Technical Library | 2023-08-16 18:09:06.0
One of our customers involved with Electronics and Aerostructures requested a test to dispense Techspray Wondermask 2204 solder mask. The dispensing locations include large and small screw holes, single through-hole vias, and connector locations consisting of multiple through-hole vias. The process needed to run quickly and reliably.
Technical Library | 2007-02-01 10:08:40.0
The increased replacement of high lead count SMT devices with BGAs and other high ball count area array packages has brought increased challenges to PCB rework and repair. Often solder mask areas surrounding BGA pad areas are damaged when components are removed.
Technical Library | 2008-07-10 12:52:18.0
This paper reviews the J-STD-004 and how it is used in flux categorization and selection. It also discusses the major types of flux formulations available, and the design, process and reliability implications of using each type. The purpose of the paper is to help the reader make an informed choice when selecting wave solder fluxes for lead-free processing.
Technical Library | 2019-05-29 01:47:22.0
1.Vias near SMD pads: Solder can flow into the via after melted. As a result cold joint will appear in the end. Check the picture below. 2.Vias on SMD pads: Solder can flow into the via more easier after melted. Check the picture below. 3.Via opening without soldermask covered. When workers solder TH parts by hand, soldering iron can touch vias sometime, then tiny amounts molten solder will stay on vias. This can lead to electrical short easily. We recommend you make all vias tenting (covered by solder mask) if it is possible.
PCBNPI-Professional PCB Fab/PCB Assembly Service Provider From China
Technical Library | 2023-06-12 19:18:24.0
As any new technology emerges, increasing levels of refinement are required to facilitate the mainstream implementation and continual improvement processes. In the case of lead-free processing, the initial hurdles of alloy and chemistry selection are cleared on the first level, providing a base process. The understanding gained from early work on the base process leads to the next level of refinement in optimizing the primary factors that influence yield. These factors may include thermal profiles, PWB surface finishes, component metallization, solder mask selection or stencil design.
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 | 2010-03-18 14:02:03.0
Selecting products that have been qualified by industry standards for use in printed circuit board assembly processes is an accepted best practice. That products which have been qualified, when used in combinations not specifically qualified, may have resultant properties detrimental to assembly function though, is often not adequately understood. Printed circuit boards, solder masks, soldering materials (flux, paste, cored wire, rework flux, paste flux, etc.), adhesives, and inks, when qualified per industry standards, are qualified using very specific test methods which may not adequately mimic the assembly process ultimately used.
Technical Library | 1999-07-21 09:04:04.0
A high volume manufacturer of printed circuit boards (PCBs) had attempted for many years to locate an adhesive that was robust enough to meet their manufacturing needs. This proved to be a challenge because they needed the adhesive to accommodate a wide range of different dispensing equipment and board designs. The two key performance criteria required from the adhesive were dispensability and adhesion...
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.
Technical Library | 2017-01-05 16:55:11.0
The July 2006 implementation of ROHS exempted automotive applications from converting to lead free technology. Nine years later, all major OEM and Tier 1 automotive manufacturers have converted or are in the process of converting to lead free circuit assembly processing. Starting with SAC (SnAgCu) alloys as a baseline for lead free soldering, in the last years several specific alloys were developed in order to improve resistance to high temperature creep, vibration survival and the ability to withstand thermal cycling and thermal shock.The paper compares three different solder alloys and two flux chemistries in terms of void formation and mechanical / thermal fatigue properties. Void content and reliability data of the alloys will be presented and discussed in relation to the acceptance criteria of a Tier 1 /OEM automotive supplier. As a result, a ranking list will be presented considering the combined performance of the alloys. In order to analyze the void formation and mechanical behavior of different solder alloys and flux chemistry combinations, statistical methods are used.
