High Performance Etchable RoHS Compliant Thick Film Gold Conductor

2018 ◽  
Vol 2018 (1) ◽  
pp. 000620-000627 ◽  
Author(s):  
Samson Shahbazi ◽  
Gregg Berube ◽  
Stephanie Edwards ◽  
Ryan Persons ◽  
Caitlin Shahbazi
Keyword(s):  
Thick Film ◽  
High Performance ◽  
Failure Modes ◽  
High Reliability ◽  
Film Surface ◽  
Wire Bonding ◽  
Aluminum Wire ◽  
Sem Images ◽  
Lead And Cadmium ◽  
Wire Bond

Abstract The thick film paste manufacturers are expected to produce conductors which are lead and cadmium free, yet have excellent fired film properties and the same performance and properties as the cadmium and lead containing formulations. The fired film surface of these conductors must be defect free (i.e. imperfections, pills, agglomerates) after multiple firing steps and must perform on dielectric as well as substrates from different suppliers. Typically, the thick film gold conductors are used in high reliability applications such as medical devices, military applications, and high frequency circuits, which require robust performance at high and low temperatures, in chemically aggressive environments, or extremely humid conditions. As circuits decrease in size and become more complex, the thick film gold properties become increasingly critical. The challenge is to develop an alternative gold conductor formulation, which can print and resolve fine features (down to 4 mil lines and spaces) as well as have the ability to be etched for higher density circuit designs (down to 1–2 mil lines and spaces). Gold conductors are typically used in conjunction with other high temperature thick films so good performance after multiple firings was also a targeted requirement. Heraeus has been proactive for the past decade in the development of thick film products that are both RoHS (lead and cadmium free) as well as REACH compliant. This paper discusses the experiments that were performed in order to understand the contribution of gold powder, organic and inorganic system to improve the fired film performance. These formulations were compared against existing gold conductors including the high performance gold conductor options as well as other available standard gold conductor options. Thin wire bonding trials including both gold and aluminum wire are used to compare influences of raw materials which includes high volume wire bonding reliability including failure modes and aged wire bond adhesion at elevated temperature exposures (300°C) for extended periods of time. In order to analyze fired film morphology and link this up to wire bond performance, SEM images of the conductor surface and cross sections were conducted. These studies resulted in a newly developed thick film gold conductor paste for use in a wide variety of applications. We present wire-bonding data with gold and aluminum wire and reliability results on both 96% Al2O3 ceramic substrates as well as on top of standard dielectrics.

Thick Film Resistor Failures

2008 ◽  
Author(s):  
Anshul Shrivastava ◽  
Ahmed Amin ◽  
Bhanu Sood ◽  
Michael Azarian ◽  
Michael Pecht ◽  
...  
Keyword(s):  
Thick Film ◽  
High Performance ◽  
Printed Circuit Boards ◽  
Failure Modes ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Physical Analysis ◽  
Circuit Boards ◽  
Molding Compound ◽  
Electron Microscopy Analysis

Abstract Thick film resistors are widely used in consumer and industrial products such as timers, motor controls and a broad range of high performance electronic equipment. This article provides information on failures due to copper dendrite growth, silver migration, sulfur atmosphere corrosion, variation of temperature, and crack due to molding compound mechanisms. It presents case studies in which a physical analysis plan was developed and executed to investigate these sites of interest on as-manufactured and failed thick film power resistors. The analysis techniques included X-ray inspection, cross-sectioning, decapsulation, and optical and environmental scanning electron microscopy analysis. A table illustrates different failure modes and mechanisms for thick film resistors, and also potential application and manufacturing factors that cause failure mechanisms, which then describe the failure modes. The article is concluded that by preventing the failure of thick film resistors, printed circuit boards can be kept in service for their full lifetime.

The Design and Evaluation of an Integrated Wire Bond-less Power Module using a Low Temperature Co-fired Ceramic Interposer

2016 ◽  
Vol 13 (4) ◽  
pp. 169-175
Author(s):  
Sayan Seal ◽  
Michael D. Glover ◽  
H. Alan Mantooth
Keyword(s):  
Low Temperature ◽  
High Performance ◽  
High Reliability ◽  
Feasibility Studies ◽  
Power Devices ◽  
Power Module ◽  
Fast Switching ◽  
Wire Bond ◽  
Power Modules ◽  
Bandgap Semiconductors

This article presents the plan and initial feasibility studies for an Integrated Wire Bond-less Power Module. Contemporary power modules are moving toward unprecedented levels of power density. The ball has been set rolling by a drastic reduction in the size of bare die power devices owing to the advent of wide bandgap semiconductors such as silicon carbide (SiC) and gallium nitride. SiC has capabilities of operating at much higher temperatures and faster switching speeds compared with its silicon counterparts, while being a fraction of their size. However, electronic packaging technology has not kept pace with these developments. High-performance packaging technologies do exist in isolation, but there has been limited success in integrating these disparate efforts into a single high-performance package of sufficient reliability. This article lays the foundation for an electronic package designed to completely leverage the benefits of SiC semiconductor technology, with a focus on high reliability and fast switching capability. The interconnections between the gate drive circuitry and the power devices were implemented using a low temperature cofired ceramic interposer.

