Modern Printed Circuits: Sierra Circuits

O C T O B E R 1 ‘13

Sierra Circuits:A Complete PCB Resource

PLUS: The Ground” Myth in PrintedCircuits

“

PCB Resin Reactor+

Ken Bahl

CEO of Sierra Circuits

concepts to reality Bringing your

is as easy as...

Copyright ©2013 Aspen Labs LLC.

Visit: digikey.com/schemeit • partsim.com • pcbweb.com

1.

Create schematics, technical diagrams, and flowcharts using your browser.

• 600+ Symbol Library• Share Schematics Online• Export High Quality Images

digikey.com/schemeit

2.

Free and easy-to-use circuit simulator that runs in your browser.

• SPICE Simulator• AC/DC/Transient Sims• Waveform Viewer

partsim.com

3.

Full featured online CAD application for designing and manufacturing electronics hardware.

• Schematic Capture• PCB Layout• BOM Integration

pcbweb.com

http://bit.ly/SJ9ugm

http://bit.ly/13zBBCn

http://bit.ly/XVO5Wt

Modern Printed Circuits CONTENTS

4

3

6

10

14

18

FEATURED ENGINEERQ & A with Giorgos LazaridisFounder of PCBHeaven.com

24

TECH ARTICLENew Construction Methods Provide Highest Quality Rigid-Flex PCBs

TECH ARTICLEThe “Ground” Myth in Printed Circuits

TECH ARTICLEThe Route to PCB

COVER INTERVIEWInterview with Ken BahlCEO of Sierra Circuits

FEATURED ARTICLEIsola’s Organic Synthesis Reactor Creates PCB Resin

44

Modern Printed Circuits

Giorgos LazaridisFounder, PCBHeaven.com

How did you get into engineering?

My passion as a child was to break my toys apart and find the “magic” hidden inside. My grandfather noticed this and began buying things for me from the local bazaars and junkyards like old radios, pick-ups, TVs, mechanical parts and other gizmos of the 80’s. I had my own junk-room (literally) in which I spent most of my childhood breaking and dismantling things apart, salvaging motors lamps and switches.

At the age of 7 I made my very first electronic project. It was a needle detector for my grandmother. I used a wooden round stick some wire and the flash light from my father’s camera. My father understood how much I loved electronics and technology. He was a ship technician traveling around the globe with merchant ships. Since then, every year I received a new tech gadget from him as a present—my first Atari 2600 game console, my first Pocket Scientific Computer PC-6, and my first PC a Hyundai XT Super 16 TE. This PC was my ticket into the programming world. I began with GW-BASIC and 8086 Assembly. I wrote many BASIC programs and I also joined a hacking team as a virus programmer. I never distributed any viruses though, I only wrote them for educational purposes. It was some kind of trend back then. Hacking was an unknown word in Greece in the early 90’s.

Until the age of 14, my knowledge and experience around electronics was limited in assembling commercial kits. Around that age, I got my first chip-related book—the SGS-Thomson High Speed CMOS manual. I then began to discover what’s inside these chips, how they work, and how to

make my own digital projects. It took me another 10 years to discover the microcontrollers and more specifically the PIC16F84. I discovered that this was the key to combine my two passions, electronics and assembly programming. By that time, Internet had well entered our lives, and this gave a good boost to my knowledge.

Tell us about your website pcbheaven.com.I decided to start this site for two reasons; first to improve my skills and knowledge, and second to gain experience. Back then, I had already discovered the power of teaching and sharing knowledge. In order for one to become a good teacher, they first must have a complete understanding of the subject. Moreover, the relationship between the teacher and student is bidirectional and ever changing. There are tons of new subjects that the teacher discovers because of a question from the student. Discovering the uniqueness of each one’s mind is the ticket to intelligence. Also, as a general principle I believe that knowledge must be freely distributed and I already had quite some knowledge to share. I uploaded the first release of my site in May 2008.

