PCB engineers

A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate. PCB's can be single sided (one copper layer), double sided (two copper layers) or multi-layer. Conductor on different layers are connected with plated-through holes called vias. Advanced PCB's may contain components - capacitors, resistors or active devices - embedded in the substrate.

PCB engineers

Career summary: PCB engineers is to carry on the PCB design and debugging, tracking system of PCB board and SMT process and solve the problem of related technologies, production and maintenance of PCB package library and standard wiring module of professional and technical personnel.

Work content

Design and modification of the PCB;

Complex PCB traces the predetermined portion;

SI debugging and associated parts specified by the PCB design simulation;

Help build and maintain schematics, PCB Layout and related production data generation;

Tracking PCB system board and SMT process, and the relevant departments and suppliers in close collaboration to solve related problems;

PCB production and maintenance of the standard package libraries and standard wiring modules;

Preparation of related PCB development, debugging log.

Occupational requirement

Education and Training:

Communications, electronic engineering, computer-related undergraduate degree or above. PCB engineers divided into the following levels: entry-level PCB engineers, PCB engineers, junior, intermediate and senior engineers PCB PCB engineer.

Work Experience:

Familiar with the process PCB board, PCB inspection standards; skilled use PowerPCB, Powerlogic, Pads2005 software for multi-layer PCB design; grasp a variety of common document conversion between PCB design software, innovative, can often put forward various PCB design to improve efficiency, PCB design quality, the system PCB structure allocation constructive proposals.

PCB engineers classification basis

Getting Started

Capacity requirements: polynomial

1. Can make a simple package, such as DIP10 wait;
2, master the basic operation of at least one PCB design software, and can formulate simple wiring width and spacing rules;
3, capable of 100 components and PCB 200 network or less for a more rational and orderly with the layout and routing;
4, can be manual or automatic routing and modified to achieve 100% routability and the DRC in full by others or custom rules;
5, have basic mechanical structure and thermal design knowledge;
6, to master some basic requirements double panel alignment.

Work:
1, a simple PCB design and modification (eg, the structure of the front panel is simple, small system board microcontroller, etc.);
2, the complex PCB traces predetermined portion;
3, with its own PCB design related debugging;
4, write related development, debug log.
Responsibilities: The PCB in part responsible for their own design.

Primary

Capacity requirements:
1 , according to the physical production of manuals and more complex packages such as RJ-45 blocks and other light and guarantee shape, pads and other dimensions entirely correct ( by physical measurements to ensure that at least can be inserted ) ;
2, more familiar with at least one PCB design software and can be stand-alone or formulate more detailed wiring rules under the guidance ;
3 , capable of 400 and 1000 network elements or less single- , double-sided and multilayer PCB has conducted more rational and orderly layout and wiring , ready to take into account in the process of thermal layout design, structural design , electromagnetic compatibility design , aesthetics and other requirements in a timely manner to the more advanced PCB engineers ask or discuss when they can not determine ;
4 , proficiency in others or custom rules manually or automatically routing and modified to achieve 100% routability and DRC completely through , basically there is no bottleneck width , the inner islands and other issues, the routing process can be seen in a small amount of principle designed and made a stupid mistake , and can correctly pin and gate swap , can modify the correct netlist and schematic ;
5, can correct import, export, mechanical drawings and understand the basic structure of the size requirements ;
6, can be developed some high-speed PCB design and simulation under the rules or guidance and stable in others ;
7 , silkscreen logo clarity, to complete a separate output GERBER other design work and proofreading ;
8 , the basic manufacturing knowledge and for the practice , the board is designed for the production of more than 50% .

Work:
1 , more complex PCB design and modification (eg, scheduling machine outside the board except the CPU board , sixteen Quad boards, etc. ) ;
2 , the complex PCB traces predetermined portion ;
3 , with its own PCB design related debugging ;
4 , for the work of all lower-level PCB engineers guidance ;
5, the write -related development, debugging logs ;( Refers to himself a certain time when no corresponding temporary design tasks , or time constraints of a PCB design , designers must deploy or strengthen , the same below ) 6 , if necessary, any low-level PCB engineer any makeup work . Responsibilities : The PCB in part responsible for their own design .

