Microtechnology Reliability
Introduction
Customer requirements and international legislation all place demands on component reliability. Specifying lifetimes and guaranteeing fitness-for-purpose are all accepted as part of the job in these times. But how can products/components/systems be qualified in these ways?
What is reliability?
A quality component is defined as one that 'meets the required functional performance under the stated conditions', while a reliable component is one that 'meets the required functional performance under the stated conditions for the required duration'. However needs are changing and components are being utilised in different applications, where conditions of use may not always be specified, therefore in-service lifetime data is not always easily found.
Throughout a product's life cycle there are three reliability regimes - early failure, random failure and wearout - which have different (and independent) failure rate behaviours. The manner in which reliability is determined can differ quite significantly between the different reliability regimes. Failure mechanisms have to be identified and cured - good manufacturing technologies and practices should be implemented at the outset. In properly controlled development and production, it is unlikely that there would be high levels of early or random failures. Therefore, the main issue is the onset of wearout of particular technologies which is related to the environment in which the components operate.
Testing reliability
The aim of Environmental Stress Screening (ESS) is to identify faults and prevent them from leaving the supplier. It is a production process and as such all units should be submitted for inspection. It is a critical element of ESS that the test does not damage good components. Conversely, Highly Accelerated Stress Tests (HAST) accelerate field failure mechanisms and test good devices to destruction in order to give an understanding of lifetime and failure modes.
One of the problems with the field of reliability engineering is that it is necessarily complex. It is clearly multidisciplinary in nature, requiring some understanding of materials, physics, electronics, statistics and an analytical approach. Determining the capability of a component or a system to meet a specific performance requirement for its intended lifetime requires considerable information. Existing data can be reused, however in the microtechnology field there are drives for operation in more extreme environments, new designs and process techniques as well as new environmental legislative requirements.
How can TWI help?
The Microtechnology and Reliability Centre at TWI has experience in over 40 methods of joining materials for small scale components and assemblies and the knowledge and facilities to help companies select the most appropriate for their requirements. TWI can call upon its extensive experience in reliability engineering, FEA modelling, electronics packaging, adhesives, materials, structural and failure analysis to give a unique perspective on product reliability and design for life issues.
Environmental Test facilities:
- HAST testing up to 150°C with 95%RH
- Humidity testing up to 85°C/85%RH
- Corrosion monitoring 100%RH at 42-48°C
- Damp heat testing from 40-120°C with 70-98%RH
- Thermal cycling from -70°C to 180°C
- Thermal shock testing from -65°C to 150°C
- Thermal storage to 400°C
- Mechanical cycling
- Design and build of specific test equipment
Facilities for failure analysis:
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Vibration stress in a wire bond
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In addition to these test and analysis facilities, TWI has several case studies to demonstrate the benefits of its modelling capabilities in the areas of finite element analysis, assessing risk reduction and production line flow. |
In the reduced time frame available to prove that your newest product design is ready for market, TWI offers the rapid product assessment package you need to carry out design validation and product evaluation.
Reliability Test Equipment in Microtechnology group
Design Environmental Ltd Environment Damp Heat Chamber |
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| Manufacturer | Design Environmental Ltd | |
| Purpose | For environmental testing of electronic and other small components and materials | |
| Temperature Range | 40°C to +120°C | |
| Humidity Range | 70% to 98% | |
Hirayama Humidity Controlled Autoclave |
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| Manufacturer | Hirayama |  |
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| Purpose | For highly accelerated stress testing of hermetic and not hermetic electronics components | ||
| Temperature Range | +50°C to +150°C (but Hast test must be done below 130°C) | ||
| Humidity Range | 45 to 95% | ||
Angelantoni Climatic Temperature Controlling Environmental Chamber |
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| Manufacturer | Angelantoni | |
| Purpose | For thermal cycling environmental testing of electronic and other small components and materials | |
| Temperature Range | -70°C to +180°C | |
Genlab Thermal Oven |
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| Manufacturer | Genlab | |
| Purpose | For thermal storage tests | |
| Temperature Range | Ambient to +400°C | |
Thermal Shock System |
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| Description: | Liquid Bath Thermal Shock Chamber | |
| Manufacturer: | Tabai Espec Corp (Japan) | |
| Cold Bath | Hot Bath | |
| Temp. Range: | -65°C to 0°C | 50°C to 150°C |
| Dwell Time: | 0-70 min | 0-70 min |
Other test and monitoring equipment:
| Micro Tensile 10 pull tester Dage 4,000 wire pull test and ball shear BT100 Die shear tester Gross leak bubble tester Lloyds tensile tester Surf-Com surface measurer Edwards He leak detector Pressure tester Unitek loop pull tester TWI 30 degree wire pull TWI ball shear tester |
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| Video microscope Set (printer) Real time x-ray IR reflow oven Wire saw Diamond saw |
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Failure Analysis and Analytical Facilities
Sample preparation
- wire saw
- diamond saw
Inspection
- NDE technology
- SEM with EDX (scanning electron microscope with energy dispersive x-ray)
- OES (optical emission spectrometry)
- DSC (differential scanning calorimetry)
- FTIR (fourier transform infra-red spectrometry)
- X-ray fluorescence
Corrosion expertise
Materials expertise
Finite Element Analysis
- Cyclic loading
- Distortion
- Electron flow
- Magnetics
- Electrostatics
- High voltage stressing
- Fatigue fracture
- Static failure
- Fitness for service
- Thermal loading
- Materials properties
- Diffusion
- Pressure
Andy Whitaker
TWI Ltd
Granta Park
Great Abington
Cambridge
CB21 6AL, UK
Tel: +44 (0)1223 899000
Fax: +44 (0)1223 894615
E-mail: micro@twi.co.uk
Copyright ©2005 TWI Ltd
