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Eerst denken, dan doen, leidt tot “right first time”! – seminarie
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Tips & Tricks – BOM & CPL Data
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during office hours. We will be more than happy to help.
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ETSEIB Motorsport Barcelona with Eurocircuits PCBs
Who are ETSEIB Motorsport Barcelona?
ETSEIB Motorsport is a team of students, formed by undergraduate engineers at the last grades of their engineering studies. The team has coordinators from the faculty that give support and lead the project.
Introduction
In a electric race car is very important do a great job with the electronic system. We do an accurate job in order to make a safe car. We should design, manufacturing, weld and program PCB’s, Eurocircuits help us in manufacturing phase printing out PCB’s like these.
BMS Slaves
The Etseib Motorsport Battery Management System is divided in two types of boards: BMS Master and BMS Slave. Eurocircuits provides us the first prototypes of BMS Slaves to test the first design of this board to ensure its good performance.
This board has a LV zone where there is a microcontroller, which communicates via SPI with 4 microchips. These chips can sense the voltage and balance every cell in the car, and also sense 12 point’s temperatures, 4 from the PCB and 8 from the cells busbars. We balance the cells by using 20 ohms resistance so the maximum current used for balancing is 217.5mAmps, and NTC sensor are also included for measuring the temperature of the PCB for safe balancing.
Figure 1: The BMS Slave PCB
Finally, it’s time to solder it. We place some paste on the PCB pad, place the components carefully over the paste and put the PCB inside the oven to solder it by using several heat treatments. We do finally cover them with coating to protect it from short-circuits.
Figure 2: Welding the BMS Slave PCB
Low Voltage Communications PCB
This small PCB has a double point achievement: The first one is to fuse the high path of the Low Voltage Battery, which supplies the whole Low Voltage System, so the Low Voltage System is protected against overcurrent situations.
The second purpose is to communicate with the Low Voltage Battery BMS by using serial UART protocol, processing all obtained data and finally introduce it into the car’s CANbus communication network to keep other ECUs of the Low Voltage Battery’s state of health and charge.
Figure 3: Low Voltage Communications PCB
DASHBOARD
In the Formula Student, the Dashboard is an ECU which works as an interface between the driver and the rest of the car. It contains a group of buttons that allow to start racing as well as changing important characteristics on the car mode and shift between different screens where important parameters of the car are displayed. Moreover, it also controls some LEDs either on the cockpit or the steering wheel to warn the driver about different facts that are important during the different dynamic events. Therefore, in our car, the Dashboard could be assumed as the driver interface controller.
In the CAT11e, the driver interface has been developed and optimised through the drivers feedback in order to make it simply and clear. For that reason, it has 4 buttons and 5 LEDs on the cockpit and 4 buttons and 2 LEDs on the steering wheel.
Figure 4: The whole drivers interface controlled by the dashboard
However, without the dashboard PCB it could not be possible to have such a reliable and useful interface that helped our time to understand at any time the car behaviour.
Figure 5: Dashboard PCB Layout
Figure 6: Dashboard PCB physical layout from Eurocircuits.
Even though it looks complex and compact, it is based on really simple circuitries and components in order to just control some buttons, LEDs and a display, which are all explained next.
Regarding the buttons, it is interesting to see that the buttons are only based on pull-down circuitries that sends a low signal (0 V) to the MCU and a high signal (3.3 V) to the MCU when the button is pressed.
Figure 7: Buttons circuitries, a simple with the example of 4 out of 8 buttons on the dashboard.
Then, with the LEDs, a N-channel MOSFET is used to enable the current through the LED or disable it when necessary. Through the MOSFET gate, the MCU sends a signal that can be high (3.3 V) or low (0 V) to turn on/off the LED. Indeed, when the input is 3.3 V, the LEDs are turned on but when the input is 0 V the LEDs are turned off.
Figure 8: Schematics of the LEDs circuitries.
Finally, regarding the LCD screen, the dashboard was the responsible to send the information to the screen in order to display whatever it was necessary at any time. In this case, the screen had a high logic level of 5 V meanwhile the MCU had a high logic level of 3.3 V. To solve this issue, the dashboard also has hand-made level shifters to translate the 3.3 V of the MCU to the 5 V of the screen.
Figure 9: Schematic of the level shifter circuitry used on the LCD screen.