What do you do when you’re not working on your website?

I work as a circuit designer and a CNC technician. I play the guitar in my free time and listen to music. I love science and more specifically physics and astronomy. Every now and then I read ancient Greek philosophy, language, and geometry just to stay in good shape. I also love solving riddles and puzzles.

What are your favorite hardware and software tools?

The oscilloscope is my number #1 tool on my workbench. I use it daily for each and every circuit. As for the software, it’s always fun to work with the Autodesk Inventor 3D for designing mechanical parts.

5

FEATURED ENGINEER

5

“Concern each failure as a valuable lesson, for if you don’t find out

how something will work, you will definitely find out how it doesn’t.”

What was the trickiest bug you ever fixed?Well, this one comes from my second job as a CNC technician. It was this medium-size CNC. The customer reported that when he pushed the power button, the NUM controller would sometimes fail. He would then have to turn the machine off and turn it back on again several times until the power button would work normally. After several hours (days) I discovered that the problem was a bad pin connection from the CPU chip of the NUM controller. The reason for the power button failure was the funniest and most interesting part: the power button would arm a large power relay. The relay was mounted onto the same surface as the NUM controller at the back of the switching cabinet. Being large enough, the relay caused vibrations when armed. These vibrations sometimes would vibrate the CPU chip inside the NUM controller for just an instance, long enough though for the controller to raise several errors. I liked this repair so much that I uploaded it to my website.

Do you have any experiential stories you’d like to share?

I had a very close contact with the 220V when I was a child. I was making this antenna that required a 220V supply up on the roof of my house. The antenna was supposed to receive strange signals—I never found out what a “strange signal” was, but I could definitely hear the hum in some bands of a toy walkie-talkie that I had. Maybe aliens? Who knows. Anyway, it seems that as I was pulling the wire it got scratched somewhere. I accidentally grabbed the wire from this scratch. My right thumb touched the copper and 220V went right through me down to the wet concrete. I can still remember each and every second while I was stuck there. My hand closed and I held the wire even tighter. The shock lasted for several seconds. I was twice a lucky guy to live – first because it was my right hand and not the left hand. And second, because my thumb got so severely burned that turned into a big blister.

And so here I am! For the next 3 days it was impossible to move my right side due to this terrible pain, but slowly I recovered. After 20

years, I still have the mark from the blister on my right thumb only to remind me how dangerous those strange signals are...

Is there anything you’d like to say to young people to encourage them to pursue electronics?

Electronics can be a very nice hobby with a bright future. As long as one likes electronics I definitely encourage them to go on with that passion. Start with small steps and try not to get disappointed from the early and inevitable failures. Concern each failure as a valuable lesson, for if you don’t find out how something will work, you will definitely find out how it doesn’t. Learn how to learn at a personal level. Each one has a different way to learn—discover yours. Share your knowledge with friends and on the Internet. Read math, study math, learn your lesson by heart. There is more than numbers behind the numbers.

But most of all, study the original text of the Euclidean Geometry. Discover the methodology and the logical steps of a harnessed and disciplined mind.

What challenges do you foresee in our industry?

Oddly enough the greatest challenge that I foresee is how humans will handle the not-so-distant future industrial innovations and technologies. Every day, we manage to harness more and more energy which can either be creative or destructive. There will be this time (maybe I will be a spectator in my 70s+) that we will face this situation. We need to either radically change our behavior and ethics, or we self-destruct.

http://www.pcbheaven.com/blogpages/Repairing_NUM_controller_on_BIMA_CNC_center

66


Latest Material and Construction Methods Provide the Highest

Quality Rigid-Flex PCB’s





ith the demand for portable electronics ever increasing, the need to produce more compact devices with complex capabilities calls for

engineering solutions that combine functionality with flexibility.

W

By Paul Tome, Flex Circuit Product Manager

Epec Engineered Technologies

7

TECH ARTICLE

7







ith the demand for portable electronics ever increasing, the need to produce more compact devices with complex capabilities calls for

engineering solutions that combine functionality with flexibility.

