What to look for when buying a used mounter A lot of enterprises on the SMT line before the first, will face the choice, in the new machine and second-hand mounter entangled between. On the new machine, the budget is too large, the delivery time is too long, engineers are not good recruitment, accessories are not good to find; buy used mounter it, the quality of the bosses will be worried about, after all, used things, mention the second-hand fear of the machine out of order. In fact, the above example is just a part of the bosses many concerns, expect fast returns, small risk, less investment in friends, or recommended to buy a used mounter. The above mentioned, buy used mounter concerns are very much, then, buy mounter to pay attention to what? Let me tell you. First, to see if the machine is overseas  Overseas mounter machines have less running time. This is a foreigner and our way of working differentiated decision. We should know that foreign enterprises are 8-hour work system, people move maneuver, people stop stop. Look at the domestic, the domestic will not be any boss stupid to do so.  Overseas mounter machine maintenance in place. Machine maintenance are often carried out, daily maintenance, monthly maintenance, quarterly action overhaul. In this way, there are very few used mounter machine failures.   Many suppliers use this as a selling point, not realizing that many companies are buying sheep's head hanging dog meat. Be sure to add to recognize.  After refurbishment and maintenance (refurbishment is not the appearance of paint on the line, but the replacement of internal precision parts and according to the new machine standard precision adjustment test), the appearance of the second-hand mounter will be the same as the new machine, and can ensure that more than 90% of the function of the new machine, can be full-speed production. Reliability, stability can be comparable to the new machine, and the price of the new machine 1/3 less.    Second, the supplier of used mounter   Many friends decided to choose the second-hand equipment will be very entangled, the domestic second-hand business is too much. Mixed fish and dragons, it is not good to choose, often by friends, but this is not very insurance, after all, is the economy and society.   Suggestion: look for large-scale suppliers. Whether it is the pre-maintenance refurbishment of equipment, training in the medium term, the latter part of the service, are done in front of small companies. (You can visit the supplier, visit their customers)    Third, the supplier recommended machine is suitable?   Many people hear that customers want 400,000 mounter, they immediately recommend a machine, do not go to understand what customers do products, how big the PCB board, which is very irresponsible. Customers should buy a machine according to their product characteristics to decide. Because there are too many used mounter machines on the market, the speed is not the same, customers must do a long-term consideration and planning before buying SMT equipment. Buy a cost-effective machine. Fourth, buy used mounter does not provide service    Now many companies have popularized this practice, but for the first on-line friends, you are not recommended to do so.   Not package service is cheaper, but the back of what went wrong, the loss of not just time. Hire an engineer outside, they say the time, they say the price, the minimum should be 10,000 dollars. That's just treating the symptoms, not the root cause. Whereas a large company providing service will respond to the service to the end, and in addition to maintenance, will cycle it.   Earlier mentioned the concept of large companies, small companies. Small companies on the three, five people every day to speculate on the kind of single. Large companies, they sell hundreds of machines a year, can provide refurbishment and after-sales service, because they have their own service team. In fact, buy used mounter, but also to understand a lot of things, just read a few articles, asked a few suppliers is far from enough. *It is good to have a site visit. Postscript: see this article friends, whether you have no intention of buying SMT equipment. All hope to help you.