With this circuitry arranged in that way, when the MCU sends a 3.3 V the gate of the MOSFET and the source are at the same voltage level and the MOSFET is not working. Therefore, the pull up has effect and its 5 V signal is sent to the LCD to be recognized as the high output sent from the MCU. However, when the MCU sends 0 V, the gate – source voltage is 3.3 V and the MOSFET is working connecting directly the input of the screen to the 0 V output of the MCU.
Finally, on the testing done in order to check the hardware and the software designed, it could be possible to see that the designed circuitry worked properly and the screen had the suitable information.
Figure 10: Screen controlled by the dashboard.
To conclude, on the electronics and the ergonomics of the car it is important the use of this interface in order to make aware of the driver about whichever dangerous circumstances they can be facing as well as the status of the car. Is for all the previous explained before that we are really pleased to Eurocircuits for the help they offered to us that enhanced the electronic and car performance in such a big way.
Figure 11: Dashboard in the race car
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Young Engineers Deliver Innovative Successes
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Supporting the Academic Motorsport Club Zurich
The Academic Motorsport Club Zurich (AMZ) consist of 65 students from the ETH Zurich and the Lucerne University of Applied Sciences, each year they design and build a complete electric racing car as well as, converting an existing race car into an autonomous (self-driving) racing car.
The project is either part of their studies or is realised in parallel to their studies and gives the students, the opportunity to convert the theory learnt in the lecture halls to real practical applications.
For the first time in Formula Student history and during the biggest engineering competition since 1972, the team of ETH Zurich achieved two overall victories. In the electric and autonomous class of the Formula Student Germany competition, they were able to get both AMZ vehicles ahead of the international competition, consisting of 3,700 students.
In addition to their victories the AMZ team scored 959 points during the Formula Student Germany competition and thus achieved the highest score every recorded during this competition.
A month earlier, students in Italy achieved the full 1000/1000 points in a Formula Student competition. No other team in the more than 35-year history of Formula Student has achieved this anywhere in the world.
Key facts about the autonomously driven racing car:
- Weight: 192kg
- Speed: 117kmh
- Acceleration: 1.6G
- Motor: Self-developed electric engines
- Drive Train – 4WD
What was realised with the Eurocircuits PCB’s:
- Implementation of the autonomous system
- General energy supply to the sensors
- CAN interface to control actuators with electronic control unit (ECU) of the car
- Control and read of the non-programmable logic of the autonomous status of the machine
- RS232 interface for reading the IMU
- High Voltage Accumulator Management System (AMS)
- Measurement of the temperature and voltage of each battery cell
- Transmitting the cell information from each AMS (at each cell) to the master controller
- 112s1p accumulator cell configuration (420V)
- 62kW discharge capacity
- cell balancing
The contribution and support of, Eurocircuits in this project has played a significant part in obtaining these outstanding results. We thank you very much for your support and cooperation.
Claas Ehmke
SLAM and Electronics, Driverless
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Blind and buried vias
Blind and buried vias
Blind and buried vias are used to connect between layers of a PCB where space is at a premium. A blind via connects an outer layer to one or more inner layers but does not go through the entire board. A buried via connects two or more inner layers but does not go through to an outer layer.
BUT:
- Not all combinations are possible. This is explained in this blog.
- Blind and buried vias add considerably to the cost of a PCB. They should only be used when absolutely necessary. To help designers of tight boards, we offer via holes down to 0.15 mm in our pooling services and down to 0.10 mm as a non-poolable option. These need minimum outer layer pad sizes of 0.45 mm and 0.40 mm respectively.
Use the “smart menu” Buildup wizard to check what blind and buried via options can be produced for your design and to work out their cost. Choose from over 700 pre-set multilayer builds, accessed by number of layers, board thickness, build and copper weight. Then add your blind and/or buried via requirements. If you can use a pre-set build you get your offer faster, the boards are easier to build and so the price is lower.
How a multilayer PCB is built.
Every multilayer build-up is constructed out of cores, pre-pregs and copper foils.
You can think of a core as a double-sided PCB. It is a rigid piece of base laminate with copper pre-bonded onto each side. If you go to the pre-defined build-ups for a 4 layer, you will see that the standard build has a core in the centre containing the copper tracking/planes for layers 2 (= inner layer 1) & 3 (= inner layer 2).
