V-Score Panelization

V-score top view

My last post talked a bit about panelization, in general. Today, I’m taking a look at V-score panelization. V-score is created by running a V-shaped blade across the top and bottom of the panel without cutting all the way through. The board in the mini-image of my prior post is V-scored. Shown above is a closeup of the V-scoring.

(Note that the cross-hatched area is not in the active circuit portion of the panel. It’s in the rails. You’d never want to cut through copper like that in part of the board that will be used. Even here, it would be best not to have copper in the path of the v-scoring blade.)

You’ll note that it’s all straight lines. V-score can only separate rectangular panelized boards. For curves, you’ll need to use a different technique.

V-score edge onThe next image down, on the left, shows an edge-on view of the V-score. You can clearly see what I mean by “without cutting all the way through.” The cut leaves enough material to hold the boards solidly together during processing, but easy to separate.

V-score de paneled edgeBy the way, we generally don’t just snap them apart. We’ve got a special tool – a bit like a pizza cutter in a fixture – specifically designed to separate them without stressing or bending the board. If we feel there’s any risk of over-stressing, we’ll use the tool.

The next image, here on the right, shows a board edge after depanelization. Note that it’s not a smooth, flat edge.

In contrast, the next image down, on the right, shows a flat milled edge. Generally, though, you can’t visually tell the difference without close examination. You can, however, feel it if you run your finger lightly along the edge. Just be careful to not get slivers.

Next time, I’ll examine tab-routing, which will permit non-rectangular shapes.

Milled edgeDuane Benson
I saw two Buffalos, two Buffalos,
Buffaloes on my lawn,
Romping all around and stomping on the ground
And all of my grass was gone.

‘Board Talk’

Today we launched Board Talk, the bulletin board for the Printed Circuit Board industry, a service brought to you by UP Media Group, Printed Circuit Design & Fab and CIRCUITS ASSEMBLY magazines.

The bulletin board — the URL is www.theprintedcircuitboard.com — is open to anyone in the industry. We’ve set up categories for PCB design, fabrication, assembly, market data, trade shows and press releases. Members are invited to create their own topics (threads) for discussing anything industry related that they have on their mind.

We also are happy to announce an agreement with the IPC Designers Council to offer Board Talk as a communications center for news, announcements and meetings, plus information on the Designers Certification program.

Please check it out!

Reliable Assembly

For those of you at my PCB West session on the Sept. 27, thanks for attending. Here’s the final presentation as delivered:


Duane Benson

PCB West Next Week

As most of you (hopefully) know, PCB West is next week. The annual conference and trade show, now in its 21st year, is the biggest and best event for the electronics design, fabrication and assembly in the Silicon Valley.

Here’s what Dave Ryder, president of Prototron Circuits, has to say about PCB West: “We have been coming to this show for a number of years now and we never fail to pick up some very good and productive leads. In fact, last year we were so busy that we barely had time to eat lunch. With all of the PCB designers attending the conference it makes this a great show for us who are in the quickturn prototype business.”

PCB West takes place Sept. 25 to 27 at the Santa Clara Convention Center. The exhibition, which is free to attend (be sure to preregister at pcbwest.com), is Sept. 26. The show floor is sold out. Check it out!

Mike’s Latest Editorial

My latest editorial from the print editions of PCD&F and CIRCUITS ASSEMBLY looks at the potential impact of robotics on electronics manufacturing.


Design Costs, But How Much?

Lots of studies find that most of the cost (75%-plus) of an electronics product is determined in the design phase.

Here’s my question: Do those studies take the BoM costs into account as part of the design cost? Or are all the “costs” in this sense value-added (design, fab, assembly, rework, etc.)?

Design Costs, But How Much?

Lots of studies find that most of the cost (75%-plus) of an electronics product is determined in the design phase.

Here’s my question: Do those studies take the BoM costs into account as part of the design cost? Or are all the “costs” in this sense value-added (design, fab, assembly, rework, etc.)?

Chatting It Up

Fresh off the success of our premiere PCB Chat, we have quite a few more planned.

