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  2. Choosing the right Surface Finish for Chip on Board assembly is crucial. One of the most frequent questions we are asked at KingCredie Technologies is how should my PCB be plated in order to ensure wire bond-ability. PCB Plating for Chip on Board Assembly must be planned in advance to ensure manufacturability of the device. This planning begins with design rules and selecting the wire bond method to be used. Common wire bond materials include aluminum or gold wire. Aluminum Wedge Wire Bonding and ENIG Plating One of the most common wire bond methods for COB assembly is aluminum wire bonding. For aluminum wire bonding to a PCB the plating can be a low cost method known as ENIG or Electroless Nickel with Immersion Gold. With ENIG plating a PCB with Copper traces is plated with a Nickel layer and then the nickel layer has a flash gold layer on top. The Flash Gold is a barrier layer to protect the Nickel from oxidation. The wire bonding connection is actually from the aluminum wire to the Nickel plating. The main advantage of this method is inexpensive plating and relatively easy wire bonding. The disadvantage is Aluminum wire bonding is less flexible than gold bonding and generally requires larger bond pad pitch compared to gold bonding. Gold Ball Wire Bonding and soft gold plating For Gold Ball Bonding to Printed Circuit Boards a thick layer of soft gold has traditionally been required. In this Case the copper traces on the PCB are plated with a nickel layer and then a soft gold layer measuring between 15 and 30 micro-inches. The gold is electroplated and when plated correctly provides an excellent surface for wire bonding. This method has the advantage allowing for fine pitch gold ball bonding. The disadvantages are high cost and the thick gold layer can cause reliability problems with surface mounted components due to gold dissolution into the solder. Gold Ball Wire Bonding with ENEPEG plating In recent years Electroless Nickel, Electroless Palladium, Immersion Gold plating has been proven to be the best compromise between cost and manufacturability. This method of plating is known and ENEPIG and is common referred to as the universal plating method. It is called universal plating because it offers good wire bond ability and good solder ability. It is suitable for RoHS solders as well as Eutectic SnPb solder. The typical plating thickness is 100 to 150 micro inches of nickel followed by 4 – 10 micro inches of palladium followed by 1-2 micro inches of gold. ENEPIG is suitable for both Gold and Aluminum wire bonding. Additionally, With recent increases in the price of gold price to levels above US$1200 per troy oz, the production cost of electronic device that required thick gold electroplating becomes extremely difficult to control. Since the cost of palladium metal has remained relatively low in comparison to gold, an opportunity for cost saving by replacement of gold with palladium is now available. At KingCredie for PCB plating with Chip on Board we recommend using ENEPIG as a preferred plating method.For more information,tell us what you want to know.
  3. most used electronic components have:Switches,DIODES,Resistors,capacitors,I can buy it here:https://www.electronic-components.hk/catalog/capacitors_cid2001597.html
  4. I will recommend the best e-site for you:www.electronic-components.hk
  5. Yesterday
  6. It's a Multilayer Ceramic Capacitor MLCC - SMD/SMT 0.22 uF 50V 0603 https://gr.mouser.com/ProductDetail/Murata-Electronics/GCJ188R91H224KA01D?qs=QzBtWTOodeUBgk6Gsyvq%2FA%3D%3D
  7. On November 20, SimScale will offer a free webinar to teach everything about resistance network modelling and how to find the resistance values with a detailed model. Thermal resistance network models represent the complex characteristics of an electrical component in a simple form that can be used to carry out thermal analysis in many ways. We can also use thermal resistance models in CFD to obtain better results without adding excessive complexity to the simulation. Learn how to use cloud-based simulation with SimScale for thermal modelling. A professional simulation project will be provided to follow along during the webinar! Participants will also receive the recording via email, so if the timezone does not suit you, it is still worth registering :) Register here: https://bit.ly/2QhSVNf Hope to see many of you there!
  8. The buyer should be aware of the quality of the product because many companies are providing the duplicate product at such a cheap rate which is very harmful to users. ]If you want the best quality rigid-flex boards, then I would like to refer you to Capel Technology Co,.Ltd , They provide the best product at a very reasonable price.
  9. Last week
  10. I recently found several good electronic components sites: Http://www.hotenda.com; Https://electronic-components.hk; Https://www.omo-ic.com; You can buy many rare models.
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  12. R7 has nothing to do with the output transistors. Instead R7 senses the amount of output current and sends its sensing voltage to the current adjustment opamp. Each of your output transistors need a series 0.33 ohm emitter resistor so that the two transistors are better matched to share the heating.
  13. Hi! I'm planning on making a electric bobbin winder for my wife for christmas. There are electric bobbin winders on the market, however, they are quite expensive and I'm not impressed with the quality of existing products. I especially do not like the noise output of the existing products. One example of such a bobbin winder is the following: https://www.youtube.com/watch?v=gBp4xZoidVM My idea is as follows: I wish to use the electric mains to power the bobbin winder (220-240V AC) I need a transformer I want a quiet motor, with low maintenance and long lifespan I will use a brushless motor I do not wish to use a gear system - I want to keep this project as minimal as possible. The bobbin winder should be directly connected to the shaft of the electric motor. The speed of the bobbin winder is equal to the output of the motor. I need a motor which accurately is able to do a wide range of RPMs. Prefferably from around 30 rpm - 7000 rpm I wish to reduce or eliminate the amount of programming and components I'm thinking of using a ESC with a single potentiometer input So, here are my questions: What electronic components do I need? (Motor, potentiometer, ESC, power supply, transformator, ...?) Are there ESCs that simply take the input of a potentiometer? Should I choose a brushless motor with a large number of poles to get a smooth running machine on low RPMs? Should I choose a motor with sensor to enable accurate speed control? What specs should my components have? In advance, thanks for any replies!
