Electronics Forum | Thu Jun 15 07:20:23 EDT 2006 | William G.
How are your experiences with stencilling 0201 components on large circuit boards, i.e. 400 * 250 mm ? Will there not be too much mismatch between between stencil and (FR4) boards? If so, would dispensing be a solution? Any other solutions?
Electronics Forum | Mon May 14 19:16:49 EDT 2001 | jagman
Dave: Actually, I'm located in the South Bay (Santa Clara)! Good guess. Now, for more in-depth information: So far, the distribution has been limited to one board out of 10 assembled, so far from one lot. The components assembled are exclusively
Industry News | 2022-01-10 16:55:15.0
The SMTA Capital Chapter Officer team is excited to provide our members with a free technical webinar on "Use of Photonic Soldering to Rework Chip Components" presented by Dr. Vahid Akhavan, Global Application Engineer at NovaCentrix. The presentation will take place on January 20th at 12:00am EST.
Industry News | 2019-11-05 22:16:43.0
Flex PCBs are thin, light weight and easy bending, this gives much difficulty in the process of component assembly. Stiffeners are used to reinforce those areas where components will be assembled. There are many different material can be used as stiffeners, like polyimide, kapton, FR-4, Aluminium, etc, designer need to select the right material based on their thickness and characteristics.
Technical Library | 2021-07-20 20:02:29.0
During the manufacturing of printed circuit boards (PCBs) for a Flight Project, it was found that a European manufacturer was building its boards to a European standard that had no requirement for copper wrap on the vias. The amount of copper wrap that was measured on coupons from the panel containing the boards of interest was less than the amount specified in IPC-6012 Rev B, Class 3. To help determine the reliability and usability of the boards, three sets of tests and a simulation were run. The test results, along with results of simulation and destructive physical analysis, are presented in this paper. The first experiment involved subjecting coupons from the panels supplied by the European manufacturer to thermal cycling. After 17 000 cycles, the test was stopped with no failures. A second set of accelerated tests involved comparing the thermal fatigue life of test samples made from FR4 and polyimide with varying amounts of copper wrap. Again, the testing did not reveal any failures. The third test involved using interconnect stress test coupons with through-hole vias and blind vias that were subjected to elevated temperatures to accelerate fatigue failures. While there were failures, as expected, the failures were at barrel cracks. In addition to the experiments, this paper also discusses the results of finite-element analysis using simulation software that was used to model plated-through holes under thermal stress using a steady-state analysis, also showing the main failure mode was barrel cracking. The tests show that although copper wrap was sought as a better alternative to butt joints between barrel plating and copper foil layers, manufacturability remains challenging and attempts to meet the requirements often result in features that reduce the reliability of the boards. Experimental and simulation work discussed in this paper indicate that the standard requirements for copper wrap are not contributing to the overall board reliability, although it should be added that a design with a butt joint is going to be a higher risk than a reduced copper wrap design. The study further shows that procurement requirements for wrap plating thickness from Class 3 to Class 2 would pose little risk to reliability (minimum 5 μm/0.197 mil for all via types).Experimental results corroborated by modeling indicate that the stress maxima are internal to the barrels rather than at the wrap location. In fact, the existence of Cu wrap was determined to have no appreciable effect on reliability.
? What is FR-4 Material? Traditionally, printed circuit boards are made of a material called FR-4 (Flame Retardant Level 4). This material is a composite made out of glass fiber and epoxy, and is laminated with copper foil on either or both sides
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