Your smartphone will travel with you everywhere. It could be on a dashboard in summer, taken out in the cold mornings, to humid coastal cities and come back with sand in the speaker grill. Customers expect it to be reliable and work for years.
The only true way to ensure this is by testing. This guide will help you understand how to buy the right test chambers for mobile device testing. Including what type of chambers you’ll need, what specs to look for, what to ask manufacturers and what to avoid.
Why Environmental Testing is Important
Smartphones have many components inside a very small sealed housing. This includes a lithium-ion battery, high density circuit boards, glass, adhesives and many connectors. This leaves little room for error. Environmental testing ensures that your design can withstand the heat, cold, humidity and dust. This will ensure a durable product with consistent performance. As there is a battery included, it is also a safety concern. Often retailers and network operators will want to see test results so it is a key part of bringing a phone to market.
Common Environmental Risks for Smartphones
High temperatures can cause your smartphone to overheat if left in a car or on a sunny surface. This can cause it to run slowly, shut down and cause battery degradation. Cold can cause the battery to lose power, and cause sluggish displays. High humidity can cause condensation inside the housing. This can cause corrosion of contacts and short circuits. Dust and sand can get into ports, speakers and buttons. This can cause wear to seals. Sudden temperature changes such as going from an air-conditioned office to the heat can cause stress on the joints between materials causing solder cracks and adhesive failure.
Components to Test on Mobile Devices
The battery comes first because its capacity, charging and safety of the battery will be affected by temperature. Printed circuit boards and solder joints are a common failure point with temperature changes. Displays and touch panels can become sluggish. Cameras, fingerprint scanners and other sensors must be accurate. Connectors like USB-C ports and SIM trays must be resistant to corrosion. Seals and adhesive joints will bond the device together and stop water and dust from entering.
Types of Environmental Test Chambers for Mobile Devices
There is no one test chamber that will do everything, most labs will have 2 or 3 different types. Most environmental testing equipment for mobile devices will fall into 4 categories.
1.Temperature & Humidity Chambers
This is the environmental test chamber for mobile devices. It will allow you to put your smartphones at set temperatures and humidity levels. Often devices will be running, charging or playing video to test performance and aging. Humidity can be tested in a damp heat environment. The Envisys ET Series can operate between -70°C to +180°C and 10% to 98% humidity. It operates well between 10°C to 85°C.
2. Thermal Shock Chambers
Thermal shock chambers move components between hot and cold areas in seconds. This is ideal for finding cracked solder joints and weak adhesive joints. Envisys thermal shock chambers operate between -45°C and +210°C and can move between hot and cold areas in less than 10 seconds.
3.Dust Chambers
This test chamber will move test dust around the device to see how well the seals are at keeping dust out. It is used to confirm IP5X and IP6X ratings (IEC 60529). Water resistance is tested separately using rain and immersion setups. Read more about how IP test chambers for testing mobile phones here.
4. Temperature Cycling Chambers
Temperature cycling will move devices between hot and cold at a set rate. This is a more gentle test than shock and will show slower fatigue on solder joints and bonded parts over many cycles. Many temperature and humidity chambers will be able to cycle. The rate of change is important. The EM-Series benchtop can cycle at around 1-5°C per minute depending on the refrigeration setup.
Things to Consider When Buying an Environmental Test Chamber
Choosing the correct test chamber will depend on what products you are testing, what standards you need to meet and what testing you will be carrying out.
1.Temperature Range
Mobile devices are commonly tested between around -20° or -40°C to +60° or +85°C depending on the spec. Component testing can be carried out at higher ranges. Ensure you choose a chamber that can cover your limits with some headroom.
2.Humidity Control
If you’re testing in a damp heat environment you’ll need a chamber with good humidity control. Ensure you know what humidity range it can handle, what the accuracy of the set point is and what temperatures it can control humidity at. Both the ET Series and EM-Series have humidity control of ±3% RH.
3.Size & Testing Capacity
The size of the chamber will depend on how many devices you wish to test and if they require cabling for power/data. Benchtop chambers such as the EM-Series between 30L to 100L are great for batch testing. Large programs will require a floor standing chamber. Ensure there is plenty of space between devices for air flow.
4. Temperature Uniformity & Stability
Even if the chamber can reach the temperature the sensor reads the corners could be hotter or colder. This would mean the devices in those areas would be tested differently. Ensure you ask for uniformity figures. The EM-Series has control accuracy of ±1.0°C and uniformity of ±1.5°C up to 125°C.
5.Standards Compliance
Ensure the chamber can carry out your required profiles. With mobile devices this will usually be parts of IEC 60068 standards. For example 60068-2-1, 60068-2-2 (dry heat), 60068-2-78 and 60068-2-30 (damp heat) and 60068-2-14 (change of temperature). Rugged devices may also be tested to MIL-STD-810. For water and dust protection see our guide on how to choose an IP test chamber.
