Technical Library | 2015-01-08 17:26:59.0
Regardless of the accelerating trend for design and conversion to Pb-free manufacturing, many high reliability electronic equipment producers continue to manufacture and support tin-lead (SnPb) electronic products. Certain high reliability electronic products from the telecommunication, military, and medical sectors manufacture using SnPb solder assembly and remain in compliance with the RoHS Directive (restriction on certain hazardous substances) by invoking the European Union Pb-in-solder exemption. Sustaining SnPb manufacturing has become more challenging because the global component supply chain is converting rapidly to Pb-free offerings and has a decreasing motivation to continue producing SnPb product for the low-volume, high reliability end users. Availability of critical, larger SnPb BGA components is a growing concern
Technical Library | 2022-03-02 21:26:51.0
The solderability of a nickel-palladium-gold (Ni-Pd-Au) finish on a Cu substrate was evaluated for the Pb-free solder, 95.5Sn-3.9Ag-0.6 Cu (wt.%, abbreviated Sn-Ag-Cu) and the eutectic 63Sn-37 Pb (Sn-Pb) alloy. The solder temperature was 245ºC. The flux was a rosin-based mildly activated (RMA) solution. The Ni-Pd-Au finish was tested in the as-fabricated condition as well as after exposure to one of the following accelerated storage (shelf life) regiments: (1) 33.6, 67.2, or 336 hours in the Battelle Class 2 flowing gas environment or (2) 5, 16, or 24 hours of steam aging (88ºC, 90%RH).
Technical Library | 2019-01-09 19:19:52.0
The electronics industry has widely adopted Sn-3.0Ag-0.5Cu solder alloys for lead-free reflow soldering applications and tin-copper based alloys for wave soldering applications. In automated soldering or rework operations, users may work with Sn-Ag-Cu or Sn-Cu based alloys. One of the challenges with these types of lead-free alloys for automated / hand soldering operations, is that the life of the soldering iron tips will shorten drastically using lead-free solders with an increased cost of soldering iron tool maintenance/ tip replacement. Development was done on a new lead-free low silver solder rework alloy (Sn-0.3Ag-0.7Cu-0.04Co) in comparison with a number of alternative lead-free alloys including Sn-0.3Ag-0.7Cu, Sn-0.7Cu and Sn-3.0Ag-0.5Cu and tin-lead Sn40Pb solder in soldering evaluations.
Technical Library | 2015-11-19 18:15:07.0
The move to lead free (Pb-free) electronics by the commercial industry has resulted in an increasing number of ball grid array components (BGAs) which are only available with Pb-free solder balls. The reliability of these devices is not well established when assembled using a standard tin-lead (SnPb) solder paste and reflow profile, known as a backward compatible process. Previous studies in processing mixed alloy solder joints have demonstrated the importance of using a reflow temperature high enough to achieve complete mixing of the SnPb solder paste with the Pb-free solder ball. Research has indicated that complete mixing can occur below the melting point of the Pb-free alloy and is dependent on a number of factors including solder ball composition, solder ball to solder paste ratio, and peak reflow times and temperatures. Increasing the lead content in the system enables full mixing of the solder joint with a reduced peak reflow temperature, however, previous research is conflicting regarding the effect that lead percentage has on solder joint reliability in this mixed alloy solder joint.
Technical Library | 2021-09-08 13:43:56.0
Manganese can be an optimal alloying addition in lead-free SAC (SnAgCu) solder alloys because of its low price and harmless nature. In this research, the mechanical properties of the novel SAC0307 (Sn/Ag0.3/Cu0.7) alloyed with 0.7 wt.% Mn (designated as SAC0307-Mn07) and those of the traditionally used SAC305 (Sn96.5/Ag3/Cu0.5) solder alloys were investigated by analyzing the shear force and Vickers hardness of reflowed solder balls. During the preparation of the reflowed solder balls, different cooling rates were used in the range from 2.7 K/s to 14.7 K/s.
Technical Library | 2017-10-05 17:13:04.0
Intermetallic compounds (IMC) in solder bonds are commonly considered critical for the reliability of interconnections. The microstructure and thermal aging characteristics of solder bonds of crystalline silicon solar cells are investigated, whereby two solders, Sn60Pb40 and a lead-free, low melting point alternative Sn41Bi57Ag2 are considered.
Technical Library | 2021-08-25 16:34:37.0
As the traditional eutectic SnPb solder alloy has been outlawed, the electronic industry has almost completely transitioned to the lead-free solder alloys. The conventional SAC305 solder alloy used in lead-free electronic assembly has a high melting and processing temperature with a typical peak reflow temperature of 245ºC which is almost 30ºC higher than traditional eutectic SnPb reflow profile. Some of the drawbacks of this high melting and processing temperatures are yield loss due to component warpage which has an impact on solder joint formation like bridging, open defects, head on pillow.
Technical Library | 2013-08-29 19:52:43.0
Au over Ni on Cu is a widely used printed circuit board (PCB) surface finish, under bump metallization (UBM), and component lead metallization. It is generally accepted that less than 3 wt.% Au in Sn-Pb solder joints inhibits formation of detrimental intermetallic compounds (IMC). However, the critical limit for Au content in Pb-free solder joints is not well established. Three surface-mount package platforms, one with a matte Sn surface finish and the others with Ni/Au finish, were soldered to Ni/Au-finished PCB using Sn-3.0Ag 0.5Cu (SAC305) solder, in a realistic manufacturing setting. The assembled boards were divided into three groups: one without any thermal treatment, one subjected to isothermal aging at 125°C for 30 days, and the third group aged at 125°C for 56 days...
Technical Library | 2008-03-31 21:35:36.0
While the situation varies from country to country, nearly one year after the EU RoHS Directive came into force implementation of lead-free solder is progressing steadily. For lead-free soldering to be considered successful it is not sufficient just to have dealt with the challenges of mass production. It is also necessary to establish that the soldered joints produced are at least as reliable as those made with Sn-37Pb alloy. In this context "reliability" means the length of time in service that the initial functionality of the joint can be maintained. In this paper we will discuss some of the issues involved in solder joint reliability through a comparison of the properties of two alloys that are widely used for lead-free wave soldering, SAC305 (Sn-3.0Ag-0.5Cu) and the Sn, Cu, Ni, Ge alloy SN100C.
Technical Library | 2009-03-27 22:22:40.0
The Sn-Ag-Cu (SAC) alloys have been considered promising replacements for the lead-containing solders for the microelectronics applications. However, due to the rigidity of the SAC alloys, compared with the Pb-containing alloys, more failures have been found in the drop and high impact applications for the portable electronic devices, such as the personal data assistant (PDA), cellular phone, notebook computer..etc
