Methods and apparatuses to stiffen integrated circuit package
A dam stiffener for a package substrate is presented. In an embodiment, the dam stiffener comprises a thermally curable polymer, and is simultaneously cured with the underfill material to act as stiffener to the substrate. In another embodiment, a curable reservoir material can be dispensed to fill the space between the integrated circuit die and the dam stiffener, forming a thick reservoir layer, acting as an additional stiffener for the package substrate.
1. A method for making an integrated circuit package, comprising:
dispensing a dam stiffener on a substrate, the dam stiffener surrounding at least an integrated circuit die and comprising a curable material; prior to thermal curing the dam stiffener, dispensing an underfill material in the space between the integrated circuit die and the substrate; and
simultaneously curing the dam stiffener and the underfill material using the same thermal curing process.
2. A method as in claim 1 wherein the substrate is one of a coreless substrate and a thin cored substrate.
3. A method as in claim 1 further comprising: flattening the substrate; and attaching the integrated circuit die on the flattened substrate.
4. A method as in claim 1 wherein the underfill is also dispensed in the space between the dam stiffener and the integrated circuit die and is confined by the dam stiffener.
5. A method as in claim 1 wherein the dam stiffener is dispensed before dispensing the underfill material.
6. A method as in claim 1 wherein the dam stiffener is positioned less than half way between an edge of the substrate and a corresponding edge of the integrated circuit die toward the edge of the substrate.
7. A method as in claim 1 wherein the height of the dam stiffener is higher than the bottom and lower than the top of the integrated circuit die.
8. A method as in claim 1 wherein the width of the dam stiffener is selected to provide a desired flatness to the substrate.
9. A method as in claim 1 wherein the viscosity of the dam material is higher than that of the underfill material.
10. A method as in claim 1 wherein the coefficient of thermal expansion of the dam material is selected to counteract a thermal warpage of the substrate.
11. A method as in claim 1 wherein the elastic modulus of the dam material is higher than that of the underfill material.
12. A method as in claim 1 wherein the dam material comprises a dispensible polymer which is thermally curable.
13. A method for making an integrated circuit package, comprising:
dispensing a dam stiffener on a substrate, the dam stiffener surrounding at least one integrated circuit die and comprising a curable material; after dispensing the dam stiffener, dispensing;
an underfill material in the space between the integrated circuit die and the substrate; and
dispensing a curable reservoir material between the dam stiffener and the integrated circuit die, wherein the cured reservoir material acts as a stiffener to the substrate.
14. A method as in claim 13 wherein the substrate is one of a coreless substrate and a thin cored substrate.
15. A method as in claim 13 wherein the coefficient of thermal expansion of the reservoir material is selected to counteract a thermal warpage of the substrate.
16. A method as in claim 13 wherein the elastic modulus of the reservoir material is higher than that of the underfill material.
17. A method as in claim 13 wherein the reservoir material comprises a dispensible polymer which is thermally curable.
18. A method as in claim 13 further comprising:
simultaneously curing the dam stiffener, the reservoir material and the underfill material.