Multi-touch Panel Testing
When the human body is close to the touchpad, the capacitance value between the sensing pad and the ground will change (general pf level). Capacitive touch pad (also known as: Surface capacitive) is through the use of the sensor detected by the change of capacitance value by calculating microprocessor, filtering interference and finally determining whether there is a human body close to achieve the key function. Compared with the traditional mechanical keys, the advantage is that there is no mechanical damage, and non-metals such as glass, acrylic, plastic can be used as the operating panel isolation, making the appearance of the product more atmospheric. In contrast, it can also realize the sliding operation that is difficult to achieve with traditional mechanical keys, so that the human-machine interface is more in line with the intuitive operation of people.
The outermost layer of the capacitive touch panel is a thin silicon dioxide hardening processing layer, and its hardness reaches 7; The second layer is ITO(conductive coating), through the conductive layer on the front of the average distribution of low-voltage conduction current, to establish a uniform electric field on the glass surface, when the finger touches the surface of the touch panel, it will absorb a small amount of current from the contact point, resulting in a voltage drop of the corner electrode, the use of sensing the weak current of the human body to achieve the purpose of touch; The function of the bottom layer of ITO is to shield electromagnetic waves, so that the touch panel can work in a good environment without interference. While the projective capacitive, which is the touch mode used by the famous Apple iPhone and Windows 7, has the feature of supporting multi-touch, which can shorten the user's learning time, just use the finger belly touch panel to avoid the use of stylus, and has higher light transmission and more power saving, more scratch resistance than resistive type (hardness up to 7H or more), greatly increase the service life without correction...
Touch technology can be divided into four kinds according to the principle of sensing, including resistive, capacitive, surface acoustic wave and optics. And capacitive can also be divided into surface capacitive and projected capacitive two kinds.
Touch technology applications:
Industrial applications (automatic processing machines, measuring instruments, centralized monitoring and control)
Commercial applications (ticketing systems, POS, ATMs, vending machines, stored value machines)
Life applications (cell phones, satellite positioning GPS, UMPC, small laptop)
Education and entertainment (e-books, portable game consoles, jukeboxes, electronic dictionaries)
Comparison of touch panel light transmission rate: resistive (85%), capacitive (93%)
Multi-touch panel test conditions:
Operating temperature range: -20℃～70℃/20%～85%RH
Storage temperature range: -50℃～85℃/10%～90%RH
High temperature test: 70℃/240, 500 hours, 80℃/240, 1000 hours, 85℃/1000 hours, 100℃/240 hours
Low temperature test: -20℃/240 hours, -40℃/240, 500 hours, -40℃/1000 hours
High temperature and high humidity test: 60℃/90%RH/240hours, 60℃/95%RH/1000hours 70℃/80%RH/500hours, 70℃/90%RH/240,500,1000hours, 70℃/95%RH/500hours 85℃/85%RH/1000hours, 85℃/90%RH/1000hours
Boiling test: 100℃/100%RH/100 minutes
Temperature shock - high and low temperature: (Temperature shock test is not equivalent to temperature cycling test )
-30℃←→80℃, 500cycles
-40℃(30min)←→70(30min)℃, 10cycles
-40℃←→70℃, 50, 100cycles
-40℃(30min)←→110℃(30min), 100cycles
-40℃(30min)←→80℃(30min), 10, 100cycles
-40℃(30min)←→90℃(30min), 100cycles
Thermal Shock Test - Liquid Type: -40℃←→90℃, 2cycles
Cold and thermal shock test-over room temperature: -30℃(30min)→R.T. (5min)→80℃(30min), 20cycles
Service life: 1,000,000 times, 2,000,000 times, 35,000,000 times, 225,000,000 times, 300,000,000 times
Hardness test: greater than hardness level 7 (ASTM D 3363, JIS 5400)
Impact Test: With more than 5kg of force, strike the panel on the most vulnerable area and the center of the panel respectively.
Pin(Tail) Pulling Test: 5 or 10kg downward pulling.
Pin Folding Test：135¢angle, left and right back and forth for 10 times.
Impact resistance test: 11φ/5.5g copper ball dropped at 1.8m height on the center surface of 1m object, 3ψ/9g stainless steel ball dropped at 30cm height.
