PCBA soldering requirements for PCB boards

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About PCBA welding process, there are many requirements for the PCBA .It must meet the requirements in order to weld.

Then why does the welding process have so many requirements for PCBA? That is because PCBA will go through many special processes in the processing. The application of special processes brings many requirements to the PCB board. If the PCB has problems, it will increase the difficulty of the PCBA soldering process. Eventually it may lead to there will be welding defects, board failure and other problems.

Therefore, in order to ensure the smooth completion of the special process, and also for the PCBA can be more easily welding. The size of the PCB board, the distance between the pads, etc. should meet the manufacturability requirements. Next, GrandePCBA will take you to see the PCBA requirements for PCB processing.

PCBA soldering requirements for PCB boards

1.PCB size

PCB width (including board edge) should be greater than 500mm, less than 460mm

PCB length (including board edge) should be greater than 500mm

If size is too small, you need to do the panel.

2.PCB board edge width

Board edge width: >5mm, the panel spacing: 8mm, the distance between the pad and the board: >5mm

3.PCB curvature

Board edge width: >5mm, panel spacing: 8mm, the distance between the pad and the board: >5mm

4.PCB board Mark point

Mark point shape: standard circle, square, triangle.

Mark point size; 0.8~1.5mm.

Mark point material: gold-plated, tin-plated, copper-platinum.

Mark point surface requirements: smooth surface, no oxidation, no dirt

Other requirements of the Mark point: there shall be no green or other obstacles within 1mm around, which is obviously different from the Mark point color;

Mark point position: more than 3mm away from the edge，and no mark point vias, test points, etc. within 5mm around.

5.PCB pads

SMD components cannot have through-holes on the pads. The through hole will allow the solder paste to flow into the hole, resulting in less tin in the parts, or the tin flow to the other side, resulting in uneven board surface, and the solder paste cannot be printed

When doing PCB design and production, it is necessary to understand some knowledge of PCBA soldering process to make the product suitable for production. Understanding the requirements of the PCBA processing plant first can make the subsequent manufacturing process smoother and avoid unnecessary troubles.

About Grande

Grande specializes in providing overall PCBA electronic manufacturing services, including electronic components procurement to PCB production and processing, SMT patch, DIP plug-in, PCBA testing, finished product assembly .Turnkey one-stop PCBA services.

The company gives full play to its competitive advantages in scale procurement and quality control, and signs long-term cooperation agreements with many electronic component manufacturers at home and abroad to ensure the quality and stable supply of raw material sources, and transfer the preferential treatment to customers.

Maintaining the purchasing advantages of IC, resistors, capacitors, inductors, transistors and other components for a long time can greatly save customers’ inventory costs, improve production turnover efficiency and save time. At present, we provide PCBA processing services for customers in the United States, the United Kingdom, Japan, Russia, France, Canada, Australia, Romania, Switzerland and other countries and regions.

Shielding Methods In High Speed ​​PCB Design

The transmission rate of high-speed PCB design and routing system is accelerating with the changes of the times, but which also brings a new challenge to it – The anti-interference ability is getting weaker and weaker. This all stems from the fact that the higher the frequency of information transmission, the more sensitive the signal and the weaker the energy, so the routing system is more and more susceptible to interference. In some common electronic equipment, such as computer screens, mobile phones, motors, radio broadcasting equipment, etc., cables and equipment are able to interfere with other components or be seriously interfered by other interference sources.

Shielding Methods In High Frequency PCB Design

Especially when using high-speed data networks, the time required to intercept a large amount of information is significantly lower than the time required to intercept low-speed data transmissions. The twisted pair in the data twisted pair can resist external interference and inter-pair crosstalk through its own twisting at low frequencies, but at high frequencies (especially when the frequency exceeds 250MHz), the twisting alone cannot achieve anti-interference. Purpose, only shielding can resist external interference.

