Patent ID: 7094632
Filing Date: 2006-08-22
Classification: H01L,H05K,Y10T

Abstract:
1. A method of devising a high-density circuit module comprising the steps of: providing a first-level CSP having contact sites along a major surface, an upper surface and a lower surface, and opposing lateral sides defining a lateral extent of the first-level CSP; providing a second-level CSP having contact sites along a major surface; attaching a form standard to the first-level CSP such that at least one curved portion of the form standard extends outside of the lateral extent of the first-level CSP to present an at least one curved outer surface, the form standard having a thickness of about 6 mils or less; providing flex circuitry having an outer set of plural flex contacts, an inner set of plural flex contacts, and a thickness of about 4 mils or less; disposing high-temperature solder paste on the contact sites of the first-level CSP; applying heat sufficient to connect selected contact sites of the first-level CSP to select ones of the inner set of plural flex contacts to form a reflowed contact having a height between 2 and 6 mils; wrapping the flex circuitry partially about the at least one curved outer surface of the at least one curved portion of the form standard such that the flex circuitry presents the outer set of plural flex contacts above the form standard and the inner set of plural flex contacts below a lower surface of the first-level CSP; disposing high-temperature solder paste on the CSP contact sites of the second-level CSP; and applying heat sufficient to connect select ones of the second-level CSP contact sites to select ones of the outer set of plural flex contacts to form a reflowed contact having a height between 2 and 6 mils; in which the flex circuitry comprises at least one flex circuit having first and second conductive layers, the first conductive layer being closer to the first-level CSP than is the second conductive layer subsequent to the step of wrapping the flex circuitry, between which layers there is an intermediate layer, the second conductive layer having demarked selected ones of the inner and outer sets of plural flex contacts.