Ten-Layer High Density Interconnect Board from Rush PCB Inc.

Written by Admin on . Posted in PCB, PCB Assembly and component, PCB Manufacturing

The advent of revolutionary new products, driven by miniaturization of components and semiconductor packages supporting advanced features, is driving the Printed Circuit Board (PCB) industry to increase the functionality of their boards within the same or reduced areas. This includes products such as the hand-held touch-screen computers, 4G network communications, and industrial and military applications such as smart ammunitions and avionics. Eminent PCB manufacturers such as Rush PCB Inc. are providing solutions for the above with High Density Interconnect (HDI) boards.

HDI PCBs use high performance thin materials as prepregs, have fine copper lines, and use the Every Layer Interconnect (ELIC) technology to offer very thin flexible PCBs with very high functional density per unit area. Advanced HDI PCBs make use of multiple layers of copper filled stacked in-pad micro-vias that enable interconnections with even greater complexity.

Rush PCB Inc. is currently building a 10-layer board with an FR4 grade prepreg (TUC-872SLKSP), starting with all layers of 1/3 oz. copper. The outermost layers of copper will be coated with Electroless Nickel Immersion Gold (ENIG), and covered with a coverlay (green mask) of thickness 0.0249” ± 0.003”. Component placement will be aided by a printed white silk screen, while the width and spacing of copper traces in each layer has been carefully calculated to give precise control on the impedance. The board has an overall size of 6.857” x 5.287” and its model number is 104-032-01 Rev 10. Rush PCB Inc. will be manufacturing 100 Numbers of this HDI PCB with a lead-time of 9 days.

Stack-Up Design

Before finalizing the design of multi-layer PCB circuit boards, designers need to confirm the structure of the circuit board primarily based on the scale, physical size, and the requirements of electromagnetic compatibility (EMC). Considering the above, designers at Rush PCB Inc. have decided to use 10 layers of circuit boards. This also decided the placement of the inner layer and the manner of distribution of different signals in these layers—the stack-up design of the multi-layer PCB. This careful planning and rational selection of the stack-up design beforehand will be saving the user a huge effort in wiring and production later.

Two major factors need to be decided once the designers have determined the number of circuit board layers. These are the distribution of the special signal layers and the distribution of the power and ground layers. However, with multi-layer circuit boards such as the 104-032-01 Rev 10, designers at Rush PCB Inc. followed some general principles to obtain the best combination of signal, ground, and power layers:

  1. The signal layer was kept next to an internal power or ground layer, shielded by the copper film of the internal power layer.
  2. To keep a tight control over the impedance, the internal power layer was integrated tightly with the ground layer, so that the thickness of the prepreg between the internal power and ground layers was kept thin, of the order of 2.00 Mils.
  3. To minimize crosstalk, no two signal layers were kept adjacent each other. As far as possible, the designers placed a ground layer in between two signal layers to avoid crosstalk.
  4. To control the ground impedance, designers placed multiple grounded internal power layers.
  5. The layer structure was designed to be symmetrical.

The final stack-up is shown in Fig.1. The overall PCB thickness is only 27.20 Mils or 0.69 mm.

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Every Layer Interconnect Technology

To achieve very high-density interconnection, designers at Rush PCB Inc. have used the Every Layer Interconnect (ELIC) technology. This is a method where each layer has its own copper filled laser-drilled micro-vias. When stacked up, it provides the opportunity for dynamic connections between any two layers in the PCB. Not only does this offer an increased level of flexibility but also maximizes the circuit density. The designers took up the additional complex challenges in routing with Via-In-Pad (VIP) and employing blind and buried vias. Laser drills were used for drilling the via holes, and they were filled up with conductive copper paste.

PCB 104-032-01 Rev 10 uses a total of 32 sets of blind and buried vias between the following layers, as shown in Fig.2:

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Impedance Control

Designers at Rush PCB Inc. have referenced the signals on the top and bottom layer to the ground plane next to them. Likewise, signals on other layers are referenced to ground planes adjacent to them. High-speed signal routing on an inner layer is sandwiched between ground and power planes. Careful design of trace width, spacing, and prepreg thickness has led to a tight control over single-ended and differential impedance as shown by calculations in Fig.3, Fig.4, Fig.5, Fig.6, and Fig.7:

Fig.3

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Preventing Delays During Your PCB Fabrication

Written by Admin on . Posted in PCB Fabrication, PCB Manufacturing

pcb fabrication

Delays in your printed circuit board fabrication can be costly and time-consuming.  In today’s world, they are a commodity that there is never enough of.  Believe it or not, there are steps you can take to avoid those dreaded delays during your fabrication process.  We are going to discuss how you can take an active role in ensuring your printed circuit board fabrication runs smoothly and on schedule.