The cable shield acts like a Faraday shield. Interfering signals enter the shield, but not the conductors. Therefore, the data transfer can operate without problems. Network transmission is blocked because shielded cables have lower radiated emissions than unshielded cables. Shielded networks (shielded cables and components) can significantly reduce the radiation level of electromagnetic energy that may be intercepted as it enters the surrounding environment.

Shielding options for different interference fields mainly include electromagnetic interference and radio frequency interference. Electromagnetic interference (EMI) is mainly low frequency interference. Electric motors, fluorescent lamps, and power lines are common sources of EMI. Radio frequency interference (RFI) refers to radio frequency interference, mainly high frequency interference. Wireless communications such as radio, television broadcasting, and radar are common sources of RF interference. For immunity to EMI, braided shielding is the most effective because of its lower critical resistance; For RFI, foil shielding is the most effective. Since the braided shielding depends on the change of wavelength, the gap generated by the braided shield allows the high-frequency signal to freely enter and exit the conductor; for the mixed interference field of high and low frequencies, the combined shielding method of the foil layer with the broadband coverage function and the braided mesh should be adopted. Generally speaking, the higher the mesh shielding coverage, the better the shielding effect.

Grande’s PCB Design Capabilities

Maximum Signal Design Rate: 10Gbps CML differential signal;
Maximum PCB Layout Layers: 40 layers;
Minimum Line Width: 2.4mil;
Minimum Line Spacing: 2.4mil;
Minimum BGA PIN Spacing: 0.4mm;
Minimum Mechanical Hole Diameter: 6mil;
Minimum Laser Drilling Diameter: 4mil;
Maximum Number of PINs: ;63000+
Maximum Number of Components: 3600;
Maximum Number of BGAs: 48+.

Advantages Grande Circuit Board Assembly

1)Strength Guarantee

▪ SMT factory: With imported SMT machines and multiple optical inspection equipment, which is able to produce 4 million points per day. Each process is equipped with QC personnel who will keep an eye on product quality.

▪ DIP production line: Two wave soldering machines and more than 10 employees who have worked for over three years. That’ s to say, these workers are highly skilled and can weld various SMT & DIP components.

2)Quality Assurance With High Cost Performance

▪ High-end equipment can paste precision special-shaped parts, BGA, QFN, 0201 package. It can also be soldered prototype PCBA via SMT machine and placing bulk materials by hand.

▪ Both samples, small and large batches can be produced. And there is no SMT Machine starting cost.

3)Rich Electronic Products SMT Soldering Experience With Stable Delivery

▪ Accumulated services to thousands of electronics companies, involving SMT soldering services for various types of automotive equipment and industrial control motherboards. Furthermore, PCBA Products are often exported to Europe and the United States, and the quality is able to be affirmed by new and regular customers.

4)Strong Maintenance Ability & Reliable After-Sales Service

▪ The maintenance engineers have sophisticated experience so that those defective boards caused by all kinds of SMT soldering can be repaired. Meanwhile, ensuring the connectivity rate of each circuit board also make sense.

▪Order problems feedback will get response, solution and solved as soon as possible.

Why SMT Assembly Cost May Rise? The 5 Most Frequently Missing Data in PCBA Inquiry

Why SMT Assembly Cost May Rise?

Since the phenomenon of “lack of chips” still exists in 2022, the serious situation of rising transportation cost and high supply chain cost has spread to the entire PCBA contract manufacturing industry, such global situation has hardly left several industries unaffected. This is why we expect SMT Assembly cost continue to rise. Here are some reasons indicates why SMT Assembly cost will increase:

1. The shortage of raw materials

Earlier we analyzed how the global shortage of “chips” affects printed circuit boards (PCBs), and the raw materials of various commodities also directly affect manufacturing costs, and the price of copper in particular is increasing significantly. Therefore, it is very important to take the time to research alternative materials when manufacturing bare PCB. There may be a selection of newer, more readily available materials that can be used in the production process. Since demand will not decrease anytime soon, it is important to plan months or years in advance, especially when supply is already limited. The supply situation will not improve in the short term.

