Technical Library | 2019-05-21 17:23:47.0
Reflow temperature profiling is the most important aspect of proper control of the solder reflow process. It may appear to some to be a magical art practiced by a select experienced few, who are able to divine the proper settings for a reflow oven by reading graphs as if they were tea leaves. This does not have to be true. This article outlines a systematic method by which engineers and technicians can implement a successful reflow process from scratch.
Technical Library | 2019-12-12 02:43:44.0
Today we discuss the reason that causes temperature humidity chamber to alarm,In most cases, the equipment alarm is caused by the improper operation in the process of use, which mainly includes following reasons:that are refrigeration system, temperature system and circulating system. First, Refrigeration system 1, refrigeration compressor overpressure alarm. If the refrigerant pressure exceeds the set value, it will stop and alarm at the same time. At this time, the fault must be eliminated and then manually reset. 2, short phase power supply, phase sequence alarm. When the external power supply of the equipment is out of phase or the phase sequence is changed, it will stop and alarm at the same time. 3. The circulating cooling water is short of water to alarm. When the water pressure of the cooling circulating water system is insufficient, it will stop and alarm at the same time, and it must wait for the fault to be eliminated and reset at the same time before it could run normally. 4, refrigeration compressor overheating alarm. When the coil of the compressor is overheated and the power supply of the line is not normal, it will stop and alarm at the same time. Second, Temperature system 1, the overtemperature alarm in the chamber. The sensors in the channel and the sample area are equipped with overtemperature protection devices, and there are also overtemperature protecter on the control panel. When the temperature in the working chamber exceeds the setting value on the controller, it will stop and alarm. 2. sample overtemperature protection. When the temperature in the sample area exceeds the protection temperature set by the controller, it will stop and alarm at the same time. The overtemperature protection of the sample is divided into upper limit protection and lower limit protection, which can be set according to the demand, Third,Circulating system 1. The alarm is caused by the overheating of the circulating fan. When the coil of the fan is over-heated, the alarm will be stopped at the same time. 2. The fan over-current alarm. When the current of the fan exceeds the allowable value, the alarm is stopped at the same time, and the normal operation can only be carried out after the fault maintenance of the overcurrent is completed. This is what we talk about today,if you have more questions,let us know.
Technical Library | 2019-05-21 00:21:26.0
Continue to talk about the dust removal from temperature humidity test chamber. Cleaning and maintenance: 1) Pls remove internal impurities inisde chamber before operation. 2) The power distribution room should be cleaned at least once a year, and the dust can be removed by vacuum cleaner. 3) The exterior chamber must also be cleaned more than once a year, which can be wiped with soapy water. Inspection and maintenance of humidifier: The water storage in humidifier should be replaced once a month to ensure clean water quality, humidifying water tray should be cleaned once a month to ensure smooth flow of water. The inspection of over-temperature protector:during the test: If the temperature is over 20 ℃ ~ 30 ℃ than the maximum value setted,the power supply of the heater will stop, the "OVERHEAT" overt-emperature warning light will automatically turn on but the fan is still in operation, if the equipment runs without operator around,the operator should check the over-temperature protector in advance to ensure wether it has been setted properly before start [wet ball over-temperature protector set to 120 ℃].
Technical Library | 2019-11-12 02:09:22.0
Thermal shock test chamber can be used for testing the chemical change or physical damage on composite materials caused by the thermal expansion and contraction of the sample in the shortest time,which is subjected to extremely and continuous high and low temperature environment.so how to check the temperature recovery time of this chamber? Normally we take following steps to inspect the temepratuire recovering time: 1.Install the temperature sensor at the specified position, and adjust the temperature controller of hot zone and cold zone to the required nominal temperature respectively. 2.The temperature increases and reduces respectively,30min after temperature in two zones reach stable status,record temperature value of the measuring point,pls set the temperature value of two zones to be required nominal temperature. 3.The temperature shock test chamber automatically places the inspected load into theh ot zone,select the corresponding retention time according to regulated standard. 4.Set the transfer time,then the inspection load is transferred from hot zone to cold zone, and the temperature of the measuring point is observed and recorded, and then the reverse conversion of the load from cold zone to hot zone is carried out according to the same method, and the temperature of the measuring point is observed and recorded. www.climatechambers.com
Technical Library | 2011-01-06 18:03:18.0
The oven recipe, which consists of the reflow oven zone temperature settings and the speed of the conveyor, will determine a specific time‐temperature profile for a given PCB assembly. In order to achieve a good quality PCB assembly, the time‐temperature
Technical Library | 2021-11-03 16:49:59.0
Ultrathin bare die chips were soldered using a novel soldering technology. Using homogeneous flash light generated by high-power xenon flash lamp the dummy components and the bare die NFC chips were successfully soldered to copper tracks on polyimide (PI) and polyethylene terephthalate (PET) flex foils by using industry standard Sn-Ag-Cu lead free alloys. Due to the selectivity of light absorption, a limited temperature increase was observed in the PET substrates while the chip and copper tracks were rapidly heated to a temperatures above the solder melting temperature. This allowed to successfully soldered components onto the delicate polyethylene foil substrates using lead-free alloys with liquidus temperatures above 200 °C. It was shown that by preheating components above the decomposition temperature of solder paste flux with a set of short low intensity pulses the processing window could be significantly extended compared to the process with direct illumination of chips with high intensity flash pulse. Furthermore, it was demonstrated that with localized tuning of pulse intensity components having different heat capacity could be simultaneously soldered using a single flash pulse.