W

By Paul Tome, Flex Circuit Product Manager

Epec Engineered Technologies

88


Rigid-Flex circuits can be shaped to fit where no other design solution can. They are an integrated hybrid of printed

circuit board and flex circuit technology and exhibit the benefits of each. This allows substantially greater freedom of packaging geometry and a significant reduction of interconnects while retaining the precision, density and repeatability of printed circuit board technology.

Applications of Rigid-Flex circuits can be found throughout the electronics industry and in the most demanding applications including aerospace, medical and military.

Rigid-Flex circuit design has evolved significantly over the past decade. Modern designs require the rigid areas to be fully capable “rigid” boards. The same limits of complexity and density are pushed as

in modern PCB’s including: fine lines/spacing, high aspect ratio vias, blind and buried vias, high layer counts (20+), higher operating temperatures, and RoHS assembly compliance.

However, some of these advances created potential via and plated hole reliability issues. Older design methods used materials and constructions containing many layers of “adhesives” within the rigid area constructions. Due to adhesives having a high coefficient of thermal expansion (10 to 20 times that of FR-4), vias are placed under a significant amount of stress during thermal cycles that occur during RoHS assembly, multiple assembly cycles, and higher system & component operating temperatures. The use of adhesives within the rigid areas may cause cracks to form in the copper plating within via holes (Figure 1).

Figure 1: The use of adhesives within the rigid areas may cause cracks to form in the copper plating within via holes.

99

TECH ARTICLEAdhesives, within a rigid-flex design, may come from any of three sources: the copper clad flex laminate itself, the coverlay construction method used and the material used to bond the rigid and flex layers into the final structure. To solve the issue of via reliability, manufacturers, material suppliers and industry standards organizations have worked together to develop solutions and specifications that eliminate or minimize the use of adhesives in these areas.

To address the use of adhesives in copper clad flex laminate, “adhesiveless” constructions were developed. Previously, copper layers were bonded to the polyimide core with either an acrylic or modified epoxy adhesive (Figure 2a). An adhesiveless laminate has the copper directly attached to the polyimide core (Figure 2b). Eliminating the adhesive bond layers allows for thinner constructions and more flexible design with vastly improved reliability. In addition adhesiveless copper clad laminates have higher operating temperature ratings, higher copper peel strengths, and the desired reduced Z-Axis thermal expansion stress on vias.

Coverlay constructions also previously presented a problem in rigid-flex designs. Older methods use full coverage coverlays that extend throughout the entire rigid area(s). Vias and plated though holes would then be exposed to the excessive Z-Axis thermal expansion stress applied by the coverlay adhesive. To solve this issue, selective coverlay constructions were developed so that coverlays are restricted to the exposed flex areas only and have a maximum 0.050” interface within the rigid areas. (Figure 3). PTH and via holes are restricted from this interface area.

Lastly, rigid and flex layers are now laminated into the final structure, using high temp no-flow FR4 prepregs rather than layers of flex adhesives. This provides a structure as dimensionally stable in the Z-Axis as standard rigid PCB designs.

IPC 2223C Sectional Design Standard for Flexible Printed Boards lists all of the above as key elements in the design of a reliable rigid-flex design that meets today’s requirements.

Epec manufactures single, double, and multi-layer flex circuits using modern rigid-flex materials and construction. Designs comply with IPC 2223C standards, which define the elimination/minimization of adhesive use within rigid areas, use of adhesiveless based substrates, and use of selective/partial coverlay construction.

During Epec’s design review and quoting process, specifications, materials, and construction are carefully examined in order to minimize and eliminate any technical issues. Areas of opportunity for improved reliability, functionality, and cost reductions are also identified to generate an accurate quote that is based on a manufacturable, reliable and cost effective design. ●

Figure 3: Coverlays restricted to the exposed flex areas only and have a maximum 0.0050” interface within the rigid areas.