On each side there are one or more sheets of pre-preg and then a sheet of copper foil. Pre-preg is glass-fibre cloth pre-(im)preg(nated) with uncured resin. The sheets of pre-preg and foil are bonded onto the core using heat and pressure. This cures the resin in the pre-preg as well as bonding the whole build. The resulting “sandwich” is then drilled and plated like a 2-sided board. For more information on the process see our movies on pcb production
How blind and buried vias are made.
We do not use depth-controlled laser drilling to manufacture blind and buried vias. We first drill one or more cores and plate through the holes. Then we build and press the stack. This process can be repeated several times.
This means:
1. A via always has to cut through an even number of copper layers.
2. A via cannot end at the top side of a core
3. A via cannot start at the bottom side of a core
4. Blind or buried vias cannot start or end inside or at the end of another blind/buried via unless the one is completely enclosed within the other (this will add extra cost as an extra press cycle is required).
These rules are incorporated into the Buildup wizard.
So on a standard 4-layer build, we can only drill buried vias between layers 2 & 3. If we do this, blind vias become impossible.
For blind vias you need to select a reversed build. Here instead of a single core at the centre between layers 2 & 3, there are two cores on the outside of the board between layers 1 & 2 and 3 & 4. Now we can drill blind vias between 1 & 2 and 3 & 4. Buried vias are no longer possible as the dielectric between 2 & 3 is pre-preg which cannot be separately drilled.
Higher layer counts work in the same way, but now it is possible to combine blind and buried vias.
Blind and buried vias can be overlapped provided that one is completely enclosed within the other (but note the extra press cycle).
A special build follows the same procedures but with different thicknesses at higher prices.
Asymmetrical builds are not possible. The build must be the same on either side of the centre. The main reason is to avoid bow and twist after pressing of the PCB.
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Eurocircuits presente en Matelec Ifema Madrid 2018
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Meet the Eurocircuits Team at Electronica 2018 in Munich!
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Tolerances on PCB – Blog
What tolerances should I design into my PCB?
Where possible design your PCB to meet industry standard mid-range tolerances. Eurocircuits use these specifications and tolerances as the basis of our lowest-cost pooling services.
For more detailed information on our Manufacturing Tolerances please see our Tolerances on a PCB page.
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Be informed – Join us at the LED Event 2018
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Tips & Tricks: Avoiding Solder Escape/Wick during Reflow
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Tips & Tricks – Why Do Components Tombstone
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Announcement! We will take a Break for Christmas
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RoboTeam Twente – The PCB’s in our Robots
At RoboTeam Twente we make a team of small soccer robots which autonomously plays against other teams. On a field of 9 by 12 meters, 8 of our robots cooperate as a team against the opponent’s team. On the inside, the robots are packed with circuit boards. These are used for driving the four wheels of the robot, kicking the ball and various other functions. In this story, I would like to tell you more about the PCBs of our robots. Our robot holds three main PCBs. One board contains the high voltage circuitry which drives the solenoid we use to kick the ball. The second board holds the microcontroller, which handles the communication with the central computer and control systems. A third board is implemented four times for each robot: once for each wheel. It contains a motor driver for the three-phase motors we use. The high voltage board uses a flyback converter to transform 12V to 300V. The high voltage is used to charge a 680µF capacitor. Since the voltage needs to be achieved in a few seconds, the 12V side produces currents up to 6A at a switching frequency of 100kHz. After charging, the capacitor is discharged over a solenoid using an IGBT. This produces a current up to 50A. The solenoid creates a magnetic field, which propels an iron bar. This bar then collides with the ball, to kick it away with a max speed of 6.5 m/s. The board with the microcontroller is the brain of the robot. It receives all commands from the central computer, which it processes and executes. The command package contains several commands, like ‘kick’, ‘dribble’ and ‘drive in this direction at this speed’. The desired direction and speed are transformed to a speed for each wheel, which is sent through PWM to the motor boards. The motor boards contain a dedicated motor driver IC with internal H-bridges. Using a PWM as input, they deliver the desired output to the three-phase motors, with a maximum current of 1.5A per wheel. The motor boards are plugged into the microcontroller board using board-to-board connectors. This means replacing boards for maintenance is easy. Since we’re now in a prototyping phase, the fast production times by Eurocircuits really help us out. We’re able to develop our design a lot faster, and with the assurance that the quality is high enough so traces don’t tear when replacing small components. Additional functions like beveled edge connectors help us with producing user-friendly boards that can connect with PCI-e headers. We would like to thank you for your support! It makes a big difference in time and quality of our work. Nahuel Manterola Electrical engineer at RoboTeam Twente
Introduction
High Voltage Board
Microcontroller Board
Motor Boards
Best regards,
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Eurocircuits wishes you a Merry Christmas and a Happy New Year
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Copper and the Board Edge
Copper and the Board Edge.