Intermediate

( According to personal ability is now broken down into specific A, B, C third gear , A High , B second place ) capacity requirements :
1 . To fully understand the various original manuals and wiring manual device that can independently produced a very complex package, such as placing the switch , and to ensure that the capabilities entirely correct ( by physical measurements to ensure that at least insert ) , on their own principles and structural requirements based on finding the right devices or replacement ;
2 , proficiency and skills in at least one operation PCB design software and can formulate a detailed wiring rules ;
3 , can be made ​​to integrate the various functional blocks and divided opinion, based on the system requirements , capable of any number of components and the PCB independent network or a reasonable division of labor and the various functional blocks of the layout and wiring , ready to consider the thermal design of the layout process, structure design , SI, PI, EMC, appearance, manufacturability and other requirements and propose solutions that can provide some layout and wiring requirements and rules for reference , such as entry-level and junior PCB engineers ;
4, can be stacked properly design board , and satisfy the performance requirements to minimize the number of layers and reduce costs ;
5, with more resistance , delay , overshoot , high-speed PCB design knowledge and analog crosstalk, loops, signal circuit , graphic integrity , inner partition slots , signal termination , etc., independently or in SI completed under the guidance of engineers and other key signal and regional SI simulation and analysis and suggest improvements ;
6 , proficiency in manual or automatic rule-driven routing and modified through , the entire board has a certain beauty, wiring process can be seen in more than 80% of the design principles and made a stupid mistake , skilled correctly pin and gate swap ;
7 ... can be an excellent communication with the principles and structural design engineer can understand more complex mechanical drawings, and to propose some principles to select the device and PCB design and structure of reasonable improvements, help system design early success ;
8, the test points and silk mark clarity, error-free , rarely commit low-level PCB design error , the error is generally not lead to revision due to PCB design , PCB for more than 90 % of the processing factory project feedback can always be resolved ;
9 , with more knowledge and manufacturability by day practice , more than 70% of the board design can be used for direct production.

Work:
A very complex PCB designs and modifications ( such as 8 -channel DVR chassis , PC motherboards , etc. ) ;
2 , commissioning and SI simulation specified part with their PCB design related ;
3, for all lower-level PCB engineers work to provide guidance and routing rules ;
4 , write related development , debug log ;
5 , the production and maintenance of Internal PCB standard package libraries and standard wiring modules ;
6 , when necessary, a lower level of any PCB concurrently work of engineers .Responsibilities:
1 , for the PCB design their own partly responsible ;
2, Internal PCB standard package libraries and standard wiring modules partly responsible for their own design ;
3 , responsible for their own SI simulation results and solutions.

Advanced

Capacity requirements:
1 . Master document conversion between all common PCB design software , switching out the basic document that can be used to modify ;
2 , familiar with high-speed PCB design and simulation all the requirements , design , or instruct others issues related to the design of the board there is no more than 80% ;
3 , has a wealth of knowledge and manufacturability for practice and guide the work of the board design or instruct others designed more than 90% can be used for direct production ;
4 , skilled rules control the high-speed , high-density layout, wiring , and the fabric module or board in a stable and reliable , while more than 80 percent can do great beauty ;
5 , very innovative , can often put forward various PCB design to improve work efficiency , PCB design quality , and other constructive proposals .

Work:
1 , involved in system design, analysis and PCB -related part of the planning and simulation ;
2 , organizing and conducting PCB design training ;
3, for all lower-level PCB engineers work to provide guidance and routing rules ;
4 , will be related to the development, debugging logs ;
5, SI simulation model search , create and regulatory files ;
6 , the entire board and system SI, PI, EMC simulation , PCB manufacturability performance evaluation, there are problems PCB cause analysis and propose effective solutions ;
7 , when necessary, a lower level of any PCB concurrently work of engineers .Responsibilities:
1, is responsible for all their work ;
2, responsible for guiding the work of all others .

PCB engineers need to pay attention

More PCB engineers , they often draw computer motherboards, and so on excellent tool Allegro is very skilled, but very unfortunately , they actually know very little about how to impedance control , how to use tools for signal integrity analysis . How to use IBIS model I think the real PCB signal integrity expert or experts should be , not just stay in the line again and again , worked on the basis of the cloth through the hole on a board is easy , a good piece of cloth so hard .

Little information

For power , the number of layers and the number of signal layers to determine the relative position of the arrangement between them is that each PCB engineers can not avoid the topic .

