Challenges and solutions for automotive ADAS

As the automotive industry continues to improve safety, vehicles need to integrate more and more peripheral photographic sensors and intelligent image processing technology to achieve advanced driver assistance systems (ADAS) such as lane departure warning, collision avoidance, blind spot monitoring, Advanced reversing photography and peripheral environment observation system with object recognition function. The common goal of manufacturers to create a completely safe driving environment is driving this trend. For example, Volvo's "Zero-by-2020" goal is that people who want to ride the new Volvo car by 2020 will no longer die or even be injured in a car accident.

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The challenge for these systems is the need to build a platform that maintains the processing performance required by these compute-intensive applications, consumes less power to avoid thermal issues, and provides a cost-effective solution that the integrators are willing to adopt, and the system The small size allows the system "brain" to be co-located with the image sensor and fit into the smart camera (if required). Image processing coexisting on the sensor constitutes a system solution in which the same intelligent photographic platform can be applied to different locations of the vehicle, such as the rear bumper - an enhanced reversing camera with object/human detection Mirrors - for blind spot monitoring; behind the rearview mirrors - for forward collision and lane departure warnings; and other peripheral cameras - for ambient observation. In addition, this distributed intelligent photography model does not burden the car's center console with additional processing requirements.


Figure 1: Advanced driver assistance system.

According to the market report, in the next few years, ADAS will not only be widely used in high-end cars, but also in more common medium and low-end cars. In addition to requiring more computing performance per application, there is a need to combine more ADAS applications on the same hardware platform. But it also raises a concern – is the current DSP and FPGA solution sufficient?

One of the biggest bottlenecks in DSP algorithm implementations is the burden of increasing external memory to keep up with read and write access speeds. Traditional DSPs offer limited parallel execution capabilities and typically require higher and higher frequency frequencies to meet processing requirements. As the frequency and frequency continue to rise, the DSP will consume more power, which in turn will generate more heat to be distributed. Although FPGA parallel execution capability is stronger than DSP, it is more difficult to program, and often requires RISC processor for post processing of data. FPGAs also have large power consumption, and the system size is large, in short, a costly solution.

The future of image recognition: multi-core parallel processing

The multi-core parallel processing performance performed by the CogniVue Image Recognition Processor (ICP) has surpassed DSP and FPGA in many ways. ICP can provide better cost performance in unit area and unit milliwatts of power.

The CogniVue APEX architecture integrates an industry-standard RISC core for managing algorithm execution and a highly parallel single instruction multiple data (SIMD) array processing engine (APU) for performing low-level, computation-intensive parallel operations inherent in image processing and analysis algorithms. . In addition to RISC and APU, this architecture also has a newly designed streaming DMA to ensure efficient data movement; and a sequencer designed for automatic and efficient sorting operations to ensure maximum efficiency. The second RISC core operates independently outside of APEX and is used to handle system-level resident procedures.

The APU internally prepares local dedicated memory for each compute unit. The image data is taken from the external memory and then streamed into the APU memory. All processing is done in the APU memory before the data flows out and is stored back in the system memory. Since the APU memory and the APU unit are located in one place, the number of external memory accesses can be greatly reduced, and high computing performance can be maintained without increasing the frequency. The APEX processing core is also separate from the rest of the ICP, which means that the APEX core operating frequency is independent of the rest of the SoC, allowing the rest of the component to operate at lower frequency frequencies, saving power. By stacking the external memory inside the package, this solution can achieve a smaller system size and save board space.

With a parallel processor core and a unique software paradigm based on streaming programming, CogniVue ICP can schedule complex vector operations and execute program code with minimal data movement. These processors implement automatic pipelined operation of algorithm primitives whenever possible, and capture this complexity through a comprehensive API, thereby hiding the complexity of system load balancing and eliminating multi-core synchronization faced by developers. problem.

The highly parallel mechanism coupled with the high ALU bandwidth architecture demonstrates a viable platform that provides sufficient redundancy and processing power to execute multiple applications in parallel on the same hardware. The flexible development platform and SDK enable users to flexibly program APEX and build highly competitive and differentiated applications. This multi-core parallel platform is favored by developers not only because it provides advanced performance, power and size features, but also ensures program code reuse in future ICPs, ensuring minimal development effort and time.


Figure 2: Parallel architecture of programmable design.

PCB SMT Stencil ,the unique goal  is to move solder paste to the bare Printed Circuit Board.