  14. The old circuit I posted above have included the resistor for the emitter of TR3 (you can see the red marking I made). Should I add more emitter resistor for this output transistor and for the newly added transistor? This is the new design I've made from the old previous circuit. Please take a look.
  15. The parallel transistors in the circuit you posted do not have series emitter resistors so the ones with high gain take a high current and the ones with a low gain take a low current. Emitter resistors help to match the transistors. This is how the output transistors are connected in parallel:
  16. The datasheet of the ULN2003 shows that the saturation voltage loss is 1.4V. Then if the battery is 3.7v the motor gets only 2.3v but if the battery is 7.4V then the motor gets 6V. You did not say how much voltage and current the motor needs. You did not say what is the stalled current of the motor. Stalled is when something stops the motor from turning, which happens the moment it is powered. If the stalled current is higher than 1A (two ULN2003 outputs in parallel) then the ULN2003 will burn out.
  17. I want to make a car, use the driver module, just have a piece of ULN2003 on hand, just think about whether you can use this chip to drive, check the DATASHEET, the current of each port is 500mA, I use the two ports in parallel Do a mouth control 1 motor, a total of 4 ports control 2 motors, the battery uses two 3.7 lithium batteries, do not know if this chip can work very well?
  18. I have no idea how the parallelized transistors look like. My friends told me to use darlington-pair for a power transistor. I have a schematic of power transistor parallel-configuration for an inveter, here's the picture: Sorry for asking this, but can you show me an example of a parallelized power transistor. Thx in advance
  19. The very old circuit you posted works poorly. TR3 is its output transistor and it gets too hot. Add a second 2N3055 transistor parallel with TR3 to share the heat and add a 0.33 ohms/2W resistor in series with each emitter to the output. The transistors collectors can be connected directly together by the heatsink if the heatsink is insulated from any other part of the circuit. If you want a 0V to -30V, 2mA to 3A power supply then make a second one of this project and use its +30V output as 0V and use its 0V output as 0V to -30V. A center-tapped transformer will produce an AC output, not DC and not variable.
  20. A tiny DC to DC buck converter board is useful for many applications, especially if it could deliver currents up to 3A (2A continuously without heatsink). In this article, we will learn to build a small, efficient, and cheap buck converter circuit. References Full Article: https://www.pcbway.com/blog/technology/DC_to_DC_Buck_Converter_Adjustable__97__Efficient__3A.html MP2315 Library: https://componentsearchengine.com/part.php?partID=930350 Altium Plugin: https://www.samacsys.com/altium-designer-library-instructions
  21. Check the link to get Thomson TV circuit board diagrams, schematics, PDF service manuals
  22. Hi, again thanks for your answer. One more little things here, can you tell me where to add a secondary output transistor for this schematic. I'm really curious to know. Thanks in advance. And also can I use a centre-tapped transformer for producing negative supply voltage? If yes how to place it in?
  23. Cyclone® III device family offers a unique combination of high functionality, low power and low cost. Based on Taiwan Semiconductor Manufacturing Company (TSMC) low-power (LP) process technology, silicon optimizations and software features to minimize power consumption, Cyclone III device family provides the ideal solution for your high-volume, low-power, and cost-sensitive applications. More detail about A40MX04-PLG68 you can find in icchipwore PHGL-S-A0002794600-1.pdf
  24. Sorry, I was wrong, you are correct. The peak of 24V RMS is 33.9V not 40V. The peak of the 28V RMS transformer I recommended is 40V. Then the full load drops the rectified voltage to 38VDC with ripple and the losses in the circuit have enough extra voltage for the output to be well-regulated 30VDC at 3A.
  25. I wanted to ask how much would a source code program with four buttons support cost. Main screen displays volts, amps, ohm, frequency, time. The program start after the set resistance is detected by the set measuring voltage 15V. Because the device works at high voltage after starting. The device simply consists of an inverter connected to the 240V network that changes it to direct current, and the microcontroller controls creating alternating current with the possibility of setting each of the mentioned parameters at one time, divided into three sections. For example: the total time is to be 30 seconds, and here it is possible to divide into three sequences: sequence 1, sequence 2, sequence 3. Settings in sequence 1: duration volt amps frequency The same in sequence 2 and sequence 3. Example: sequence 1: 3 seconds 180 volt 1.3Amp 500 Hz - sequence 2: 7 seconds 180V 1Amp 250Hz - sequence 3: 4 seconds 180V 0.8Amp 50Hz While maintaining smooth transition from sequence 1 to 3 and the ability to enable and disable one of the sequences. Let's say that this possibility is the first program. Ultimately 10 programs also with the option of enabling or disabling one of the programs. The current year, month, day and time can be set. All parameters can be saved and I do not know what is better sd card or usb stick, To read in the Excel format in the form of a table. This is an introduction to my project. Because the program will be developed.
  26. Without a clear description nobody can help in this matter. Sorry.
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