Prototype Simulation Tool Enhances Competitive Edge
Jeff Skinner, Vice President of Engineering

Key to a successful mix of resources is the addition of engineering tools that enhance Controltek's capabilities and productivity. To this end, Controltek recently purchased a product offered by Mentor Graphics called Hyperlynx. This tool includes a pre-layout simulator called LineSim, and a post layout simulator called BoardSim. Hyperlynx simulation capabilities are a proactive method for Controltek to produce initial circuit board layouts with fewer design issues, thereby reducing the number of prototype circuit board iterations. This translates to less engineering development time and faster time to market for Controltek's client companies.

Circuit board layout poses many challenges to the PCB designer, these challenges become greater as circuit board speed and density increase. A successful circuit board layout must address the issues of signal integrity, crosstalk and EMI. Signal integrity address the quality of the signals traveling down each circuit board trace. When the load at the receiving end is not matched to the characteristic impedance of the trace, part of the signals power is reflected back to the source resulting in ringing and distortion. To prevent this, termination circuits are used to bring about a match between the characteristic impedance of the trace and the load. Determination of the proper impedance termination method and values is often iterative. Without simulation tools, iteration implies multiple circuit board fabrication runs, an expensive approach. With simulation tools, the designer can check the performance of the design for acceptable signal quality and adjust the termination method and component values until the desired result is achieved prior to initial release of the PCB for fabrication. Crosstalk refers to interference between signals. When signal traces are in close proximity to one another, the current in one conductor trace can induce a signal into other adjacent traces. Proper signal spacing and routing are key to preventing crosstalk. Again, the use of simulation tools allows a check of signal trace routing and spacing for crosstalk effects prior to initial release of the PCB for fabrication. EMI is radiated energy that can interfere with the operation of other nearby equipment. High speed signals with fast edge rates radiate significant amounts of electromagnetic interference. European common market directives specify the maximum allowable level of electromagnetic radiation that can be emitted by any system as a function of frequency. Complying with these directives is usually an iterative process that is both time consuming and expensive. By using Hyperlynx the designer can get a measure of the amount of radiated energy the layout is producing and adjust signal edge rates or add high frequency filtering as required to comply with allowable levels prior to PCB release.

As an example of the usefulness of the Hyperlynx tools, consider the case of figure #1. Here two probe points on the same signal are examined in Hyperlynx simulation, one probe at the source and the other probe at the destination point. As can be seen from the figure, overshoot and undershoot exist on the signal at both the source and

Figure #1

destination points. This is a result of an impedance mismatch with the signal trace causing a portion of the signal power to be reflected back to the source. By adding an impedance termination to the circuit and adjusting the values in the termination circuit the quality of the signal is dramatically improved. Figure #2 shows the same signal at the same source and destination points after proper termination has been determined through Hyperlynx simulation. As can be seen by the plots in figure #2, the quality of the signal has been greatly improved. We no longer see the overshoot and undershoot on the signal as was the case in Figure #1.

Figure #2

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Developing Material Supply Agreements
Sean P. Neill, Vice President of Operations

"The use of Material Supply Agreements has allowed ControlTek to make purchasing decisions based on customer needs rather than our latest order."
Sean Neill, Vice President Operations.

ControlTek has many MSA success stories. By coordinating closely with a customer to develop a Material Supply Agreement we reduced the lead time of a 16 week assembly down to one week. ControlTek has found MSA's to be beneficial in other ways as well. We discussed our manufacturing process for a specific product with the customer and identified two pieces of material that accounted for 80% of the cost. ControlTek's in-house design division was able to revise the product's design to utilize less expensive and more readily available materials. This resulted in a significant cost reduction in the assembly that ControlTek passed on to the customer.

ControlTek has initiated Material Supply Agreements (MSA) with key customers by communicating openly about challenges we face in material procurement. Some of those challenges may be:

• Material Availability - strategic purchases, forecasting, build volume fluctuations
• Quality - Engineering design changes, documentation, warranty/repair,
• Communication of cost drivers - Assembly process, materials

When developing a Material Supply Agreement with a customer, consider the following:

• Understand the issues most important to your customer. Is it lead time, price, quality?
• Do your research! Know the cost drivers for the product or product line. Is it labor intensive? Is there a significant material requirements that limit your ability to lower the product price?
• On time delivery. Analyze the delivery requirements for methods to reduce cost.

