Methods and apparatus for package on package devices

Abstract

Package on package (PoP) devices and methods of packaging semiconductor dies are disclosed. A PoP device is formed by connecting a top package and a bottom package together using a plurality of PoP connectors on the bottom package connected to corresponding connectors of the top package. The PoP device further comprises a plurality of dummy connectors contained in the bottom package and not connected to any corresponding connector in the top package.

What is claimed is: 
     
       1. A device comprising:
 a first substrate; 
 a first die attached to a first surface of the first substrate; 
 a second substrate attached to the first substrate, the first die being interposed between the first substrate and the second substrate; 
 one or more signaling connectors interposed between the first substrate and the second substrate; and 
 a plurality of dummy connectors interposed between the first substrate and the second substrate, the plurality of dummy connectors not passing electrical signals between the first substrate and the second substrate, the plurality of dummy connectors being connected to only one of first substrate and the second substrate, wherein a first dummy connector is a different size than a second dummy connector. 
 
     
     
       2. The device of  claim 1 , further comprising one or more intermediate connectors electrically coupling the one or more signaling connectors to the second substrate. 
     
     
       3. The device of  claim 2 , wherein the one or more intermediate connectors comprise solder balls. 
     
     
       4. The device of  claim 1 , further comprising an encapsulant, wherein the first die is exposed through the encapsulant. 
     
     
       5. The device of  claim 4 , wherein the encapsulant encircles the plurality of dummy connectors and the one or more signaling connectors. 
     
     
       6. The device of  claim 1 , further comprising an encapsulant, wherein the encapsulant covers an upper surface of the first die. 
     
     
       7. The device of  claim 1 , wherein the first dummy connector of the plurality of dummy connectors is of a different size from a first signaling connector of the one or more signaling connectors. 
     
     
       8. The device of  claim 1 , wherein the one or more signaling connectors comprise a plurality of signaling connectors arranged in a pattern, and wherein the plurality of dummy connectors comprise a first number of dummy connectors in a first corner of the pattern and a second number of dummy connectors in a second corner of the pattern, the first number being different than the second number. 
     
     
       9. A device comprising:
 a first substrate; 
 a first die attached to a first surface of the first substrate; 
 a second substrate attached to the first substrate, the first die being interposed between the first substrate and the second substrate; 
 an encapsulant on the first surface of the first substrate, the encapsulant extending to at least an upper surface of the first die, an uppermost surface of the encapsulant being spaced apart from the second substrate; 
 one or more first connectors extending through the encapsulant to the first substrate, the one or more first connectors electrically coupling the first substrate to the second substrate, wherein the encapsulant has a first height and the one or more first connectors have the first height and wherein the one or more first connectors have curved sidewalls from a first side of the encapsulant to a second side of the encapsulant; 
 onetwo or more dummy connectors extending through the encapsulant to the first substrate, the onetwo or more dummy connectors interposed between the first substrate and the second substrate, the onetwo or more dummy connectors not being electrically coupled between a conductive element and the first substrate; and 
 one or more second connectors extending between corresponding ones of the one or more first connectors and the second substrate, wherein a first dummy connector is a different size than a second dummy connector. 
 
     
     
       10. The device of  claim 9 , wherein the encapsulant covers the first die. 
     
     
       11. The device of  claim 9 , wherein the one two or more dummy connectors are exposed through the encapsulant. 
     
     
       12. The device of  claim 9 , wherein the one or more first connectors are arranged a pattern around a periphery of the first substrate, the one or more first connectors being placed around the first die, the first die being spaced apart from the one or more first connectors, wherein a first one of the one two or more dummy connectors is placed at a corner of the first die and a second one of the one two or more dummy connectors is placed at a corresponding corner of the pattern of the one or more first connectors. 
     
     
       13. The device of  claim 9 , wherein a first dummy connector is a different size than a second dummy connector. 
     
     
       14. A method comprising:
 providing a first substrate; 
 attaching a first die to the first substrate; 
 forming an encapsulant layer over the first substrate, wherein after the forming the encapsulant layer the encapsulant layer having has a signaling connector and a first dummy connector extending through an encapsulant of the encapsulant layer to the first substrate, the encapsulant layer being interposed between the signaling connector, the first dummy connector and the first die, wherein the encapsulant layer comprises a first material that has a straight sidewall which extends from a first side of the encapsulant layer to an opposite side of the encapsulant layer, the opposite side being in physical contact with the first substrate, wherein a second dummy connector extends through the encapsulant layer to the first substrate, the second dummy connector being a different size than the first dummy connector; 
 removing a portion of the encapsulant layer to expose the signaling connector and the first dummy connector; and 
 attaching a second substrate to the signaling connector, wherein the first dummy connector is electrically isolated from electrical devices on the second substrate. 
 
     
     
       15. The method of  claim 14 , wherein an upper surface of the first die is exposed through the encapsulant layer. 
     
     
       16. The method of  claim 14 , wherein the encapsulant layer is in contact with a top surface and sidewalls of the first die. 
     