2. The workforce remains a challenge

Labor cost and fees vary based on the geographic location of the business, regardless of industry. The PCBA manufacturing industry is facing labor shortages, which may be another factor affecting future cost. The shortage of front-line workers such as solder workers and DIP plug-in workers is particularly tense. In this industry, quality is paramount, so finding cheap labor substitutes isn’t always a viable option. Hiring inexperienced short-term labor will make PCBA boards more prone to defects and cause problems in the production process, such as delays, downtime or worse. As labor continues to be required to maintain quality at the necessary level, costs may increase as a result.

3. Market demand continues increasing

Demand will continue to rise as more and more products require PCBAs. Due to the shortage of raw materials and labor, the supply capacity of the product will be in a situation of short supply and may cause the end-user cost to rise. It’s just a matter of supply and demand.

However, with the development and promotion of new prevention and control measures, the global unblocking is worth looking forward to, and we expect a certain correction in mid-2022.

The 5 Most Frequently Missing Data In PCBA Inquiry

Most electronic engineering project teams will prepare inquiry files before looking for PCBA manufacturer. In the process of serving all kinds of customers, it is also found that some customers will miss some minor inquiry files details. These details are also important for calculating total cost and time estimates and should be submitted when inquiry. Common omissions are as follows:

1. PCB Solder Mask Details

In addition to clicking yes for the solder mask, there are some basic details to share to the pcba manufacturer. These details include:

1) Solder mask (top, bottom or top and bottom);

2) Solder mask type (LPI-Liquid Light Imaging);

3) Solder mask color (green, blue, black, red, white or transparent);

4) Solder mask surface finish (semi-gloss or matte);

5) Panels coated with solder mask;

2. Surface Finish

The SMT of the surface finish of the PCB affects the quality of solder paste printing. Commonly used surface treatments include Hot Air Solder Leveling (HASL), Electroless Nickel Immersion Gold (ENIG), Electroless Nickel Palladium Immersion Gold (ENEPIG), etc. Therefore, if not specified correctly, the wrong type of surface finish will have a negative impact on the overall PCBA manufacturing efficiency. This is an important detail that is often missed when asking for a quote.

3. Silk Screen Printing

Another often overlooked detail is screen printing. Just like with solder mask, it’s not enough to click “yes” in the silkscreen options. Questions about whether double-sided is required and what color is required should also be answered.

4. Impedance Details

The controlled impedance requirements of the circuit board determine the selection of various parameters. Therefore, if it is not provided, the quotation will be delayed, because the quotation engineer need to judge by guessing or multiple corroboration.

5. Lamination Details

The number of layers, the stacking order, the thickness of each layer, the total thickness of the stack, etc., are all about the details of the stack, which should not be missed.

Common Circuit Design Reference & Precautions In PCB Design

1. Common Design Reference of Keying Circuit

1)The R1 pull-up resistor clamps the uncertain signal at a high level through a resistor, maintaining it in an untriggered state or returning to the original state after being triggered. (Advice to add)

2)The C1 capacitor reduces key jitter and high-frequency signal interference. (Advice to add)

3)R2 current limiting resistor (values ​​ranging from 100 ohms to 10k, if there is an internal pull-up, the value should not be too large, otherwise the current is not enough to pull down the IO port) to protect the IO port to prevent overcurrent and high voltage from burning out the IO It has the effect of absorbing static electricity or some high-voltage pulses. (Advice to add)

4)D1ESD diode Electrostatic protection diode to prevent electrostatic interference or damage to the IO port. (This is based on the cost and protection level requirements of the PCB to decide whether to add or not)

2. Design Reference For External Signal Input (Similar To Keying Circuit)

1)The R3 pull-up resistor clamps the uncertain signal to a high level through a resistor, and maintains it in a non-triggered state or returns to the original state after being triggered. (If the external connection line is relatively long and the internal pull-up capability of the chip is relatively weak, it is recommended to add it. Usually the communication distance is not long, and it can be omitted if there is an internal pull-up)

