Analysis On The Reason And Countermeasure Of PCB Size Expansion

- Jul 25, 2017 -

  Analysis on the Reason and Countermeasure of PCB Size Expansion

  1, the substrate size stability, especially the supplier of each laminated CYCLE size between the consistency; even if the same specifications of different substrate CYCLE dimensional stability are within the specifications, but because of the consistency between The poor quality of the plate can be caused by the first board to determine a reasonable after a layer of internal compensation, due to differences between the different batches of plate material caused by the subsequent mass production plate size difference; At the same time, there is a material anomaly is In the process of the outer layer of the process after the transfer process to find the contraction of the plate; in the production process had a separate batch of plate in the shape of the process before the data measurement process found that the puzzle width and the length of the ship relative to the outer layer of graphics The ratio of the transfer rate is 3.6mil / 10inch, and the specific data are shown in the following table. After investigation, the X-RAY measurement and the outer layer transfer rate of the abnormal batch plate are controlled in the outer layer Of the current process monitoring is still not find a better way to monitor;

  2, puzzle design: conventional board puzzle design are symmetrical design, graphics transfer magnification in the normal case of the PCB size of the finished product has no significant impact; but part of the plate in order to enhance the utilization of sheet metal, Cost of the process and the use of non-symmetrical structure of the design, the distribution of different parts of the PCB size of the PCB will bring a very significant impact on the consistency, even in the PCB process we can in the laser blind hole drilling Hole and the outer graphics transfer exposure / solder mask exposure / character printing process found in such asymmetric design of the plate in the various parts of the alignment of the situation relative to the conventional plate more difficult to control and improve;

  3, an inner layer of graphics transfer process: here on the finished PCB board size to meet customer requirements play a very critical role; such as an inner layer of the transfer of the film rate of compensation to provide a large deviation of its not only can lead directly to the finished product PCB Graphic size can not meet customer requirements, but also can cause the follow-up of the laser blind hole and its bottom connection disk alignment caused by LAYER TO LAYER between the insulation performance down to short circuit, and the outer graphics transfer process in the blind / blind hole problem;

  According to the above analysis, we can take appropriate measures to monitor and improve the anomaly;

  1, the substrate material size stability and inter-batch size of the consistency of the monitoring: regularly provided by different suppliers of dimensional stability of the substrate test, from which to track the same specifications between the different batches of latitude and longitude data differences , And the appropriate use of statistical techniques to analyze the substrate test data; which can also be found in relatively stable quality suppliers, while SQE and procurement departments to provide more detailed supplier selection data; for individual batches of the base Poor dimensional stability caused by the plate in the outer layer of the transfer occurred after the serious expansion, the current production can only be produced by the first board of the measurement or shipments to be measured when the survey to find; but the latter on the batch management requirements, A number of large quantities of production prone to mixed plate;

  2, puzzle design should be the use of symmetrical structure of the design, so that the puzzle within the various units to maintain the relative expansion and contraction; if possible, should communicate with the customer recommended to allow the edge of the process in the plate etching / Character and other identification methods will be the shipping unit in the puzzle within the location of the specific identification; this method in the asymmetric way to design the effect of the plate will be more obvious, even if the puzzle due to graphics asymmetry caused by the size of each unit size Poor, and even caused by the local blind hole at the bottom of the connection can also be extremely easy to determine the abnormal unit and before the shipment out of its handling, and will not cause out of the customer package caused by abnormal complaints;

  3, the production rate of the first board, through the first board to scientifically determine the production of a plate within the inner layer transfer rate; in order to reduce production costs and other suppliers to change the substrate or P film, this point is particularly important; When the plate is out of the control range, it should be processed according to its unit hole if it is secondary drilling. If the conventional processing process board can be released to the outer layer according to the actual situation, the paper should be adjusted by the film rate. Hole plate, the handling of abnormal plate to be particularly careful to ensure that the finished plate of the graphic size and the target to the hole (secondary drilling) distance; with the second accumulation of the first board plate magnification collection list;

  4, the process of monitoring: the use of outer or sub-plate in its laminated X-RAY production of drilling hole when the hole measured in the plate internal target data to analyze whether it is within the control and Qualified the first board of the corresponding data collected to determine whether the plate size is abnormal expansion, the next table can refer to; after theoretical calculations, usually here the magnification should be controlled within +/- 0.025% to meet the conventional board The size of the request;

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