The use of Material Supply Agreements has been a positive experience for ControlTek and our customers. MSA's may be time consuming, however, they have opened the lines of communication with our customers and enabled us to provide high quality low cost electronic assemblies on a consistent basis.

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Pin In Paste (PIP) Reflow Soldering
Joe Herz, Senior Manufacturing Engineer

Implementation of Pin In Paste (PIP) can eliminate the wave and/or hand soldering processes, removes manual insertion stations, minimizes board handling and material handling operations. With some up front work in component selection and PCB layout, the PIP process can reduce the customer's overall costs.

ControlTek is constantly looking for ways to reduce the cost of manufacturing and increase levels of quality and throughput. Where applicable, advanced processing methods can be used to achieve this.

The traditional approach to assembly of printed circuit boards using both through-hole and surface mount components includes two solder process technologies - reflow and wave soldering. In many cases, especially with low to medium volume processing, hand soldering of some components is necessary. If a circuit assembly was not designed to minimize process steps and maximize throughput, excessive costs can result. This is a challenge faced often within the Manufacturing Engineering group here at .

Most of odd form components are connectors, transformers and shields, which very commonly require a strong solder joint for mechanical strength or high current. So, through hole components are required by many designs. The Pin In Paste (PIP) process is a method available that can eliminate wave and/or hand soldering for these types of components. The technique is simple, reliable and can result in significant yield improvement and simplified lower cost production.

Simply put, PIP is a method used to solder through hole components within the Surface Mount (SMT) Process. Solder paste is printed onto through hole land patterns, the parts are hand or machine placed and then reflow soldered along with the SMT parts.

There are several design criteria that need to be met for PIP to be applicable:

• The component(s) must be capable of surviving the reflow soldering process (225C max).
• The component(s) must have some form of standoff that allows clearance for the printed solder paste.
• Clearances around the through holes need to be sufficient to allow over-printing of solder paste.
• Pin to hole diameter ratios need to be adequate.

A recently launched product at presented some serious challenges. The PCB was 12 layers and .093 thick with SMT components on both sides. Around the perimeter of the assembly were 25 dual row, right angle connectors some of which had heavy thermal connection to several layers. Hand soldering presented a challenge as the heat sinking effects of the thermal connections made it almost impossible to achieve complete solder fill on all through holes. Selective wave soldering would have been an option but the bottom side SMT components had not been laid out with the proper clearances to allow for fixturing. Fortunately, the connectors on the assembly were reflow capable and had the standoff needed to employ PIP. The solder printing stencil was modified by opening apertures to allow paste printing on the through holes. A 100% yield was achieved for these parts.

ControlTek's Manufacturing Engineering group is available to assist all customers with their Design for Manufacturing challenges. Please give us a call.

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Employee Spotlight: Harly Horton - ControlTek Test Engineer
Stacey Smith, Vice President of Human Resources

"ControlTek's model of design, manufacture and test of electronic assemblies brings tremendous value to the customer. A customer can come to ControlTek in any phase of a project and we can give them the services they need to achieve their business goals."
Harley Horton, Test Engineer

For this edition of the ControlTek Newsletter, the employee spotlight shines on Test Engineer, Harley Horton. As a member of ControlTek's team for just over a year, Harley provides a fresh look at an employer that has been in the electronic design and manufacturing services industry for three decades.

Harley's focus is designing test systems for electronic assemblies. He combines his skills and experience in electronics, computer programs and mechanical devices to develop test strategies that ensure quality products are delivered. By using tools such as National Instruments Test Lab, Harley works with customers to develop economical test solutions that ensure all requirements are met.

Harley is a Montana native who relocated to the Pacific Northwest to pursue his career in electronics while enjoying outdoor activities such as mountain biking and hiking.

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