Writing durability: 100,000 characters or more (width R0.8mm, pressure 250g)
Touch durability: 1,000,000, 10,000,000, 160,000,000, 200,000,000 times or more (width R8 mm, hardness 60°, pressure 250g, 2 times per second)
Test equipment:
Test equipment
Test Requirements and Conditions
Temperature & humidity test chamber
Equipment features: high-strength, high-reliability structural design - to ensure the high reliability of the equipment; working room materials for the SUS304 stainless steel - corrosion resistance, strong anti-fatigue thermal function, long service life; high-density polyurethane foam insulation materials - to ensure that the heat loss is reduced to a little; the surface of the plastic spraying treatment - to ensure that the equipment's lasting corrosion-resistant function and the appearance of the life; high-strength temperature-resistant Silicone rubber sealing strip - to ensure the high sealing of the equipment door.
High temperature & high humidity test chamber
High temperature and high humidity test chamber series, passed the CE certification, offer 34L, 64L, 100L, 180L, 340L, 600L, 1000L, 1500L and other volume models to meet the needs of different customers. In design, they use environment-friendly refrigerant and high-performance refrigeration system, parts and components are used in the international famous brand.
Two-Zone(Basket Type)
Thermal shock test chamber
Applicable to the assessment of products (the whole machine), parts and components, etc. to withstand rapid changes in temperature. Thermal shock test chambers can understand the impact of the test sample once or repeatedly due to temperature changes. The main parameters affecting the temperature change test are the high and low temperature values of the temperature change range, the retention time of the sample at high and low temperature, and the number of test cycles.
Three-zone (Ventilation Type)
Thermal shock test chamber
TS series thermal shock test chambers have complete equipment specifications - two-zone(basket type), three-zone (ventilation type) and horizontal movement type are available for users to choose, fully meeting the various requirements of different users; The equipment can also provide standard high and low temperature test function to achieve the compatibility of temperature shock and high and low temperature test; high strength, high reliability of the structure design - ensure the high reliability of the equipment.
Bellcore GR78-CORE is one of the specifications used in early surface insulation resistance measurement (such as IPC-650). The relevant precautions in this test are organized for reference of personnel who need to carry out this test, and we can also have a preliminary understanding of this specification.
Test purpose:
Surface Insulation Resistance Testing
1. Constant temperature and humidity test chamber: the minimum test conditions are 35°C±2°C/85%R.H., 85 ±2°C/85% R.H.
2. Ion migration measurement system: Allowing insulation resistance of the test circuit to be measured under these conditions, a power supply will be able to provide 10 Vdc / 100μA.
Test procedure:
a. The test object is tested after 24 hours at 23°C (73.4° F)/50%R.H. environment
b. Place limited Test patterns on an appropriate rack and keep the test circuits at least 0.5 inches apart, without obstructing air flow, and the rack in the furnace until the end of the experiment.
c. Place the shelf in the center of the constant temperature and humidity test chamber, align and parallel the test board with the air flow in the chamber, and lead the line to outside of the chamber, so that the wiring is far away from the test circuit.
d. Close the furnace door and set the condition to 35 ±2°C, at least 85%R.H. and allow the furnace to spend several hours stabilizing
e. After 4 days, the insulation resistance will be measured and the measured value will be recorded periodically between 1 and 2,2 and 3,3 and 4, 4 and 5 using an applied voltage of 45 ~ 100 Vdc. Under the test conditions, the test is sent out the measured voltage to the circuit after 1 minute. 2 and 4 are periodically at an identical potential. And 5 periodically at opposite potentials.
f. This condition only applies to transparent or translucent materials, such as solder masks and conformal coatings.
g. As for multilayer printed circuit boards required for insulation resistance testing, the only normal procedure will be used for insulation resistance testing circuit products. Extra cleaning procedures are not allowed.
Related test chamber： temperature and humidity chamber
Method of conformity determination:
1. After the electron migration test is completed, the test sample is removed from the test furnace, illuminated from the back and tested at 10 x magnification, and will not be found to reduce the electron migration (filamental growth) phenomenon by more than 20% between the conductors.
2. adhesives will not be used as a basis for republication when determining compliance with the 2.6.11 test method of IPC-TM-650[8] to examine appearance and surface item by item.
Insulation resistance does not meet the requirements of the reasons:
1. Contaminants weld the cells like wires on insulating surface of substrate, or are dropped by water of test furnace (chamber)
2. Incompletely etched circuits will reduce insulation distance between conductors by more than permitted design requirements
3. Chafes, breaks, or significantly damages the insulation between conductors
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