PCB Stencil , SMT Stencil, SMD Stencil , Laser Stencil , What is it?

Apart from all types of Printed Circuit Boards (PCBs) such as Prototype PCB , Aluminum PCB , HDI PCB , Flexible PCB , Rigid Flex PCB , Thick Copper PCB, High TG PCB , JHYPCB also manufactures solder paste stencils to meet Surface Mount Technology (SMT) requirements.

PCB Stencils, also called SMT stencils, SMD stencil, play a key role in transferring accurate amount of solder paste to correct positions on bare circuit boards ready for assembly. In other words, stencils can fast and efficiently ensure the most accurate solder paste amount and optimal electrical connection. With solder stencils, it is possible to use metal squeegee blades to apply solder paste easily over the openings on PCBs and make stencil to be well aligned with the surface of the advanced circuit board.

All of our SMT Stencils stencils are 100% laser-cut type 304 full-hard stainless steel, ensuring the finest quality finish on the market today. We use a .001" laser beam with 98% overlap creating an extremely smooth hole that provides the best paste release. Most stencil fabricators use a .003" laser leaving mouse bites on the aperture edge. You can choose a PCB Prototype stencil, a frameless foil stencil, or a rigid permanently mounted stencil. Both the frameless and framed stencils come in various sizes to accommodate your printer and stencil requirements.

PCB Stencil produced by JHY PCB

PCB Stencil Types Available:

1. Laser-cut stencils

The openings are lasered on 100% stainless steel. Generally speaking, this kind of stencil can be produced with high quality and a high degree of precision within a short time.

  • Advantages: high accuracy; barely influenced by objective elements; trapezoid opening beneficial for demoulding; suitable for accurate cutting; reasonable price;

  • Disadvantages: relative low manufacturing speed.

Laser-cut SMT Stencil

2. Chemical-etch stencil

The openings are etched into the metal using acid. Usually this kind of stencil offers better protection on material temper and hardness.

  • Advantages: one-time formation; relatively high manufacturing speed; low cost;

  • Disadvantages: tending to form sand clock shape or large openings; numerous manufacturing stages and accumulating errors; unsuitable for fine pitch stencils; bad for environmental protection.

3. Prototype PCB Stencil (Low-volume manual printing. Ideal for prototypes)

When prototyping dictates fast action with minimal cost, our prototype stencils are the best solution. Prototype Stencils gives you a quality stencil and framework so you can handle assembly from the convenience of your own desk.

Prototype SMT Stencil Features:

  • Eliminate the registration difficulty associated in hand printing with a flat piece of metal
  • Eliminate printer set up for short run prototypes
  • Allow quick alignment for repeatability
  • Save money over full size stencils designed for automated printers<
  • Squeegee included
Prototype SMT Stencil Specs:
Technology 100% laser cut
Material Used Stainless Steel
Stencil Thickness 0.06 ~ 0.3 mm
Minimum Cut Width 0.05 mm
Maximum Size 736 X736 mm
Aperture Tolerance within 0.007mm
Allow for Fiducial Data Yes
Delivery 1 ~2 Day

Prototype PCB Stencil (Low-volume manual printing. Ideal for prototypes)

4. NEW Prototype PCB Stencil Kit (with leaded or lead/free solderpaste)

Includes Prototype Stencil, one board holder, leaded or lead-free solder paste (must specify), temperature marker, squeegee, ESK-safe gloves and alcohol wipe. 

5. NEW Pick and Place Tool

Handy and convenient for low quantity prototype assembly using the Prototype Stencils.  Re-usable, includes vacuum bulb and vacuum clips with diameters of 3/8", 1/4", and 1/8".

6. Framed SMT Stencils (Also called "Glue-in" or Mounted Stencils)

Framed stencils are laser-cut stencils designed for high volume screen-printing. With a framed stencil, your stencil is securely mounted to either a cast or extruded aluminum stencil frame a stencil frame using a mesh border, allowing for complete control.