2)C2 capacitor prevents high frequency signal interference. (Note that if the input frequency signal is relatively large, the capacitance value of C2 should be correspondingly reduced, or C2 should be omitted directly)

3)The R4 current limiting resistor protects the IO port to prevent the IO port from being burned out by overcurrent and high voltage, and has the effect of absorbing static electricity or some high-voltage pulses. ( Advice to add )

4)D2ESD diode electrostatic protection diode to prevent electrostatic interference or damage to the IO port. (This is based on the cost and protection level requirements of the PCB to decide whether to add or not)

3. Output Circuit Relay Design Reference

1)U1 optocoupler separates high and low voltage to prevent high voltage interference and achieve electrical isolation.

2)The D5 1N4148 freewheeling diode bai protects the element from being broken down or burned out by the induced voltage. It is connected in parallel to both ends of the element that generates the induced electromotive force, and forms a loop with it, so that the high electromotive force generated by it will continue in the loop. The current consumption is used to protect the components in the circuit from being damaged.

4. Darlington Transistor Design Reference Application

Darlington transistors are generally used in stepper motor drives. In fact, they can be used for motor speed regulation, high-power switching circuits, driving relays, driving LED light sources with relatively high power, and using PWM to adjust the brightness.

1)The R6, R7, and R8 resistors are used to limit the current to prevent the damage of the ULN2001, resulting in the high voltage being directly input to the IO of the MCU (because the ULN2001D itself has a 2.7K resistor, the R6, R7, and R8 can be omitted here. If some driver chips do not have resistors, the most It’s better to add it yourself, you can check the data sheet of the selected chip for the specific situation)

2)COM terminal is connected to the power supply When the output terminal is connected to an inductive load, the load does not need to add a freewheeling diode. The chip is designed with a diode, and only the COM port needs to be connected to the load power supply. When connecting to other loads, the COM port can be left unconnected.

3)When using the RC step-down circuit to supply power to ULN2001D, since the RC step-down voltage cannot prevent the transient high voltage fluctuations on the power grid, a 104 capacitor must be connected to the COM terminal and the ground terminal of the ULN2001D. In other applications, This capacitor may not be added.

5. Operational Amplifier Design Reference Application

Using the op amp to collect the current current of the load ingeniously, you can accurately know the current operation of the load and whether it is working normally, which is very easy to use. There are also many very delicate and practical circuits in operational amplifiers, which will be shared with you one by one in the future. You can also search online for some classic circuits of operational amplifiers, there are many places for reference.

1)GND2 is the ground terminal of the load. It is connected to the common ground through the R16 resistor (R16 should be selected according to the size of the load current), and there will be a small voltage difference.

2)This circuit is a proportional operation circuit in the same phase, so the voltage of the sampling terminal = the voltage of the input terminal * (1+R9/R11) = 69 times the input voltage. You can modify R9 to adjust the magnification according to the measurement range.

6. MOSFET  Design Reference Application (Control Power Output On & Off)

7. Input Power Design Reference Application

If the circuit cost is relatively tight, components can be appropriately deleted as needed.

1)F1 self-recovery fuse, overcurrent protection, the threshold value can be adjusted according to the actual load current.

2)The D10 Schottky diode reduces the influence of the power supply of the rear stage on the front stage, prevents the positive and negative connections of the power supply from burning out the rear stage circuit, and prevents the current from flowing backward when the power supply is turned off, but there is a voltage drop of about 0.4V through the diode, which needs to be considered. After the 0.4V step-down, will it be lower than the normal working voltage of the subsequent circuit?
3)TVS tube input voltage is too high protection, generally take 1.4 times the normal input voltage.

What’s The Maximum Temperature Resistance of PCB?

