#fastpcba

In the process of PCBA processing, how to do solder paste printing is the key point

Solder paste printing is very important for PCBA. It directly affects the overall soldering effect of PCBA. In the process of PCBA processing, how to do solder paste printing has become a problem that must be considered by production managers. The effect of solder paste printing consists of four parts: stencil, solder paste, printing process, and detection method. Below, FASTPCBA will give you a specific analysis.

1. Steel mesh The opening of the stencil must be appropriately enlarged or reduced according to the layout of the electronic components on the PCBA board to determine the amount of tin on the pad, so as to achieve the best soldering effect, avoid the occurrence of tin connection, less tin, etc., which requires craftsmanship The engineer conducts a rigorous evaluation. In addition, the material of the steel mesh is also critical, which affects the tension of the steel mesh and the life of repeated use.

In addition, the cleaning and storage environment before feeding the steel mesh is particularly critical. Strict cleaning must be carried out every time before going online, and check whether the vias are blocked or there is tin dross. Some PCBA manufacturers recommend purchasing a stencil tension meter, and perform a tension test of the stencil before each feeding.

2. Solder Paste Solder pastes need to be selected from mid-to-high-end brands, such as Senju, Vitero, etc., and it is better to contain active ingredients such as gold or silver. The solder paste must be stored strictly in a refrigerator at 2 to 10 degrees Celsius, and relevant statistics must be made for each storage and delivery. The recovery of solder paste must be strictly controlled within the scope of the IPC standard, and the tin paste must be strictly implemented before going online. Paste mixing program.

3. Solder paste printing At present, manufacturers are using fully automatic solder paste printers, whose equipment can well control the printing strength and speed and other parameters, and has a certain automatic cleaning function. The operator only needs to set the parameters in strict accordance with the regulations.

In the mass production process, it is particularly important to detect the phenomenon of blocked holes and deviations of the stencil, especially when some defects detected by SPI after printing show an upward trend, it is necessary to stop the machine to check the operating conditions of the stencil itself.

4. SPI printing effect detection After the solder paste printing machine, it is particularly important to configure the SPI solder paste detector, which can effectively detect many defects such as small tin, continuous tin, gap, wire drawing, offset and so on in the solder paste printing process. So as to maximize the overall welding PPM value.

The development of society is fast. People are paying more and more attention to health, and the equipment in the medical industry puts forward higher requirements on the performance of pcb materials. What are the technical requirements for reliability, high frequency, high speed, and high conductivity of pcb in medical treatment?

Medical PCB circuit boards have become one of the most complex and challenging in the industry. Many people in the industry have said that medical PCB and ordinary PCB are the same board. Is there any difference?

To sum up, the medical PCB circuit board has the following aspects:

1) "Safety" and "Reliability": These are the core issues of PCB boards in the medical industry. Life support products or high-end products refer to IPC-3 level standards, and non-life support or low-end products refer to IPC-2. The large-scale medical terminal establishes its independent standard enterprise standard, strictly controls the reliability of the product. So this point is very important.

2) Long service life: General product warranty time is more than 5 years, large medical equipment requires at least 10 years, and the product lasts for a long time. The difference between medical PCB and ordinary PCB is still there.

3) Large hierarchical span: from consumer medical products that meet conventional requirements, to mid- and high-end medical products that meet high reliability and high stability requirements, to small portable products that meet high-density, high-integration, and smart Versatile and multifunctional wearable medical products.

4) Product conservative: The application of new medical technologies and new products to the market is slow, and the verification and testing of new products is repeated, which often requires comprehensive evaluation.

5) Traceability: Products require strict process records and product traceability. Some large-scale medical terminals require the traceability of PCB processing records for 10 years.

6) The process and fire protection requirements of medical pcb boards are different. The ordinary pcb process has different methods for spraying tin and cleaning the board. On the premise of taking process measures and ensuring quality and safety, it can be used for repairs as appropriate.

7) The general medical PCB demand is small, the process requirements are many, back drilling, multiple pressing, mixed pressure, high precision, special impedance, thick copper, thick gold, embedded copper block, etc. The price focus will be very low, which is also different from ordinary pcb boards.

Among all medical PCB board materials, FR-4 is the most widely used. For medical PCB design, there will be differences in the choice of FR-4 board based on the positioning of its own products and the control of the price of raw materials. For circuit boards used in medical equipment, reliable medical pcb circuit board manufacturers should be selected.

FASTPCBA is a manufacturer of medical pcb manufacturing and pcb assembly Manufacturer in China for 20 years.

We Through ISO9001, ISO14001, ISO13485 Certification, it not only proves that under the quality assurance system, FASTPCBA can continuously provide high-quality products that meet the needs of medical device customers, and further demonstrates our company's higher requirements for product quality standards. We have a professional engineering team available to assist you with Medical PCB Manufacturing & PCB Assembly Services.

