Flip-chip component
View Patent ↗A flip-chip component includes a chip with pads located on the chip and a chip frame, wherein the chip frame is arranged around the chip and is attached to the chip so that the active surface of the chip is substantially planar with a surface of the chip frame. A redistribution layer is attached to the chip and chip frame, and interconnections mechanically connect the redistribution layer and a board. Aspects of the invention improve the reliability of the flip-chip package by reducing shear stresses in the interconnections between the package and a board during changing temperatures. This is achieved by carefully selecting the material of the chip frame and designing the placement of the interconnections so that thermal expansion of the package matches that of the board during changing temperatures.
1. A flip-chip component comprising:
a chip, wherein the chip includes pads located on an active surface of the chip;
a chip frame, wherein the chip frame is arranged around the chip and is attached to the chip so that the active surface of the chip is substantially planar with a top surface of the chip frame;
a redistribution layer overlying the active surface of the chip and the chip frame; and
interconnections disposed over the top surface of the chip frame, the interconnections disposed at a first distance from a neutral point on the active surface of the chip, wherein the interconnections are provided to electrically and mechanically connect the redistribution layer with a board, wherein a thermal expansion of an assembly comprising the chip and the chip frame in a region of the interconnections is equal to a thermal expansion of the board in the region of the interconnections, wherein the interconnections are arranged substantially equidistantly on a circular ring, with a center of the ring being the neutral point of the chip, and wherein the interconnections are arranged in a single row forming the circular ring.
2. The flip-chip component of claim 1 , wherein a coefficient of thermal expansion of the chip frame is chosen such that the thermal expansion of the assembly comprising the chip and the chip frame in the region of the interconnections is equal to the thermal expansion of the board.
3. The flip-chip component of claim 1 , wherein coefficients of thermal expansion of the chip, the chip frame and the board satisfy the following equation:
CTE board *z*ΔT= ( CTE mold. comp *x*ΔT )*2 +CTE chip *y*ΔT
wherein z is a radial spacing of the interconnections from the neutral point of the chip, y is a width of the chip, and x is a distance between the interconnections and an edge of the chip, the distance of each interconnection from the neutral point being ½*y+x.
4. The flip-chip component of claim 1 , wherein the interconnections comprise conductive materials.
5. The flip-chip component of claim 1 , wherein the interconnections comprise solder balls.
6. The flip-chip component of claim 1 , wherein the interconnections comprise conductive polymer bumps.
7. The flip-chip component of claim 1 , wherein the redistribution layer electrically connects the pads located on the chip and the interconnections.
8. The flip-chip component of claim 1 , wherein a coefficient of thermal expansion of the chip frame at any temperature is greater than a coefficient of thermal expansion of the board at the same temperature.
9. The flip-chip component of claim 1 , wherein an effective coefficient of thermal expansion of the chip frame over a temperature range is greater than an effective coefficient of thermal expansion of the board over the same temperature range.
10. The flip-chip component of claim 1 , wherein the component further includes the board.
11. The flip-chip component of claim 1 , wherein there are no other interconnections between the interconnections and the neutral point.
12. The flip-chip component of claim 1 , wherein the interconnections are arranged so that thermo-mechanical stresses induced in the interconnections during temperature changes are about zero.
13. A flip-chip component comprising:
a chip, herein the chip includes pads located on the chip;
a chip frame, wherein the chip frame is arranged around the chip and is attached to the chip so that an active surface of the chip is substantially planar with a surface of the chip frame;
a redistribution layer attached to the chip and the chip frame; and
interconnections, wherein the interconnections are provided to mechanically connect the redistribution layer to a board, wherein the interconnections are arranged so that thermo-mechanical stresses induced in the interconnections during temperature changes are zero, wherein the interconnections are arranged substantially equidistantly on a circular ring, with a center of the ring being a neutral point of the chip, and wherein the interconnections are arranged in a single row forming the circular ring.
14. The flip-chip component of claim 13 , wherein an effective coefficient of thermal expansion of the chip frame over a temperature range is greater than an effective coefficient of thermal expansion of the board over the same temperature range.
15. The flip-chip component of claim 13 , wherein a coefficient of thermal expansion of the chip frame at a temperature is greater than a coefficient of thermal expansion of the board at the same temperature.
16. The flip-chip component of claim 13 , wherein an effective thermal expansion of an assembly comprising materials other than the interconnections and the board over a temperature range is substantially equal to an effective thermal expansion of the board over the same temperature range.
17. The flip-chip component of claim 13 , wherein the component further includes the board.
18. A flip-chip component comprising:
pads disposed on an active surface of a chip;
a chip frame, wherein the chip frame is arranged around the chip and is attached to the chip so that the active surface of the chip is substantially planar with a top surface of the chip frame; and
interconnections disposed over the top surface of the chip frame, the interconnections disposed at a first distance from a neutral point on the active surface of the chip and arranged radially around the neutral point, wherein the interconnections are provided to electrically and mechanically connect a redistribution layer with a board, and wherein a coefficient of thermal expansion of the chip frame is selected such that a thermal expansion of an assembly comprising the chip and the chip frame in a region of the interconnections is equal to a thermal expansion of the board in the region of the interconnections, wherein the interconnections are arranged radially in a single row around the neutral point.
19. The flip-chip component of claim 18 , wherein the interconnections are arranged so that thermo-mechanical stresses induced in the interconnections during temperature changes are about zero.