Tomorrow (Feb. 7), SMT process consultant Phil Zarrow will take your questions. Designers may remember Phil from some of the past PCB West and PCB East conferences, where he spoke on DfM/DfA.

Next week we will host the IPC-2581 Consortium, taking questions on the new data transfer standard.

On March 2, yours truly will discuss the IPC Apex Expo trade show.

We begin accepting questions for the chats a few days early, so don’t worry if you can’t make the live event. Transcripts are available in real-time and after, too.

A New Trend in Assembly Shows?

Years ago, three major events dotted the US electronics assembly trade show landscape. They included Nepcon East, Surface Mount International, and the mother of them all, Nepcon West.

While Nepcon West was the undisputed champ, all three shows were worth attending, and exhibitors often made new product announcements at each one.

Interestingly, and for reasons too detailed to get into here, none of those shows exist today. And for much of the 2000s, the place to roll out new products became IPC’s Apex. Other events were relegated to regional status, and traditionally were staffed as much by distributors as by OEMs.

There’s a few small signs that trend may be shifting again. While IPC Midwest, taking place this week in the Chicago suburbs remains a local show (and honestly, could they make seeing the exhibitor list any more user-unfriendly?), SMTAI is at long-last beginning to fill the niche for a seasonal alternative to Apex. To wit, we’ve received numerous press releases of late reporting new products to be introduced at SMTAI. That’s evidence suppliers see the venue as a viable place to make product launches.

Also at SMTAI, on Oct. 18, I am cochairing (with CIRCUITS ASSEMBLY columnist Sue Mucha) a panel titled “Global Strategies for Lowering EMS Costs” at SMTAI in Ft. Worth, TX. Topics include EMS in Eastern Europe; networking technical trends; improving quality, delivery and cost in high mix manufacturing; and vapor phase technology, and feature speakers from Kimball, Tailyn, Fabrinet and IBL Technologies. We conclude with a panel on building an EMS cost model.

I can’t mention these events without touting our own. Next week marks the 20th annual PCB West conference and exhibition at the Santa Clara (CA) Convention Center. Traditionally the industry’s leading conference for printed circuit board design and fabrication, we have beefed up the electronics assembly side (with a big assist from the Silicon Valley SMTA Chapter). Highlights include papers on low silver solder alloys, advanced packaging, new plasma-based PCB surface finishes, and lead-free electronics risk reduction, presented by such leading companies as Hewlett-Packard and Amkor. Check out the program at pcbwest.com.  We really hope to see you there.

Electricity Use in Pb-Free


An obvious disadvantage of lead-free electronics soldering assembly is that the oven must be hotter and therefore will use more electricity (versus SnPb37 soldering). But is the extra amount of electricity significant?

KIC’s Brian O’Leary claims that a typical SMT oven uses $7,000 worth of electricity a year at $0.072/Kilowatt hour (Kwh) or about 100,000 Kwh. That number strikes me as about right, as a household uses about 5-20,000 Kwh per year.

In the late 1990s there were 35,000 SMT lines in the world. At a 3% growth rate that would be about 50,000 lines now. So worldwide SMT reflow oven use would be about 5E9 KWhr (50,000 ovens x 100,000 Kwh/per year) worldwide.

With most heat loss be due to convection, the increase in energy use will be approximately proportional to the difference between the oven temperature and the room temperature (25°C). An oven processing tin-lead solder would run at about 210°C versus lead-free’s 250°C. So the added energy for a lead-free oven would be about (250-25)/(210-25), or about 22% more. So if all assembly lines in the world are SMT the added energy use would be about 0.22x 5E9 Kwh = 1E9 Kwh. The cost of this extra electricity would be about $100 million at $0.10/ Kwh. The electronics industry generates about $1.5 trillion in sales. So this added cost would be about 0.0067% of sales. Since world electrical use is about 150,000 E9 Kwhr per year, this increase is about 1/150,000 of all of the electrical use or 0.00067%.

So although more electricity is used, the increase is not significant to the value of the electronics sold or the total world use of electricity.

Best Wishes,

Dr. Ron