Technical Library | 2024-04-08 15:46:36.0
A designed experiment evaluated the influence of several variables on appearance and strength of Pb-free solder joints. Components, with leads finished with nickel-palladium-gold (NiPdAu), were used from Texas Instruments (TI) and two other integrated circuit suppliers. Pb-free solder paste used was tin-silver-copper (SnAgCu) alloy. Variables were printed wiring board (PWB) pad size/stencil aperture (the pad finish was consistent; electrolysis Ni/immersion Au), reflow atmosphere, reflow temperature, Pd thickness in the NiPdAu finish, and thermal aging. Height of solder wetting to component lead sides was measured for both ceramic plate and PWB soldering. A third response was solder joint strength; a "lead pull" test determined the maximum force needed to pull the component lead from the PWB. This paper presents a statistical analysis of the designed experiment. Reflow atmosphere and pad size/stencil aperture have the greatest contribution to the height of lead side wetting. Reflow temperature, palladium thickness, and preconditioning had very little impact on side-wetting height. For lead pull, variance in the data was relatively small and the factors tested had little impact.
Technical Library | 2022-10-31 17:09:04.0
The global transition to lead-free (Pb-free) electronics has led component and equipment manufacturers to transform their tin–lead (SnPb) processes to Pb-free. At the same time, Pb-free legislation has granted exemptions for some products whose applications require high long-term reliability. However, due to a reduction in the availability of SnPb components, compatibility concerns can arise if Pb-free components have to be utilized in a SnPb assembly. This compatibility situation of attaching a Pb-free component in a SnPb assembly is generally termed "backward compatibility." This paper presents the results of microstructural analysis of mixed solder joints which are formed by attaching Pb-free solder balls (SnAgCu) of a ball-grid-array component using SnPb paste. The experiment evaluates the Pb phase coarsening in bulk solder microstructure and the study of intermetallic compounds formed at the interface between the solder and the copper pad.
Technical Library | 2019-10-29 02:55:33.0
For every 10 ℃ increase in temperature, the reaction rate is twice to three times. This means that for every 10 ℃ increase in temperature, the life span of the product will be halved, and when the temperature rises by 20 ℃, the life span of the product will be reduced to 1/4. High temperature will lead to aging, oxidation, evaporation, physical deformation and so on. Low temperature will lead to embrittlement, ice formation, viscosity and solidification degree, loss of mechanical strength, physical shrinkage and so on. When the product is shipped, stored and operated in the environment, it will be endangered. In addition, each product has regulatory and certification requirements, and it is important to evaluate reliability and durability before it is put on the market. In general, according to the IEC60068 test standard, it requires the volume of the laboratory to be at least five times the total volume of the sample under test. Haida constant temperature and humidity box can help you meet this demand. So with the fast developmement of manufacturing industry,test becomes a necessity to see wether the product is able to meet regulated standards in R&D satge,Climatest Symor specializes in handling temperature and humidity,we supply environmental test chamber to China State-owned Research Institutes and laboratories,and obtain excellent reputation from international cllients,our company put much efforts on chamber R&D ,striving to supply best-quality climate simulation equipment and after-sale service. For details,pls visit our official website www.climatechambers.com
Technical Library | 2019-11-13 02:09:44.0
Dry oven is a must instrument almost for every laboratory in different industries,with nearly 20 years efforts and innovation,Climatest now masters core technique of dry oven manufacturing,no matter on temperature uniformity or temperature stability.Behind the quality is 15 years of consistent persistence,strong belief in excellence; from design to R & D to production, from promotion to sales to installation; every step should reach excellence,What you see, you use our products, you choose, you feel that we do our best,this is our faith. Dry Ovens are used to dry or temper electronic components,material tests,torrefaction, wax-melting ,high temperature aging ,preheating and sterilization in industrial and mining enterprises, laboratories and scientific research institutes. .Exterior chamber is made by reinforced steel with painting; working chamber made by anti-corrosion stainless steel SUS#304 .Intelligent PID control, LED controller with over-temperature alarm,timing range within 0~9999min .Hot air circulation system composed of Germany imported low-noisy air blower and optimal air duct which ensure uniform temperature distribution .Double layers of glass door, large transparent window to observe specimen .Forced air convection Climatest manufactures desktop and floor-standing models with RT+10°C-200°C,250°C,300°C,350°C,400°C temperature range,and customized as per special requirement,if you wanna know more details about our dry oven,please visit our product page:https://climatechambers.com/industrial-dry-oven/200-degree-c-hot-air-oven.html
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.