Effects of Bond Pad Thickness on Shear Strength of Copper Wire Bonds

2017 ◽  
Vol 2017 (HiTEN) ◽  
pp. 000068-000073 ◽  
Author(s):  
Subramani Manoharan ◽  
Chandradip Patel ◽  
Stevan Hunter ◽  
Patrick McCluskey
Keyword(s):  
Shear Strength ◽  
Shear Test ◽  
Failure Modes ◽  
High Reliability ◽  
Copper Wire ◽  
Test Method ◽  
Ball Bond ◽  
Wire Bond ◽  
Industry Standards ◽  
Wire Bonds

Abstract Copper (Cu) wire bonding is now widely accepted as a replacement for gold (Au), however, its use in high reliability applications is limited due to early failures in high temperature and humid conditions. The Au to Cu wire transition is mainly driven by cost savings though there are other advantages to Cu such as better electrical and thermal conductivity, slower intermetallic compound (IMC) formation and reduced wire sweep during transfer molding. Some automotive, industrial and aerospace industries are still reluctant to adopt Cu wire bonded products due to perceived risks of wire and bond pad cracks, the potential for corrosion, and some lack of understanding about its reliability in harsh conditions. A wire bond is considered good if destructive sampling qualification tests and periodic monitors pass for the batch. Tests include wire pull strength, wire bond shear, IMC coverage, and thickness of bond pad aluminum (Al) remaining beneath the bond. Nondestructive inspections also verify acceptable ball diameter and Al “splash”. This paper focuses on the bond shear test and its contribution to Cu ball bond reliability assessment, especially when changing Al bond pad thickness. A new revision of the JEDEC Wire Bond Shear Test Method, JESD22-B116B, has just been released, to include Cu wirebonds for the first time. It helps to clarify shear test failure modes for Cu ball bonds. However, there are still questions to be answered through research and experimentation, especially to learn the extent to which one may predict Cu ball bond reliability based on shear test results. Pad Al thickness is not considered in the current industry standards for shear test. Yet bond pad Al thickness varies widely among semiconductor products. This research is intended to contribute toward improved industry standards. In this study, power and time bonding parameters along with bond pad thickness are studied for bond strength. Several wire bonds are created at different conditions, evaluated by optical microscope and SEM, IMC% coverage and bond shear strength. Similar bonding conditions are repeated for bond pads of 4um, 1um and 0.5um thickness.

NSOP Reduction for QFN RF-IC Packages

2016 ◽  
Vol 2016 (1) ◽  
pp. 000530-000534
Author(s):  
Mumtaz Y. Bora
Keyword(s):  
Form Factor ◽  
Failure Modes ◽  
Cost Effective ◽  
Wire Bonding ◽  
Lead Frame ◽  
Front End ◽  
Wire Bond ◽  
The Wire ◽  
Copper Lead ◽  
Rf Ic

Abstract Wire bonded packages using conventional copper lead frame have been used in industry for quite some time. The growth of portable and wireless products is driving the miniaturization of packages resulting in the development of many types of thin form factor packages and cost effective assembly processes. Proper optimization of wire bond parameters and machine settings are essential for good yields. Wire bond process can generate a variety of defects such as lifted bond, cracked metallization, poor intermetallic etc. NSOP – Non- stick on Pad is a defect in wire bonding which can affect front end assembly yields. In this condition, the imprint of the bond is left on the bond pad without the wire being attached. NSOP failures are costly as the entire device is rejected if there is one such failure on any bond pad. The paper presents some of the failure modes observed and the efforts to address NSOP reduction [1].

Scanning Electron Microscopy in Hybrid Microelectronics

1976 ◽  
Vol 34 ◽  
pp. 456-457
Author(s):  
S. Khadpe ◽  
R. Faryniak
Keyword(s):  
Integrated Circuits ◽  
Thick Film ◽  
Integrated Circuit ◽  
Failure Modes ◽  
Three Dimensional ◽  
Circuit Components ◽  
Hybrid Microcircuit ◽  
Electrical Connections ◽  
Scanning Electron

The Scanning Electron Microscope (SEM) is an important tool in Thick Film Hybrid Microcircuits Manufacturing because of its large depth of focus and three dimensional capability. This paper discusses some of the important areas in which the SEM is used to monitor process control and component failure modes during the various stages of manufacture of a typical hybrid microcircuit.Figure 1 shows a thick film hybrid microcircuit used in a Motorola Paging Receiver. The circuit consists of thick film resistors and conductors screened and fired on a ceramic (aluminum oxide) substrate. Two integrated circuit dice are bonded to the conductors by means of conductive epoxy and electrical connections from each integrated circuit to the substrate are made by ultrasonically bonding 1 mil aluminum wires from the die pads to appropriate conductor pads on the substrate. In addition to the integrated circuits and the resistors, the circuit includes seven chip capacitors soldered onto the substrate. Some of the important considerations involved in the selection and reliability aspects of the hybrid circuit components are: (a) the quality of the substrate; (b) the surface structure of the thick film conductors; (c) the metallization characteristics of the integrated circuit; and (d) the quality of the wire bond interconnections.

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