Technical Library | 2023-01-10 20:08:36.0
Nickel corrosion in ENIG and ENEPIG is occasionally reported; when encountered at assembly it manifests as soldering failures in ENIG and wire bond lifts in ENEPIG. Although not common, it can be highly disruptive, resulting in missed deliver schedules, supply chain disruption, failure analysis investigations, and liability - all very costly.
Technical Library | 2022-12-05 16:22:13.0
This paper reviews the possible causes and effects for no-fault-found observations and intermittent fail- ures in electronic products and summarizes them into cause and effect diagrams. Several types of inter- mittent hardware failures of electronic assemblies are investigated, and their characteristics and mechanisms are explored. One solder joint intermittent failure case study is presented. The paper then discusses when no-fault-found observations should be considered as failures. Guidelines for assessment of intermittent failures are then provided in the discussion and conclusions.
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 | 2013-01-17 15:34:33.0
The use of an electroless nickel, immersion gold (ENIG) surface finish comes with the inherent potential risk of Black Pad failures that can cause fracture embrittlement at the interface between the solder and the metal pad. As yet, there is no conclusive agreed solution to effectively eliminate Black Pad failures. The case studies presented are intended to add to the understanding of the Black Pad failure mechanism and to identify both the plating and the subsequent assembly processes and conditions that can help to prevent the likelihood of Black Pad occurring.
Technical Library | 2021-09-15 18:53:20.0
Many printed circuit board assemblies (PCBAs) have relays that are soldered to the PCB. If such an electromechanical component fails, it can cause the whole device to fail, just like any other electronic component. The spectrum of root causes that lead to an increased contact resistance or a complete contact failure is totally different from what usually occurs in the electronics domain. This article provides a detailed analysis of these failures and the corresponding root causes, many of them self-centering.
Technical Library | 2017-11-08 23:22:04.0
Due to the ongoing trend towards miniaturization of power components, the need for increased thermal conductivity of solder joints in SMT processes gains more and more importance. Therefore, the role of void free solder joints in power electronics becomes more central. Voids developed during soldering reduce the actual thermal transfer and can cause thermal damage of the power components up to their failure. For this reason, the company has developed a new technique to minimize the formation of these voids during the soldering process.
Technical Library | 2013-01-17 15:37:21.0
A problem exists with electroless nickel / immersion gold (ENIG) surface finish on some pads, on some boards, that causes the solder joint to separate from the nickel surface, causing an open. The solder has wet and dissolved the gold. A weak tin to nickel intermetallic bond initially occurs, but the intermetallic bond cracks and separates when put under stress. Since the electroless nickel / immersion gold finish performs satisfactory in most applications, there had to be some area within the current chemistry process window that was satisfactory. The problem has been described as a 'BGA Black Pad Problem' or by HP as an 'Interfacial Fracture of BGA Packages…'[1]. A 24 variable experiment using three different chemistries was conducted during the ITRI (Interconnect Technology Research Institute) ENIG Project, Round 1, to investigate what process parameters of the chemical matrix were potentially satisfactory to use and which process parameters of the chemical matrix need to be avoided. The ITRI ENIG Project has completed Round 1 of testing and is now in the process of Round 2 TV (Test Vehicle) build.
Technical Library | 2014-12-11 18:00:09.0
The growth of portable and wireless products is driving the miniaturization of packages resulting in the development of many types of thin form factor packages and cost effective assembly processes. Wire bonded packages using conventional copper lead frame have been used in industry for quite some time. However, the demand for consumer electronics is driving the need for flip chip interconnects as these packages shorten the signals, reduce inductance and improve functionality as compared to the wire bonded packages. The flip chip packages have solder bumps as interconnects instead of wire bonds and typically use an interposer or organic substrate instead of a metal lead frame (...) The paper provides a general overview of typical defects and failure modes seen in package assembly and reviews the efforts needed to understand new failure modes during package assembly. The root cause evaluations and lessons learned as the factory transitioned to thin form factor packages are shared
Technical Library | 2021-12-29 19:52:50.0
Medtronic seeks to quantify the thermal aging limits of electroless Ni-electroless Pd-immersion Au (ENEPIG) surface finishes to determine how aggressive the silicon burn-in process can be without loss of solderability. Silicon burn-in (power testing at elevated temperature) is used to eliminate early field failures, critical for device reliability. Thermal aging due to burn-in or annealing causes Ni and Pd diffusion to and oxidation on the surface. Surface oxides limit wetting of the PbSn solder, affecting electrical connectivity of components soldered afterburn-in. Isothermal aging of two ENEPIG surface finishes was performed at 75°C-150°C for 100 hrs-1500hrs to test the thermal aging limits and identify how loss of solderability occurs.
Technical Library | 2016-09-08 16:27:49.0
In this investigation a test matrix was completed utilizing 900 electrodes (small circuit board with parallel copper traces on FR-4 with LPI soldermask at 6, 10 and 50 mil spacing): 12 ionic contaminants were applied in five concentrations to three different spaced electrodes with five replicas each (three different bare copper trace spacing / five replications of each with five levels of ionic concentration). The investigation was to assess the electrical response under controlled heat and humidity conditions of the known applied contamination to electrodes, using the IPC SIR (surface insulation resistance) J-STD 001 limits and determine at what level of contamination and spacing the ionic / organic residue has a failing effect on SIR.
