PCB Assembly

Low-volume PCB assembly

Publish Date:2020-10-15

For the processing of low-volume PCB assembly, there are many factors to be considered in PCB wiring. In actual production, the effect can not be achieved simply by using automatic wiring tools, which is not only related to PCB production cost, electromagnetic interference between components, beautiful appearance, and many other factors, but also affects the effect of SMT chip processing.

1、 For double-sided boards or multilayer boards, the lines on both sides of the circuit board should be perpendicular to each other to prevent mutual induction and crosstalk.

2、 Wiring priority: priority of key signal lines, such as power supply, analog small signal, high speed signal, clock signal and synchronous signal.

3、 If the PCB board is equipped with high current devices, such as relays, indicator lights and horns, the ground wire should be separated to reduce the noise on the ground wire.

4、 If there is a small signal amplifier on the circuit board of SMT chip processing plant, the weak signal line before amplification should be far away from the strong signal line, and the line must be as short as possible, and it should be shielded by ground wire if possible.

5、 In order to reduce the interference of the board, SMT electronic factory should leave a large gap between the parallel signal lines. If there are two signal lines close to each other, it is better to take a grounding wire between the two lines, which can play a shielding role. The distance between high voltage signal lines needs to consider the requirements of insulation resistance and breakdown voltage under the worst conditions.

6、 When designing signal transmission line for SMT chip proofing, it is necessary to avoid too large steering angle, so as to prevent reflection due to sudden change of characteristic impedance of transmission line. Uniform arc line or obtuse angle with certain size can be considered. In addition, the copper foil is easy to be peeled or warped at the outer corner of the tip.

Low-volume PCB assembly

Ideaspcb.com Share from several aspects to analyze and select SMT small batch SMT processing plant

  1. A high-quality electronic processing factory is bound to have a good reputation, which shows that it is reliable, trustworthy and can continue to develop well in this industry.
  2. SMT chip processing production qualification can be reflected in many ways, such as ISO9001 quality management system, or from the previous partners and products to check whether the production and processing capacity is qualified.
  3. A high-quality SMT processing plant is bound to provide perfect service, including pre-sale, sale and after-sale links, especially after-sale service is the most important. High quality service ability and attitude can provide solutions at the first time when customers need, and actively solve every after-sales quality problem in the after-sales link.
  4. In order to attract customers, there may be some chip processing plants that offer lower than the average market price for publicity, so as to get more orders. In fact, the cost and profit of SMT chip processing or dip plug-in in the electronic processing industry are nearly transparent now. The seemingly low quotation may bring the final inferior products, and the price for quality problems is much higher than the processing cost. As the old saying goes, we get what we pay for, which is reasonable, so what we need to do is to choose the electronic processing plants with acceptable quotation and excellent processing quality to cooperate, rather than blindly pursuing the lowest processing cost.

The above four aspects are the important basis for selecting SMT small batch SMT processing manufacturers. In addition, product quality, technical support, value creation, etc. can become the criteria for judging whether SMT processing manufacturers are worthy of cooperation. Here, also reminds the enterprise to choose must be careful.

Low-volume PCB assembly

Ideaspcb . Com provides one stop solution for PCBA production , Focus on model for 20 years / Low volume PCB assembly, SMT chip, dip welding, PCB production, electronic components procurement, PCBA full turnkey solution.
Many people have heard about the production and processing of low volume PCB assembly , But I didn’t know the whole detailed process. SMT proofing refers to the process of experimental production before batch manufacturing and small batch trial production in the factory.

The following is an aspcb . COM: the whole process of low volume PCB assembly.

