIGH-SPEED MULTI-LAYER BALL GRID ARRAY PACKAGES
First Claim
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1. A method for designing placement locations of micro vias of a via layer of a transmission line in a multi-layer ball grid array (BGA) package for a semiconductor die, comprising:
- determining a target impedance value for the via layer, wherein the determined target impedance value for the layer is along a smooth impedance curve between an impedance of a bump and an impedance of a ball of a BGA;
determining placement location of at least one signal via of micro vias, wherein the placement location follows design constraints of manufacturing;
performing an analytical calculation to determine initial placement locations of a plurality of ground vias of the micro vias of the via layer;
adjusting the placement locations of the plurality of ground vias by taking the design constraints of manufacturing into consideration; and
calculating an impedance of the via layer by using a simulation tool after the placement locations of the vias have been adjusted.
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Abstract
Broadly speaking, the embodiments of the present invention fill the need for methods of designing vertical transmission lines for optimal signal transition in multi-layer BGA packages. By controlling the impedance and geometry continuity of micro vias in each micro via layer in the package to follow smooth impedance and geometry curves from layer to layer, the return loss and insertion loss of the transmission line can be reduced or controlled to within acceptable ranges.
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Citations
20 Claims
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1. A method for designing placement locations of micro vias of a via layer of a transmission line in a multi-layer ball grid array (BGA) package for a semiconductor die, comprising:
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determining a target impedance value for the via layer, wherein the determined target impedance value for the layer is along a smooth impedance curve between an impedance of a bump and an impedance of a ball of a BGA; determining placement location of at least one signal via of micro vias, wherein the placement location follows design constraints of manufacturing; performing an analytical calculation to determine initial placement locations of a plurality of ground vias of the micro vias of the via layer; adjusting the placement locations of the plurality of ground vias by taking the design constraints of manufacturing into consideration; and calculating an impedance of the via layer by using a simulation tool after the placement locations of the vias have been adjusted. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for designing placement locations of micro vias of a via layer of a transmission line in a package for a semiconductor die to widen a range of operating frequencies of devices in the semiconductor die, comprising:
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determining a target impedance value for the via layer, wherein the determined target impedance value for the layer is along a smooth impedance curve between an impedance of a bump and an impedance of a ball of a ball grid array (BGA); determining placement location of at least one signal via of micro vias, wherein the placement location avoids geometry discontinuities in the transmission line; calculating a distance between ground vias of the micro vias of the via layer and the at least one signal vias to determine initial placement locations of the ground vias; and calculating an impedance of the via layer by using a simulation tool after the placement locations of the vias have been adjusted. - View Dependent Claims (11, 12, 13, 14, 15, 16, 20)
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17. A computer readable medium including program instructions for designing placement locations of micro vias of a via layer of a transmission line in a package for a semiconductor die to widen a range of operating frequencies of devices in the semiconductor die, comprising:
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program instructions for determining a target impedance value for the via layer, wherein the determined target impedance value for the layer is along a smooth impedance curve between an impedance of a bump and an impedance of a ball of a ball grid array (BGA); program instructions for determining placement location of at least one signal via of micro vias, wherein the placement location avoids geometry discontinuities in the transmission line; program instructions for calculating a distance between ground vias of the micro vias of the via layer and the at least one signal vias to determine initial placement locations of the ground vias; and program instructions for calculating an impedance of the via layer after the placement locations of the vias have been adjusted. - View Dependent Claims (18, 19)
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Specification