Figure 2a: Copper layers bonded to the polyimide core with either a crylic or modified epoxy adhesive.

Figure 2b: An adhesiveless laminate has the copper directly to the polyimide core.


The “Ground” Myth in Printed Circuit Boards

by Bruce ArchambeaultContributing Author

The term “ground” is probably the most misused and misun-derstood term in EMC engineering, and in fact, in all of circuit design. Ground is considered to be a zero potential region with zero resistance and zero impedance at all frequencies. This is just not the case in practical high-speed designs. The one thing that should be remembered whenever the term “ground” is used, is that “ground is a place where potatoes and carrots thrive.” By keeping this firmly in mind, many of the causes of EMC problems would be eliminated.

1010

TECH ARTICLE

1111

The term “ground” is a fine concept at DC voltages, but it just does not exist at

the frequencies running on today’s typical boards. All metal has some amount of resistance, and even if that resistance was near zero ohms, the current flowing through a conductor in a loop creates inductance. Current through that inductance results in a voltage drop. This means that the metal ground plane/wire/bar/etc. has a voltage drop across it, which is in direct contradiction with the intention and definition of ground.

The important point is that for EMI/EMC we need to consider the current, not the voltage, in our signal paths. Since current must always flow in a loop back to its source, the return current path must be considered as well as the intended signal path along a PCB trace. Any interruptions to the return current path can have serious negative effects to the EMI/EMC performance of a PCB. A very slight deviation in return current path can result in enough inductance to dramatically increase emissions.

The return current path is also very important when considering mother/daughter board configurations. Figure 1 shows a simple four-layer board example of a mother/daughter board configuration and a signal path from the mother board to the daughter card through a connector. If we consider how the return current will flow from this configuration, we should expect that the return current will spread out to include displacement current through the dielectric between GND and PWR, as well as local decoupling capacitors (depending on their distance and the plane separation). Figure 2 shows the return current for this configuration. The added return current path length results in additional inductance in the total path, resulting in a ‘noise’ voltage between the two GND planes (across the connector). This noise voltage will drive the wide, thin, monopole-like antenna, resulting in increased emissions.

However, if we had simply considered the return current path and routed the signal trace so that it was referenced to the same plane (PWR or GND), the return currents are able to stay close to the signal trace (Figure 3), and emissions are greatly reduced.

Signal Path Connector

GND

PWR

Signal Layers

Figure 1: Initial Two Board Configuration

Signal Path Connector

GND

PWR

Signal LayersReturn Current

Figure 2: Return Current Paths for Initial Configuration

Signal PathConnector

DecouplingCapacitors

DisplacementCurrent

GND

PWR

Signal Layers

Figure 3: Improved Return Current Design

1212


When we consider the return current path, more ‘ground’ is not always the ‘right’ answer.For example, on a recent design, there was a 144 pin connector with many high speed signals traveling from one board to the other. It was determined that 30 pins could be used for ‘power’ and ‘ground’ combined. At least five pins must be ‘power’ so there would not be an excessive DC voltage drop across the connector. How many of the remaining 25 pins should be ‘ground’?

In this particular design, it turned out that about 2/3 of the total signal pins were referenced to the ‘power’ plane, and only 1/3 referenced against the ‘ground’ plane. This meant that of the total 30 possible power/ground pins, 2/3 should be ‘power’ and only 1/3 should be ‘ground.’ More ‘ground’ pins was NOT the best design for this case. Of course, once we consider both the ‘power’ and the ‘ground’ pins to be return current paths, it is obvious we should distribute them throughout the signal pins to keep the return current deviation as small as possible (compared to putting all the ‘ground’ pins at the ends of the connector, etc.).