Arrangement of the general principles of veneer layers :

Below the surface element ( the second layer ) of a ground plane , the device provides a reference plane and the shield wire to the top ;

All signal layers as adjacent to the ground plane ;

Try to avoid directly adjacent two signal layers ;

Main power corresponding to the adjacent possible ;

Both symmetric laminate structure .

For the motherboard layer arrangement , parallel to the existing motherboard is difficult to control long-distance wiring , the board-level operating frequency 50MHZ above (50MHZ can refer to the following cases , be relaxed ) , the proposed arrangement principles:

Component side , the welding surface is a complete ground plane ( shield ) ;

No parallel wiring layer adjacent ;

All signal layers as adjacent to the ground plane ;

The key signal and adjacent strata , not across partitions.

Note : When setting the specific PCB layers , these principles should be flexibility on the basis of the above principles to understand , according to the actual needs of the board , such as: the need for a critical layer wiring , power supply, case , etc. split ground planes determine the layer arrangement , should not be applied mechanically , or grasped one o'clock hold.

The following is a specific arrangement of the veneer to explore layers :

Four-layer board , preferred Option 1 , Option 3 is available

Solutions Power layers to layers of signal layers 1234
1 1 1 2 S G P S
2 1 2 2 G S S P
3 1 1 2 S P G S

Scenario 1 This scenario four- layer PCB primary election set program , under the surface there is a ground plane element , the key signal is preferably cloth TOP layer ; As for thickness settings , the following recommendations:

Meet impedance control Xinban (GND to POWER) should not be too thick , in order to reduce the power distribution impedance ground plane ; ensure decoupling effect of the power planes ; shielded in order to achieve a certain effect, someone tried to power ground plane on the TOP, BOTTOM layer , namely the use of Option 2 .

This program wants to achieve shielding effect , at least the following shortcomings:
Power, ground, too far apart , large power plane impedance
Power ground plane due to the impact of component pads , etc. , very incomplete
Since the reference plane is not complete , the impedance discontinuity signal

In fact , due to the extensive use of surface-mount devices, more and more dense for the next device , the power of this program , to almost impossible as a complete reference plane , is expected to be difficult to achieve shielding effect ; limited scope of the program 2 . However, in individual veneer , the program may well be the best layer 2 set program .

The following is the program two use cases ;

Case ( a special case ) : the design process , there has been the following:

A, the entire board without power plane , only GND, PGND each plane ;

B, the entire board traces simple, but as an interface filter plates , wiring radiation must be concerned ;

C, the plate is less chip components , the majority of plug-ins.

Analysis:
1 , since the board without power plane , power plane impedance problem would not exist ;

2 , due to the small chip components (single-sided layout ) , if the plane of the surface layer to make the inner alignment, the basic integrity of the reference plane is guaranteed, and the second layer may be a small amount of copper to ensure the alignment of the top reference plane ;

3 , as an interface filter board , PCB layout radiation must be concerned , if the inner alignment, surface to GND, PGND, traces are well shielded , radiation transmission lines under control ;

For these reasons, when the board layer arrangement , decided to adopt Option 2 , namely : GND, S1, S2, PGND, because the surface is still a small amount of short traces , and the underlying ground plane was full , we S1 the copper wiring layer to ensure the alignment of the surface reference plane ; five interfaces filter plate , the same analysis for the above , the program designer decides to use two equally well be provided classic layer .

Exceptions cited above , is to tell everyone to understand the principle of layer arrangement , rather than mechanical copying .

Solution 3: This solution with a similar solution for the main device , or in the case of the layout of the key signal BOTTOM underlying wiring ; generally limit the use of this scheme ;

Six panels : preferred Option 3 , Option 1 is available , the backup program for six panels 2,4 , preferred Option 3 , the preferred wiring layer S2, followed by S3, S1. Main power and ground cloth corresponding 4,5 layer thickness when setting S2-P increased spacing between the narrow spacing between the P-G2 ( G1-S2 corresponding narrow spacing between the layers ) , to reduce the impedance of the power plane , reducing the impact on the power of S2 ;

Higher cost when required , can be a solution , preferably a wiring layer S1, S2, followed by S3, S4, compared to Option 1, Option 2 ensures that the power of adjacent ground plane to reduce the source impedance , the S1, S2 , S3, S4 all exposed, only have a good reference plane S2 ;

For higher local , small signal demanding applications Scheme 3 Scheme 4 is more suitable than that provides excellent wiring layer S2.

