Method of making a semiconductor chip assembly with a bump/base heat spreader and a cavity in the bump

Abstract

A semiconductor chip assembly includes a semiconductor device, a heat spreader, a conductive trace and an adhesive. The heat spreader includes a bump, a base and a flange. The conductive trace includes a pad and a terminal. The semiconductor device extends into a cavity in the bump, is electrically connected to the conductive trace and is thermally connected to the bump. The bump extends from the base into an opening in the adhesive, the base extends vertically from the bump opposite the cavity and the flange extends laterally from the bump at the cavity entrance. The conductive trace is located outside the cavity and provides signal routing between the pad and the terminal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. application Ser. No. 12 / 616,773 filed Nov. 11, 2009 and a continuation-in-part of U.S. application Ser. No. 12 / 616,775 filed Nov. 11, 2009, each of which is incorporated by reference. This application also claims the benefit of U.S. Provisional Application Ser. No. 61 / 330,318 filed May 1, 2010 and U.S. Provisional Application Ser. No. 61 / 350,036 filed Jun. 1, 2010, each of which is incorporated by reference.[0002]U.S. application Ser. No. 12 / 616,773 filed Nov. 11, 2009 and U.S. application Ser. No. 12 / 616,775 filed Nov. 11, 2009 are each a continuation-in-part of U.S. application Ser. No. 12 / 557,540 filed Sep. 11, 2009 and a continuation-in-part of U.S. application Ser. No. 12 / 557,541 filed Sep. 11, 2009.[0003]U.S. application Ser. No. 12 / 557,540 filed Sep. 11, 2009 and U.S. application Ser. No. 12 / 557,541 filed Sep. 11, 2009 are each a continuation-in-part of U.S. application Ser. No. 12...

AI Technical Summary

Benefits of technology

[0079]The present invention has numerous advantages. The heat spreader can provide excellent heat spreading and heat dissipation without heat flow through the adhesive. As a result, the adhesive can be a low cost dielectric with low thermal conductivity and not prone to delamination. The bump and the flange can be integral with one another, thereby enhancing reliability. The bump can have a tapered sidewall and a highly reflective surface layer. As a result, the bump can focus the light generated by an LED chip mounted on the bump within the cavity, thereby enhancing the light output. Furthermore, the cavity can provide a well-defined space for a color-shifting encapsulant deposited on the LED chip. As a result, the color-shifting encapsulant can be dispensed into the cavity in a small consistent amount, thereby enhancing optical performance and reducing cost. The base can include a selected portion of the conductive layer laminated to the dielectric layer, thereby enhancing reliability. The adhesive can be sandwiched between the bump and the substrate, between the base and the substrate and between the flange and the substrate, thereby providing a robust mechanical bond betwee

Problems solved by technology

Semiconductor devices are susceptible to performance degradation as well as short life span and immediate failure at high operating temperatures.

The heat not only degrades the chip, but also imposes thermal stress on the chip and surrounding elements due to thermal expansion mismatch.

LEDs include high power chips that generate high light output and considerable heat.

Unfortunately, LEDs exhibit color shifts and low light output as well as short lifetimes and immediate failure at high operating temperatures.

Furthermore, LED light output and reliability are constrained by heat dissipation limits.

However, since the plastic and the dielectric layer typically have low thermal conductivity, the PBGA provides poor heat dissipation.

However, since the lead frame type interposer has limited routing capability, the QFN package cannot accommodate high input/output (I/O) chips or passive elements.

However, manually dropping the heat slug into the central opening is prohibitively cumbersome and expensive for high volume manufacture.

Furthermore, since the heat slug is difficult to accurately position in the central opening due to tight lateral placement tolerance, voids and inconsistent bond lines arise between the substrate and the heat slug.

The substrate is therefore partially attached to the heat slug, fragile due to inadequate support by the heat slug and prone to delamination.

The heat slug is therefore non-planar and difficult to bond to.

As a result, the assembly suffers from high yield loss, poor reliability and excessive cost.

However, the insulating layer sandwiched between the metal co

Images