Manufacturers of electronic devices, I am home audio equipment keyless entry systems for cars increasingly looking for a reliable, inexpensive method to identify and track products through the cycle of production, distribution, sales and after-sales warranty. Self-contained, automated monitoring system that requires a durable, legible code, an internal circuit board can be used to uniquely identify each product. The code mustrobust enough to survive the production processes including wave soldering and board cleaning, must not affect circuit performance and the need to store information in the small room-conscious real estate boards.
The 2D matrix code provides the possibility of alphanumeric strings in very small areas of the PCB to save. Laser marking technology provides a permanent method for applying 2D matrix codes to most board substrates. The high resolution andwith high precision laser-guided marker offers the possibility of well-defined, high reliability regardless of the code to create the code size. Laser marking also provides the user with a computer controlled marking and for easy implementation into automated tracking of products.
ECC 200 2D Matrix Codes
Two-dimensional bar codes encode information in the form of a checkerboard pattern on the cells / off. Specific advantages of Data Matrix codes of conventional 1D barcodesinclude:
· Encoding information in digital format, such as encryption of analog data to the contrary conventional bar codes.
• Ability to print directly to low-contrast components, without having to enter a label
· To offer very high information density - the highest among the other major 2D codes, which means that you can use a variety of information in a small space means space.
• It is scalable, which means that you can print and read at different levels of magnification - only limitedthe resolution of the available print and imaging techniques.
• Due to the high density of information regarding Data Matrix codes, they also offer built-in error correction techniques to recover fully the message encoded in a Data Matrix symbol, even if the brand is damaged and missing as much as 20% of that symbol.
• You must read with cameras that scan like a laser beam for reading conventional bar codes, so that they can be read in any media used toOrientation.
Data Matrix ECC 200 is the most popular 2-D symbology widely used in automotive, aerospace, electronics, semiconductor, medical and other units of production-level traceability applications. Data Matrix codes are generally not replaced traditional linear bar codes, but are used where traditional barcodes were too big, not enough memory, or were illegible.
Data Matrix code structure
The 2D matrix codes appear as"Chessboard" with the individual squares (cells) that are on the (white) or off (black) state. The code consists of four different elements.
• The Finder model "L" consists of a fixed number of cells in the left margin and bottom of the code that directs the reader to the provision of the Code 2D.
• The track is a sequence of clock on / off cells on the right side and top of the code, counting the rows / columns to the designated player.
• The area is the data modelBlack and white cells in the L-model and the clock keeps track of the contents of the alphanumeric code.
• The area can be quiet all the code must be free of all functions which may be visible to the reader. The quiet zone should be at least two rows / columns wide by building codes of square cells. The quiet zone should be at least four rows / columns are built to the codes range of circular cells (points).
ECC 200 Data Matrix codes can be up to 3116 numerically, 2335alphanumeric characters or 1,555 bytes of binary information in a column of 144 by 144 serial line. Symbol size more realistic PCB can still get a significant amount of information.
Laser Marking Systems
The laser marking system comprises a laser source, optical beam shaping and beam steering.
The laser is an amplifier produces a bright beam of light collimated light of a specific wavelength. For FR4 and solder mask applications,more users choose the air-cooled CO2 laser at 10640 nm wavelength far infrared. This laser provides different performance and cost advantages, and produces excellent results mark.
The laser beam is mounted by two mirrors, projected at high speed, high precision galvanometer. During the rotation of the mirror, under the direction of the computer system scans the laser beam on the target surface marker to "paint" the desired image labeling.
After the laserBeam by the beam steering mirror is deflected, is concentrated in the smallest place possible flat-field focusing. The mounting flat-field focus is the development of a multi-element optical device to obtain the focal plane of the laser beam focused on a relatively flat area of consensus marking. The focused laser light increases the power density and power associated with marking.
The function of the laser beam path is to focus the laser beam on a small spotand scan the laser beam on the target surface at high speed and precision. With the configuration is the CO2 laser focal spot diameter and thickness of the associated line marking of 0.0035 "to 0.004". You can read the text characters "can and 2D matrix codes to individual features as small as one to build 0,004" points as small as 0040.
