Electroplating process and role Acid dip: the main role is to remove the oxide layer on the board surface, to avoid water brought into the copper cylinder and affect the content of sulphuric acid. Cleaner: This cleaner is acidic and its main function is to remove fingerprints, grease and other residues from the surface of the board to keep it clean. Therefore, the grease, fingerprints should be prevented as a priority: and must pay attention to the compatibility of the resist layer and the matching between other fluids in the same line, and reduce the surface tension, the ability to exclude air bubbles in the hole. Micro-etching: As all kinds of dry film resist have additives to promote adhesion deep into the copper layer, 20~50u" of copper should be removed in this step to ensure a fresh copper layer to obtain good adhesion. Washing: The main function is to wash the residual solution from the board surface and the holes. Copper plating: The main components of the copper plating solution are copper sulphate, sulphuric acid, chloride ions, contaminants and other additives. Their respective roles are as follows: Copper sulphate: to provide the basic conductive copper ions required for plating to occur, the concentration is too high, although the operating current density can be slightly higher than the upper limit, but due to the concentration gradient difference is large, easy to cause Throwingpower**, and copper ions are too low, because the deposition rate is easily greater than the speed of diffusion movement, resulting in hydrogen ion reduction and the formation of scorching. Sulphuric acid: To provide a conductive acid ion to the bath. The ratio of sulphuric acid to copper is usually considered as "18g/l of copper metal + 180g/l of sulphuric acid" to maintain the acid to copper ratio above 10/1, 12:1 is better, ** not less than 6:1, high acid and low copper amount is prone to scorching, while low acid and high copper is not conducive to ThrowingPower. Chlorine ion: Its function is twofold, to help dissolve the anode properly and to help other additives to form a glossy effect, but too much chlorine ion will easily cause polarisation of the anode. Insufficient chloride ions can lead to abnormal consumption of other additives and imbalances in the bath (even fog deposition or step plating at very high levels; levelling** at too low levels). Other additives: The combined function of all other organic additives can achieve a regular crystalline arrangement of the lustre effect and improve the physical strength of the plating, while a relative excess of additives can easily cause the decomposition and oxidation of organic matter, pollution of the bath, increase in the frequency of activated carbon treatment, or an increase in the co-precipitation ratio of organic matter, resulting in increased internal stress and reduced ductility of the plating. Pollutants: Organic and inorganic pollutants can be distinguished, as the destruction of the equiaxial crystalline structure causes physical deterioration and co-precipitation causes deterioration in appearance. The sources of organic contamination are: oxidative decomposition of lustre agents, inks, dry films, baths, filters, anode bags, hanger cladding films and other filtered out substances and environmental pollutants. The sources of inorganic pollution are: environmental pollution, water pollution and basic material pollution.

SMT process flow and process description 一, chip components single-side mount process 1. Incoming material inspection Description: Check whether the components, pads, solder paste have oxidation, whether the solder composition matches, integrated circuit pins and its coplanarity. 2. Printing solder paste Description：Through solder paste printing machine or SMT solder paste printing table, printing special scraper and SMT leakage board will SMT solder paste leakage printing to the PCB pads. 3. Check the printing effect Description: Check whether the printed circuit board solder paste leakage, adhesion, the amount of solder paste is appropriate, etc. 4.SMD Description：Finish the placement by the placement machine or vacuum suction pen, tweezers, etc. 5. Check SMT placement effect Description: Check whether the posted components are put on the deviation, put on the reverse or leak, and repair, narrow pitch components need to use microscope entity check. 6. Check reflow soldering process setting Description: Check the working conditions of reflow soldering, such as power supply voltage, temperature curve setting, etc. 7. Reflow soldering Description: Reflow soldering by SMT reflow equipment. 8. Check the welding effect and *final inspection Description: Check whether there are welding defects and repair. 二, chip components double-sided placement process 1.Incoming material inspection 2.Screen printing A side solder paste 3. Check the printing effect 4. Mount A-side components, check the effect of SMD 5.Reflow soldering 6.Check the soldering effect 7. Print B-side solder paste 8.Check the printing effect 9. Mount B-side components, check the effect of patching 10.Reflow soldering 11.Repair check 12.