Framed SMT Stencil Features:

  • Unique Process for smooth aperture walls
  • Very clean laser-cut apertures
  • Excellent print performance
  • Excellent for high-volume stencil printing on printed circuit boards
  • Unique process creates permanent non-removable non-fading fiducial
  • All framed SMT stencils are double bonded to extreme wear
  • 24-hour turnaround standard
Framed SMT Stencil Specs:
Technology 100% laser cut
Material Used Stainless Steel
Frame Types Cast, Space Saver
Stencil Thickness 0.06 ~ 0.3 mm
Minimum Cut Width 0.05 mm
Maximum Size 736 X736 mm
Aperture Tolerance within 0.007mm
Allow for Fiducial Data Yes
Allow for Panelized Data Yes
Delivery 1 ~2 Day

Framed PCB Stencil Specification

Framed PCB Stencil Area

Maximum Squeegee Area

300mm*400mm (11.81inch*15.75inch)

120mm*220mm (4.72inch*8.66inch)

370mm*470mm (14.57inch*18.5inch)

200mm*300mm (7.87inch*11.81inch)

400mm*600mm (15.75inch*23.62inch)

220mm*400mm (8.66inch*15.75inch)

400mm*700mm (15.75inch*27.56inch)

220mm*500mm (8.66inch*19.69inch)

400mm*800mm (15.75inch*31.5inch)

220mm*600mm (8.66inch*23.62inch)

400mm*900mm (15.75inch*35.43inch)

220mm*700mm (8.66inch*27.56inch)

400mm*1000mm (15.75inch*39.37inch)

220mm*800mm (8.66inch*31.5inch)

400mm*1200mm (15.75inch*47.24inch)

220mm*1000mm (8.66inch*39.37inch)

400mm*1400mm (15.75inch*55.12inch)

220mm*1200mm (8.66inch*47.24inch)

420mm*520mm (16.54inch*20.47inch)

240mm*340mm (9.45inch*13.39inch)

450mm*550mm (17.72inch*21.65inch)

270mm*370mm (10.63inch*14.57inch)

500mm*800mm (19.69inch*31.5inch)

320mm*600mm (12.6inch*23.62inch)

500mm*1200mm (19.69inch*47.24inch)

320mm*1000mm (12.6inch*39.37inch)

550mm*650mm (21.65inch*25.59inch)

340mm*440mm (13.39inch*17.32inch)

584mm*584mm  (23inch*23inch)

380mm*380mm (15inch*15inch)

736mm*736mm (29inch*29inch)

480mm*480mm (19inch*19inch)

Framed SMT Stencil

7. Frameless SMT Stencil - Foil/Plate Only (for universal frames)

Foil or Plate Only stencils are designed to work within interchangeable plate or "universal" systems. Also referred to as "reusable", these stencils do not need to be permanently glued into a frame.

Frameless SMT Stencils also referred to as foils are laser cut solder paste stencils designed to work with stencil tensioning systems known as reusable stencil frames. This type of stencil does not need to be permanently glued in a frame. Frameless stencils are significantly less expensive than framed stencils and provide money-saving storage while still delivering superior quality and performance.

Frameless SMT Stencil Features:

  • Reduced storage space requirements
  • Significantly less expensive than framed stencils
  • Excellent for prototype Printed Circuit Board Assembly or short runs
  • Smooth aperture walls, can be used for 16 Mil pitch and below and for Micro BGA's
  • 24-hour turnaround standard

Frameless SMT Stencil Specs:
Technology 100% laser cut
Material Used Stainless Steel
Stencil Thickness 0.06 ~ 0.3 mm
Minimum Cut Width 0.05 mm
Maximum Size 280 X 380 mm
Allow for Fiducial Data Yes
Allow for Panelized Data Yes
Delivery 1 ~2 Day

Frameless SMT Stencil

8. Frameless SMT Stencil - Foil/Plate Only (for hand printing)

For times when you need precise control for smaller production runs, our Foil or Plate Only stencils are ideal. These frameless stencils allow you to hand print with precision just the amount you need and can be stored conveniently.

9. Electroformed SMT Stencils

Electroformed SMT stencils are nickel-based, electroform foils permanently mounted in a stencil frame using a mesh border to tightly stretch the stencil foil taut in the frame. Electroformed stencils offer the best paste release characteristics available and are frequently used for fine pitch (20 mil to 12 mil pitch) SMT applications on printed circuit boards. They are also used for µBGA's, Flip Chip, and Wafer Bumping (12 mil to 6 mil pitch).

