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.
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.
Industry Directory | Manufacturer
Buyers of Scrap Materials and Surplus Machinery, Equipment and Inventories Precious Metal Refining Warehouse Liquidation PCB & Electronic Scrap Recycling Purchasing of Used Surplus Semiconductor
Industry News | 2011-09-21 13:59:11.0
FCT Assembly announces that it will showcase its new line of no-clean, halogen-free solder pastes along with its latest stencil technologies in Booth #206 at the upcoming SMTA International Conference & Exhibition.
Industry News | 2012-01-24 16:23:30.0
FCT Assembly will showcase its new line of no-clean, halogen-free solder pastes along with its latest stencil technologies in Booth #612 at the upcoming IPC APEX Expo.
Industry News | 2018-10-18 07:56:58.0
Wave soldering process defectives and handling solution
New Equipment | Solder Materials
With its tin-copper-nickel-germanium alloy, SN100C is a popular lead-free wave soldering alloy. Although initially developed to address the need for an economical wave solder, it has since been found that its properties make SN100C ideal for reflow a
New Equipment | Assembly Services
Factory supply cable utp cat5e and cat6 lan cable 305m (Rhonda(at)z-crown.com cable utp cat5e: 1.Conductor:24AWG,bare copper 0.51 +/-0.01 mm, 2.Insulation: High density polyethylene, minimum thickness of 0.19 mm 3.Conductor diameter 0.92 +/- 0
New Equipment | Assembly Services
Factory supply cable utp cat5e and cat6 lan cable 305m (Rhonda(at)z-crown.com cable utp cat5e: 1.Conductor:24AWG,bare copper 0.51 +/-0.01 mm, 2.Insulation: High density polyethylene, minimum thickness of 0.19 mm 3.Conductor diameter 0.92 +/- 0
Thermally Managed � Heat Dissipating PCB�s (Printed Circuit Boards) By STABLCOR Corporation STABLCOR TM Printed Circuit Board Material Product Information STABLCOR Corporation has developed a new printed circuit board technology that has the followin
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