When we consider the most important concerns for good EMI/EMC design, the schematic is not as important as the physical layout of the signal path and the return current. Since today’s high speed PCBs have many layers and are very complex, it is difficult for an engineer to examine each critical signal path for a good return current path. Automated EMC rule checking tools can examine each net in turn, regardless of the PCB complexity. The key to selecting an automated rule checking tool is to make sure it can interface well with your existing design process, it is easy to use, and it can display rule violations in a graphical and easy to understand manner.

The most important EMC design rules for high speed PCBs concern the return current path. Since the return current will always find a path that minimizes the inductance of that path, the return current will always flow on the nearest plane, whether it is called ‘ground’ or ‘power’ or ‘carrots’. When traces cross a split in the return plane (for example if a trace is routed next to a power layer with multiple power islands), the return current’s path is interrupted. Changing layers within the PCB so that the return current must also change planes will also interrupt the return current path. Remember, the return current must always get back to its source. It will get back to its source. The only question is whether it will be a path that is beneficial to you, or if it will cause problems. So, “Do you feel lucky today?” It is always best to design ‘on purpose’ rather than ‘by luck’. ●

When we consider the most important concerns for good EMI/EMC design, the schematic is not as important as the physical layout of the signal path and the return current.

13

TECH ARTICLE

13

eeweb.com/register

Join Today

http://bit.ly/jd6Wcw

1414


When it comes to turning your design or circuit into a real life, three-dimensional object, there is one step that can make a big difference to this being successful. Laying out your PCB is just as important a skill as designing the circuit. In this article, I want to look at some of the key steps and the approach I take when taking the route to PCB.[

THEROUTETO PCB

Paul Clarke

Electronics Design Engineer

15

TECH ARTICLE

15

I currently use a software package called PADs at ebm-papst, which in my view is a great package if you can find someone else to afford and purchase it. However, no matter what package you use, you can still achieve the same results. So where do we start?

Assuming that I have all the footprints I need and I’m happy with the circuit drawings and components, I will print out the circuit schematics. It is important to have these at hand; you’re going to convert these line drawings into real copper. Next, I import or load up all the component footprints into my layout package.

There are two possible approaches. You can either be an auto-route person or, like me, route the entire board by hand. For designs that do not have large numbers of buses and are primarily embedded micros, hand routing is just as quick as auto-routing. I say this because I would have to check track width rules like, “Is the net set to the correct width to carry the current?” I would also go back and check that signal lines are not next to power rails or noise sources. Therefore, in my head I can do this as I route and get the best layout I want, using my brain as the auto-router and design-rule checker.

I start by grouping the components into areas around the outside of the board. For instance, let’s say I have a switch mode power supply—all these routes end up in a jumble over on one side. So do not overlap; just place them side-by-side in a grid to get an idea of the board area required. I do this for each block of the circuit, and this is why having the schematic in front of you is useful—you can see if the 100nF cap is for the power supply or needs to go next to an IC for decoupling. I move these blocks around until I can see where I want the flow or interfacing edges of each block to go until I’m ready to move on.

Figure 1: Analog

Figure 2: Digital

1616


Assuming I have a PCB outline I will create a physical representation and start placing connectors—the ones that just have to go somewhere. I glue on the connectors so I can’t accidentally move them. It is then important to check PCB size and the location of the connectors to see if they fit in the enclosure.I then start routing the board in one of two ways. Most of my boards are two or four layers. Regardless of the number of layers, I think about the board as a 3D object. The circuit layout can be broken down into two types: One type of layout deals more analogue circuits with short routes between a resistor and an IC or between a few caps and regulators (See Figure 1). The other type of layout is for digital circuit with long runs of two or more routes running between multiple devices. One example would be routing an SPI bus (See Figure 2).

I try and start with the analogue circuits and lay out the components and tracks as they appear in the circuit diagram. If you

Figure 3: Ground Track

“ For designs that do not have large numbers of buses and are primarily embedded micros, hand routing is just as quick as auto-routing.”