  1. After receiving the material and PCB board, arrange the material quantity of personnel list to confirm whether the production is sufficient.
  2. According to the customer’s information (Gerber document), the purchasing department will send out the steel mesh.
  3. The engineering personnel make the placement program according to the customer information (BOM file, Gerber data, coordinate file, silk screen map).
  4. The production dispatcher should import the program data into the machine and adjust the machine according to the data.
  5. After all the materials are ready, the order starts to go online.
  6. The material clerk uses Feida to load the materials on Feida.
  7. Using the loading machine, start to put the PCB on the production line and transport it to the bottom of the printing machine through the track.
  8. Use Zhengshi A5 printing machine, put the steel mesh on it, print it on the steel mesh through the solder paste according to the adjusted procedure, and brush the PCB pad to the solder paste through the steel mesh.
  9. Start to use the placement machine for placement production.
  10. After pasting a board, use the first piece detector to detect the direction of some components of the board. For each component parameter, the first piece detector also checks according to the customer BOM. If there is BGA or precision chip, use the X-ray machine to check whether the chip is mounted OK.
  11. After there is no problem in the first article inspection, reflow soldering is arranged.
  12. After reflow soldering, use X-ray to inspect the board with BGA again, to check whether the tin on the inside of BGA is OK, whether there is continuous tin, empty soldering, etc.
  13. After there is no problem with the first piece of first board, the remaining number of boards will pass through the furnace according to the normal pasting, and be detected by AOI detection instrument. The main purpose is to detect whether there are reverse, tin connection, false welding and other problems with the pasted boards. If there are problems, they will be sent to the maintenance personnel for maintenance.
  14. After the patch is finished, if there is plug-in material on the board and the sample quantity, it will be handed over to the post welding personnel to use the soldering iron to weld the material on the PCB board, batch quantity, and use the wave soldering to weld directly through the furnace.
  15. There is no plug-in material, so it can be packaged and delivered directly after the placement.
  16. After the plug-in welding is completed, the overall quality personnel will inspect it. After the inspection is OK, the plug-in will be packed and the personnel will be arranged to deliver the goods.
Low-volume PCB assembly
Low-volume PCB assembly

Cost advantage – although the traditional scale economy has known large production, it has a significant cost advantage in the changing technology scheme low capacity PCB production. First, you won’t get more production boards than you need. In addition, the board will not become redundant as technology changes.

Low-volume PCB assembly

In the prototype phase, you often improvise your product in terms of design and functionality. Low volume PCB assembly means you will not encounter defective products. In addition, because you can outsource small batch PCB assembly, this means lower management costs for your own business. You can also save valuable time available in other production areas. For lower batches, you can also save storage costs, in case you encounter a large inventory load, and if the prototype fails, it can also lead to excess inventory. Therefore, low volume PCB assembly can provide low-cost testing methods Turnover time – low yield also has a rapid turnaround time. Therefore, you can quickly assess whether there are any design changes. This in turn shortens the time to market and can be a source of significant competitive advantage in the world today.

Low-volume PCB assembly

Agility – the agility of an enterprise to respond to changes if there is an attribute between business success and failure. Low volume PCB assembly itself provides the enterprise with this advantage because the enterprise will not encounter a large number of products and has the advantage of rapid turnover time. By better understanding whether there are any defects in the product, no matter whether the design needs to make any changes, the enterprise can combine the product with the customer requirements very quickly. There is no doubt that the chances of success are increasing.

Low-volume PCB assembly

The quality end product – PCB’s ability to turn around time fast prototyping and early detection of defects, your advantage is to improve the product and enter the market with high-quality products. This has a long way to go in terms of improving credibility because the product has been successful in the market and has brought a reputation to the manufacturer.
It’s also possible for startups and amateurs – businesses are no longer just big business companies. Through the low volume PCB assembly and low cost related to the test idea, the business has become a fair competition environment. For small businesses and amateurs, it’s easy to test their ideas without having to invest a lot of money. For startups that want investors, it is easy to get proof of concept in addition to the paper business plan.

Low-volume PCB assembly

In a word, low volume PCB assembly has many advantages, which saves management costs from outsourcing. Small order size can automatically shorten the turnover time. In addition, it is a simple and low-cost method to test product design concepts without a lot of costs.
Thank you very much for coming to our Shenzhen IDEASPCBb technology. We are a professional PCB  manufacturer, which specializes in fast proofing, large, low volume PCB assembly. The whole production process is controlled by computer and barcode tracking. Only a few factories in China have this production technology. At the same time, we also provide SMT patch, plug-in machine, PCBA finished product assembly one-stop service. Quality assurance, punctuality of delivery, affordable price, welcome to consult quotation!

Printed circuit board mound, also known as "fill" or "fill bare printed circuit board," is a process that involves many different stages.

