Solderability Characteristics of Palladium , Palladium Nickel , Hard and Soft
Palladium and palladium alloys are the only serious ahematives to gold as an "electronic finish". In the past, the major impetus for such a substitution has been economic; however, today palladium's technological advantages are generally recognized. This is especially true in the connector markets where the material properties (e.g. hardness, ductility, thermal stability, etc.) of palladium are in many instances superior to hard gold. Recent advances in plating technologies coupled with a m r e thorough understanding of the materials properties have expanded the use of electroplated palladium and palladium alloys in the PCB, semiconductor and optoelectronic packaging markets. To assess the suitability for such applications, the wire bondability and solderability of these finishes need to be investigated.
SURFACE FINISH FOR ELECTRONIC PACKAGING WITH LEAD-FREE SOLDERS
Current trends in the preservation of our environment are forcing the electronic industry to seriously consider lead-free solders. In a variety of options such as Tin alloys with Indium, Bismuth, Silver, Zinc and others, the issues of their functional performance involves their solderability to the substrate. Clearly, good fatigue characteristics, tensile strength, ductility, adequate melting temperature and acceptable material cost may not be utilized if the solder requires aggressive fluxes or its "spreadability" is inadequate. Thus, a lead-free solder applied on a substrate engineered for good solderability becomes a viable packaging tool. We have tested a variety of multilayer finishes developed at AT&T for applications on PWBs and MCMs and established that they can be successfully utilized in lead-free soldering processes. In this paper, we discuss experimental details and solderability results with some of the viable lead-free solders.
Interaction of Diclofop-Methyl and MCPA on Wild Oats (Avena fatua)
Diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate} loses part of its activity on wild oats (Avena fatua L.) when it is applied in combination with ester or amine formulations of MCPA {[4-chloro-o-tolyl)oxy] acetic acid.} Uptake of diclofop-methyl is reduced in the presence of commercial formulations of MCPA, particularly amine formulations, which are only partly compatible with the diclofop-methyl formulation. With added MCPA, regardless of formulation, hydrolysis of diclofop-methyl to the acid diclofop is slowed down, both in intact wild oat plants and in a crude leaf extract. At the same time, conversion of any acid formed to inactive conjugates is accelerated in the presence of MCPA. It is concluded that the loss of activity of diclofop-methyl by MCPA can be accounted for by the effects of MCPA on uptake and metabolic conversion of diclofop-methyl.