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Seamark ZM PCB BGA X-ray Inspection system Equipment -14 years experience in SMT field, Our experience will provide good solutions. X-Ray Inspection, BGA reworks tation,Full auto X ray SMD component machine


Seamark ZM PCB BGA X-ray Inspection system Equipment -14 years experience in SMT field, Our experience will provide good solutions.
X-Ray Inspection, BGA reworks tation,Full auto X ray SMD component machine

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3 technical articles »

Bead probe technology - increase ICT test coverage

Nov 21, 2018 | Joy Rong +8618779975930

Bead probe technology - increase ICT test coverage Bead probe technology is an exclusive patent application by Agilent (Keysight Technologies). Using existing wiring to increase ICT (In-Circuit-Test) test point coverage without additional board space, to increase printing. Test points on the board to achieve assembly ICT testing can be used for ICT testing purposes. he density of the parts on the board is getting denser and denser, but the space is getting smaller and smaller, especially the board of the mobile phone. The first thing to be sacrificed is the test point that does not have any function. Many bosses think: "Quality is manufactured, As long as the quality of the board assembly is completed, there is no need for subsequent electrical testing. Which engineer can guarantee that the product does not have a bug? The assembly plant also cannot guarantee that they have zero defects in assembling the board. Various design and assembly challenges are showing that it is difficult to abandon the traditional ICT, and only other methods (such as AOI, AXI) to ensure the quality of the PCB assembly, so more and more Many companies are starting to use ICT again, but the space on the board will get smaller and smaller only, and there is room for test points, so smart Agilent came up with this kind of trace on the existing trace. The method of printing solder paste replaces the "bead probe" method of the test point. The purpose of Agilent is of course to hope that the entire electronics industry can continue to maintain ICT operations, and purchase more of its 3070 series ICT test machine from them. The traditional ICT test method uses a pointed probe to form a loop on a circular test point. This method requires a large area of test point, and then the probe must be shot like a target. , it needs to use more board space; the bead probe technology is just reversed, it wants the test point to try not to occupy the space of the board, in order to form a loop with the probe, so the solder paste is printed, let test point becomes higher, and larger diameter flat probe (50, 75, 100 mils) is used to increase the chance of contact with the test point. In theory, this is really a big breakthrough in test points, but there are still many techniques to overcome in practice. Printing solder paste on the wiring is likely to cause poor contact between the probe and the test point due to the residual flux. For this point, a number of probe manufacturers have designed probes for use with bead probes.  (Image taken from ingun)  The printing of solder paste needs to be very precise. In particular, the lead-free solder paste cohesion is worse than tin-lead solder paste, which requires more precise solder paste printing. The high tin-printing amount determines the solder height. If the soldering height at the test point is not enough, the ICT misjudgment rate will increase. . This involves the solder paste printing process, the accuracy of the steel plate, and the tolerances of the board. If the width of the wiring is too small, it is easy to be inadvertently inferred by the probe, or other external force due to insufficient adhesion. In generally, it recommended that the minimum wiring width be more than 5 mils. It is said that some operators have successfully tested 4 mils, but as the width of the wiring is smaller, the misjudgment rate of ICT is higher. It is recommended to increase the width of the wiring and then mask it with green paint, which will be stronger.   (Image taken from ingun,These beads were pressed into the shape of the probe beads with a force of 2.0 N on the left and a force of 3.0 N on the right.) Does the use of bead probe technology affect the quality of high frequencies? According to Agilent's test report, it will not affect the performance of high frequencies. Is there a capacitive or antenna effect using the bead probe technology? According to Agilent's response, there is no such problem in the current test and customer response. What is the reliability of the bead probe technology? According to Agilent's reply, there were no problems with testing 200 cycles. In addition, Agilent strongly recommends that the factory use this bead probe technology. It is best to have a test period of more than six months, because it needs to choose solder paste, fine-tuning the opening of the steel plate, the amount of solder paste, and Adjust the type and accuracy of the ICT test probe. Therefore, in the initial experiment, it is best to have both traditional round test points and new bead test points on the board....