There are three options under our Advanced options heading which may be confusing:
- Copper up to board edge
- PTH on the board edge
- Round-edge plating.
Here’s how to sort them out.
Copper up to Board edge.
To avoid damage to the copper during the profiling operation we normally ask for a minimum distance between the copper features and the edge of the PCB. This distance is:
- 0.25 mm on outer layers with breakrouting
- 0.40 mm on inner layers with breakrouting
- 0.45 mm on all layers with V-cut scoring.
These figures are needed to accommodate industry-standard manufacturing and machining tolerances. For V-cut scoring it is also necessary to accommodate the V of the cutter.
Sometimes it is necessary to run a copper plane up to the board edge. In this case select “Copper to board edge”. There is no extra charge for this but it alerts our engineers to set up a different cutter speed.
“Copper to board edge” should normally only be used for planes and large copper areas where any slight damage to the copper will not impact on the performance of the PCB.
Tracks must not be placed within the minimum distance of the board edge where they could be damaged. Our engineers will raise an exception whenever they find tracks within the exclusion zone.
If we find pads within the minimum distance of the board edge, we will clip them back to restore the minimum copper-free space unless:
- the pads are part of an edge connector (usually with a bevelled edge)
- the pads are marked as “up to the board edge” in a separate mechanical layer
- the clipping is more than 25% of the pad surface in which case we will send an exception to the customer.
NOTE.
Copper to board edge cannot be combined with V-cut scoring.
PTH on board edge.
Also called “castellated holes”.
These are plated holes cut through on the board edge and used to join two PCBs either by direct soldering or via a connector. As the process requires extra steps, plated holes on the board edge are a cost-option.
Your data should clearly show the holes and the profile. Ideally include the information in a mechanical layer.
TIPS.
- There must be enough spare space on the edge of the PCB for us to hold the PCB in the production panel during manufacture. If you need castellated holes on all 4 sides, email us your design or proposed profile as early in the design process as possible. We can then confirm that it is manufacturable or suggest any necessary changes.
- You must have pads on top and bottom layer (and on inner layers where possible) to anchor the plating securely to the PCB.
- As a general rule the holes should be as large as possible to ensure good soldering to the mother PCB. We recommend 0.80 mm and above. Minimum end size possible is 0.5mm.
- All surface finishes are possible but our preference is for selective gold over nickel for the smaller sizes.
Round edge plating.
This means that most or part of the edge of a PCB or a cut-out is plated from the top side to the bottom side.
This may be to ensure a good ground to a metal casing or for shielding purposes.
To manufacture a board with round-edge plating we rout the board profile where the edge plating is required before the through-hole plating process. This involves extra process steps so round-edge plating is a cost option.
TIPS.
- There needs to be a band of copper on each side for the plating to connect to.
- As we need to hold the circuit within the production panel during processing we cannot plate round 100% of the edge. There must be some gaps so that we can place rout tabs. If you need a very high percentage of edge-plating, email us your design or proposed profile as early in the design process as possible. We can then confirm that it is manufacturable or suggest any necessary changes.
- Indicate clearly in a mechanical layer where you need round-edge plating.
- Selective chemical nickel-gold is the only surface finish suitable for round-edge plating.
The post Copper and the Board Edge appeared first on Eurocircuits.
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PCB Prototypes on a 5 Day Delivery for a 7 Day Price
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The post PCB Prototypes on a 5 Day Delivery for a 7 Day Price appeared first on Eurocircuits.
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Southern Electronics 2019
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The post Southern Electronics 2019 appeared first on Eurocircuits.
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A&T Event 2019
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The post A&T Event 2019 appeared first on Eurocircuits.
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Embedded World 2019
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The post Embedded World 2019 appeared first on Eurocircuits.
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