17

TECH ARTICLE

17

don’t have lots of over lapping nets in a 2D drawing then it should be easy to do the same on the PCB. If I can keep it all to one side of the board I will; this allows for another circuit to sit on the other side. I have used this technique often with RPM monitoring circuits for fans and then have the PWM drive circuit on the other side of the board. They both have to feed to and from the microcontroller and device, in this case a fan, so it is good if they run in parallel.

For a digital layout, I will run the lines together as much as possible but I do not try to stay to one side of the board only. I will however use a rule: blue = horizontal, red = vertical. The blue and red refer to the bottom and top sides of the board as it is displayed in the CAD package. By running these lines only horizontal on one side of the board and vertical on the other, it will minimize the number of board layers required.

However, there are no hard rules, and when you have a digital embedded circuit you will have both types of layout to deal with. This means I will layout each block as it fits each layout profile above. Digital and analogue lines from the micro will follow a more blue/red rule until they reach the analogue type circuits. This allows me to break out the signals from the micro and keep tight and compact analogue circuit’s ring fenced from each other.

There is, however, one very important part of the circuit I have not talked about yet, the power rails. Now it’s not hard to remember to connect power rails like your +5 or +3.3 volt lines but people do forget about the ground or 0 volt rail. For each section of circuit or large device, I always check that I

run a 0-volt trace out and connect it back. I try and use “around the outside” rule. OK, not a great sounding rule but this means that I will have a track that runs around the whole of the outside of the board in a loop and then run feeds into these blocks. It’s also good to highlight the whole track and see where it’s running. Can you bridge a gap (Figure 3)? The better your 0-volt connections the more likely your board will work well!

Once complete, I then tackle the flood plan. Now I know not everyone worries about this but I do a copper flood on top and bottom connected to 0 volts. By maximizing the 0-volt tracks the flood will reach all parts of my board and I will have good connections throughout.

Finally, I will run connection and clearance design rule checks that are built into PADs to flag silly errors before generating a final export to the mechanical engineer. He will, in my case, check that there are no 0603 resistors sitting under an IC when it was meant to be on the back of the board. I only made that mistake once! I then can send off my files for the board to be made. It is a good idea to be certain that all the components will fit on the board. I once worked at a place where we had a PCB mill that could drill and cut the tracks from blank sheets of copper. This was a good way to see if everything fit in the right place before spending money on prototype boards.

There are many hard and fast rules you can add to your design approach, but these simple and basic principles allow me to design a board with minimal errors and reduce my chance of a re-spin. ●

18


A Complete PCB Resource

Sierra Circuits was founded by current CEO Ken Bahl back in 1986.

After working at various manufacturing companies at the engineering level, Bahl

took a job at Simonds Precision in Vermont as Vice President of Operations.

At the time, Simonds Precision began to develop a subcontract manufacturing

division that assembled PCBs for IBM. It was this division that led Bahl to start

his own company that specialized in PCB manufacturing, which in turn became

Sierra Circuits.

We spoke with Bahl about the origins of Sierra Circuits, the ways in which the

company ensures the highest quality quick turn PCBs, and the unique customer

relationships that allow for continued success.

Sierra Circuits:Ken Bahl


COVER INTERVIEW

19

A Complete PCB Resource

Sierra Circuits was founded by current CEO Ken Bahl back in 1986.

After working at various manufacturing companies at the engineering level, Bahl

took a job at Simonds Precision in Vermont as Vice President of Operations.

At the time, Simonds Precision began to develop a subcontract manufacturing

division that assembled PCBs for IBM. It was this division that led Bahl to start

his own company that specialized in PCB manufacturing, which in turn became

Sierra Circuits.

We spoke with Bahl about the origins of Sierra Circuits, the ways in which the

company ensures the highest quality quick turn PCBs, and the unique customer

relationships that allow for continued success.

Sierra Circuits:Ken Bahl


20


What are the most challenging aspects of your quickturn prototyping service?

