Phil Zarrow: This video is for electronics assembly engineers, technicians, and managers that are seeking to improve stencil printing. It includes details about how stencil printing and pin and paste with preforms can reduce costs.
Dr. Lasky, one of the nemesis of the assembly process has always been printing. It's been chronicled that at least 65% of the defects in the assembly process have been traced back to printing, and, in some cases, even more. When we really examine it, we see it comes down to stencil design in a lot of cases. Where can a manager or engineer find guidance in this area?
Dr. Ronald C. Lasky: I developed a software tool called StencilCoach®, and this will help you design, what I call, standard apertures – that's apertures for a plastic quad flat pack or ball grid array. You enter things like the thickness of the stencil and the width of the pad, and it will tell you the aperture for the plastic quad flat-pack aperture, and if you enter the pad diameter, or, if it's a square, the side for the ball grid array, it will tell you the right aperture for the ball grid array package. In both cases, it will help you to the standards; the standard for the plastic quad flat pack, as you're aware, is an aspect ratio of 1.5, and for a ball grid array pack, which is 0.66.
Phil Zarrow: Very good, so it covers all components, whether they're leaded, passives, area arrays, bottom terminated components?
Dr. Ronald C. Lasky: Yeah, and for passives there's another special feature. As you're aware, with passives, you can often print too much solder paste, and you'll get solder balling, and, so, the software tool has built into it the design parameters for what is called the home-plate design. If you use this part of the software tool, it will help you to successfully design the apertures for passive components, so you don't have solder balling.
Phil Zarrow: Very good, so we have aspect ratios, area ratios, excellent. Intrusive soldering, pin and paste where we're attempting to reflow through-hole components. What about designs for getting adequate solder for those?
Dr. Ronald C. Lasky: That's something the industry is very interested in, because it can save a lot of money, you don't have to do the wave soldering, but you do have to print a lot of solder paste. Part of the tool is such that it will help you to design the aperture, so that you can print enough solder paste. It asks you questions like, “What is the diameter of the pin?,” “What is the diameter of the hole?,” “The length of the pin?,” and so forth. But, some cases, this doesn't really work, because you just can't print enough solder paste, so the tool also has another feature in which it will help you design the apertures assuming you're using solder preforms.
You can either try it without preforms first, because that will save the cost of the preform, but, if it doesn't work for you, then you can use the part of the tool that will help you design with preform.
Phil Zarrow: Contingency plan, excellent. This is a very versatile, powerful tool. Where can we find it?
Dr. Ronald C. Lasky: You can find this tool at www.indium.com.
Phil Zarrow: Excellent. Dr. Lasky, thank you.
Dr. Ronald C. Lasky: Thank you.
Keywords: indium, Indium Corporation, pin and paste preforms, Dr. Ron Lasky, ronlasky@aol.com, Phil Zarrow, itm@itmconsulting.org, stencilCoach, ball grid array,plastic quad flat pack, package aperture, passives, bottom terminated, solder balling, home plate design,
intrusive soldering, pin and paste, solder preforms