In order to ensure the quality of the finished product of the PCB board production process, reliability and adaptability tests are required. The temperature resistance test of the PCB board is to prevent the PCB board from exploding, blistering, delamination and other adverse reactions at excessively high temperatures, resulting in poor product quality or direct scrapping, which is a problem that needs attention. So what is the maximum temperature resistance of the PCB board, and how to do the heat resistance test?

The temperature problem of the PCB board is related to the temperature of its raw materials, solder paste, and surface parts. Usually, the PCB board can withstand a maximum temperature of 300 degrees for 5-10 seconds; The temperature is about 260 for lead-free wave soldering, and about 240 for lead-free wave soldering.

PCB Board Heat Resistance Test

1. First prepare the PCB board production board and tin furnace.
Sampling 10*10cm substrate (or laminated board, finished board) 5pcs; “(Copper-containing substrate without foaming and delamination).
Substrate: 10cycle or more; Laminate: LOW CTE 150 10cycle or more; HTg material 10cycle or more; Normal material 5cycle or more.
Finished board: LOW CTE 150 above 5cycle; HTg material above 5cycle; Normal material above 3cycle.

2. Set the temperature of the tin furnace to 288+/-5 degrees, and use a contact thermometer to measure and correct it.

3. First dip the flux with a soft brush and apply it to the surface of the board, and then use the crucible tongs to take the test board and immerse it in the tin furnace. After 10 seconds, take it out and cool it to room temperature.

4. If there is a problem of bubbling and bursting of the board visually, stop the tin immersion and analyze the initiation point f/m immediately. If there is no problem, continue to cycle until the board bursts, with 20 times as the end point.

5. The blistering area need to be sliced ​​and analyzed to understand the source of the detonation point and take pictures.

The PCB board will have some bad problems at overheating temperature. Therefore, it is necessary to understand the temperature resistance of the PCB board of different materials in detail, and not exceed its maximum limit temperature, so as to avoid the scrap of the PCB board and increase the cost.

Grande PCB Board Production Capacity

Energy production 2 to 14 layers, 14-22 layers can be produced by proofing.
Minimum trace width/spacing: 3mil/3mil BGA spacing: 0.20MM
Minimum aperture of finished product: 0.1mm Size: 610mmX1200mm
Ink: Japan Tamura, Taiyo, Futoken;
FR4: Shengyi, Kingboard, Haigang, Hongren, Guoji, Hazens, South Asia,
(Shengyi S1130/S1141/S1170), Tg130℃/ Tg170℃ Tg180℃ and other high TG plates)
High frequency board: Rogers (Rogers), Taconic, ARLLON;
Surface technology: Spray tin, lead-free spray tin, ENIG, full board gold plating, plug gold plating, full board thick gold, chemical immersion tin (silver), anti-oxidation (OSP) blue glue, carbon oil

Differential Lines Routing Requirements & Operation Skills In PCB Design

The popularity of high-speed serial buses has made more and more differential signals on the PCB. Then, how to perform differential lines in PCB design?

PCB Design Differential Lines Routing Requirements
The impedance requirements of various differential lines are different. According to the PCB design requirements, the differential impedance and the corresponding line width spacing are calculated by the impedance calculation software, and set to the constraint manager. Differential lines are coupled to each other to reduce common-mode interference, and should be routed in parallel as far as possible, and there should be no vias or other signals between the two lines. To reduce the loss, ground vias can be added near the layer-changing holes when the high-speed differential line is changed.

Differential Lines Routing Operation Skills In PCB Design
1. Activate the routing command, select the Route→connect command, and then select the defined differential signal line. At this time, the defined differential line will be pulled out at the same time.
2. Support single-line routing mode. When single-line routing mode is required for local routing, click the right mouse button in the routing command state, and select from the pop-up shortcut menu.
Single Trace Mode command mode.
3. When differential lines routing is placed in a small space, you can switch to Neck Mode. Also, click the right mouse button in the routing command state, and select the Neck Mode command in the pop-up shortcut menu.
4. Select the appropriate differential via pattern in the light of the routing requirements. Click the right mouse button in the routing instruction state, and select the Via Pattern command in the pop-up shortcut menu.

