Circuits Assembly Online Magazine - Features

Features Articles

When it comes to application, less is more.

Clive Ashmore Self-adjusting paste deflectors save solder paste and simplify cleaning.

Regular readers of my column are certainly well aware of the challenges around print process variability and the impact even small changes can have on printing results. With a procedure as dynamic as printing, ensuring every input is spot-on is critical to a good outcome, especially in the age of miniaturization. This holds true for what many would consider even the most minor of details: the paste deflector.

Every squeegee our company supplies to a manufacturer comes with a set of paste deflectors. These very simple pieces of formed metal are mechanically connected to the squeegee body with two bolts, and their job is to keep the solder paste material from moving outside the print area. They act like dams to keep material within the angle of the squeegee. While paste deflectors play an important role in reducing material waste and maintaining material integrity, they don’t come without challenges. Setting the height of the paste deflectors is a manual operation, and getting them just right can be tricky. If the deflector is set a bit too low, when the squeegee comes down to meet the stencil and pressure is applied, the deflectors will actually grind into the stencil. At worst, the deflector can punch a hole through the stencil, but it will most certainly leave a trail or coin the stencil if set even slightly too low (FIGURE 1). To avoid damage, operators often set the deflectors a little higher to permit a margin of error. This approach, however, lets paste run underneath the gap, and enables material to run up the outside of the squeegee, which can also introduce process problems.

Martin Wickham Using x-ray in a nonstandard way is useful in process development.

Here are three different examples of paste after placement or prior to through-hole component insertion. The images shown here are not necessarily defects, and it may seem strange to use x-ray to inspect paste deposits after printing, but it can be very useful for in-process control and ideal for preproduction runs.

FIGURE 1 shows a QFN/LGA. In this case we are interested in the placement force and the degree of paste displacement on the center pad under the device. Normal practice is to look at the degree of paste variation between printing and placement. It’s even more important when there are multiple rows of outer terminations.

E. Jan Vardaman The annual ECTC revealed exciting advancements on single- and multi-die packages.

The IEEE Electronics Components and Technology Conference (ECTC) at the end of May welcomed nearly 1,500 attendees to the sunshine state of Florida to discuss the latest developments in electronics packaging technology.

A panel discussion on the first evening focused on the topic Panel Fan-Out Manufacturing: Why, When and How? The panel was designed as a jury, with a customer (Qualcomm) surrounded by round wafer proponents (TSMC, Amkor’s Nanium) on one side and panel proponents (Deca Technologies, IZM Fraunhofer consortium) on the other. No conclusion was reached regarding the “right” path to meet customer requests for lower-cost packaging (in this case Qualcomm), but clearly panel processing could be an option. Exactly when panels would move into high-volume manufacturing remained a mystery, but in the audience representatives from Samsung Electro-Mechanics (SEMCO) watched carefully for the reaction. SEMCO continues its development of a panel line, while Nepes and Powertech Technology (PTI) indicate lines are ready. Unimicron continues its research on panel processing and presented a paper discussing stress and warpage for its RDL-first panel FO-WLP.

Susan Mucha In the OEM-EMS relationship, getting to win-win requires a clearly stated business case.

One of the recurring themes I hear in electronics manufacturing services (EMS) is how challenging it is for many program managers and salespeople to negotiate with customers. I’m often told the industry has changed, but when I ask hard questions I tend to find that the biggest change is that the people doing the negotiation seem to know a lot a less about the business of building electronic products than their predecessors. And this isn’t just on the EMS side. Years ago, OEMs put highly technical senior people on the team that managed outsourcing efforts. While those people were tough negotiators, they negotiated based on strong knowledge of the processes and challenges inherent in electronics manufacturing. Similarly, EMS program managers (PMs) were often pulled from operations. If expenses were increasing, they had the knowledge to explain the reason a price increase was necessary.

Peter Bigelow Quality programs should ensure quality, not hamstring ingenuity.

From time to time, new terms take hold that sound critically important, become heavily, if not overly, used in business conversation, and often are both misleading and oxymoronic. Such is the case with the now frequently used “single point of failure.”

I do not think it’s possible to go through a facility or quality audit by a large customer where they are not searching for – and certainly identifying – what, in their opinion, is an unacceptable single point of failure. In my experience, the single point the auditor or customer identifies is usually neither more nor less critical than any other aspect of the process, is usually not a single point, and is usually not more than a process – or processes – the person who cites it does not understand.