Eight plate : 2,3 preferred embodiment , a program available

For a single power supply , a program of the program to reduce the ratio of two adjacent wiring layers , and the corresponding increase of the ground adjacent to the main power supply to ensure that all the signals in the adjacent layer and the ground plane , the cost is : a sacrificial layer wiring ; for double power situation , recommended Option 3 , Option 3 take into account the non- adjacent wiring layers laminated structure symmetry, and other places adjacent to the main power advantages, but S4 should be the key to reducing cabling ; Scenario 4: no adjacent wiring layers , layer pressure symmetrical structure , but higher power plane impedance ; should be appropriately increased 3-4, 5-6 , 2-3, 6-7 narrowing the distance between layers ;

Scenario 5 : Compared with Option 4 , to ensure that the power ground plane adjacent ; But S2, S3 adjacent , S4 to P2 reference plane ; For wiring between the key and the bottom line is less S2, S3 can be controlled between harassed under this scenario, the situation can be considered ;

10 laminates : Recommended solutions 2,3 , 1,4 programs available

Scenario 3: 3-4 and 7-8 to expand their spacing, narrow 5-6 pitch to the main power supply should be placed in its corresponding 6,7 layer ; preferred wiring layer S2, S3, S4, followed by S1, S5; this program or less suitable for signal routing requirements of the occasion, both the performance and cost ; recommend that you use ; but need to be taken to avoid a parallel between the S2, S3, long-distance wiring ;

Programme 4: EMC effect is excellent, but the program 3 to sacrifice a wiring layer ; at cost less demanding , high EMC target, and must be a key board dual power planes , the proposed use of such programs ; preferred wiring layer S2, S3, in the case of single-supply layer , first consider Option 2 , followed by a consideration of the program . Option 1 has a clear cost advantage, but too much of adjacent wiring , parallel long-term is difficult to control ;

Twelve Shelf : Recommended solutions 2,3 , 1,4 programs available , Alternative 5

The above scenario, the program has excellent EMC performance of 2,4 , 1,3 scheme has better cost ;

For more than 14 layers and layers of veneer , due to the diversity of its portfolio case , there is no longer enumerate . We can follow the above arrangement in principle , a detailed analysis of the actual situation .

These layers are arranged as a general principle , for reference only, specific design process based on the number of signals we can supply layers, wiring layers, special wiring needed requirements, as well as the ratio of the power , ground split , combined with the above arrangement principle flexibility

6 laminates after each program where ?

6 layers and layers of 8

Six panels , preferred Option 3, Option 1 is available , an alternative 2,4

Program power ground signal 123 456
1 1 1 4 S1 G S2 S3 P S4
2 1 1 4 S1 S2 G P S3 S4
3 1 2 3 S1 G1 S2 G2 P S3
4 1 2 3 S1 G1 S2 G2 P S3

Eight plate : 2,3 preferred embodiment , a program available

Program power ground signal 12,345,678
1 1 2 5 S1 G1 S2 S3 P S4 G2 S5
2 1 3 4 S1 G1 S2 G2 P S3 G3 S4
3 2 2 4 S1 G1 S2 P1 G2 S3 P2 S4
4 2 2 4 S1 G1 S2 P1 P2 S3 G3 S4
5 2 2 4 S1 G1 P1 S2 S3 G2 P2 S4

EMC problems

In the layout should also be noted when EMC suppression Oh ! ! This is very good grasp of distributed capacitance exists at any time ! !

How grounded !

Originally PCB design must consider many factors , different circumstances require different factors to consider . Moreover , I am not PCB engineers, experience is not rich

Ground segmentation and tandem

Ground is to suppress electromagnetic interference, one of the important means to improve the EMC performance of electronic devices . Proper grounding can raise the ability of the product to suppress electromagnetic interference EMI and reducing external product launch.

Meaning grounded

Electronic devices " to " usually has two meanings : one is "Earth" ( safely ) , the other is a " systematic basis land" ( signal ground ) . Refers to the establishment of low resistance grounding system between the plane and a potential conductive path . " Then the earth " is a potential basis of the earth , and the earth as a zero potential , the metal casing of electronic devices, circuit reference point connected with the earth .