Grande Design Capability
Maximum signal design rate: 10Gbps CML differential signal;
Maximum PCB design layers: 40 layers;
Minimum line width: 2.4mil;
Minimum line spacing: 2.4mil;
Minimum BGA PIN spacing: 0.4mm;
Minimum mechanical hole diameter: 6mil;
Minimum laser drilling diameter: 4mil;
Maximum number of PINs: ;63000+
Maximum number of components: 3600;
Maximum number of BGAs: 48+.

PCB Design Service Process
1. The customer provides schematic to inquiry PCB design;
2. Grande evaluates the quotation according to the schematic and customer PCB design requirements;
3. The customer confirms the quotation, signs the contract, and prepays the project payment;
4. Afrer receiving advance payment, Grande starts to arrange Layout Engineer to layout;
5. Once the layout completed, Grande provides a screenshot of the document to the customer for confirmation;
6. The customer confirms OK, settles the balance, and provides PCB design information.

Why Occur Tin Beads in PCB Assembly?

During assembling PCB, there may be a lot of small issues, such as plating delamination and solder balls. So, why occur tin beads in PCB Assembly?

Reasons Why Occur Tin Beads in PCBA 

1. When the PCB board leaves the liquid solder, it is super easy to form tin beads. This is because when the PCB board and the tin wave are separated, a tin column will be pulled between them. Once the tin column broken and dropped back to the tin cylinder, solder will sputter out, and the solder will fall on the PCB board to form tin beads. Therefore, when designing the tin wave generator and tin cylinder, attention should be paid to reducing the falling height of tin. Small drop height helps reduce dross and spatter.

2. The second reason for the formation of solder balls is the outgassing of volatile substances in the PCB board and solder mask. If there are cracks in the metal layer of the through hole of the PCB board, the volatilized gas of these substances will escape from the cracks after heating, forming tin beads on the component surface of the PCB board.

3. The third cause of solder ball formation is related to flux. Flux can be left under components or between the PCB and the carrier (a tray used for selective soldering). If the flux is not sufficiently preheated and burns out before the PCB touches the tin wave, tin spattering and beading can occur. Therefore, the preheat parameters recommended by the flux supplier should be strictly followed.

This is the reason for the formation of tin beads in PCB Assembly. Apart from that, there are also plenty of other tiny reasons that can cause tin beads. However, with the development of science and technology, technicians have also begun to have rich experience in the production of tin beads. It may be the charm of science and knowledge that it can quickly help technicians find ways to deal with it.

Advantages of car key circuit board assembly

1)Strength Guarantee

▪ SMT factory: With imported SMT machines and multiple optical inspection equipment, which is able to produce 4 million points per day. Each process is equipped with QC personnel who will keep an eye on product quality.

▪ DIP production line: Two wave soldering machines and more than 10 employees who have worked for over three years. That’ s to say, these workers are highly skilled and can weld various SMT & DIP components.

2)Quality Assurance With High Cost Performance

▪ High-end equipment can paste precision special-shaped parts, BGA, QFN, 0201 package. It can also be soldered prototype pcba via SMT machine and placing bulk materials by hand.

▪ Both samples, small and large batches can be produced. And there is no SMT Machine starting cost.

3)Rich Electronic Products SMT Soldering Experience With Stable Delivery

▪ Accumulated services to thousands of electronics companies, involving SMT soldering services for various types of automotive equipment and industrial control motherboards. Furthermore, PCBA products are often exported to Europe and the United States, and the quality is able to be affirmed by new and regular customers.

4)Strong Maintenance Ability & Reliable After-Sales Service

▪ The maintenance engineers have sophisticated experience so that those defective boards caused by all kinds of smt soldering can be repaired. Meanwhile, ensuring the connectivity rate of each circuit board also make sense.

▪Order problems feedback will get response, solution and solved as soon as possible.