Electroformed SMT Stencil Features:

  • The smooth trapezoidal sidewalls of an electroformed stencil allow for better paste release
  • Nickel has a lower coefficient of friction compared to stainless steel
  • Electroform foils are harder than full hard stainless steel of comparable thickness, providing for longer stencil life
  • 24-hour turnaround standard

Electroformed SMT Stencil Specs:
Technology Electroforming
Material Used Nickel
Suitable Applications All Component Pitches
Aperture Tolerance within 0.007mm
Stencil Thickness 0.06 ~ 0.3 mm
Positional Accuracy ± 0.008mm
Delivery 1 ~2 Day

What's the difference between a framed stencil and a frameless stencil?

A framed PCB stencil will have a 0.5" to 1.5" thick metal frame around it, similar to a picture frame. Framed stencils are often used by contract manufacturers, assembly and board houses, and large scale production facilities and are commonly placed in a manual or automated stencil printing machine. Frameless stencils are a thin sheet of material cut with a small border around your design. For example pictures on these products, please visit our Gallery.

What's the difference between Polyimide and Stainless Steel?

All stencils are made with high quality Polyimide and Stainless Steel. We use only the industry leading Stainless Steel, designed specifically for stencils. These materials are ideal for prototype or Multilayer PCB .

Stainless Steel: 0.0007" Laser spot size, 0.001" minimum aperature size.
Polyimide Film: 0.003" Laser spot size, 0.005" minimum aperature size.

Polyimide has a lower precision rate due to the way it is processed and its ability to withstand heat during the cutting process. Minor variances will occur when the material reacts to the laser. Paste release is great, but this material should be limited to a small number of uses and with components 0402 or bigger.

The minimum aperature size for Polyimide is 0.005" vs 0.001" for Stainless Steel. Polyimide also has a natural curl in the material caused by the way the film is manufacturered, this is outside of our control. Stainless Steel provides the ultimate in precision and quality, with a 0.0007" spot size, and exceptional paste release with a truly flat surface. If you want the absolute best reflow experience, there is no comparison, Stainless Steel is the superior material.

Analysis and Treatment of Common Problems in PCB SMT stencil

  • Insufficient solder paste
Insufficient solder paste may cause poor bonds and contact between components and the board. The common causes of insufficient solder paste are poor gasketing, clogged stencil apertures, insufficient solder paste bead size, paste/stencil being used beyond recommended life span, stencil not wiped clean, or low squeegee pressure.

  • Smudging/bridging
The main causes of smudging/bridging are excessive squeegee pressure, inadequate stencil wiping, poor contact between the board and stencil, high temperature or humidity, or low solder paste viscosity.

  • Misalignment print
A typical misalignment print is usually caused by the vision system not spotting fiducials, PWB or stencil stretch, poor contact between the board and the stencil, or weak board support.

  • Bow and twist
A PCB Board not fixed properly during solder paste printing gives poor results and increases soldering related issues. Normally, solder paste printing equipment can handle warpage of 1.0 to 3.0 mm but beyond this limit needs some special jigs or fixtures to hold the PCB. It may be difficult to tackle thick and small boards compared to thin and bigger size boards.

How to Determine Stencil Size?

Stencil size is composed by two parts: internal size and overall size. Internal size is the size compatible with that of PCB ready to be assembled while overall size refers to the size compatible with printer parameter limit. As long as both sizes are accurately designed, stencil will be able to make full use of its functions.

How to Determine Stencil Size

Internal size of stencil can be figured out conforming to the following rule:
  • Width of Framed Stencil = width of PCB + 100mm while its Length = length of PCB + 100mm
  • Width of Frameless stencil = width of PCB + 200mm while its Length = length of PCB + 200mm

For example, if one circuit board size is 50*50mm, then the size of its framed stencil should be around 150*150mm and the size of its frameless stencil should be around 250*250 mm.

It's easy to remember and operate so it worked for manual solder paste printing in SMT assembly prior to the advent of automatic printer. It can be said that different PCB sizes lead to generations of different internal sizes of stencil.

When it comes to automatic solder paste printer, however, it's relatively solid. Overall size of stencil has to be determined by parameter limit of the equipment, that is, printer, because stencil has to work within the range of printer with a frame. Different printers feature different parameter regulations. As far as PCBCart is concerned, the stencil size compatible with our printer can be either 650mm*650mm or 736mm*736mm.

PCB designers have to focus on internal size of stencil, they don't need to care about its overall size since it is generally determined by the parameters of printer in your contract assembler workshop.

How to Use PCB SMT Stencils?

PCB Stencil

PCB Stencil,SMT Stencil,SMD Stencil,Laser Stencil

JingHongYi PCB (HK) Co., Limited ,