Temporary chip attach using injection molded solder

Abstract

An improved method for performing an improved Temporary Chip Attach utilizing an Injection Molded Solder (IMS) process to allow efficient testing of die for creating a Known Good Die Bank. The IMS is applied to the testing substrate to form a column on the substrate. The die to be tested can then be attached to the IMS column with C4 solder. A slight reflow is then applied to the die, allowing some of the C4 to melt, and form an electrical connection with the corresponding IMS column. After testing, the die can be removed along with the C4 from the IMS column or permanently attached the substrate by performing a full reflow of the C4.

Description

FIELD OF THE INVENTION[0001]The present invention generally relates to semiconductor manufacturing methods. More particularly, the present invention relates to temporary electrical connections for use in temporary chip attach applications.BACKGROUND[0002]In the microelectronics industry, there are Known-Good-Die (KGD) chips, which are die (chips) that have been tested and burned-in, and are known to be good prior to sale. Moreover, it is necessary that chips used to populate a multi-chip module (MCM) be (KGD) chips prior to being placed on the MCM, so that it is not necessary to reflow the module excessive times to replace die (chips) that may be defective.[0003]One method of producing KGD chips is to test the die on an Alumina Based Ceramic carrier. The Alumina Based Ceramic carrier can be a standard single-chip substrate. If the tested die is found to be good, the die is removed and put in a Known-Good-Die bank. The Alumina Based Ceramic, standard single-chip substrate is then cle...

AI Technical Summary

Benefits of technology

The present invention provides a method for attaching a chip to a substrate using an injection molded solder column. The method involves forming a pad on the substrate by applying a high temperature solder, placing the chip on top of the pad, and then performing a partial reflow to create a joint between the chip and the solder column. The method reduces the required time and complexity of Temporary Chip Attach and allows for easier testing of the chip. The patent also describes the use of different solder compositions and methods for removing the chip from the solder column.

Problems solved by technology

However, problems arise when a chip is temporarily mounted on a carrier with chip solder balls to provide sufficient electrical connectivity to facilitate test and burn-in at elevated temperatures.

One problem is that it is difficult to then remove the chip from the Temporary Chip Attach (TCA) carrier (substrate) without damage to the chip solder balls or the carrier.

Glass ceramic based carriers are much more fragile then alumina based Ceramic based carriers and it is even more difficult for them to withstand the removal process.

The process to convert a standard substrate to a TCA substrate is expensive, complicated, and not well defined or controlled.

First, only alumina based substrates can be readily used.

If the original application was for use on a glass ceramic substrate, then the testing results for the die on an alumina based substrate may not match the die performance when placed on the glass ceramic substrate due to differences arising from substrate contributions.

The inaccuracies in the testing results can cause improper sorting of the tested die.

This special processing and design work is expensive and time consuming.

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