Rogers PCB is a type of high-frequency board produced by Rogers. It is different from the conventional PCB board——epoxy resin. There is no glass fiber in it, and ceramic base is used as the high-frequency material. Rogers Printed Circuit Board has superior dielectric constant and temperature stability, and its dielectric constant has a thermal expansion coefficient that is very consistent with that of copper foil, which can be used to improve the deficiencies of PTFE substrates; it is very suitable for high-speed designs, as well as commercial microwave and radio frequency applications . Because of its low water absorption, it can be used as an ideal choice for high-humidity applications, providing customers in the High Frequency PCB industry with the highest quality materials and related resources, and fundamentally controlling product quality.

Rogers series classification:

RO3000 series: Based on ceramic-filled PTFE circuit materials, the models are: RO3003, RO3006, RO3010, RO3035 high-frequency laminates.

RT6000 series: Based on ceramic-filled PTFE circuit materials, it is designed for electronic circuits and microwave circuits that require high dielectric constant. The models are: RT6006 dielectric constant 6.15, RT6010 dielectric constant 10.2.

TMM series: composite materials based on ceramics, hydrocarbons, and thermosetting polymers, models: TMM3, TMM4, TMM6, TMM10, TMM10i, TMM13i, etc.

Currently, Rogers PCB board materials are more widely used models: Rogers ht800, Rogers 6002, Rogers 5880 circuit board, Rogers 5880 board, Rogers 5880, Rogers 4701, Rogers 4350 b, Rogers 4003 c, Rogers 4003, etc.

FASTPCBA is professional in Making PCB, PCBA and Components Sourcing.we has been ISO9001, ISO14001, ISO13485, IATF16949 certifications.

PCB Type: rigid, flexible, rigid-flex, single sided, double sided, multilayer etc.

PCBA Services: * Prototype PCB Assembly * Low-Volume, High Mix PCB Assembly * High-Volume PCB Assembly * Consigned & Partial PCB Assembly * Full Turnkey PCB Assembly * Cable & Wire Harness Assembly * Box Build Assembly Services

Welcome to send us Gerber file and Bom list, I will support you with high quality and preferential price.

https://www.pcba-suppliers.com/

 With the continuous development of the electronics industry, the technical level of PCB boards is also constantly improving. The common processes mainly include tin spraying, immersion gold, gold plating, OSP, etc. In fact, tin spraying is divided into lead-free spray tin and lead spray tin. The following PCB PCBA manufacturer FASTPCBA will introduce the difference between them.

1. From the surface of tin, lead-tin is brighter, and lead-free tin (SAC) is relatively dim. The wettability of lead-free is slightly worse than that of lead-free.

2. Lead in lead is harmful to human body, but lead-free is not. The leaded eutectic temperature is lower than that of lead-free. How much depends on the composition of the lead-free alloy. For example, the eutectic of SNAGCU is 217 degrees, and the soldering temperature is the eutectic temperature plus 30 to 50 degrees. It depends on actual adjustments. The leaded eutectic is 183 degrees. Lead is better than lead-free in mechanical strength and brightness.

3. The lead content of lead-free tin does not exceed 0.5, and the lead content reaches 37.

4. Lead will increase the activity of the tin wire during the soldering process. Lead-tin wire is better than lead-free tin wire, but lead is toxic, and long-term use is not good for the human body, and lead-free tin has a higher melting point than lead-tin. This makes the solder joints much stronger.

5. Lead will increase the activity of tin during soldering. With lead-tin wire, it is easier to use when compared with lead-free tin wire, and lead-free tin spray has a higher melting point than lead-tin spray, and the solder joints will be much stronger.

6. The price of lead-free tin spraying and lead-free tin spraying for PCB proofing is the same, there is no difference.

What are the differences between lead-free and lead-free spray tin on PCB boards, and what are the differences?

1. PCB board lead-free tin spraying belongs to the environmental protection category and does not contain harmful substances "lead", the melting point is about 218 degrees; the temperature of the tin spraying furnace needs to be controlled at 280-300 degrees; the peak temperature needs to be controlled at about 260 degrees; over. The temperature is 260-270 degrees.

2. PCB board with lead and tin spray is not classified as environmentally friendly. It contains harmful substances "lead", with a melting point of about 183 degrees; the temperature of the tin spray furnace needs to be controlled at 245-260 degrees; the peak temperature needs to be controlled at about 250 degrees; over. The temperature is 245-255 degrees.

The above is the analysis of FASTPCBA, I hope to help you.

Regarding the surface treatment of PCB production, we introduced Hot Air Solder Leveling earlier. Hot Air Solder Leveling removes excess materials, but PCB production, from the first process to the final end, requires many processes. It takes a long time and the substrate will rust when exposed to the air. So, how to protect the substrate from damage? FASTPCBA gives you a brief introduction.

OSP (Organic Solderability Preservatives), also known as copper protective agent, is essentially to act as a barrier between copper and air. The process is: on the surface of bare copper, a chemical method is used to grow a layer of organic film. This film has anti-oxidation, thermal shock resistance, and moisture resistance to protect the copper surface from rust, oxidation, and sulfide in a normal environment. Wait. However, in the subsequent welding high temperature, this protective film must be easily removed by the flux quickly, so that the copper surface can be combined with the molten solder in a very short time to become a strong solder joint.