 

Communication

Follow up is an extremely important factor during the fabrication process.  Placing your project at the top of your “things to do list” is a must.  If you are communicating with your fabricator through email, or phone, you must be sure to answer any messages left in a timely manner.  Not answering them promptly can cause an interruption of the manufacturing, especially if a question is being asked or your guidance is needed.

 

Identify Long Lead-Time Parts

You may not realize it, however, some of the parts that are necessary for your project may take up to six months or longer to receive.  Working closely with your manufacturer as soon as you can will help them determine what they order and how quickly they can get it.  Printed circuit board manufacturing is not like shopping at your favorite grocery store, they will not always have the products in stock.

Also Read: Uses of Printed Circuit Board Components & Technology

 

Correct Documentation

You should always keep your product documentation up to date with the correct information.  Speaking with the manufacturer candidly to find out what their specific requirements are is the best way to understand what they need, this way there will not be any confusion.  This will also help eliminate any unnecessary mistakes that will inevitably cause delays in the manufacturing process.

Product Demand Information

Never wait until you are out of (or almost out of) your product.  This only increases stress, time, and cost.  The cost of shipping overnight is much higher than normal shipping methods.  Come up with a way to order your supplies before you run out to avoid additional cost, stress, and time.

Consider a Domestic Manufacturer

Although the cost may be less expensive, you may end up paying a higher cost in the end.  You want to consider the following;

  • Shipping prices will be higher with overseas manufacturers
  • Communication may become more difficult due to time differences
  • The difference in time may also result in the delay of delivery

Find a Manufacturer Who Can Handle the Entire

Manufacturing Process

A manufacturer who can provide their services from start to finish is the most beneficial option for your project.  This saves time because it cuts down on the amount of time it takes to get from one manufacturer to another, be worked on, and then shipped back to the original fabricator.  It makes smarter business sense to keep your product in one place from beginning to end so it can be shipped directly to you.  It also will stop the “blame game” if something is defective you know who is responsible.

Also Read: PCB Fabrication Making a World of Possibilities a Realty

 

 

New High-Density, Direct Connection for PCB’s

Written by Admin on . Posted in PCB, PCB Manufacturing

pcb

A new high-density direct connection for printed circuit boards has been placed on the market by Phoenix Contact.  Dubbed the SDDC 1.5 connection system it offers four to thirty-two conductors using “SKEDD” plug-ins.  Using the SDDC 1.5 eliminates the need for a header and soldering during the manufacturing process, saving money.   Using a push-in spring connection allows wires to be terminated to the connector.  It has also been designed with solid, stranded wires that include a ferrule which can be pushed into the terminal block while the spring clamp stays closed.  Removing the wires is simple by pressing the orange spring lever with a regular screwdriver.  It has a range of 3.5-mm centerline and works with 24 to 16 AWG wires, can handle currents up to 8 A at 300 V UL, and provides the push-in spring connection.  Its double row design is the latest in SKEDD Technology that uses a gas-tight connection.

The SDDC 1.5 connection system’s contact zone consists of two flexible parts that allow contacts to be easily adjusted with the use of plated through-holes on the printed circuit board.  The good news for manufacturer’s is that the design is so easy, it will not add to the cost of manufacturing, in fact, it can save on the production costs.  When inserted there is enough force that will create a gas-tight connection, requiring nothing special for the PCB.  The connection stability of the board is achieved by locking pins that expand with the push of the orange locking tabs.  It can potentially be used in building automation, HVAC systems, elevators and escalators, and white goods.

Also Read: View on PCB Design and Implementation today and in the future

Features include;

  • Allows you to save time during wire termination with its push-in connection
  • There is no need for a plug and header combination with its direct plug-in onto the PCB
  • Cost effective, only one component is necessary
  • Free positioning
  • Secure locking
  • Up to 25 mating and unmating cycles, for easy replacement
  • Intuitive use through color coded actuation lever
  • Quick and convenient testing using integrated test option

The SDDC 1.5 connection system is the newest high-density direct connection for printed circuit boards, that reduces manufacturing costs while allowing free positioning on the printed circuit board.  This is good news for the early adopters of this connection system, the implementation process does not require additional parts, the opposite is true, it only requires one component, does not require soldering and can be manufactured without using any tools.  Adding the integrated test option is simply another reason for considering the use of this connection system when necessary.

Also Read: Why it is Necessary to Control Humidity in PCB Assemblies

There is no doubt that the printed circuit board is the most important aspect of any technological project.  Meeting the industries demand for smaller, more effective, devices will continue to be a part of the PCB manufacturer’s responsibility.  The SDDC 1.5 connection system is an example of the latest in technological advances that we continue benefit from.  We look forward to the next advancement in PCB manufacturing!

 

 

References

Thomasnet.com

Phoenix Contact