Electronics Forum | Sat Nov 08 09:42:22 EST 2003 | ethercom
Hi: I have seen this problem before. It is caused by improper curing of solder mask by the fab manufacturer. When you run the board thru' wave solder, and then wash the board, you see the problem of white residue. However, when you apply heat, you c
Electronics Forum | Thu Jul 05 10:45:01 EDT 2001 | dougie
Steven, There is a load of info on this if you check through the archives. Quick pointer though are: Solder balls are caused by paste creeping under the component at placement. The part is placed and the paste is squashed under the component, when t
Technical Library | 2008-04-08 17:42:27.0
Concern about the failure of lead-free BGA packages when portable devices such as cell phones are accidentally dropped and a general concern about the resistance of these packages under shock loading has prompted an interest in the impact strength of the soldered BGA connection. This paper reports the results of the measurement of the impact strength of lead-free 0.5±0.01mm diameter BGA spheres on 0.42mm solder mask defined pads on copper/OSP and ENIG substrates using recently developed equipment that can load individual BGA spheres at high strain rates in shear and tension.
Technical Library | 2019-09-24 15:41:53.0
This paper focuses on three different coating material groups which were formulated to operate under high thermal stress and are applied at printed circuit board manufacturing level. While used for principally different applications, these coatings have in common that they can be key to a successful thermal management concept especially in e-mobility and lighting applications. The coatings consist of: Specialty (green transparent) liquid photoimageable solder masks (LPiSM) compatible with long-term thermal storage/stress in excess of 150°C. Combined with the appropriate high-temperature base material, and along with a suitable copper pre-treatment, these solder resists are capable of fulfilling higher thermal demands. In this context, long-term storage tests as well as temperature cycling tests were conducted. Moreover, the effect of various Cu pre-treatment methods on the adhesion of the solder masks was examined following 150, 175 and 200°C ageing processes. For this purpose, test panels were conditioned for 2000 hours at the respective temperatures and were submitted to a cross-cut test every 500 h. Within this test set-up, it was found that a multi-level chemical pre-treatment gives significantly better adhesion results, in particular at 175°C and 200°C, compared with a pre-treatment by brush or pumice brush. Also, breakdown voltage as well as tracking resistance were investigated. For an application in LED technology, the light reflectivity and white colour stability of the printed circuit board are of major importance, especially when high-power LEDs are used which can generate larger amounts of heat. For this reason, a very high coverage power and an intense white colour with high reflectivity values are essential for white solder masks. These "ultra-white" and largely non-yellowing LPiSM need to be able to withstand specific thermal loads, especially in combination with high-power LED lighting applications. The topic of thermal performance of coatings for electronics will also be discussed in view of printed heatsink paste (HSP) and thermal interface paste (TIP) coatings which are used for a growing number of applications. They are processed at the printed circuit board manufacturing level for thermal-coupling and heat-spreading purposes in various thermal management-sensitive fields, especially in the automotive and LED lighting industries. Besides giving an overview of the principle functionality, it will be discussed what makes these ceramic-filled epoxy- or silicone-based materials special compared to using "thermal greases" and "thermal pads" for heat dissipation purposes.
HP-520SPI Load a new program in 1 minute, 20 seconds Inspect a full size PCB in 8 seconds or less Closed Loop Feedback on X/Y, Theta, Insufficient-Excess Solder Paste and also Under Stencil Cleaning System
SMTnet Express, March 17, 2022, Subscribers: 25,805, Companies: 11,547, Users: 27,113 Creep Corrosion On Lead-Free Printed Circuit Boards In High Sulfur Environments The material and process changes required to eliminate lead from
The Surface Finish Effect on the Creep Corrosion in PCB SMTnet Express May 10, 2012, Subscribers: 25098, Members: Companies: 8865, Users: 33085 The Surface Finish Effect on the Creep Corrosion in PCB First published in the 2012 IPC APEX EXPO
PCB Libraries, Inc. | https://www.pcblibraries.com/Forum/when-should-a-pad-use-windowpane-paste-mask_topic2600_post10599.html
(regardless of the method used to achieve this), and by how much the mask should be reduced? It seems there must be some formulas or rules of thumb used to balance the solder load applied to the various pads of an arbitrary package design
| http://etasmt.com/cc?ID=te_news_industry,3761&url=_print
Solder Joint Reliability, or SJR, is the ability of solder joints to remain in conformance to their visual/mechanical and electrical specifications over a given period of time, under a specified set
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