Printed Circuit Vocabulary Knowledge Printed Circuit Vocabulary Knowledge - Basic Vocabulary Usually, smt engineers use PCB drawing tools are foreign engineers to study out, almost all of them are English words, although some of the tools and software is translated into Chinese, but mastering these commonly used printed circuit vocabulary is still a great benefit. Here to introduce the following. 1, base material: base material 2, laminate: laminate 3, covered with metal foil base material: metal-clad bade material 4、Copper clad laminate: copper-clad laminate (CCL) 5、Single-sided copper-clad laminate: single-sided copper-clad laminate 6、Double-sided copper-clad laminate：double-sided copper-clad laminate 7、Composite laminate: composite laminate 8、Thin laminate：thin laminate 9、Metal core copper-clad laminate：metal core copper-clad laminate 10、Metal base copper-clad laminate：metal base copper-clad laminate 11、Flexible copper-clad dielectric film：flexible copper-clad dielectric film 12、Base material：basis material 13、Pre-impregnated material: prepreg 14、Bonding sheet：bonding sheet 15、Pre-impregnated bonding sheet: preimpregnated bonding sheer 16、Epoxy glass substrate：epoxy glass substrate 17、Laminate for additive process：laminate for additive process 18、Prefabricated inner laminate: mass lamination panel 19、Inner core plate: core material 20、De-copper foil surface：foil removal surface 21、Laminate surface：unclad laminate surface 22、Base film surface：base film surface 23、Adhesive surface：adhesive faec 24、Original finish surface: plate finish 25、Rough surface：matt finish 26、Longitudinal direction：length wise direction 27、Mold to: cross wise direction 28、Cut to size panel：cut to size panel 29、Catalyzed plate：catalyzed board ,coated catalyzed laminate 30、Coated catalyzed laminate：adhesive-coated catalyzed laminate 31、Adhesive-coated uncatalyzed laminate: adhesive-coated uncatalyzed laminate 32、Bonding layer：bonding layer 33、Bonding film: film adhesive 34、Adhesive coated dielectric film：adhesive coated dielectric film 35, unsupported adhesive film: unsupported adhesive film 36, cover layer: cover layer (cover lay) 37, reinforced sheet: stiffener material 38、Copper foil surface: copper-clad surface 39, phenolic paper copper-clad laminate: phenolic cellulose paper copper-cladlaminates (phenolic/paper CCL) 40、Epoxy paper copper-clad laminates: epoxy cellulose paper copper-clad laminates(epoxy/paper CCL) 41, epoxy glass fabric copper-clad laminates: epoxy woven glass fabric copper-clad laminates 42、Epoxy glass fabric paper copper-clad laminates: epoxy cellulose paper core, glass cloth surfacescopper-clad laminates 43, epoxy glass cloth glass fiber composite copper-clad laminates: epoxy non woven/woven glass reinforcedcopper-clad laminates 44、Polyester glass fabric copper-clad laminates: ployester woven glass fabric copper-clad laminates 45、Polyimide glass fabric copper-clad laminates：polyimide woven glass fabric copper-clad laminates 46、Bismaleimide/triazine/epoxide woven glassfabric copper-clad lamimates 47, epoxy synthetic fiber fabric copper-clad laminate: epoxy synthetic fiber fabric copper-clad lamimates 48, polytetraethylene glass fiber copper-clad laminate: teflon/fiber glass copper-clad laminates 49、Ultra thin laminate: ultra thin laminate 50, ceramics base copper-clad laminate: ceramics base copper-clad laminates 51, UV blocking copper-clad laminates: UV blocking copper-clad laminates Printed circuit vocabulary knowledge - basic vocabulary Introduction is complete.

Basic requirements for lead-free solder in electronic assembly Basic processes for lead-free soldered assemblies include: a. Lead-free PCB manufacturing processes; b. 96.5Sn/3.5Ag and 95.5Sn/4.0Ag/0.5Cu eutectic and near eutectic alloy systems for solder paste applications; c. 99.3Sn/0.7Cu eutectic alloy systems for wave soldering applications; d. 99.3Sn/0.7Cu alloy systems for hand soldering applications.   Although these are feasible smt process, but the implementation of several major problems, such as raw material costs are still higher than the standard Sn / Pb process, an increase in the limitations on the degree of wetting, the requirement to maintain the wave soldering process in an inert air state (to have a sufficient amount of nitrogen), and the possibility of reflow soldering temperatures to the limit of the temperature range (between 235 ~ 245 ℃) and improve the thermal properties of the various components of requirements etc.   As far as lead-free alternatives are concerned, there is no universally recognized set of specifications, and after many discussions with many professionals in the field, we have come up with some technical and application requirements below:    Metal Price Many assembly manufacturers require that Pb-free alloys be priced no higher than 63Sn/37Pb, but unfortunately all existing Pb-free alternatives cost at least 35% more than 63Sn/37Pb. The cost of the metal is one of the *most* important factors when choosing lead-free solder rods and wires; when making solder paste, it is not yet as sensitive to the price of the metal because the cost of the technology is a relatively high percentage of the overall manufacturing cost.    