For low volume PCB assembly, to maximize production and minimize cost, What should consider some restrictions. Also, What should consider human factors before designing. Here are some of the factors that IDEANSPCB summarizes:

Low-volume PCB assembly

1) If the wire spacing is less than 0.1 mm, the etching process can not be carried out because if the etching solution can not effectively diffuse in the narrow space, part of the metal will not be etched out.
2) If the wire width is less than 0.1 mm, it will break and damage during the etching process.
3) The pad size should be at least 0.6 mm larger than the hole size.
The following constraints determine the design method of the panel:
1) The size performance of the reproduction camera used for the original film of the product;
2) Tabulated dimensions of original drawings;
3) The smallest or largest operating size of the circuit board;
4) Drilling accuracy;
5) Excellent linear etching equipment.
In the design, from the perspective of low volume PCB assembly, the following parameters should be considered:
1) The diameter of the hole depends on the maximum material condition (MMC) and minimum material condition (LMC). Who should select the diameter of the hole of an unsupported component in such a way that the MMC of the pin is subtracted from the MMC of the hole, and the difference is between 0.15-0.5mm. Moreover, for the band pin, the difference between the pin’s nominal diagonal and the inner diameter of the unsupported hole will not exceed 0.5mm, and not less than 0.15mm.
2) Place smaller components reasonably so that larger components will not cover them.
3) The thickness of solder resist shall not be greater than 0.05mm.
4) The screen-printed logo cannot intersect with any pad.
5) The top half of the circuit board should be the same as the bottom half to achieve structural symmetry because asymmetric circuit boards can bend.
From the perspective of quality control of low volume PCB assembly, an important factor to be considered is that IT should pay special attention to the possible short circuit problem caused by the inclination between the inserted components and their theoretical positions before welding. According to experience, What should keep the maximum allowable inclination of component pins at 15 degrees from the theoretical position. Within the corner. When the diameter difference between the hole and pin is large, the inclination can be up to 20 degrees. For vertically mounted components, the inclination can reach 25. Or 30 degrees, but this will lead to a reduction in package density. Figure 3-13 shows the package of the TO-18 transistor with different pin inclination. In the figure, the installation position of the to-i8 transistor is 2mm away from the printed circuit board. If the aperture is IMM, the inclination can reach 20 degrees. Of course, the pin itself does not have any inclination.
The assembly mode of multiple circuit boards usually makes the field maintenance as easy as pulling out the circuit board for the replacement. Of course, the precondition is that each independent circuit board can exercise its unique function. There will not be much disassembly for replacing circuit boards, and the minimum number of soldering / desoldering is ensured. Therefore, the design of PCB must consider its maintainability.
In the production of low volume PCB assembly, the required welding technology and equipment also add many limitations to the circuit board’s design and layout. For example, in wave soldering, the groove’s maximum size, the distance between the edges, and the operating space are all important factors. Simultaneously, designers must be aware of what the final product should look like as much as possible and try their best to protect its most sensitive parts.
There are four main steps in the assembly process of low volume PCB assembly.

  1. Application of solder paste: similar to T-shirt shielding, the solder paste template uses a thin stainless steel template to apply solder paste on the components, and What will install the components on the printed circuit board. When using solder, a chemical called flux is used to help melt the solder paste and bond it to the circuit board’s surface.
  2. Pick and place components: after applying solder paste, the next step in the circuit board assembly process is to pick and place the machine. This is where the surface mount components are placed on the printed circuit board. This process was done manually by the circuit board assembler, who will use a pair of tweezers to pick up and place components. However, with the advent of robotics, this step has been automated to achieve greater consistency and accuracy.
  3. Soldering: after all components are installed, place the printed circuit board on the conveyor belt and move the conveyor belt to the reflux furnace. Inside the oven, the circuit board is heated to melt the solder paste and permanently bond the components to the circuit board itself. Where the circuit board includes components other than SMD, it may be necessary to insert through-hole components. However, in these cases, more professional welding methods are needed.
  4. Testing and quality control: in some cases, the movement of the printed circuit board during the reflow process may cause component dislocation, resulting in poor connection, no connection at all, or incorrect component connection. That’s why it’s important to check and do some testing to ensure the board’s functionality. Even if all the above steps are carefully completed, the circuit board may fail the function test. The failed PCB can be scrapped or recycled, and the process will start again until the final result is a fully functional PCB.
    Once the finished product of low volume PCB assembly passes the function test, we can confirm the design, put it into production in large quantities, assemble the shell, and put the finished product online.