PCB marking
To celebrate the printed circuit board, the heat generated by the laser beam to create heat affected the surface of the platecontrast, the sign read. The process requires no labels, stencils, stamps or other supporting hardware or consumption.
For PCB applications, several variations of this technique for the various boards / coating materials and conditions used.
· Breathing welding or other protective coatings on FR4 boards -
The laser beam can alter the structure of the coating, making it easier to remove a contrasting look, or completelyBase coat to the underlying substrate or copper plate exposed.
Other topics addressed · FR4 -
The laser beam alters the surface structure of production FR4 look almost white.
Nd block Ink Screen Printing -
For users, the screen can already identify the components or other solid information on the cards, a white screen printing ink pad as a backdrop for the function of the 2D matrix code to improve readability. This technique is particularly useful when ...
orBackground color of the card is similar to the color of the laser mark.
circuit or obscure the underlying image readers marking.
o The material on board is not suitable for laser marking, such as ceramic substrates.
2D Matrix Code Verification
The review of content and readability of 2D matrix codes is an important step in the overall quality program. After the marking of each circuit, the reader verifies the integrity of the brand before the indexThe laser marking head to the next marker position. The reader retrieves the alphanumeric string from the 2D code and compares it with the string of text that should be disclosed.
The reader will also assess the readability of the code on a variety of parameters, including foreground / background contrast, geometric accuracy (angle, perpendicularity, etc.) and dimensional stability of both marked and unmarked cells. The 2D matrix codes are then passed as classified (green), warning (yellow)or not (red). For the efficiency of overall production, the laser system is programmed so that only some 2D codes selected to test on a plate, then automatically the examination of each code-switch when the readability of the code falls below a certain level .
Readers today do an excellent job of reading 2D codes of lower contrast. When the laser marking system is installed on the assembly line with 2D matrix readers behind the laser marker, the player verification can be configured to evaluate theCodes on the performance of the older player in the valley is based on consistent performance during the assembly of warranty.
Performance marking
The typical printed circuit board is a fully automatic markers, SMEMA-compatible, laser marking system of conveyor belts. The overall productivity of the laser marker is a multistep process that included the marking cycle. The necessary steps towards a multi-panel arrays are signs ...
1 Transport and placement of the plateLabel field.
2 Placing fiducials (optional)
3 Identification of the first circuit array
4 Verification of the selected 2D matrix code (optional)
5 The movement of the laser marking head to the next circuit in the array.
6 Repeat steps 3 and 4 for the remaining circuits in the matrix.
7 Carry the pot from the laser marking system (equivalent to bring the next course)
Cost of Ownership
The cost is much lower$ 1.00 per hour. Utilities are typical requirements 110VAC, 1-Phase, 12A. A source of compressed air for pneumatic needs. Total cost of utilities at maximum laser power (the laser would operate at less than 80% of NP) are $ 0.12 per hour. The primary element of consumption is the CO2 laser tube, which replaced every 3 to 5 years must be at a cost of usually $ 1.000,00 to € 1.500,00. Assuming 40 hours per week of work and life of the tubes of three years, would equate the cost of replacing the tube $ 0.18hour for a total cost of $ 0.30 per hour in the worst conditions. Actual operating costs will be lower, from less than maximum power consumption and longer tube life.
Typical applications for PCB laser marking, the cost for the identification of less than $ 0.0003 for each circle.
Summary
The electronics industry is looking for a cost-effective and technically efficient to apply machine-readable codes on printed circuit boards since 1980. Early attempts includedLaser Marking linear bar codes on the edge to edge, a huge challenge for the orientation and labeling linear bar code reader next to the tracks, and a challenge for bar code readers. Bar code contents of some characters, for reasons of space and the bar code characters per inch capacity is limited.
The development of the 2D matrix code with the duration and speed resolution of the combined laser-guided marking offers manufacturers a reliable, affordable, flexible andverifiable means to uniquely identify each product through to production, sales and after-sales service.
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