The PCB manufacturing process is certainly one of the most complex industrial fabrication processes. Every step requires perfect quality control, beginning with the selection of exactly the right material and every subsequent manufacturing process. Any one variable that is not precisely controlled among dozens of steps could easily scrap the boards. In a quickturn environment, when you commit to a turnaround of from one to five days, quality must be consistently perfect. To achieve that quality, the equipment must be perfectly maintained and all wet processes must be continuously monitored. The manufacturing staff must be highly trained to regulate each process perfectly and the handling procedures for the product must also be precise. The human factor is the biggest challenge in the PCB and prototyping business—there simply is no time to scrap and remake prototype PCBs. All of the exacting control I mentioned is dependent on people, so a crucial aspect of the quickturn prototype business is managing people.

You’ve been at it for many years and I’m sure your processes have evolved and your customers’ requirements have evolved as well. How would describe your relationship with your customers and how that has developed?

Customer relationships have always been directly dependent upon the level at which you are meeting the customers’ needs. Two things have happened since the beginning of our business. One, the technology has exploded. Designs today are much more complex compared to when we started. Designers today need a lot more assistance so that they can give us a manufacturable design. We have responded by changing our internal organization to provide that service to them. Two, designers need a lot more education so that they can design good products independently. We are bolstering our efforts in both of these directions. To help our customers better achieve manufacturable designs, we are

With no prior experience in PCB manufacturing, Ken Bahl built, from the ground up, one of the most successful prototyping businesses available today.

COVER INTERVIEW

21

providing them with stackups and guidelines for feature sizes. To help them improve their design abilities, we are providing them with such tools as a stackup planner, a material selector, and online DFM assistance so that they can be independent. Those efforts are helping them to provide us with good files to produce their boards.

Let’s talk about how the technology in your manufacturing has changed over the years.

Because of the wireless revolution, more and more functionality is being designed per square inch of real estate. This requires finer and finer traces, spaces, and the use of sequential lamination processes, which challenges layer-to-layer registration. This defined the change required in our manufacturing processes.

“Customer relationships have

always been directly dependent upon the

level at which you are meeting the

customer needs.”

22


We have a continuously refined registration process, which gives us the ability to hold a drill-to-copper clearance within 2 to 3 mils. We are creating processes to be able to do a 1-mil line and space. Our effort in improving these areas is ongoing.

Could you talk about how you got started with flex circuits and the company’s success with those products?

We got started in flex because we were motivated by a few very high-tech military customers. They saw our registration capability and gave us R&D projects to do very high-layer-count rigid-flex boards. We completed those projects successfully and have now been building flex for about five years. We

now have a plan to provide a full line of flex products. Within the next two to three years, we will be setting up a separate plant for flex.

What are the most promising new technologies you see in PCB prototyping?

We have been working with a new technology that will help us achieve fine lines with more reliable yields. When the time is right, we will make an announcement. This technology will help us produce consistent quality on sub 3-mil lines; hopefully, down to 0.5 mil.

In terms of your business, where do you see the largest growth potential?

I see the largest growth potential in providing turnkey products to our customers. When we make a PCB, buy components, and assemble them, we can provide the best overall turnaround time and prevent a lot of customer-related issues. Our turnkey turnaround time of from five to ten days provides a tremendous time-to-market value. When we provide value to our customers, our business grows. The second biggest potential is to create the same turnkey service, but do it completely online. This will provide the ultimate customer service and ease of doing business in this complex business environment.

The industry needs to work on totally integrated automated processes to help designers from schematic entry through assembly and thereby aid them to quickly realize a design free from errors. This is the best way we can help them. We have superb engineering services, so designers can talk to experts and hash out any issues they might be facing with manufacturing or design. We work with customers on that level. ●

“ The industry needs to work on totally integrated automation processes to help designers from schematic entry through assembly.”