SMT BGA voids Formation and prevention

Nov 13, 2018 | Joy Rong

Address: 10 Building, Huaide Cuihai Industrial Park, Fuyong Street, Bao'an, Shenzhen, China Tel: +8618779975930 E-mail: Written by Joy Rong More details: SMT BGA voids Formation and prevention News: The 2nd China Manufacturing Technology-Automation Exhibition (CMM) & the 1st China Electronics Manufacturing Resource Exhibition (CEM) was held at the Dongguan International Convention and Exhibition, such as B&P, Anda, Huancheng, Deshen Huawei, OPPO, VIVO, Xiaomi, ZTE, Foxconn, Flextronics, Lenovo and so on, More than 500 electronic manufacturing companies participated in the exhibition. In the annual feast of the field, the realization of mobile phone production automation can reduce 60% of employees? BGA voids cause current-intensive effects and reduce the mechanical strength of the solder joint. Therefore, from the perspective of reliability, the cavity should be reduced. So how can you reduce BGA voids? There are many reasons for the formation of BGA voids, such as the crystal structure of the solder joint alloy, the design of the PCB, the deposition amount of the solder paste, the reflow soldering process used, and the voids in the soldering process. Next, we will explain the formation and prevention of BGA solder joint voids from the layer of solder paste to reduce the number of BGA solder joint void formation. 1.Furnace temperature curve is improperly set ① In the temperature rising section, the gradient is set too high, causing the rapidly escaping gas to detach the BGA from the pad; ② The duration of the heating section is not long enough. When the temperature rises, the gas that should be volatilized has not completely escaped. This part of the gas continues to escape during the reflow phase, affecting the fluxing system to play a role in the reflow phase. 2. The solder paste solvent is not properly matched ① During the heating phase, the rapidly escaping gas propels up the BGA, causing misalignment and barriers; ② During the reflow phase, a considerable amount of gas still escapes from the solder paste system, but is limited by the narrow space between the BGA and the pad. These volatile gases cannot smoothly escape through this space, causing them to be squeezed. Molten solder joints. 3. Insufficient ability of solder paste to wet the pad 4. The surface tension of the solder paste system is too high during the reflow phase 5. The solder paste system has a high non-volatile content 6. Carrier rosin quality 7. The amount of rosin used Another reason for the BGA cavity is the back-wetting phenomenon during the welding process. The formation of this phenomenon is related to the duration of action of the active material in the solder paste system and the duration of action. During the BGA reflow soldering process, BGA pads are more prone to this undesirable phenomenon than SMT solder paste soldering. After realizing these influencing factors, the corresponding testing measures were added in the research and development. For example, we introduced a thermogravimetric analyzer to conduct thermal analysis on the materials to be used and the solder paste produced, to visually understand these thermal characteristics, and to test Differences between design assumptions and actual performance, measures are taken to overcome them to ultimately meet the process requirements; and surface tension measurements are performed. The appropriate surface tension range is finally determined by measuring the surface tension of the solder paste system and its affected objects at different temperatures. Family of Industrial X-ray inspection machine & BGA rework station Last Article: SMT BGA solder ball inspection method Next Article: Detecting advantages of AOI and X-ray Inspection Equipment Maybe you still are interested in: Importance of X-ray inspection technology in the SMT FAI/ First Article Inspection Highest Quality levels Tool X-ray for industries-SMT/batteries/ceramic/Electronic /semiconductor; The difference between the detection equipment AOI & X-RAY ...

Reasons for BGA insufficient solder & short

Nov 13, 2018 | Joy Rong

Reason for BGA insufficient solder & short-There are cases of insufficient solder & solder short in BGA, and some BGA solder ball inspection methods. Written by Joy Rong Reasons for BGA insufficient solder & short There are cases of insufficient solder and solder short in BGA soldering, but it is also possible. Because the PCB BGA board has too much gap due to heat shrinkage (CTE), the edge of the BGA board is upturned. The smile curve is formed, and the circuit board is too long due to TAL (Time Above Liquidus), and the temperature difference between the upper and lower furnaces of the reflow furnace is too large, and the two-phase interaction forms a circuit board to bend down,Caused the so-called cry curve. If the cry curve, smile curve is severely deformed, short-circuit and air-welding of the BGA will be formed at the same time, which is usually the case when both occur at the same time. The picture shows that the BGA smile curve and the cry curve on the printed circuit board strongly squeeze the BGA solder balls, causing several short circuits. In general, consider reducing the slope of the reflow oven, either by preheating the BGA to eliminate thermal stress, or by requiring BGA manufacturers to use higher Tg to overcome it. Other reasons for BGA insufficient solder: 1.Circuit board pads or BGA solder balls are oxidized. In addition, printed circuit boards or BGAs with improper moisture resistance will have similar problems. 2.Solder paste expired. 3.Insufficient solder paste printing. 4.The temperature profile is poorly set, and the furnace temperature should be measured at the insufficient solder. In addition, when the temperature rises too fast, it is more likely to cause the above-mentioned cry curve, smile curve problems. 5.Design issues. For example, Via-in-pad will cause a decrease in solder paste, which may also cause the solder ball to be hollow and blow up the solder ball. 6.Head in Pillow. This phenomenon often occurs when the BGA board or printed circuit board is deformed by reflow. When the solder paste is melted, the BGA solder ball does not touch the solder paste. When cooling, the BGA carrier board and the board are deformed. Decrease, the solder ball falls back to the cured solder paste. In general, there are several methods for analyzing insufficient solder and solder short (for details, please refer:SMT BGA solder ball inspection method): 1.Microscope. 2.X-Ray inspection machine. ( Tel/whatspp/wechat +8618779975930 ) 3.Red Dye Penetration. 4.Cross section. Family of Industrial X-ray inspection machine & BGA rework station Last Article: SMT BGA solder ball inspection method Next Article: Formation and prevention of SMT BGA voids Maybe you still are interested in: As PCB designer and technician/Buyer, you do not know technologies Skills? Highest Quality levels Tool X-ray for industries-SMT/batteries/ceramic/Electronic /semiconductor; The difference between the detection equipment AOI & X-RAY More details:

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