Technical Library | 2023-09-07 14:38:31.0
A repeat customer specializing in high-technology interconnect, sensor, and antenna solutions, partnered with us to dispense small volumes of solder paste (Indium 10.1 SAC305 T6SG 78%m) onto backplane connectors – gold pads 0.175mm x 0.225mm. We performed a test requiring 0.200mm diameter or smaller dots to demonstrate the dispensing capability required.
Technical Library | 2019-06-04 10:19:46.0
Interconnection technology relies very heavily on the ability of the conductors on a printed wiring assembly to maintain reliable signal integrity. Harsh environmental factors can precipitate a loss of conductivity due to oxidation and corrosion. Connections are typically soldered or inserted using pressure fitted connectors to obtain enough surface contact to meet the electrical conductivity requirements. In pressure contacts, surface integrity is especially critical where the abrasive effects of retraction and insertion can wear off the metallic finish from the contact area. This can expose the underlying copper or nickel and lead to increased resistance at the contact points. These types of conductors are frequently found in card edge connectors where the terminations are plated with a layer of nickel and gold (frequently referred to as gold fingers). A hard gold is typically used containing very small amounts of nickel and cobalt to increase the wear resistance.
Technical Library | 2019-06-07 14:49:54.0
ACI Technologies was contacted in regards to poor solder joint reliability. The customer submitted an assembly that was exhibiting intermittent opens at multiple locations on a ball grid array (BGA) component. The assembly’s functionality did not survive international shipping, essentially shock and vibration failures, immediately making the quality of the solder joints suspect. The customer was asked about the contract manufacturer and the reflow oven profile as well as the solder paste and surface finish used. The ACI engineering staff evaluated the contract manufacturer’s technique and determined that they were competent in the methods they used for placing thermocouples in the proper locations and developing the reflow oven profile. The surface finish was unusual, but not unheard of, in that it was hard gold over hard nickel, rather than electroless nickel immersion gold (ENIG). The customer was able to supply boundary scan testing data which showed a diagonal row of troublesome BGA pins.
Technical Library | 1999-05-07 11:28:39.0
There are many things that can go wrong when soldering to gold plate over nickel surfaces. First of all, we know that gold and solder are not good friends, as any time solder comes into contact with gold, something seems to go wrong. Either the solder bonds to the gold and eventually pulls off as the tin and gold cross-migrate, leaving voids; or the solder completely removes the gold and is expected to bond to the metal which was under the gold.
Technical Library | 2021-11-03 16:49:59.0
Ultrathin bare die chips were soldered using a novel soldering technology. Using homogeneous flash light generated by high-power xenon flash lamp the dummy components and the bare die NFC chips were successfully soldered to copper tracks on polyimide (PI) and polyethylene terephthalate (PET) flex foils by using industry standard Sn-Ag-Cu lead free alloys. Due to the selectivity of light absorption, a limited temperature increase was observed in the PET substrates while the chip and copper tracks were rapidly heated to a temperatures above the solder melting temperature. This allowed to successfully soldered components onto the delicate polyethylene foil substrates using lead-free alloys with liquidus temperatures above 200 °C. It was shown that by preheating components above the decomposition temperature of solder paste flux with a set of short low intensity pulses the processing window could be significantly extended compared to the process with direct illumination of chips with high intensity flash pulse. Furthermore, it was demonstrated that with localized tuning of pulse intensity components having different heat capacity could be simultaneously soldered using a single flash pulse.
Technical Library | 2014-08-07 15:13:44.0
Gold embrittlement in SnPb solder is a well-known failure mechanism in electronic assembly. To avoid this issue, prior studies have indicated a maximum gold content of three weight percent. This study attempts to provide similar guidance for Pb-free (SAC305) solder. Standard surface mount devices were assembled with SnPb and SAC305 solder onto printed boards with various thicknesses of gold plating. The gold plating included electroless nickel immersion gold (ENIG) and electrolytic gold of 15, 25, 35, and 50 microinches over nickel. These gold thicknesses resulted in weight percentages between 0.4 to 7.0 weight percent.
Technical Library | 2013-01-18 02:42:14.0
ENIG (Electroless Nickel/Immersion Gold) is to deposit nickel gold plating which has good solderability, wear resistance , leveling appearance and small electric resistance. It included 4 steps that are pretreatment, immersion nickel, immersion gold and Post treatment...
Technical Library | 2020-11-15 21:01:24.0
ENIG, electroless nickel immersion gold is now a well-regarded finish used to enhance and preserve the solder-ability of copper circuits. EPIG, electroless palladium immersion gold, is a new surface finish also for enhancing and preserving solder-ability but with the advantage of eliminating Electroless Nickel from the deposit layer. This feature has become increasingly important with the increasing use of high frequeny PWB designs whereby nickel's magnetic properties are detrimental. We examine these two finishes and their respective soldering characteristics as plated and after steam aging and offer an explanation for the performance deviation.
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 | 2014-11-06 16:43:24.0
This paper summarizes the results of recent investigations to examine the effect of electroless nickel process variations with respect to Pb-free (Sn-3.0Ag-0.5Cu) solder connections. These investigations included both ENIG and NiPd as surface finishes intended for second level interconnects in BGA applications. Process variations that are suspected to weaken solder joint reliability, including treatment time and pH, were used to achieve differences in nickel layer composition. Immersion gold deposits were also varied, but were directly dependent upon the plated nickel characteristics. In contrast to gold, different electroless palladium thicknesses were independently achieved by treatment time adjustments.
