Technical Library | 2015-08-13 15:52:40.0
Pad cratering has become more prevalent with the switch to lead free solders and lead free compatible laminates. This mainly is due to the use of higher reflow temperature, stiffer Pb-free solder alloys, and the more brittle Pb-free compatible laminates. However, pad cratering is difficult to detect by monitoring electric resistance since pad cratering initiates before an electrical failure occurs. Several methods have been developed to evaluate laminate materials' resistance to pad cratering. Pad-solder level tests include ball shear, ball pull and pin pull. The detailed methods for ball shear, ball pull, and pin pull testing are documented in an industry standard IPC-9708. Bansal, et al. proposed to use acoustic emission (AE) sensors to detect pad cratering during four-point bend test. Currently there is an industry-working group working on test guidelines for acoustic emission measurement during mechanical testing.
Technical Library | 2023-01-10 20:15:42.0
Over the past years there has been consistent growth in the use of electroless nickel / immersion gold (ENIG) as a final finish. The finish is now frequently being used for PBGA, CSP, QFP and COB and more recently gathered considerable interest as a low cost under-bump metallization for flip chip bumping application. One of the largest users for this finish has been the telecommunication industry, were millions of square meters of PCBs with ENIG have been successfully used. The nickel layer offers advantages such as multiple soldering cycles and hand reworks without copper dissolution being a factor. The nickel also acts as a reinforcement to improve through-hole and blind micro via thermal integrity. In addition the nickel layer offers advantages such as co-planarity, Al-wire bondability and the use as contact surface for keypads or contact switching. Especially those pads, which are not covered by solder need a protective coating in corrosive environment – such as high humidity or pollutant gas.
Technical Library | 2019-05-01 23:18:27.0
Moisture can accelerate various failure mechanisms in printed circuit board assemblies. Moisture can be initially present in the epoxy glass prepreg, absorbed during the wet processes in printed circuit board manufacturing, or diffuse into the printed circuit board during storage. Moisture can reside in the resin, resin/glass interfaces, and micro-cracks or voids due to defects. Higher reflow temperatures associated with lead-free processing increase the vapor pressure, which can lead to higher amounts of moisture uptake compared to eutectic tin-lead reflow processes. In addition to cohesive or adhesive failures within the printed circuit board that lead to cracking and delamination, moisture can also lead to the creation of low impedance paths due to metal migration, interfacial degradation resulting in conductive filament formation, and changes in dimensional stability. Studies have shown that moisture can also reduce the glass-transition temperature and increase the dielectric constant, leading to a reduction in circuit switching speeds and an increase in propagation delay times. This paper provides an overview of printed circuit board fabrication, followed by a brief discussion of moisture diffusion processes, governing models, and dependent variables. We then present guidelines for printed circuit board handling and storage during various stages of production and fabrication so as to mitigate moisture-induced failures.
Technical Library | 2020-10-27 02:02:17.0
Solder powder size is a popular topic in the electronics industry due to the continuing trend of miniaturization of electronics. The question commonly asked is "when should we switch from Type 3 to a smaller solder powder?" Solder powder size is usually chosen based on the printing requirements for the solder paste. It is common practice to use IPC Type 4 or 5 solder powders for stencil designs that include area ratios below the recommended IPC limit of 0.66. The effects of solder powder size on printability of solder paste have been well documented. The size of the solder powder affects the performance of the solder paste in other ways. Shelf life, stencil life, reflow performance, voiding behavior, and reactivity / stability are all affected by solder powder size. Testing was conducted to measure each of these solder paste performance attributes for IPC Type 3, Type 4, Type 5 and Type 6 SAC305 solder powders in both water soluble and no clean solder pastes. The performance data for each size of solder powder in each solder paste flux was quantified and summarized. Guidance for choosing the optimal size of solder powder is given based on the results of this study.
Technical Library | 2019-11-20 22:44:25.0
Salt spray test chamber is used to test teh salt corrosion resistance ability of hardware, metal and other auto parts,the chamber can quickly detect the corrosion resistance degree of products in the temperature, humidity and salt spraying environment, which can effectively improve production efficiency. So what is the reason why such a salt spray test chamber does not spray? As per our past maintenance experience,there are below reasons,customers can have a look,hope it is helpful: 1, the spray tower is blocked; 2, water pipes clogged, water flow can not go in; 3, the air compressor stops running,pls open the air compressor button; 4, main switch of the air compressor outlet is not turned on,pls turn on. 5, the solenoid valve fails, the pressure meter is broken or the pressure is too low, pls check with Climatest and repair it. 6, when the nozzle is clogged, the nozzle should be carefully removed and cleaned,because it is fragile. 7, if the spray pressure is normal, the position of the nozzle glass is also correct, but what is the reason for not spraying? In this case, it is necessary to carefully observe whether there is dirt at the contact surface of the nozzle. If so, clean up the dirt and the spray can be carried out normally. That‘s all we‘re going to talk about today. If you have any questions, follow us on facebook, Please feel free to ask us questions.
Technical Library | 2019-10-24 06:29:59.0
Making your novel electronic item design ready for mass fabrication and printed circuit board assembly consists of a lot of steps as well as risks. I will provide a few recommendations about how to neglect pricey errors and how to reduce the time to promote your novel item designs. You can hire printed circuit board assembly services for this. As soon as you have accomplished your product as well as printed circuit board design, you wish to get started developing prototypes prior to you commit to big fabrication volume. A lot of design software packages, for instance, PCB layout design software, as well as an industrial design software program, possess simulation potentials incorporated. Carrying out a simulation facilitates curtailing numerous design mistakes prior to the first prototype is developed. In case you are developing an intrusive item, you might desire to think about a modular design wherein all of the chief functionalities are situated in individual modules. All through your testing, you could then swap modules that don’t cater to the design limits. Spinning individual modules would be swifter and more cost-effective in comparison to spinning a complete design. Counting on the design intricacy, you can mull over manually mounting printed circuit board elements to bank dollars. Nonetheless, for medium to big intricacy this procedure likely to be very time taking, typically in case you wish to create numerous prototypes. Hence it makes sense thinking about a contract manufacturer for the assembly. Whilst running miniature quantity fabrication runs, the fabrication setup expenditure will usually control the by and large prototype constructs expenditure. Whilst seeking a subcontractor, it is finest to choose a vendor that focuses on prototype builds to reduce the cost. Prototype printed circuit board fabricators characteristically join the circuit boards of a number of clients which efficiently shares the setup expenditure in the midst of some customers. The disadvantage is that you would characteristically only be able to want among numerous standard printed circuit board material thicknesses as well as sizes. Apart from choosing a supplier with low setup expenditure, choosing a firm that would moreover be capable to manage your whole fabrication runs curtails mistakes because switching fabricators have the chance of errors owing to a specific supplier interpreting fabrication design data in a different way. This manner your design is already translated into the particular machine data that implies little or no setup expenditure for your final fabrication. A few PCB manufacturers also provide printed circuit board design services that are awesome plus if you do not possess experience with the design. Moreover, these vendors would be capable to help you in case there are issues with your design folders and be capable to detect issues prior to the fabrication.
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