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Method of bonding wires

Imported: 24 Feb '17 | Published: 06 Jan '04

Siu Wing Or, Honghai Zhu, Yam Mo Wong, Honyu Ng

USPTO - Utility Patents

Abstract

A method of bonding wires between a semiconductor die and a substrate on which the die is mounted includes providing an ultrasonic transducer (

1). The transducer (

1) includes an ultrasonic energy generation device (

2), an ultrasonic vibration amplifying device (

3) coupled at one end (

10) to the ultrasonic energy generation device (

2), a bonding tool (

5) coupled to the opposite end (

12) of the ultrasonic vibration amplifying device (

3), and a mounting structure (

4) located between the ends (

10, 12) of the ultrasonic vibration amplifying device (

3). The method also includes performing a first wire bond by operating the ultrasonic transducer (

1) at a first ultrasonic frequency and performing a second wire bond by operating the ultrasonic transducer (

1) at a second ultrasonic frequency, the second ultrasonic frequency being different from the first ultrasonic frequency.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

An example of a method of performing a wire bond in accordance with the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a conventional ultrasonic transducer for wire bonding;

FIG. 2 is a plan view of the ultrasonic transducer;

FIG. 3 is a cross-sectional view of the ultrasonic transducer along the line A—A of FIG. 2;

FIG. 4 is a side view of the ultrasonic transducer;

FIGS. 5

a to

5

i are graphs showing the vibration amplitude distribution for a number of different ultrasonic frequencies along the length of the transducer shown in FIGS. 1 to

4;

FIG. 6 is a graph of frequency versus electrical admittance for the ultrasonic transducer; and

FIG. 7 is a block diagram showing a control system for operating the transducer.

Claims

1. A method of bonding wires between a semiconductor die and a substrate on which the die is mounted the method comprising the steps of:

2. A method according to claim 1, wherein the vibration amplitude is substantially maximum at the bonding plane.

3. A method according to claim 1, wherein the first wire bond is performed between a wire and a contact pad on the die and the second wire bond is performed between a wire and a contact area on the substrate.

4. A method according to claim 1, further comprising the steps of:

5. A method of bonding wires between a semiconductor die and a substrate on which the die is mounted comprising:

6. A method according to claim 5, wherein the vibration amplitude is substantially a maximum at the bonding plane.

7. A method according to claim 5, wherein the first wire bond is performed between a wire and a contact pad on the die and the second wire bond is performed between a wire and a contact area on the substrate.

8. A method according to claim 5, further comprising the steps of: identifying additional ultrasonic frequencies for which the vibration amplitude is substantially zero at the energy generation plane and at the mounting plane and non-zero at the bonding plane; and

9. A method according to claim 2, wherein the first wire bond is performed between a wire and a contact pad on the die and the second wire bond is performed between a wire and a contact area on the substrate.

10. A method according to claim 2, further comprising the steps of:

11. A method according to claim 6, wherein the first wire bond is performed between a wire and a contact pad on the die and the second wire bond is performed between a wire and a contact area on the substrate.

12. A method according to claim 6, further comprising the steps of:

13. A method according to claim 1, wherein the frequencies of vibration of the energy generation device from which the first and second frequencies are selected are determined by analyzing modes of the transducer which can be excited in a given frequency range.

14. A method according to claim 13, wherein the modes of vibration are modeled using finite element analysis.

15. A method according to claim 13, including the step of verifying a vibration amplitude distribution of the modes of vibration experimentally by using a technique selected from electronic frequency sweeping and mechanical vibration technique.