The process of OSP is: degreasing-micro etching-pickling-pure water cleaning-organic coating-cleaning, which is easier than other surface treatment processes. The purpose of micro-etching is to form a rough copper surface to facilitate film formation. The thickness of the microetching directly affects the film formation rate. Therefore, to form a stable film thickness, it is very important to keep the thickness of the microetching stable.

It is best to use DI water for washing before film formation to prevent the film formation liquid from being contaminated. It is also best to use DI water for washing after film formation, and the PH value should be controlled between 4.0-7.0 to prevent the film from being polluted and damaged. The film should not be too thin or too thick, it is more appropriate between 0.2-0.5um.

OSP has three types of materials: Rosin, Active Resin and Azole. The most widely used OSP is the azole OSP. The azole OSP has been improved for about 5 generations, which are named BTA, IA, BIA, SBA and the latest APA.

BTA (Benzotrichlorazole) is a white, light yellow, odorless, crystalline fine powder. It is stable in acids and alkalis, and is not prone to oxidation-reduction reactions. It can form stable compounds with metals. However, BTA is sensitive to humidity, has a short inventory life (3 months), cannot withstand repeated heating, and its performance is not very good. AI (alkylimidazole) is transparent, difficult to detect, and not used in large amounts.

In the PCBA welding process, due to the influence of welding materials, technology, personnel and other factors, it will lead to the phenomenon of poor PCBA welding. Next, FASTPCBA mainly introduces the common poor welding of circuit boards.

1. Too much residue on PCBA board

Excessive residues on the PCB board may be caused by not preheating before soldering or the preheating temperature is too low, and the temperature of the tin furnace is not enough; the speed of the PCB board is too fast; the anti-oxidant and anti-oxidation oil are added to the tin liquid; the flux coating Too much; the component feet and the orifice plate are out of proportion (the holes are too large), which causes the flux to accumulate; in the flux application process, the thinner and other elements are not added for a long time.

2. Corrosion, green components, black pads

Mainly because of insufficient preheating, there are many flux residues and too many harmful residues; the flux that needs cleaning is used, but there is no cleaning after soldering.

3. Welding

Welding is a very common defect, and it is very harmful to PCB boards. Mainly related to the amount of flux coating is too small or uneven; some pads or solder feet are severely oxidized; PCB wiring is unreasonable; the foaming tube is blocked and the foaming is uneven, resulting in uneven flux coating; operation when hand dipping tin Improper method; unreasonable chain inclination; related to the inequality of crests.

4. Cold welding

The surface of the solder joints is like tofu. Mainly because the temperature of the electric soldering iron is not enough, or the vibration of the weldment before the solder is condensed, the bad solder joint is not strong, and the conductivity is weak, and the external force can easily cause the failure of the component.

5. White solder joints

Rugged, dull. Generally, it is formed because the temperature of the soldering iron is too high or the heating time is too long. The strength of the bad solder joint is not enough, and it is easy to cause the failure of the component to be disconnected by the external force.

6. Pad peeling

The main reason is that the pad is formed after being subjected to high temperature and peeled off from the printed circuit board, and this bad solder joint is very easy to cause the failure of the component.

7. tin beads

Process: low preheating temperature (the flux solvent is not completely evaporated); the speed of the PCB board is fast, and the preheating effect is not reached; the inclination of the chain is not good, there are bubbles between the tin liquid and the pcb, and tin beads are generated after the bubbles burst; Improper operation when tinning; humid working environment; PCB problems: the board surface is wet and moisture is generated; the layout of the holes for the PCB to run out is unreasonable, forming a gas trap between the PCB and the tin liquid; the PCB planning is unreasonable, and the parts are too densely formed Depressed.

PCBA refers to the entire process of PCB blank board through SMT loading or DIP plug-in. Then, what process does PCBA processing and proofing go through? FASTPCBA engineer break it down for you today:

1. Communicating consultation and matching materials.

2. Engineering process evaluation.

3. The quotation is divided into three parts: PCB board light board, electronic components and processing fee. PCBA is a one-stop service, and all process costs from engineering documents to finished products are evaluated.

4. DFM file compilation.

5. Purchase materials. Usually the PCBA processing plant collects the components.

6. The warehouse receives, retrieves and prepares materials.

7. Processing and entering the production link. Including PCB proofing, SMT placement, etc.

8. Testing, including function test, burn-in test, programming test, signal test, etc.

9. Assembly, including single product assembly, component integrated assembly, etc. In this link, it is necessary to strictly control static electricity to cause damage to the finished products that have passed the test.

Through a simple combing of the entire process, I believe you have a preliminary understanding of the production process of a professional PCBA processing plant. Because compared with traditional PCB processing, there are only more material procurement, material inspection and sample storage, SMT placement and so on.