Technical Library | 2023-04-17 17:05:47.0
In an ideal world, manufacturing devices would work all of the time, however, every company receives customer returns for a variety of reasons. If these returned parts contributed to a fail, most companies will perform failure analysis (FA) on the returned parts to determine the root cause of the failure. Failure can occur for a multitude of reasons, for example: wear out, fatigue, design issues, manufacturing flaw or defect. This information is then used to improve the overall quality of the product and prevent reoccurrence. If no defect is found, it is possible that in fact the product has no defect. On the other hand, the defect could be elusive and the FA techniques insufficient to detect said deficiency. No-clean flux residues can cause intermittent or elusive, hard to find defects. In an attempt to understand the effects of no-clean flux residues from the secondary soldering and cleaning processes, a matrix of varying process and cleaning operation was investigated. Of special interest, traveling flux residues and entrapped residues were examined, as well as localized and batch cleaning processes. Various techniques were employed to test the remaining residues in order to assess their propensity to cause a latent failure. These techniques include Surface Insulation Resistance1 (SIR) testing at 40⁰C/90% RH, 5 VDC bias along with C32 testing and Ion Exchange Chromatography (IC). These techniques facilitate the assessment of the capillary effect the tight spacing these component structures have when flux residues are present. It is expected that dendritic shorting and measurable current leakage will occur, indicating a failing SIR test. However, since the residue resides under the discrete components, there will be no visual evidence of dendritic growth or metal migration.
Technical Library | 2019-04-08 23:21:29.0
Climatest Symor® adopts molecular sieve to dry air, the whole system is controlled by microcomputer, when humidity is high, It will start to absorb moisture,when the humidity reach the pre-set value, it will stop absorbing, and then discharge the water to outside the cabinet by heating,again and again by automatic control. The most effective and environment-friendly moisture-absorbing desiccant is molecular sieve, molecular sieve is the microporous crystal material synthesized by silicon and aluminium oxide. In order to keep the crystal net discharge to be zero, atoms with cations are located in the crystal structure.and the cation used in these synthetic crystals is usually sodium. At present, there are two kinds of molecular sieves widely used in the dry box industry: Class A and Class X. Molecular sieves are synthesized, shaped and activated under strictly controlled production processes. The whole controlled sythesis process can ensure consistency of the three-dimensional pore size. 3A molecular sieve pore size is 3 angstroms, 4A molecular sieve pore size is 4 angstroms; 13X molecular sieve pore size is 8.5 angstroms. The working principle of molecular sieve: Molecular sieves adsorb molecules onto the crystal surface by physical attraction force. Since 95% surface area of the molecular sieve is within aperture,it needs to screen the adjacent molecules by different size. Only small size molecules can enter into the inner adsorption surface of the molecular sieve through the crystal aperture. This selective adsorption phenomenon is called molecular sieve effect. The molecular sieve adsorption capacity and charge density (polarity) are further related to the adsorbed molecules. The molecular sieves can further distinguish which of the mixed molecules can be adsorbed and determine to what extent the charge density can allow the molecules to be adsorbed onto the crystal. Water molecules are particularly small (2.6 angstroms), that belong to highly polar molecules (very strong positive and negative electron density), and are easily adsorbed by molecular sieves, even under very low moisture condition,once the water molecules are adsorbed,they will be firmly fixed on the crystal. The environment-friendly moisture absorption device is equipped with molecular sieve. When it’s absorbing, the memory alloy controller is in tensile state, and the spring is in contractive state,which just make the valve contact the outer baffle, this insulates the outside air from inside dry box air to achieve dehumidification purpose; and after molecular sieve absorbed moisture inside dry box and become saturated, the program will automatically control the memory alloy device to shrink it so that the valve reaches the inner baffle position. Meanwhile, due to the shrinkage of the memory alloy, the spring is stretched and the valve is pulled out of the outer baffle,so that the moisture in molecular sieve will be discharged into the outside. after the dehumidifying process finished, the program automatically control and reset the memory alloy and spring,to restart absorbing status.
Technical Library | 2019-11-15 02:20:26.0
Material Aging Test-UV Weathering Test Chamber 1.What is UV aging? UV aging chambers use fluorescent ultraviolet lamp as light source to simulate UV radiation and condensation in natural sunlight, and to carry out accelerated weather resistance test in order to obtain the result of weather resistance of the material. UV aging detection is widely used in non-metallic materials, organic materials (such as coatings, paints, rubber, plastics and their products) under the change of sunlight, humidity, temperature, condensation and other climatic conditions to test the aging degree and situation of related products and materials. 2.Why we should do UV aging test? When the product is placed in the ambient environment, there will be different problems taken place, such as appearance changes, including cracking, speckle, powdering or color change, and even performance degradation,which may be due to the loss of components in the resin resulting in chemical bonds changes inside the molecular structure, this is mainly caused by sunlight, industrial exclusion of waste gas, bacteria and so on. The aging performance of the product directly affects the lifespan of the product, so aging test become significant,non-metallic materials, organic materials (such as paints, paints, rubber, plastics and their products) are subject to changes in sunlight, humidity, temperature, condensation and other climatic conditions to test the degree and condition of aging of related products and materials. The natural aging test is to put the plastic specimen under the sun exposure, and it is directly under the natural climate environment,to test the material performance under various factors such as light, heat energy, atmospheric humidity, oxygen and ozone, industrial pollution and the like, the most harsh climate condition should be selected,or near the actual application area of the material, the test site shall be open and flat, no obstacle to affect the test results,the specimen holder shall be facing the equator and at an angle of 45 ° from the ground. When the main performance index of the specimen has been reduced, the test s/b terminated when it achieve the minimum allowable use value . in most case,the test is terminated when the product primary performance index falls to 50% of the initial value. The natural aging process is a very slow process, and there is a great difference in different geographical conditions, which brings difficulties to evaluate the aging resistance of the product. It is an attempt to make an evaluation of the aging performance of the plastic in a shorter time,that is accelerated aging test. The accelerated aging test can be used to simulate the human light source of the fluorescent lamp, including the carbon arc lamp, the xenon arc lamp and the fluorescent ultraviolet lamp, and the artificial light sources can generate more light than the natural sunlight on the ground. When these artificial light sources are used, it is also common to use the combination of the condenser to simulate the rain drop, the dew and the like to conduct the aging test on the product.
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