     
       17. The device of  claim 14 , wherein the first dummy connector provides no electrical connection between a conductive element and conductive pad on the first substrate. 
     
     
       18. The method of  claim 14 , wherein the removing the portion of the encapsulant layer exposes surface of the first die. 
     
     
       19. The method of  claim 18 , wherein the attaching the second substrate to the signaling connector comprises attaching the signaling connector to the second substrate using an intermediate connector, the intermediate connector protruding from the second substrate. 
     
     
       20. The method of  claim 19 , wherein the intermediate connector is a solder ball. 
     
     
       21. A device comprising:
 a first substrate;   a first die attached to a first surface of the first substrate;   an encapsulant on the first surface of the first substrate, the encapsulant extending to at least an upper surface of the first die facing away from the first substrate, the encapsulant having a straight sidewall extending between a first side of the encapsulant to a second side of the encapsulant;   one or more first connectors extending through the encapsulant to the first substrate, wherein at least one of the one or more first connectors comprises a first material in physical contact with the first substrate, the first material extending to a point located within the encapsulant;   two or more dummy connectors extending through the encapsulant to the first substrate, the two or more dummy connectors not being electrically coupled between a conductive element and first substrate; and   one or more second connectors extending over corresponding ones of the one or more first connectors, wherein a first dummy connector is a different size than a second dummy connector.   
     
     
       22. The device of claim 21, wherein the encapsulant covers the first die. 
     
     
       23. The device of claim 21, wherein the two or more dummy connectors are exposed through the encapsulant. 
     
     
       24. The device of claim 21, wherein the one or more first connectors are arranged a pattern around a periphery of the first substrate, the one or more first connectors being placed around the first die, the first die being spaced apart from the one or more first connectors, wherein a first one of the two or more dummy connectors is placed at a corner of the first die and a second one of the two or more dummy connectors is placed at a corresponding corner of the pattern of the one or more first connectors. 
     
     
       25. A device comprising:
 a first package comprising a first die placed on a first surface of a first substrate and a first connector connected to a second surface of the first substrate; and   a second package comprising a second die, a second connector and a dummy connector, the second connector and the dummy connector extending through an encapsulant, the encapsulant being interposed between the dummy connectors and the second die, the encapsulant being non-conductive, wherein the dummy connector has a curved sidewall extending from a first side of the encapsulant to a second side of the encapsulant;   wherein the first connector is connected to the second connector, and the dummy connector is not electrically connected to the first package, wherein the dummy connector is of a different size from a size of the second connector.   
     
     
       26. The device of claim 25, further comprising a first plurality of connectors connected to the second surface of the first substrate, a second plurality of connectors, and a third plurality of dummy connectors, wherein any of the first plurality of connectors is connected to one of the second plurality of connectors, none of the third plurality of dummy connectors is connected to any connector of the first package. 
     
     
       27. The device of claim 25, wherein the first connector is connected to a bottom surface of the first substrate and the first die is placed on a top surface of the first substrate. 
     
     
       28. The device of claim 25, wherein the first substrate is selected from a group consisting essentially of a packaging substrate, a printed-circuit board, and a high-density interconnect. 
     
     
       29. The device of claim 25, wherein the first die is a memory chip or a logic chip. 
     
     
       30. The device of claim 25, wherein the first substrate comprises a redistribution line (RDL) on a surface of the first substrate. 
     
     
       31. The device of claim 25, wherein the second package comprises a plurality of dies. 
     
     
       32. The device of claim 25, wherein the second die is a memory chip or a logic chip. 
     
     
       33. The device of claim 25, wherein the second connector comprises copper. 
     
     
       34. The device of claim 25, wherein the dummy connector comprise copper. 
     
     
       35. A device comprising:
 a first die attached to a first surface of a first redistribution structure;   an encapsulant in physical contact with the first surface, the encapsulant extending to at least an upper surface of the first die facing away from the first surface, the encapsulant comprising a first material throughout the encapsulant, the first material having a first external sidewall which is straight from a first surface of the encapsulant to a second surface of the encapsulant opposite the first surface;   one or more first connectors extending through the encapsulant to the first surface of the first redistribution structure; and   two or more dummy connectors extending through the encapsulant to the first surface of the first redistribution structure, the two or more dummy connectors not being electrically coupled between a conductive element and the first surface, wherein a first dummy connector is a different size than a second dummy connector.   
     
     
       36. The device of claim 35, wherein the encapsulant covers the first die. 
     
     
       37. The device of claim 35, wherein the two or more dummy connectors are exposed through the encapsulant. 
     
     
       38. The device of claim 35, wherein the one or more first connectors are arranged a pattern around a periphery of the first substrate, the one or more first connectors being placed around the first die, the first die being spaced apart from the one or more first connectors, wherein a first one of the two or more dummy connectors is placed at a corner of the first die and a second one of the two or more dummy connectors is placed at a corresponding corner of the pattern of the one or more first connectors.