Technical Library | 2019-09-24 15:41:53.0
This paper focuses on three different coating material groups which were formulated to operate under high thermal stress and are applied at printed circuit board manufacturing level. While used for principally different applications, these coatings have in common that they can be key to a successful thermal management concept especially in e-mobility and lighting applications. The coatings consist of: Specialty (green transparent) liquid photoimageable solder masks (LPiSM) compatible with long-term thermal storage/stress in excess of 150°C. Combined with the appropriate high-temperature base material, and along with a suitable copper pre-treatment, these solder resists are capable of fulfilling higher thermal demands. In this context, long-term storage tests as well as temperature cycling tests were conducted. Moreover, the effect of various Cu pre-treatment methods on the adhesion of the solder masks was examined following 150, 175 and 200°C ageing processes. For this purpose, test panels were conditioned for 2000 hours at the respective temperatures and were submitted to a cross-cut test every 500 h. Within this test set-up, it was found that a multi-level chemical pre-treatment gives significantly better adhesion results, in particular at 175°C and 200°C, compared with a pre-treatment by brush or pumice brush. Also, breakdown voltage as well as tracking resistance were investigated. For an application in LED technology, the light reflectivity and white colour stability of the printed circuit board are of major importance, especially when high-power LEDs are used which can generate larger amounts of heat. For this reason, a very high coverage power and an intense white colour with high reflectivity values are essential for white solder masks. These "ultra-white" and largely non-yellowing LPiSM need to be able to withstand specific thermal loads, especially in combination with high-power LED lighting applications. The topic of thermal performance of coatings for electronics will also be discussed in view of printed heatsink paste (HSP) and thermal interface paste (TIP) coatings which are used for a growing number of applications. They are processed at the printed circuit board manufacturing level for thermal-coupling and heat-spreading purposes in various thermal management-sensitive fields, especially in the automotive and LED lighting industries. Besides giving an overview of the principle functionality, it will be discussed what makes these ceramic-filled epoxy- or silicone-based materials special compared to using "thermal greases" and "thermal pads" for heat dissipation purposes.
Technical Library | 2021-07-20 20:02:29.0
During the manufacturing of printed circuit boards (PCBs) for a Flight Project, it was found that a European manufacturer was building its boards to a European standard that had no requirement for copper wrap on the vias. The amount of copper wrap that was measured on coupons from the panel containing the boards of interest was less than the amount specified in IPC-6012 Rev B, Class 3. To help determine the reliability and usability of the boards, three sets of tests and a simulation were run. The test results, along with results of simulation and destructive physical analysis, are presented in this paper. The first experiment involved subjecting coupons from the panels supplied by the European manufacturer to thermal cycling. After 17 000 cycles, the test was stopped with no failures. A second set of accelerated tests involved comparing the thermal fatigue life of test samples made from FR4 and polyimide with varying amounts of copper wrap. Again, the testing did not reveal any failures. The third test involved using interconnect stress test coupons with through-hole vias and blind vias that were subjected to elevated temperatures to accelerate fatigue failures. While there were failures, as expected, the failures were at barrel cracks. In addition to the experiments, this paper also discusses the results of finite-element analysis using simulation software that was used to model plated-through holes under thermal stress using a steady-state analysis, also showing the main failure mode was barrel cracking. The tests show that although copper wrap was sought as a better alternative to butt joints between barrel plating and copper foil layers, manufacturability remains challenging and attempts to meet the requirements often result in features that reduce the reliability of the boards. Experimental and simulation work discussed in this paper indicate that the standard requirements for copper wrap are not contributing to the overall board reliability, although it should be added that a design with a butt joint is going to be a higher risk than a reduced copper wrap design. The study further shows that procurement requirements for wrap plating thickness from Class 3 to Class 2 would pose little risk to reliability (minimum 5 μm/0.197 mil for all via types).Experimental results corroborated by modeling indicate that the stress maxima are internal to the barrels rather than at the wrap location. In fact, the existence of Cu wrap was determined to have no appreciable effect on reliability.
Technical Library | 2019-12-13 00:39:29.0
Salt spray corrosion chamber can test the ability of material and its protective layer to resist salt mist corrosion, or compare the process quality of similar protective layers, at the same time; this equipment is suitable for parts, electronic components, protective layer of metal material and other industrial products. Salt spray test is divided into neutral and acid test. What is the difference between neutral and acid in salt spray test? First, the temperature applied in the test method is different: Neutral test: a. Laboratory:35°C ±1°C, b. Saturated air drums:47°C ±1°C Acid test: a. Laboratory:50°C ±1°C, b. Saturated air drums:63°C ±1°C Second, the production material is different,neutral test chamber adoptes the traditional PVC plates, acid test chamber asopts PP sheet,which is more high temperature resistance and suits strong acid test. Third. Different test methods satisfied Neutral salt spray chamber according to GB/T 2423.17-2008, GB/T 2423.18-2000, salt spray test method and GB/T 10125-1997, GB/T 10587-2006, GB10593.2-1990, GB/T 1765-1979, GB/T 1771-2007, GB/T 12967.388, GB/T 1705.8-2008, etc. In addition to the test methods specified in the national standard, acid salt spray chamber also needs to expand the standard setting such as IEC,MIL,DIN,ASTM,IS,CNS. Last, Comparison of neutral test solutions China: NaCI distilled water solution NaCI mass concentration (50 ±5) g ≤ l pH value 6.5 ≤ 7.2 United States: distilled water solution NaCI mass concentration 5% ±1% pH value 6.5 ≤ 7.2 Germany: NaCI distilled water solution NaCI mass concentration (50 ±5) g ≤ l pH value 6.5 ≤ 7.2 Japan: NaCI distilled water solution NaCI mass concentration 5% ±1% pH pH value 6.5 ~ 7.2 France: NaCI distilled water solution NaCI mass concentration 5% pH 6.5 ≤ 7.2 https://climatechambers.com/articles&latestnews/difference-between-neutral-and-acid-salt-spray-corrosion-test.html
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