The Difference & Connection of Solder Paste, Tin Paste & Flux In SMT Assembly

In the process of SMT Assembly, we will often come into contact with three kinds of pastes, namely solder paste, tin paste and flux paste. The names of the three pastes are similar, but from a professional point of view, they will be quite different.

The Difference & Connection of Solder Paste, Tin Paste & Flux In SMT Assembly

In fact, from a certain point of view, solder paste, tin paste and flux are the same thing, that is, solder paste, but the name is different in Chinese. tBut there are many people who regard solder paste and flux as a product. As a matter of fact, solder paste is paste, whose main component is a paste-like object composed of metal alloy powder.

However, the flux is different, which mainly plays the role of a flux, and its main components are rosin, active agent and solvent. A certain proportion of flux paste will be added to the solder paste during the production process.

The role of tin paste: Alloy powder; To complete the mechanical and electrical connection between electronic components and circuit boards.

The role of solder paste:
1. The carrier of tin powder particles provides suitable rheology and wet strength, which is conducive to the transfer of heat to the soldering area, reduces the surface tension of the solder, and prevents the re-oxidation of the solder and the welding surface during welding.
2. Remove the oxide layer of the soldering surface and tin powder particles, and form a protective layer and a safe residue layer on the surface of the soldering point.
3. The proportion of flux paste can be arbitrarily mixed with various solder powders (tin, silver, copper, bismuth, lead), and can also be mixed with high, medium and low temperature solder powders (100-260) ℃. After being formulated into solder paste, it has the advantages of good solderability, continuous printing and less residue.

To sum up, solder paste, tin paste, and flux actually refer to two products – paste and flux. It is also very simple to distinguish these three. From the appearance color, you can distinguish between the solder paste and tin paste. The solder paste is yellowish, but the tin paste will be gray or black. This is because the component of tin powder is added to the solder paste, and the solder paste is only a pure paste to play a certain role in soldering.

The above is the introduction of the difference and connection of solder paste, tin paste and flux in SMT Assembly.

PCBA Capability

1. Maximum Board: 310mm*410mm(SMT);
2. Maximum Board Thickness: 3mm;
3. Minimum Board Thickness: 0.5mm;
4. Minimum SMD Component: 0201 package or components above 0.6mm*0.3mm;
5. Maximum Weight of Mounted Component: 150 grams;
6. Maximum Component Height: 25mm;
7. Maximum Component Size: 150mm*150mm;
8. Minimum Pin Spacing: 0.3mm;
9. Minimum Spherical Component (BGA) Spacing: 0.3mm;
10. Minimum Spherical Component (BGA) Ball Diameter: 0.3mm;
11. Maximum Component Placement Accuracy (100QFP): 25um@IPC;
12. SMD Capacity: 3-4 million points/day.

Advantages of PCB Assembly In Grande

1. Highly Professional: Grande focuses on PCBA Samples, small and medium batches; For 2 Layer Simple Sample PCBA, Grande promises to deliver within 3-7 working days after the materials are confirmed to be OK.
2. Professional Equipment: Advanced equipment tailored for sample and small and medium batch production, and can be pasted with 0201, BGA spacing 0.3MM, QFN, CSP, CON and other components.
3. Professional Technology: 100% of technical backbones have more than 5 years of work experience, and 85% of front-line operators have more than 3 years of work experience.
4. Grande implements the 5S and 6σ concepts in daily operations, and it is expected that the shipment will be checked at least 7 times.
5. Grande promises that the soldering pass rate is above 99%. If the customer finds soldering defects, the company promises to repair it free of charge.

How To Do BGA Repair For PCBA Board?

There are some bad BGA soldering issues in PCBA board sometimes. If there is a problem with the soldering of a BGA, as a result,  then the whole board will have issue. In this case, BGA repair is required.

