Papers by Karl Pfluke
by Karl Pfluke , Richard H. Short
The advent of Lead-Free Soldering presents many manufacturers with the need to Wave Solder using
Lead-Free Alloys . These alloys melt and are soldered at temperatures well above conventional SNPB processing temperatures. This creates several well-documented problems. This article offers a proven and practical alternative to the Lead-Free Wave Soldering Process.
lead-free, wave solder flux, pb-free, Rework, solder preforms, solder paste, solder reliability
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Posted on 1 Jan 2009
by Karl Pfluke , Richard H. Short
German version of Eliminate Lead-free Wave Soldering.
lead-free, wave solder flux, German language, pb-free, Rework, solder preforms, solder paste, solder reliability
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Posted on 1 Jan 2009
by Rick Lathrop, Karl Pfluke
For crystalline silicon solar cell front contact metallizations, silver thick film formulations are ubiquitous. For backside contact pads, either silver or silver/ aluminum formulations are common. The trend for back contact metallizations is towards low lay down formulations, resulting in thin fired films. Although there are many different reflow methods used to “string” cells together, the need for fast wetting, leach resistant and well adhered front and rear contact metallizations are common to all methods. In order to accurately predict a material's compatibility with the module assembly process, quantitative tests needed to be developed due to an absence of industry standard tests. Classic thick film solder pot leaching and wire peel adhesion tests do not emulate the solar module assembly process well. Although more similar in process, SMT solderability tests also lack close correlation. To fill this gap, several solderability tests specifically designed for module assembly and cell metallizations have been developed and will be discussed in detail. These tests are, in fact, a hybrid of SMT and thick film tests but tailored, for the solar module assembly process. Wetting assessment is accomplished by measuring the reflowed area and height of a precise volume of solder using a confocal measuring system. For ribbon adhesion, manual and automated methods are compared, as well as various peel angles. From these studies, a ribbon attach method and adhesion test emerges suitable for benchmarking contact metallization formulations. Recommendations on how to recognize and prevent silver leaching are also discussed.
tabbing ribbon, metallization, silver leaching, adhesion, wetting
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Posted on 20 Oct 2011
by Karl Pfluke
White Paper Video
Photovoltaic Module Assembly Using SMT Assembly Materials and Processes
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EMS providers specializing in SMT are seeking to diversify and fill capacity. Photovoltaic module assembly is a popular choice. PV cell stringing in solar module assembly is achieved using many common SMT materials and processes. Solders, fluxes, and reflow technologies produce electrical interconnects in a-Si and c-Si photovoltaic assembly technology.
flux, bus ribbon, solar, tabbing ribbon, CIG, Copper Indium Gallium, photovoltaic
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Posted on 1 Jul 2009
by Karl Pfluke
Increasingly, electronics manufacturing services (EMS) providers specializing in SMT are seeking to diversify and fill capacity. Photovoltaic (PV) solar cell module assembly is becoming a popular choice to meet those goals. PV cell stringing in solar module assembly is achieved using many common SMT materials and processes. Solders, fluxes, and common reflow technologies produce electrical interconnects in both a-Si and c-Siphotovoltaic technology.
CIG, flux, solder, photovoltaic solar cell assembly, solar module assembly, SMT
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Posted on 6 Jun 2011
by Karl Pfluke , Dr. Ronald C. Lasky , Ross B. Berntson
Surface mount assembly has dominated its through-hole predecessor since the early 1990s. The higher density and lower ultimate cost of SMT makes it a preferred assembly technology. However, the mechanical strength of through-hole connections continues to make through-hole the technology of choice in assembling connectors. This presentation will describe the primary methods currently used for through-hole connector assembly: 1) selective wave solder, 2) pin-in-paste (PIP)i reflow, 3) hand soldering and 4) solder preforms. We will show how solder preforms are an excellent alternative when PIP provides insufficient solder.
The wave solder method requires specialized equipment and processes to solder connectors. Pin-in- paste reflow evolved as a way to accomplish through-hole assembly without additional equipment or process steps. In the PIP method, the additional solder required to fill the though-hole barrel is deposited by overprinting the pad in the area of each connector pin, using standard SMT equipment. During reflow, the solder wicks to each pin forming the solder fillet.
This paper explains why pin-through-paste reflow methods based on overprinting solder paste have become more challenging due to an increasing use of Organic Solderability Preservative (OSP), fine- feature devices (e.g. fine pitch connectors) and densely populated PCB layout designs that conflict with requirements for successful use of step-stencils. This paper also shows an example where solder preforms were used to provide extra solder volume for each pin. This work demonstrates how solder preforms provide a viable manufacturing solution to ensure complete through-hole solder joints.
lead-free, pb-free, through-hole connectors, selective wave soldering, mixed technology, intrusive reflow, pin-in-paste, solder preforms
[Permanent Link to this Paper ]
Posted on 1 Jan 2009