* Final inspection Attention matters: 1: A, B side of the distinction is the circuit board in components less and small for A side, components more and large for B side. 2: If both sides have large package components, you need to use a different melting point of the solder paste. That is: A side with high temperature solder paste, B side with low temperature solder paste 3: If there is no different temperature of the solder paste, you need to add a step, that is, after the completion of step 7, you need to A side of the large package components        With SMD red glue sticky, and then the B side of the operation. 4: Other steps operation with process (a) 三, research and development in the mixed board placement process 1. incoming material check Description: check whether the components, pads, solder paste have oxidation, whether the solder composition matches, integrated circuit pins and its coplanarity. 2. Drop coating solder paste Description: Use SMT solder paste dispenser, air compressor to drop coating the solder paste in SMT syringe to PCB pads. 3. Check the effect of drip coating Explanation: Check whether the amount of solder paste drip coated is suitable, whether there is leakage of coating or sticking. 4. Placement of components Description：Finished by vacuum suction pen or tweezers, etc. 5. Check the effect of SMD Description: Check whether the pasted components are put on the wrong side, put on the opposite or leak, and repair. 6. Reflow soldering Description: Reflow soldering by HT series desktop small SMT reflow soldering equipment. 7. Check the welding effect Description: Check whether there are welding defects and repair. 8. Solder the plug-in parts Description：Finished by electric soldering iron, solder wire and flux with. 四, double-sided mixed batch production placement process 1.Incoming material check 2. Screen printing A side solder paste 3. Check the printing effect 4. Mount A-side components 5.Check the effect of mounting 6.Reflow soldering 7.Check the soldering effect 8.Printing B-side red glue 9.Check the printing effect 10.Placement of B-side components 11.Check the effect of placement 12.Curing 13.Insert THT components on A side 14.Check the effect of insertion 15.Wave soldering 16.Repair solder joint cleaning test Description: Caution and operation process as described above.

Laminating process Surface mount adhesives (SMAs) are used in wave soldering and reflow soldering to keep components in place on printed circuit boards (PCBs) and to ensure that components are not lost during transfer on the assembly line. 　　  Most surface mount adhesives (SMAs) used in PCB assembly are epoxies, although polypropylene (acrylics) are also used for special applications. Epoxies have become a more mainstream adhesive technology worldwide following the introduction of high-speed drip systems and the electronics industry's mastery of how to handle products with relatively short shelf life. Epoxy resins generally provide good adhesion to a wide range of circuit boards and have very good electrical properties.  Epoxy chip adhesive formulations offer a wide range of benefits to the user, including good dripability, continuous and consistent dot profile and size, high wet and cure strength, fast cure, flexibility and resistance to temperature shock. Epoxy resins allow high speeds for very small glue dots, providing very good on board curing electrical properties, no dragging lines and no collapsing during the heat cure cycle. (As epoxy resins are heat sensitive, they must be stored under refrigerated conditions to ensure *great shelf life.) 　　  Using visual inspection or automated equipment, SMA must contrast with the typical green or brown boards. Red and yellow have become the two basic adhesive colours due to the use of automated visual control systems to aid the inspection process. However, the ideal colour is determined by the visual comparison between the board and the adhesive.　　  Typically, the heat curing of epoxy resins takes place in-line, in an infrared (IR) channel oven. The *lowest* temperature to start curing is 100°C, but in fact curing temperatures range from 110 to 160°C. Temperatures above 160°C speed up the curing process, but tend to cause fragile glue joints.　　  Adhesive strength is key to the performance of the adhesive and is determined by many factors such as adhesion to the component and PCB, the shape and size of the adhesive dot and the level of cure. The three *common* causes of insufficient adhesive strength are insufficient cure, insufficient glue volume and poor adhesion.　　   Glue dot profile The flow characteristics of the glue, or rheology, affect the formation of the epoxy resin glue dot as well as its shape and size.  SMA allows for fast and controlled drops of glue in order to form a defined shape of glue dot. In order to ensure a good and stable glue dot profile, the glue is cleverly designed to be shake-soluble (i.e., thinning when stirred and thickening when stationary). In this process, the viscosity of the SMA is reduced when subjected to shear forces during dripping, allowing easy flow. When the glue hits the PCB surface, it rapidly re-structures and regains its original tackiness.　　  