Apparatus and method for inter-chip or chip-to-substrate connection with a sub-carrier
View Patent ↗The present invention is directed to a method and an apparatus where the standard wire bonding of TBGA's is replaced using a solid intermediate subcarrier on which the die may be flip chipped and which may then be flip chipped onto the substrate. The subcarrier has a number of conductors replacing the wire bond. In this manner, a better reflection suppression, better impedance matching, smaller conductor pitch and other advantages are achieved. The subcarrier may also be used for mounting multiple dies in a single substrate.
1. A method of electrically connecting a die to a substrate, comprising:
providing a die having an upper surface with a number of connecting points;
providing a substrate having an upper surface, a lower surface, a cavity adapted to receive the die, a number of connection points at the upper surface of the substrate, and a number of connection elements for connection to an electrical circuit external to the substrate;
introducing the die into the cavity;
providing a subcarrier including a number of individually shielded electrical conductors;
electrically connecting connection points of the die to connection points of the substrate by positioning the subcarrier with respect to the die and the substrate; and
wherein the electrical conductors are shielded by a number of vias.
2. The method according to claim 1 wherein electrically connecting connection points of the die to connection points of the substrate by positioning the subcarrier with respect to the die and the substrate comprises:
fixing the die and the subcarrier element in relation to each other so that connection points of the die obtain electrical connection to at least one of the conductors of the subcarrier element; and
fixing the subcarrier element and the substrate in relation to each other so that conductors of the subcarrier element obtain electrical connection to at least one of the connection points of the substrate and so that the die is introduced into the cavity.
3. The method according to claim 2 further comprising providing a second die having an upper surface having a number of connection points, and wherein:
the cavity is adapted to receive both the die and the second die;
fixing the die and the subcarrier element in relation to each other further comprises fixing the second die and the subcarrier element to each other so that connection points of the second die obtain electrical connection to at least one of the conductors of the subcarrier element; and
fixing the subcarrier element and the substrate in relation to each other further comprises introducing the second die in the cavity.
4. A method of electrically connecting a die to another element, comprising:
providing a die having an upper surface having a number of connection points;
providing an element having an upper surface with a number of connection points;
providing a subcarrier element having a surface with a number of individually shielded electrical conductors;
providing a substrate having a number of connection points and a cavity adapted to receive the die and the other element;
fixing the die and the subcarrier element in relation to each other so that connection points of the die obtain electrical connection to at least one of the conductors of the subcarrier element;
fixing the subcarrier element and the element in relation to each other so that the connection points of the element obtain electrical connection to at least one of the conductors of the subcarrier element;
introducing the die and the element in the cavity;
providing electrical contact between the substrate and at least one of the die, the element, and the subcarrier element; and
wherein the electrical conductors are shielded by a number of vias.
5. A method according to claim 4 , wherein providing electrical contact between the substrate and at least one of the die, the element, and the subcarrier element further comprises fixing the subcarrier element and the substrate in relation to each other so that connection points of the substrate obtain electrical connection to at least one of the conductors of the subcarrier element.
6. The method according to claim 5 , wherein the connection points of the die, the element, and the substrate define at least substantially congruent planes.
7. The method according to claim 6 , wherein the conductors of the subcarrier element define a plane parallel to the congruent planes.
8. The method according to claim 4 , wherein the connection points abut the conductors so as to obtain the electrical connection.
9. The method according to claim 4 , wherein the connection points are electrically connected to the conductors.
10. The method according to claim 4 further comprising providing a heat sink.
11. The method according to claim 10 , wherein providing the substrate further comprises:
providing the cavity in a manner such that at least part of the cavity is in thermal contact with the heat sink; and
providing thermal contact between the heat sink and at least one of the die, the subcarrier element, and the element.
12. The method according to claim 11 , wherein thermal contact is provided by a thermally conducting material selected from a group consisting of at least one of a fluid, a glue, an epoxy, a resilient material, and a foam.
13. The method according to claim 4 , wherein providing the subcarrier element further comprises providing the subcarrier element that is substantially stiff and electrically insulating and has a number of electrical conductors on a surface.
14. The method according to claim 4 , wherein some of the conductors are provided so as to have the same or equivalent predetermined characteristic impedance.