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 | 2014-10-02 20:10:07.0
Sn3.0Ag0.5Cu (SAC305) is the most popular near eutectic lead-free alloy used in the manufacturing processes. Over the last several years, the price of silver has dramatically increased driving a desire for lower silver alloy alternatives. As the results, there is a significant increase in the number of alternative low/no silver lead-free solder alloys available in the industry recently.In this paper, we'll present the performance and process capability of various low/no silver alloy solder pastes. Data from printability, wetting test, slump test, solder ball test, voiding, etc… will be discussed and compared with the control SAC305 solder paste. Benefits and concerns of using low/no silver alloy solder paste materials will also be addressed.
Technical Library | 2015-02-19 16:54:34.0
Pad cratering is an important failure mode besides crack of solder joint as it’ll pass the regular test but have impact on the long term reliability of the product. A new pin pull test method with solder ball attached and positioning the test board at an angle of 30º is employed to study the strength of pad cratering. This new method clearly reveals the failure mechanism. And a proper way to interpret the finite element analysis (FEA) result is discussed. Impact of pad dimension, width and angle of copper trace on the strength is included. Some findings not included in previous research could help to guide the design for better performance
Technical Library | 2021-04-21 15:10:16.0
Voids affect the thermal characteristics and mechanical properties of a solder joint, thereby affecting the reliability of the solder interconnect. The automotive sector in particular is requiring the mitigation of solder voids in various electronic control modules to the minimum possible level. Earlier research efforts performed to decrease voids involved varying the reflow profile, paste deposit, paste alloy composition, stencil aperture, and thickness. Due to the various advantages they offer, the use of Ball Grid Array packages is common across all industry sectors. They are also prone to process voiding issues. This study was performed to determine if vacuum assisted reflow process can help alleviate the voids in area array solder joints. Test parameters in this study largely focused on vacuum pressure level and vacuum dwell time.
Technical Library | 2022-10-31 18:35:40.0
Voids affect the thermal characteristics and mechanical properties of a solder joint, thereby affecting the reliability of the solder interconnect. The automotive sector in particular is requiring the mitigation of solder voids in various electronic control modules to the minimum possible level. Earlier research efforts performed to decrease voids involved varying the reflow profile, paste deposit, paste alloy composition, stencil aperture, and thickness. Due to the various advantages they offer, the use of Ball Grid Array packages is common across all industry sectors. They are also prone to process voiding issues. This study was performed to determine if vacuum assisted reflow process can help alleviate the voids in area array solder joints. Test parameters in this study largely focused on vacuum pressure level and vacuum dwell time.
Technical Library | 2022-03-16 19:48:18.0
Dendrites, Electrochemical Migration (ECM) and parasitic leakage, are usually caused by process related contamination. For example, excess flux, poor handling, extraneous solder, fibers, to name a few. One does not normally relate these fails with environmental causes. However, creep corrosion is a mechanism by which electronic products fail in application, primarily related to sulfur pollution present in the air.1 The sulfur reacts with exposed silver, and to a lesser extent, exposed copper. This paper will explore various aspects of the creep corrosion chemical reaction
Technical Library | 2020-12-29 20:55:46.0
Voiding in solder joints has been studied extensively, and the effects of many variables compared and contrasted with respect to voiding performance. Solder paste flux, solder powder size, stencil design, circuit board design, via-in-pad design, surface finish, component size, reflow profile, vacuum reflow, nitrogen reflow and other parameters have been varied and voiding quantified for each. The results show some differences in voiding performance with respect to most of these variables but these variables are not independent of each other. Voiding in solder joints is a complex issue that often requires multiple approaches to reduce voiding below required limits. This paper focuses on solutions to voiding for commonly used bottom terminated components (BTCs).
Technical Library | 2019-10-18 10:37:25.0
It usually does not make any logic to invest in costly fabrication equipment in case you just desire to spin some prototypes and rather outsource your Printed Circuit Board assembly as well as prototype fabrication to a trustworthy vendor. I would provide a few tips as to what to consider when seeking a contract manufacturer. The two most common procedures associated with Printed Circuit Board Assembly are through-hole technology and surface mount technology. Talking about the difference between through-hole technology and surface mount technology. Through-hole elements have metal leads, & these metal leads are supplied through-plated holes inside the circuit board. On the other hand, SMT elements might or might not have leads, nevertheless most significantly, they are developed to be soldered onto the surface of the circuit boards straight on the same side as the element body. A lot of contract manufacturers would provide a quick quote mechanism over their site for the fabrication of circuit boards as well as assembly of prototypes. This would bank your time when comparing various vendors. Ensure that the quote system facilitates you to fill your details, for instance, board material, thickness, copper thickness, milling, etc. in order that you can avail of a precise quote devoid of any surprises afterward. And this is quite necessary. Typically the cost per board would decline as quality upgrades. This is owing to the fairly high setup price of circuit board fabrication over and above component assembly. A few vendors would employ a system where they unite boards from various consumers. This manner the setup price would be circulated among numerous clients. When you fabricate an item, you clearly don’t desire to have to fabricate a big quantity of boards straight away whilst you improve your design. One restriction with small quantity prototypes though is that the option of materials & material thicknesses would be constrained. In case you are employing a particular material then opportunities are there will not be any other clients employing the same material. Additionally, lead time plays a major role in indecisive prices. A longer lead time facilitates the fabricator more liberty in slotting your fabrication. This is basically reflected in cheaper prices that would view in the quote section. Clearly, if you are in a hurry and desire to be moved to the summit of the pile you would require splurging more dollars. Ensure that your contract fabricator would support the file sort for producing which you offer. The most general format for printed circuit board fabrication is the Gerber format nonetheless a few vendors would moreover embrace board files from general printed circuit board software products. A few suppliers also provide in house printed circuit design. Even in case, you create your board yourself, choosing a vendor with design services might prove resourceful in case there is an issue with your files. In this scenario, your vendor could make swift changes that would neglect pricey delays. If you are looking for an Electronic Manufacturing Services (EMS Assembly) provider, then the web is the best to search.
Technical Library | 2013-06-13 15:31:24.0
Electromigration (EM) is a mass transportation mechanism driven by electron wind force, thermal gradient, chemical potential and stress gradient. According to Moore’s law, number of transistors on integrated circuits (ICs) doubles approximately every 2 years. Moore’s law holds true since its introduction in 1970s. This insatiable demand for smaller ICs size, larger integration and higher Input/Output (IO) count of microelectronics has made ball grid array (BGA) the most promising connection type in electronic packaging industry. This trend, however, renders EM reliability of solders joints a major bottleneck to hinder further development of electronics industry...
Electronic Packaging Laboratory, State University of New York
Technical Library | 2016-01-21 16:52:27.0
Solder paste has long been viewed as "black magic". This "black magic" can easily be dispelled through a solder paste evaluation. Unfortunately, solder paste evaluation can be a challenge for electronic assemblers. Interrupting the production schedule to perform an evaluation is usually the first hurdle. Choosing the solder paste properties to test is simple, but testing for these properties can be difficult. Special equipment or materials may be required depending upon the tests that are chosen. Once the testing is complete, how does one make the decision to choose a solder paste? Is the decision based on gut feel or hard data?This paper presents a process for evaluating solder pastes using a variety of methods. These methods are quick to run and are challenging, revealing the strengths and weaknesses of solder pastes. Methods detailed in this paper include: print volume, stencil life, response to pause, open time, tack force over time, wetting, solder balling, graping, voiding, accelerated aging, and others.
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