Four methods for PCBA processing to do BGA rework

1) Formal Installation Method (Using Ball-Setting Fixture)

1. Place the cleaned and flat BGA pads upwards and place them on the BGA support platform at the bottom of the ball placement fixture.
2. Prepare a small template that matches the BGA pad. The opening size of the template should be 0.05-0.1mm larger than the diameter of the solder ball; The disc is aligned and secured.
3. Place the BGA with the paste flux or solder paste printed on the BGA support platform at the bottom of the ball placement tool, with the printing side facing up.
4. Move the stencil to the top of the BGA (the position that has been aligned in the front), evenly skim the solder balls on the stencil, and shake the ball-setting tool so that there is exactly one solder ball in each leak hole on the surface of the stencil. The solder balls are pulled off the stencil with tweezers.
5. Remove the template.
6. Check whether there is a lack of solder balls on each pad of the BGA device, and fill up the solder balls with tweezers.

2)Manual Placement of Solder Balls

1. Place the BGA chips with the paste-like flux or solder paste printed on the workbench, with the flux-like or solder paste face up.
2. Like the SMT assembly, use tweezers or a suction pen to place the solder balls one by one on the printed paste flux or solder.

3)Directly print an appropriate amount of solder paste and form solder balls through reflow soldering

1. Increase the thickness of the template when SMT is processing the template, and slightly enlarge the opening size of the template.
2. Printing solder paste.
3. Reflow soldering. Solder balls are formed after soldering due to surface tension.

4)Reflow Soldering

Perform reflow soldering as described in the previous section on BGA Repair Process. When soldering, the solder balls of the BGA chips are facing upward, and the amount of hot air is adjusted to the minimum to prevent the solder balls from being blown away. After the reflow soldering process, the solder balls are fixed on the BGA chips. It is carried out in a reflow soldering furnace. The soldering temperature is slightly lower than that of the reflow soldering of the assembly board. After the ball placement process is completed, the BGA chips should be cleaned and mounted and soldered as soon as possible to prevent the solder balls from being oxidized and the device getting damp.

Conclusion

Among the above 4 ball placement methods, the front mounting method (using the ball placement fixture) has the best effect;The flip-chip method (using the ball placement equipment) is the method used for BGA chips packaging, because we purchase the solder balls from the solder paste manufacturer. Poor dimensional accuracy, resulting in some solder balls with small diameters that cannot be activated by paste flux or solder paste; The efficiency of manually placing solder balls is relatively low; Directly printing Shixing solder paste and forming solder by reflow soldering The ball method is the easiest, but this kind of solder ball has poor density and is prone to voids.

Why Occur Tin Beads in PCB Assembly?

During assembling PCB, there may be a lot of small issues, such as plating delamination and solder balls. So, why occur tin beads in PCB Assembly?

Reasons Why Occur Tin Beads in PCBA 

1. When the PCB board leaves the liquid solder, it is super easy to form tin beads. This is because when the PCB board and the tin wave are separated, a tin column will be pulled between them. Once the tin column broken and dropped back to the tin cylinder, solder will sputter out, and the solder will fall on the PCB board to form tin beads. Therefore, when designing the tin wave generator and tin cylinder, attention should be paid to reducing the falling height of tin. Small drop height helps reduce dross and spatter.

2. The second reason for the formation of solder balls is the outgassing of volatile substances in the PCB board and solder mask. If there are cracks in the metal layer of the through hole of the PCB board, the volatilized gas of these substances will escape from the cracks after heating, forming tin beads on the component surface of the PCB board.

3. The third cause of solder ball formation is related to flux. Flux can be left under components or between the PCB and the carrier (a tray used for selective soldering). If the flux is not sufficiently preheated and burns out before the PCB touches the tin wave, tin spattering and beading can occur. Therefore, the preheat parameters recommended by the flux supplier should be strictly followed.

This is the reason for the formation of tin beads in PCB Assembly. Apart from that, there are also plenty of other tiny reasons that can cause tin beads. However, with the development of science and technology, technicians have also begun to have rich experience in the production of tin beads. It may be the charm of science and knowledge that it can quickly help technicians find ways to deal with it.

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