6. Controller
Ensure you have a touchscreen controller with profiles, real time monitoring and data logging. Alarms for overheating, door opening and sensor faults are very important for overnight testing. A large clear screen will help with set up. The ET Series has a 10.1 inch screen. This means it can be set up quickly and reduces any errors made by the operator. Ensure you know where the cabling ports are as many devices will be powered and monitored during testing.
7. Efficiency & Running Costs
Not only will you have to pay for the initial purchase but the chamber will use power for refrigeration, heating and humidification. Some chambers will also require cooling water. A smaller chamber that is sized to your load will usually be cheaper to run. Good insulation and sealing on doors will also help reduce energy loss during long tests. Ask what the power, water and regular maintenance costs are.
Questions to Ask Manufacturers
A good environmental test chamber for testing smartphones should have the following answers.
1. What Accuracy do they have?
Ask what the accuracy, uniformity and fluctuation are. How were they measured? The ET Series has temperature accuracy of 0.1°C to ±1.2°C. This is measured at the control sensor with 0.1°C resolution.
2. What Standards do they support?
Ask what standards and testing they can carry out. Don’t just ask if it is IEC compliant. Ask for profiles or test reports. For mobile devices this should include the IEC 60068 tests you carry out. If you are looking to get dust or water equipment from the same supplier you should also ask if it can carry out IEC 60529.
3.Can they carry out Long Duration Testing?
Damp heat and aging can be carried out for 500 or 1000 hours. Ensure the refrigeration system is designed for duty.
4. What is their Maintenance Schedule?
Ask what needs maintaining and how often. This will include refrigeration, humidifier cleaning, seals and calibration. It is common to have calibration every 6-12 months. This can be traced back to NABL or NIST.
5.Can they be Monitored Remotely?
This will save you time. Ask if you can monitor your tests from your desk or phone. Ensure the controller can be accessed via Ethernet, have alarms and data exporting. If your test fails at 2 you will know straight away and someone can help.
6.What Service do they Offer?
Who will install and commission the chamber? How will operators be trained? How quickly will engineers come out if there is a breakdown? Are spares held locally?
Common Mistakes When Purchasing a Test Chamber
Most people make the same mistakes when purchasing.
1. Cheap Chamber
A cheap chamber may not have good uniformity and a poor cooling system. This can cause incorrect results. This can end up costing you more in extra testing and delaying your launch. Be sure to compare the chambers and how they work. Look at the running costs over the lifetime.
2.Not Thinking Ahead
New phone models will have new batteries, materials and standards. The chamber may not be suitable this year. Ensure you have some headroom in the temperature range, size and humidity control.
3.No Recovery Time
When you open the door to place devices in or devices are powered causing heat the chamber needs to return to the correct temperature. If it has a slow recovery time all your tests will take longer. This could cause your samples to go out of their limits. Ask for recovery times with a load.
4.No After Sales Support
If the chamber is sitting idle whilst you wait for a spare part this will delay your entire testing schedule. Choose a manufacturer that has service engineers and a clear support process. Ask users how quickly issues were resolved. Can calibration and preventative maintenance be done on site?
Conclusion
You need to ensure the chamber you purchase is suitable for your devices and standards. Ensure you know what tests you require and look at the temperature range, humidity control, size, uniformity and recovery times. Ask manufacturers for clear figures. A good smartphone reliability test chamber from a manufacturer that can back it up will give you results for years. Knowing how to purchase test chambers for mobile device testing will save you money on features you don’t need and ensure you have the features you need. Envisys engineers can help you find the right chamber for your testing. From benchtop units like the EM-Series to full size ET Series chambers.
FAQs
1.What Environmental Testing is done on Mobile Devices?
Typically low temperature operation & storage, damp heat, temperature cycling, thermal shock and dust/water ingress for IP ratings.
2.How do Manufacturers Test Smartphones for Extreme Temperatures?
The phones will be placed in a temperature chamber and kept at set high and low temperatures. Often devices will be running or charging whilst in the chamber. This will ensure the device is performing well, battery is behaving correctly and no physical damage. Shock and temperature cycling will cause sudden or repeated changes between the extremes.
3.What is the Ideal Size for Mobile Device Testing?
This will depend on how many devices you are testing. Benchtop chambers between 30L to 100L are ideal for small batches. Large floor standing chambers are ideal for high volume testing.
4.Can Environmental Test Chambers Simulate Real World Conditions for Smartphones?
Yes. They can simulate heat, cold, humidity, sudden temperature changes and dust. This means you can test years of use in weeks.