The ground plane is connected with the earth , often for the following considerations :
A, improve the stability of the circuit operation of the system equipment ;
B, electrostatic discharge ;
C, to provide security staff * .

The purpose of the grounded

A, safety considerations , namely the protection of the ground ;
B, the voltage signal to provide a stable reference potential of the zero point ( a signal or systematic ) ;
C, shield grounding .

The basic grounding

There are three basic types of electronic equipment grounding mode: single-point ground , multi-point grounding , floating .

Single-point ground
Is the single-point ground system, only one physical reference point is defined as a ground point , each of the other points to be grounded is connected to this point .

Single-point ground for low -frequency circuits (1MHZ less ) . If the system frequency is very high, so that the operating wavelength and system ground lead length can be compared , the single-point grounding have a problem. The length of the ground wire is close to 1 / 4 wavelength , it is like a short-circuited transmission line terminals , ground current, the voltage standing wave distribution form , ground into a radiating antenna , and can not act as a " ground" effect .

To reduce ground impedance to avoid radiation, the length of the ground should be less than 1 /20 of the wavelength . In dealing with the power circuit , generally can be considered a single point grounding. For PCB extensive use of digital circuits , because of its rich in high harmonics, generally do not recommend the use of single-point grounding.

Multi-point grounding
Multi-point grounding is the grounding point of each device is directly connected to the ground plane from its recent , so the length of the shortest ground lead .

Multi-point grounding circuit structure is simple , significantly reducing ground line may appear high frequency standing wave phenomena applicable to the frequency higher (> 10MHZ) occasions. But multi-point grounding may result in the formation of many ground loop inside the device , thereby reducing equipment resilience to external electromagnetic fields . In the case of multi-point grounding , pay attention to the ground loop problems, especially networking between different modules , devices . Electromagnetic interference caused by ground loops :

Should be an ideal ground zero potential , physical entity zero impedance . However, the actual ground resistance component have the inherent reactance component , when the current through the ground , it is necessary to generate a voltage drop. Ground with other connection ( signal, power lines, etc. ) constitute a loop , when the time -varying electromagnetic field coupled to the circuit , the electromotive force induced in the ground loop, loop coupled to the load by the way , constitute a potential threat to EMI .

Floating
Refers to a floating ground system grounding device electrically insulated from the earth .

Since some floating own weaknesses , not suitable for large-scale systems in general , and its grounding rarely used

Grounding on the general principle of selecting :

For a given device or system , the highest frequency of interest ( corresponding wavelength ) into the upper , when the length of the transmission line L> in, high-frequency circuit is considered , on the contrary , low frequency circuit is considered . According to a rule of thumb , for less than 1MHZ circuits using single point grounding is good; For higher 10MHZ, the multi-point ground better. For frequencies in between , as long as the longest transmission line length L is less than / 20 in, you can single- point ground to avoid common impedance coupling.

For grounded generally selected the following principles:

( 1 ) low-frequency circuit (<1MHZ), recommend using single point grounding ;

( 2 ) high-frequency circuits (> 10MHZ), recommended the use of multi-point grounding ;

( 3 ) high-frequency mixing circuit mixing the ground .

( 4 ) 100.00%
Not

Salary Quotes

Average monthly salary of between 3000-7000 yuan.

Development Path

China PCB industry after nearly 20 years of rapid development, has become the world's most important and irreplaceable production base, so the importance of the PCB engineers understood that the rapid development in the employment prospects of its considerable until after the accumulation of experience management positions in development to project managers.

PCB engineers caveats

About PCBway

Since 2003 PCBWAY has been the leading PCB quick turn manufacturer specializing in both Prototype and Production quantities, Initially produced single-sided and double-sided printed circuit boards for the consumer electronics market. PCBWAY is ranked among the top 4 board fabricators in asia and is well-known for its expedited turn time capabilities and its reliable best on-time shipping record.

Today, we have over 450 operators with high modern facilities to manufacture multi-layer PCB up to 12 layers. Backing up with a group of professional engineers, and well established quality system. PCBWay has grown to become a major PCB manufacturer in Asia to serve in diverse customers base such as electronics appliance, communication, educational electronics, power supplies, Automationsetc.

Our mission is to become one of leading PCB manufacturer that provide in high quality product with total customer satisfaction.

For more information about PCB, or to learn more about the online quote and ordering process, please visit //www.PCBway.com.