Melting point Most assemblers (not all) require a solid phase temperature* as low as 150°C in order to meet the operating temperature requirements of electronic equipment,* and a high liquid phase temperature depending on the specific application.   Wave soldering rods: For successful wave soldering, the liquid phase temperature should be lower than the oven temperature of 260°C. Solder wires for manual/machine soldering: the liquid phase temperature should be below the soldering iron tip operating temperature of 345°C.    Solder Paste: The liquid phase temperature should be below the reflow temperature of 250°C. This temperature is the practical temperature limit for many existing reflow ovens. Many engineers require * high reflow temperature should be lower than 225 ~ 230 ℃, however, there is not a viable solution to meet this requirement. It is generally accepted that the alloy reflow temperature closer to 220 ℃ the better the results, can avoid the higher reflow temperature is * ideal, because it can make the degree of damage to the components to * low, * minimize the requirements for special components, but also can be the circuit board discoloration and warping to * low, and to avoid excessive oxidation of the pads and wires.    Good electrical conductivity This is a basic requirement for electronic connections. Good thermal conductivity In order to dissipate heat, the alloy must be able to transfer heat quickly. Smaller solid-liquid temperature range Non-eutectic alloys solidify at a temperature range between the liquid-phase temperature and the solid-phase temperature, and most metallurgists recommend keeping this temperature range within 10°C in order to form good solder joints with fewer defects. If the alloy solidifies over a wide range of temperatures, there is a risk of weld joint cracking and premature equipment damage.    Low-toxicity alloys and their components must be non-toxic, so this requirement will be cadmium, thallium and mercury are excluded from the scope of consideration; some also require that toxic substances can not be used by-products of refining, and therefore bismuth is excluded, because bismuth is mainly derived from the by-products of lead refining.    Good Solderability The alloy should have sufficient wetting under existing equipment and no-clean flux conditions to be used with conventional no-clean fluxes. As the cost of inerting the wave is not too high, so it is acceptable to wave soldering plus inert environment conditions of use requirements; but in terms of SMT reflow, the alloy * good to have the ability to reflow under the air, because of the high cost of inerting the reflow oven.    Good physical properties (strength, tensile, fatigue, etc.) The alloy must be able to provide the mechanical strength and reliability that can be achieved with 63Sn/37Pb without protruding fillet welds on through-hole devices (especially for alloys with a wide solid-liquid coexistence temperature range).    Production Repeatability/Melting Point Consistency The electronic assembly process is a high-volume manufacturing process that requires both repeatability and consistency to be maintained at a high level, and certain alloys cannot be given consideration if their compositions are not repeatable under high-volume con

Lead-free soldering knowledge Nowadays, in electronic assembly technology, people's environmental awareness is getting stronger and stronger, from the environmental protection, legislation, market competition and product reliability and other aspects, lead-free is imperative.    However, the current lead-free from theory to application are still immature, has not yet formed a relatively uniform normative standards.   The challenge of lead-free process on components is first of all high temperature resistance. To consider the impact of high temperature on component packaging. As the traditional surface mount components of the packaging material as long as they can withstand high temperatures of 240 ℃ to meet the soldering temperature of the leaded solder, and lead-free soldering, for complex products welding temperature as high as 260 ℃, so the component package is able to withstand high temperatures is a problem that must be considered.   In addition to consider the impact of high temperature on the internal connection of the device, IC's internal connection method has a gold ball welding, ultrasonic pressure welding, and flip-flop welding and other methods, especially BGA, CSP and the combination of composite components, modules and so on, new components, such as flip-flop BGA, CSP, the internal encapsulation of the chip bumps with the solder paste is Sn-3.5Ag welding, the melting point of 221 ℃, if such devices If such a device for lead-free soldering, then the device's internal solder joints and surface assembly of the solder joints almost at the same time and then melted, solidified once, which is very harmful to the reliability of the device. Therefore, the internal connection materials of lead-free components should also meet the requirements of lead-free soldering.   