COVER INTERVIEW

23Copyright 2013, Silicon Frameworks, LLC PCBWeb.com

ep page master fp.indd 1 3/11/13 10:34:41 AM

http://bit.ly/XVO5Wt

2424


ISOLA’S ORGANIC SYNTHESIS REACTOR CREATES PCB RESIN


is a global material sciences company that develops polymers for advanced

multilayer printed circuit boards. Its R&D facility in Chandler, Arizona

recently expanded to include an internally designed, production-scale organic synthesis reactor that

will allow the company to develop unique polymer resin systems. With the ability to create resins

on site, Isola can distance itself from suppliers to enable completely proprietary products. However,

building a reactor of this complexity is no easy task. We spoke with Stan Wilson, the manager of the

Isola reactor project, about the process of developing with the reactor in-house and how it enables

the company to be more efficient in all aspects of PCB development.

ISOLA GROUP

25

FEATURED ARTICLE

25



is a global material sciences company that develops polymers for advanced

multilayer printed circuit boards. Its R&D facility in Chandler, Arizona

recently expanded to include an internally designed, production-scale organic synthesis reactor that

will allow the company to develop unique polymer resin systems. With the ability to create resins

on site, Isola can distance itself from suppliers to enable completely proprietary products. However,

building a reactor of this complexity is no easy task. We spoke with Stan Wilson, the manager of the

Isola reactor project, about the process of developing with the reactor in-house and how it enables

the company to be more efficient in all aspects of PCB development.

ISOLA GROUP

2626


Reactor Overview

When making printed circuit boards, you must begin with building blocks made of resin. In the past, Isola was tied to an outside resin manufacturer to supply them with the necessary materials for the building blocks. Once they received these resins from the manufacturers, the Isola team would add their own components in what they call their compounding area to bring the quality up to their standards and formulations.

According to Wilson, by having the reactor on-site, they are able to create a resin unique to the marketplace. “Our reactor synthesizes the resin and allows us to create a proprietary resin system that our otherwise competitors will be buying off the shelf.” With the base resin, the reactor basically heats it up and allows some of its molecules to separate in order to add components to change its structure. “It actually gives us good control of our own resin system,” Wilson explained to us, “especially in the high-performance market

we’re targeting today.” This added control of the process removes the complexities of referring to an outside source, allowing more freedom to test and tailor it to the company’s high standards. This is a fairly new capability for Isola and, according to Wilson, is unique to their competition.

Isola’s reactor allows them to synthesize resin to create a proprietary resin system that competitors will end up buying off the shelf.

Design Concept of 800 Liter Reactor

27

FEATURED ARTICLE

27

From Prototype to Production-Size

Stan Wilson oversaw the reactor’s creation as project manager along with Charles Lehman, another engineer on the team. All of the production for the reactor and R&D facility was done in-house with Isola’s own design team. Initially, the team used a relatively small, 100-litre prototype reactor that allowed them to come up with a unique resin. From there, the team saw the need for a bigger reactor that would be more cost-effective and convenient for customizing their products. “We went from a 100-litre reactor to a 800-litre, production-sized reactor,” Wilson told us. “This allows us to run projects at production levels to be able to supply the market.”

The reactor took years to design and build after modeling from the prototype reactor. “It was a pretty intense project,” Wilson recalled, “The company put a lot of funds into making this happen.” Going from the prototype reactor to the production-sized reactor was a two-year process, with the reactor going into full production mode this past fall. It turns out it was worth the wait. “The feedback I’ve gotten has all

been positive.” Wilson told us. “It has surpassed our requirements and is working better than we initially thought in terms of reaction time, batch size, and consistency.” Since time to market is very important to Isola’s customer base when designing PCB boards, the convenience of the on-site reactor has also proven to be a major benefit. Isola is now able to respond quickly to changing market conditions and environments to help their customers and OEMs get their product to market faster. ■

Above: (From left) Charles Lehmann, Michael He, Stan Wilson

Modern Printed Circuits: Sierra Circuits

Documents

Transcript of Modern Printed Circuits: Sierra Circuits