Patent Application
20060024982
Embodiments of the present invention are related to the field of integrated circuit packaging.
Current substrate components with a high thermal mass, for example a circuit board with a surface mount Land Grid Array (LGA) Socket, may require significant air flow over the surface of the components during a reflow process in a forced air convection oven to reduce the temperature differential between the outer edges and the center of the components. With a lower temperature gradient between the outer edges of the component and the center of the component, the reflow process for the high thermal mass may be enhanced. Also the thermal mass of the LGA socket with integrated direct socket loading fixture may be much higher than previous sockets.
Additionally, with the current pick and place cover designs, it is possible for a package to be engaged in the socket with the pick and place cover attached to the socket. This may lead to accidental assembly of the LGA socket onto a motherboard while a package is installed in the LGA socket, thereby damaging the package.
The present invention will be described by way of exemplary embodiments, but not limitations, illustrated in the accompanying drawings in which like references denote similar elements, and in which:
Embodiments of the present invention include, but are not limited to a socket cover with a recessed center, a method for using the socket cover, and a system adapted to use the socket cover.
Various aspects of the illustrative embodiments will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments.
Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.
The phrase “in one embodiment” is used repeatedly. The phrase generally does not refer to the same embodiment. However, it may. The terms “comprising”, “having” and “including” are synonymous, unless the context dictates otherwise.
As will be described in more detail below, in various embodiments, the recessed area in a pick and place cover allows for ventilation openings to be placed close to the center of a socket during reflow. For reflow in a forced air convection oven, the position and/or cross sectional area of holes through the pick and place cover may be key factors in improving air flow into the socket.
A flat surface in the center of the pick and place cap may be helpful for vacuum cup suction to pick and place during surface mount technology assembly. However, this means the holes through the cover will not be in the center of the pick and place cover, and the holes will be over the LGA socket contact field. Further, large vertical holes through the pick and place cover may create the risk of foreign material falling into the LGA socket contact area. This adds risk to the contact electrical performance either through contamination of the LGA socket contacts or damage of LGA socket contacts.
However, in various embodiments, by adding a recessed area to the pick and place cover, and using the sidewall related to this recessed area, the ventilation holes may be horizontal or diagonal, thus reducing the risk of foreign material falling into the LGA socket contact field. Moreover, the ventilation holes may also be close to the center of the socket.
Additionally, the recessed area of the pick and place cover will not allow for a package to be assembled in the LGA socket with the pick and place cover attached to the socket. The recessed area will interfere with the top of the package and the pick and place cover will pop off if a package is in the LGA socket.
As will be described in more detail below, socket cover 100a with one or more openings 150 located in the hollowed center 120, allows for air flow to be near the center of socket 100b. Resultantly, a reflow process applied to socket 100b in a forced air convection oven may be improved by the reduction in temperature gradient between the outer edges of socket 100b and the center of socket 100b. Further, the one or more openings 150 disposed on the one or more sidewalls 140 may reduce risk of contamination or damage to the socket contacts, especially when contrasted with socket covers 200 that have openings 230 distributedly disposed on a first plane 210 as shown in
For ease of understanding, portion 110 and portion 130 are illustrated as generally parallelepiped for the embodiment shown in
In various embodiments, socket cover 100a has one or more alignment tabs 160 that extend away from the first portion towards the second portion. The first portion 110 of the socket cover 100a comprises a first side and a second side, the second side faces the second plane, and the second side has a contour substantially conforming to a contour of a surface of the thermal mass 165. Further, in another embodiment, the thermal mass 165 has a hollowed center 170, and the second portion 130 and the one or more sidewalls 140 substantially conform to the complementary thermal mass' hollowed center 170. For ease of understanding, a restatement of the previous sentence would be that the hollowed (recessed) portion 120 of the socket cover 100a fits inside of the hollowed center 170 of the thermal mass. In some embodiments, the thermal mass is a surface mount Land Grid Array.
Next, in one embodiment, a heat source is applied to the socket package and the substrate in a reflow process that couples the socket 100b to a substrate while the socket cover 100a remains removably engaged to the socket 100b 303. The heat, in the form of a convection airflow, migrates/flows over the socket 100b through the openings defined by the edges in the socket cover 100a. In various embodiments, the substrate comprises a printed circuit board. In other embodiments, the socket comprises a surface mount Land grid Array socket.
Holder 404 is employed to hold a substrate 180. Pick and place unit 402, as described earlier, is employed to pick and place a socket package (having the socket cover of
The transport unit 406 is employed to move substrate 180 into oven 408 with the socket package placed thereon, i.e. the socket remains removably mated with the underside of the socket cover.
Oven 408 is then employed to apply heat to the combination (i.e. the socket package and the substrate) to attach the socket to the substrate 180, while the socket cover remains removably mated to the socket. As described earlier, the openings of the recessed center of the socket cover facilitates improved airflow for applying heat to the combination.
Except for the pick and place unit 402 adapted to pick and place the novel socket of
Thus, it can be seen from the above descriptions, embodiments for a novel socket cover for a socket, method for using such a socket cover, and a system adapted to use such a socket cover have been described. While the present invention has been described in terms of the foregoing embodiments, those skilled in the art will recognize that embodiments of the present invention are not limited to the embodiments described. Embodiments of the present invention can be practiced with modification and alteration within the spirit and scope of the appended claims.
Therefore, the description is to be regarded as illustrative instead of restrictive on the present invention.