The majority of leaded components are plated with Sn/Pb, while there are many types of plating on the surface of lead-free components. Which kind of plating * good, there is no conclusion, so there is still to be lead-free components to improve the standard.   Lead-free process on the requirements of the flux, first of all, due to the chemical reaction between the flux and the alloy surface, so different alloy compositions to choose a different flux. Lead-free flux must be specially formulated. With the deepening of the lead-free process, the quality of lead-free solder paste has improved greatly due to the efforts of solder manufacturers. Current lead-free solder joints have improved in appearance from previous years.   The issue of lead-free solder reliability is of great concern to both manufacturers and users. In particular, the current is in a special stage of transition from leaded to lead-free soldering, lead-free materials, printed boards, components and other aspects of the absence of standards, and even in the reliability of the test methods are not standardized, the reliability is very worrying. The current stage of lead-free process, especially in China is still in a relatively confusing stage. Due to the mixed use of leaded and lead-free, especially when the lead-free soldering end of the components using leaded solder and leaded process, serious reliability problems will occur, these problems are not only the current transition stage of lead-free soldering to pay attention to, but also for the transition stage of leaded soldering is also a problem to pay special attention to.   Because lead is relatively soft and easily deformed, the hardness of lead-free solder joints is higher than that of Sn/Pb, the strength of lead-free solder joints is also higher than that of Sn/Pb, and the deformation of lead-free solder joints is smaller than that of Sn/Pb solder joints, but these do not equate to good reliability of lead-free. Due to the poor wettability of lead-free solder, so the hollow, displacement, monumental and other welding defects are more, in addition to the high melting point, if the activation temperature of the flux can not match the high melting point, due to the high temperature of the flux wetting area, a long time, it will make the soldering surface at high temperatures to re-oxidize and can not take place in the wetting and diffusion, and can not form a good interfacial alloy layer, and the result leads to the interface of the solder joints combined strength (tensile strength) Poor and reduce reliability.   According to the U.S. Wei-Foundation, Agilent and other companies, such as reliability tests, such as thrust test, bending test, vibration test, drop test, after hot and humid, high and low temperature cycling and other reliability test results, by and large, there is a relatively similar conclusions: most of the civilian, communications and other fields, due to the use of the environment is not too much stress, lead-free solder joints mechanical strength is even higher than the leaded ones, but in the use of But in the use of high stress places, such as high and low temperatures, low air pressure and

SMD fuses on single cell lithium batteries SMD fuses in the single-cell lithium battery applications Preface: Currently, more and more products use lithium batteries as the power supply for the system circuit. Lithium batteries have a small size, high energy density, and no memory effect, but also can be recycled for multiple use and other advantages. But lithium batteries also have accidents. 2009.1.30 Yuexiu District, Guangzhou, Donghua South Road, Lenovo computer store occurred in a cell phone lithium battery explosion, a young man in the store carotid aorta rupture, died on the spot. So the safety of lithium batteries is also increasingly attracting attention. Lithium battery protection board to choose the right chip fuse is also very important. Now back to business I. The composition of a single lithium battery Lithium batteries are mainly composed of battery cells and battery protection boards. The main function of the lithium battery protection board: (1) overcharge protection (2) Over-discharge protection (3) Over current / short circuit protection Lithium battery protection board main components: 1, protection IC   2, MOSFET  3, SMD FUSE II. Single-cell lithium battery protection board on the choice of fuse 1, package: according to the customer's circuit board to determine the trial size, generally 1206/0603 size. 2, rated voltage: 24V or more 3, rated current: generally 5A (taking into account the fuse in the lithium battery protection board is 2 times protection, so the protection IC protection delay should be taken into account). 　　(To take into account the protection IC protection delay time to determine the fuse blowing time) 4, Cold resistance: below 15mΩ. 5, safety requirements: UL certification 6, Comply with RoHS requirements and Halogen-Free requirements. Chip fuse in the single-cell lithium batteries on the application of the talk here.