Mechanisms for forming package structure
View Patent ↗Embodiments of mechanisms for forming a package structure are provided. A method for forming a package structure includes providing a semiconductor die and forming a first bump structure and a second bump structure over the semiconductor die. The second bump structure is thinner and wider than the first bump structure. The method also includes providing a substrate having a first contact pad and a second contact pad formed on the substrate. The method further includes forming a first solder paste structure and a second solder paste structure over the first contact pad and the second contact pad, respectively. The second solder paste structure is thicker than the first solder paste structure. In addition, the method includes reflowing the first bump structure and the second bump structure with the first solder paste structure and the second solder paste structure, respectively, to bond the semiconductor die to the substrate.
1. A method for forming a package structure, comprising:
providing a semiconductor die;
forming a first bump structure and a second bump structure over the semiconductor die, wherein the second bump structure is thinner and wider than the first bump structure;
providing a substrate having a first contact pad and a second contact pad formed thereon;
forming a first solder paste structure and a second solder paste structure over the first contact pad and the second contact pad, respectively, wherein the second solder paste structure is thicker than the first solder paste structure; and
reflowing the first bump structure and the second bump structure with the first solder paste structure and the second solder paste structure, respectively, to bond the semiconductor die to the substrate.
2. The method for forming a package structure as claimed in claim 1 , wherein the step of forming the first bump structure and the second bump structure comprises:
forming a first under bump metallurgy (UBM) structure and a second UBM structure over the semiconductor die, wherein the second UBM structure is wider than the first UBM structure; and
forming a first bump and a second bump over the first UBM structure and the second UBM structure, respectively, wherein the second bump is thinner and wider than the first bump.
3. The method for forming a package structure as claimed in claim 2 , wherein volumes of the first bump and the second bump are substantially the same.
4. The method for forming a package structure as claimed in claim 2 , wherein a thickness difference between the first bump and the second bump is substantially equal to a thickness difference between the second solder paste structure and the first solder paste structure.
5. The method for forming a package structure as claimed in claim 2 , wherein the step of forming the first bump and the second bump comprises:
placing a first solder ball and a second solder ball over the first UBM structure and the second UBM structure, respectively; and
reflowing the first solder ball and the second ball to form the first bump and the second bump, respectively.
6. The method for forming a package structure as claimed in claim 5 , wherein shapes and sizes of the first solder ball and the second solder ball are substantially the same.
7. The method for forming a package structure as claimed in claim 2 , the first UBM structure and the second UBM structure are simultaneously formed.
8. The method for forming a package structure as claimed in claim 1 , wherein the second bump structure is formed over a high stress region of the semiconductor die.
9. The method for forming a package structure as claimed in claim 8 , wherein the second bump structure is formed over a corner region of the semiconductor die.
10. The method for forming a package structure as claimed in claim 1 , wherein the step of forming the first solder paste structure and the second solder paste structure comprises:
positioning a stencil over the substrate, wherein the stencil has a first opening and a second opening exposing the first contact pad and the second contact pad, respectively, wherein the second opening is larger than the first opening; and
applying a solder material over the stencil such that portions of the solder material penetrate through the first opening and the second opening to form the first solder paste structure and the second solder paste structure.
11. The method for forming a package structure as claimed in claim 1 , wherein the first solder paste structure and the second solder paste structure are simultaneously formed.
12. The method for forming a package structure as claimed in claim 1 , wherein a volume of the second paste structure is larger than a volume of the first paste structure.
13. The method for forming a package structure as claimed in claim 1 , wherein a surface of the substrate is substantially parallel to a surface of the semiconductor die after bonding the semiconductor die to the substrate.
14. A method for forming a package structure, comprising:
providing a semiconductor die;
forming a first bump structure and a second bump structure over the semiconductor die, wherein the second bump structure is thinner and wider than the first bump structure;
providing a substrate;
forming a first solder paste structure and a second solder paste structure over substrate, wherein the second solder paste structure is thicker than the first solder paste structure; and
reflowing the first bump structure and the second bump structure with the first solder paste structure and the second solder paste structure, respectively, to bond the semiconductor die to the substrate.
15. The method for forming a package structure as claimed in claim 14 , wherein the step of forming the first bump structure and the second bump structure comprises:
forming a first under bump metallurgy (UBM) structure and a second UBM structure over the semiconductor die, wherein the second UBM structure is wider than the first UBM structure; and forming a first bump and a second bump over the first UBM structure and the second UBM structure, respectively, wherein the second bump is thinner and wider than the first bump.
16. The method for forming a package structure as claimed in claim 15 , wherein volumes of the first bump and the second bump are substantially the same.
17. The method for forming a package structure as claimed in claim 15 , wherein a thickness difference between the first bump and the second bump is substantially equal to a thickness difference between the second solder paste structure and the first solder paste structure.
18. The method for forming a package structure as claimed in claim 14 , wherein the step of forming the first solder paste structure and the second solder paste structure comprises:
positioning a stencil over the substrate, wherein the stencil has a first opening and a second opening, and the second opening is larger than the first opening; and
applying a solder material over the stencil such that portions of the solder material penetrate through the first opening and the second opening to form the first solder paste structure and the second solder paste structure.
19. A method for forming a package structure, comprising:
providing a semiconductor die;
forming a first bump structure and a second bump structure over the semiconductor die, wherein the second bump structure is thinner and wider than the first bump structure;
providing a substrate;
forming a first solder paste structure and a second solder paste structure over substrate, wherein the second solder paste structure is thicker than the first solder paste structure; and
connecting the first bump structure and the second bump structure with the first solder paste structure and the second solder paste structure, respectively, to bond the semiconductor die to the substrate.
20. The method for forming a package structure as claimed in claim 19 , wherein a thickness difference between first bump structure and the second bump structure is substantially equal to a thickness difference between the second solder paste structure and the first solder paste structure.