Technical Library | 2007-11-29 17:20:31.0
Programs have been developed to predict the expected yield of flip chip assemblies, based on substrate design and the statistics of actual manufactured boards, as well as placement machine accuracy, variations in bump sizes, and possible substrate warpage. These predictions and the trends they reveal can be used to direct changes in design so that defect levels will fall below the acceptable limits. Shapes of joints are calculated analytically, or when this is not possible, numerically by means of a public domain program called Surface Evolver. The method is illustrated with an example involving the substrate for a flip chip BGA.
Technical Library | 2024-05-31 19:29:15.0
A tight tolerance machine isn't necessarily a specific machine type. Rather, it's any machine capable of producing parts with precision tolerances. This means minimal variation in the final dimensions of the part. These cutting-edge tools are meticulously engineered to achieve exceptionally precise measurements within minuscule margins. This is accomplished with CNC, or computer numerical control, a manufacturing method that automates the movement of a machine and optimizes for precision. With technology and advanced techniques, these machines ensure that every component meets exact specifications, guaranteeing unparalleled accuracy in manufacturing processes.
Technical Library | 2018-08-29 21:17:53.0
No-clean solder pastes are widely used in a number of applications that are exposed to wide variations in temperature during the life of the assembled electronics device. Some have observed that cracks can and do form in flux residue and have postulated that this is the result of or exacerbated by temperature cycling. Furthermore, the potential exists for the flux residue to soften or liquefy at elevated temperatures, and even flow if orientated parallel to gravity. In situations such as in automotive electronics, where significant temperature cycling is a reality and high reliability is a must, concern sometimes exists that the cracking and possible softening or liquefying of the residue may have a deleterious effect on the electrical reliability of the flux residue. This paper will attempt to address this concern.
Technical Library | 2016-06-16 15:29:31.0
Embedding components within the PC board structure is not a new concept. Until recently, however, most embedded component PC board applications adapted only passive elements. The early component forming processes relied on resistive inks and films to enable embedding of resistor and capacitors elements. Although these forming methods remain viable, many companies are choosing to place very thin discrete passive components and semiconductor die elements within the PC board layering structure. In addition to improving the products performance, companies have found that by reducing the component population on the PC board's surface, board level assembly is less complex and the PC board can be made smaller, The smaller substrate, even when more complex, often results in lower cost. Although size and cost reductions are significant attributes, the closer coupling of key elements can also contribute to improving functional performance.This paper focuses on six basic embedded component structure designs described in IPC-7092.
Technical Library | 2013-08-13 09:49:53.0
One of the common issues I’ve noticed when visiting shops that use crimp force monitors (CFMs) is that the CFMs are usually turned off, regardless of the brand, because engineers and operators are not using them properly. Why, with all of their benefits, are CFMs not being used regularly by employees? One of the biggest problems is the lack of understanding of the variables affecting the CFM’s ability to detect variations. Crimp quality detection is similar to baking a cake. There are a lot of ingredients and if one ingredient is missing or of bad quality, you likely are not going to achieve your desired result. This article will go back through the basics of a crimp quality detection system and discuss what ingredients or variables you need to consider before switching off that CFM.
Technical Library | 2019-02-06 22:02:08.0
The High Density Packaging (HDP) user group has completed a project to evaluate the majority of viable Dk (Dielectric Constant)/Df (Dissipation Factor) and delay/loss electrical test methods, with a focus on the methods used for speeds above 2 GHz. A comparison of test methods from 1 to 2 GHz through to higher test frequencies was desired, testing a variety of laminate materials (standard volume production with UL approval, low loss, and "halogen-free" laminate materials). Variations in the test board material resin content/construction and copper foil surface roughness/type were minimized. Problems with Dk/Df and loss test methods and discrepancies in results are identified, as well as possible correlations or relationships among these higher speed test methods.
Technical Library | 2019-06-06 00:19:02.0
More and more people and things are using electronic devices to communicate. Subsequently, many electronic products, in particular mobile base stations and core network nodes, need to handle enormous amounts of data per second. One important link in this communication chain is high speed pressfit connectors that are often used to connect mother boards and back planes in core network nodes. These new high speed pressfit connectors have several hundreds of thin, short and weak pins that are prone to damage. Small variations in via hole dimensions or hole plating thickness affect the connections; if the holes are too small, the pins may be bentor permanently deformed and if the holes are too large they will not form gas tight connections.The goal of this project was to understand how rework of these new high speed pressfit connectors affects connection strengths, hole wall deformations and plating cracks.
Technical Library | 2020-03-19 00:23:15.0
In this study, the question was how to perform statistically reliable robust- ness tests for the non-contact drop-on-demand printing of functional fluids, such as solder paste and conductive adhesives. The goal of this study was to develop a general method for hypothesis testing when robustness tests are performed. The main problem was to determine if there was a statistical difference between two means or proportions of jet printing devices. In this study, an example of jetting quality variation was used when comparing two jet printing ejector types that differ slightly in design. We wanted to understand if the difference in ejector design can impact jetting quality by performing robustness tests. and thus answer the question, "Can jetting differences be seen between ejector design 1 and design 2"?
Technical Library | 2021-05-06 13:45:49.0
The high-sensitive micro eddy-current testing (ECT) probe composed of planar meander coil as an exciter and spin-valve giant magneto-resistance (SV-GMR) sensor as a magnetic sensor for bare printed circuit board (PCB) inspection is proposed in this paper. The high-sensitive micro ECT probe detects the magnetic field distribution on the bare PCB and the image processing technique analyzes output signal achieved from the ECT probe to exhibit and to identify the defects occurred on the PCB conductor. The inspection results of the bare PCB model show that the proposed ECT probe with the image processing technique can be applied to bare PCB inspection. Furthermore, the signal variations are investigated to prove the possibility of applying the proposed ECT probe to inspect the high-density PCB that PCB conductor width and gap are less than 100 μm.
Technical Library | 2023-05-22 17:46:29.0
Over the past several years, much research has been performed and published on the benefits of stencil nano-coatings and solvent under wipes. The process improvements are evident and well-documented in terms of higher print and end-of-line yields, in improved print volume repeatability, in extended under wipe intervals, and in photographs of the stencil's PCB-seating surface under both white and UV light. But quantifying the benefits using automated Solder Paste Inspection (SPI) methods has been elusive at best. SPI results using these process enhancements typically reveal slightly lower paste transfer efficiencies and less variation in print volumes to indicate crisper print definition. However, the improvements in volume data do not fully account for the overall improvements noted elsewhere in both research and in production.
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