The dot profile is also influenced by the recovery rate of the shake, the viscosity at zero shear rate and other factors. The actual dot shape may be "pointed"/conical or hemispherical. However, the dot profile is defined by non-viscous parameters such as dot volume, drip needle diameter and off-board height. That is, for a given grade of glue, it is possible to produce either very high narrow glue dots or low wide glue dots by adjusting their parameters.　　  After placement, the drips of glue have two requirements: they must be smaller in diameter than the gap between the pads and be high enough to connect the gap between the PCB surface and the component body without interfering with the placement head. The gap in the glue is determined by the height of the pads above the PCB soldermask and the difference in thickness between the end metal and the component body. This gap can vary, being smaller than 0.05mm for flat chip components and larger than 0.3mm for SOP (small-outline package) and QFP.　　  High drops of glue ensure good glue coverage on components with a high height above the ground. A high glue point also allows the glue to be squeezed out between components with a low ground clearance without fear of contamination of the pad. Typically, two sets of drip parameters are used together for the same level of glue: one produces a high, high volume glue dot for components with high ground clearance, and the other provides a medium height and volume glue dot for flat sheet components and MELF (metal electrode face) components.　　  The glue dot size is also controlled by the ratio of the inner diameter of the selected nozzle to the height above the ground. Typically, the dot width to height ratio ranges from 1.5:1 to 5:1 (h/w = 0.2 to 0.6), depending on the parameters of the drip system and the grade of glue. These ratios can be optimised for any component by adjusting the machine settings.　　  Moisture in the glue joints may boil during curing, causing voids, weakening the glue joints and opening pathways for solder to penetrate underneath the component, possibly c

The use of LED flexible light bars LED strip lighting is mainly used for decorative purposes. As the LED strip is not very well understood, there are many customers who will miss some links in the calculation of the project quotation, giving themselves some extra unnecessary costs. The following is an example of some products to share how to calculate the project installation cost of LED strip lights: 1, LED strip length: calculate the total length of the required LED strip. LED strip can be divided into three groups of cut off the use of the general 60 LED per meter LED strip length of 50mm per group, 30 LED per meter LED strip length of 100mm per group. understand this can be calculated according to the construction effect design drawings the actual need to use The number of LED strips to be used. Generally set aside about a meter of spare length is good, so as to avoid excessive procurement resulting in a waste of resources.      2, LED strip power: because the purchase of LED strip does not distribute power, so after calculating the length of the required LED strip, to calculate the power required to match the power supply. The power of different LED strips varies, so the power of the matching power supply should be chosen with care. The following is a list of LED strip power: 0603LED strip: 12V, 60 LEDs per metre, 1.5W per metre 1210LED strip: 12V, 60 LEDs per metre, 4.8W per metre 5050LED Flexible Strip: 12V, 30 LEDs per meter, 7.2W per meter 5050 LED strip light: 12V, 60 LEDs per meter, 14.4W per meter        For example, if you buy a 5050 LED strip with a 12V, 4A power supply, you can only take 6 metres of 5050 LED strip with one power supply. Because the power of 5050LED strip is 7.2W per metre, the total power of 6 metres is 43.2W, while the rated power of the power supply is 48W. It is generally not recommended to use the power supply at full capacity, as this has a great impact on the life of the power supply. If you need 100 meters, then the corresponding 4A power supply will need to be equipped with * less than 16.    3, LED soft strip controller: for RGB soft strip, it must be equipped with a controller to be effective, and a controller can control the length of the LED soft strip from 5 meters to 20 meters, mainly depending on which specification of controller is chosen. Thus, after purchasing the RGB strip, you will also need to purchase additional controllers depending on the length of the controller, or additional RGB amplifiers (each amplifier can be extended by 5 metres). Do not make the mistake of thinking that one controller can achieve all the control requirements of an RGB soft strip, this is a misconception.        Let's say you buy a 100m RGB strip and the controller you choose is a conventional controller, i.e. each controller has a 5m control range. Then a 100m RGB strip would require 20 RGB controllers, or one RGB controller and 19 amplifiers.