Want to improve your electronics manufacturing? Learn what is a circuit card assembly and how to optimize your circuit card assembly process. This guide provides steps to enhance efficiency. You will also learn about advanced techniques.
What’s The Importance of an Optimized Circuit Card Assembly Process?
An optimized circuit card assembly (CCA) process is crucial. This guarantee of performance is reliable. You can use 10-20 components. Included are 0.5 mm pitch QFPs. Also included are 0402 capacitors.
A 0.4 mm ball pitch is imposed on BGAs. This is precise placement; ±50-micron tolerances keep signal issues to a minimum. These occur at 25-50 MHz.
Crosstalk is also reduced. It is of vital importance to automate the optical inspection (AOI). Instead, these systems use 5 MP cameras. They are advanced algorithms. AOI identifies misalignments. These are 1-2 mil. Also, they find solder defects. Examples are insufficient solder and poor wetting.
This reduces rework by 5-10%. Throughput increases. This is 10-20 boards/hr. It’s due to this that their manufacturing costs decrease by 15-20%. First-pass yield improves.
This is by 3-5%. Processes that are optimized improve quality. Wave soldering is a technique. In addition, selective soldering is also used. This reduces failures. These are 1-2%. And at the end, customer satisfaction is increased. They also reduce warranty claims.
Design for Manufacturing (DFM) in Circuit Card Assembly Process
- Component Placement
Placement impacts circuit card assembly. Keep 0.1 inches between those SOIC parts. These have 0.025-inch leads. Place the big BGA CPU first. This one has 1,440 pins. Place small 0402 capacitors nearby. These are 100nF. This helps machines place 1,000 parts per hour. Heat-generating parts need space. This is a 5A voltage regulator. - PCB Layout
Layout affects circuit card assembly. Use 2-ounce copper for those 10-mil traces. These carry 3 amps. Keep 50-mil spacing between traces. This avoids shorts. It meets IPC-2221 Class 2. Vias connect the layers. Use those 10-mil vias for signals. These go up to 1 GHz. Place mounting holes. These are 0.125-inch and 0.1 inches from the edge. - Materials
Materials are important for circuit card assembly. FR4 is common. It has a dielectric constant of 4.5. Its glass transition temperature (Tg) is 130°C. Use lead-free solder paste. This is SAC305. It has 96.5% tin. It also has 3% silver and 0.5% copper. This solder melts at 217°C. Use no-clean flux. This has a specific gravity of 1.05. - DRC
DRC finds errors. These are in circuit card assembly. Check trace spacing. This is 8 mils on inner layers. Ensure solder mask clearance. This is 5 mils. Verify those annular rings. These are 25-mil for 10-mil vias. Look for silkscreen errors. These might be missing designators. DRC helps. - Testability
Testability matters in circuit card assembly. Use test points. These are 0.025-inch square. You can do in-circuit testing. Place test pads on those edges. These are 100-mil spaced. Design for JTAG. This is boundary scan testing. You can use IEEE 1149.1. This tests all connections. Testability helps find defects.
| Feature | Component Placement | PCB Layout | Materials | DRC | Testability |
| Accuracy | ±0.05 mm | 0.5 mm spacing | FR-4, 1.6 mm | 10 μm | ≥1.2 mm pads |
| Layers | 2-sided placement | 4-layer boards | Multi-layer substrates | 4-layer check | Test trace layers |
| Standards | IPC-A-610 | IPC-2221 | RoHS compliant | IPC-D-275 | IEEE 1149.1 |
| Inspection | AOI machines | CAD validation | Material verification | SPI integration | ICT and boundary |
| Thermal Tolerance | 260°C soldering | 260°C design spec | High-temp epoxy | Thermal checks | Reflow test |
| Placement Machines | SMT pick-and-place | HDI optimization | Material grading | Design automation | Functional tools |
Table on Design for Manufacturing (DFM) in Circuit Card Assembly Process!
Streamlining the Circuit Card Assembly Process with Automation
- Pick-and-Place: Machines place tiny components. These include 0402 resistors. They also place SOT-23 transistors. Furthermore, they place SOIC-8 integrated circuits. Cameras ensure accuracy. Lasers also ensure accuracy. Placement becomes fast and precise. Consequently, this reduces errors. You can achieve 90% better results.
- AOI: Automated Optical Inspection uses cameras. These cameras have 5 megapixels. Moreover, they capture 1000 images per second. The resolution is 10µm. This checks for defects. Some examples are missing parts. Others are solder bridges. Misaligned components are another defect. Incorrect polarity is also checked. Ultimately, this ensures high-quality circuit card assembly. This is according to IPC-A-610 standards.
- Robotic Soldering: Robots solder packages. Some are QFP-100. Others are BGA-256 components. Temperature control is precise. The range is between 200°C and 300°C. Different soldering techniques are used. For instance, there’s wave soldering. This uses 60/40 tin-lead solder. Additionally, there’s selective soldering. This uses a nitrogen atmosphere. As a result, connections become strong and reliable.
- Automated Testing: Machines test circuit card assemblies. They test for functionality. One method is JTAG boundary scan. Another is in-circuit testing. Flying probes are used. These have 100MHz frequency. Also, bed-of-nails fixtures are used. These have 10,000 test points. This ensures the boards work. In addition, it identifies any problems.
- Conveyors: Conveyors move assemblies. Specifically, they move circuit card assemblies. They move them between workstations. Belts are used. These have different speeds. Rollers are also used. These have adjustable width. Sensors and PLCs control the flow. This automates production. In turn, this improves efficiency. You can expect a 20% increase.
Optimizing Material Selection for Your Circuit Card Assembly Process
- Substrates
FR4 substrates are common. These have a Tg of 130-170°C. Plus, they have a CTE of 12-16 ppm/°C. But for high-frequency, use PTFE. PTFE has a Dk of 2.2-2.5. And it has a Df of 0.0005-0.001.
Also, alumina dissipates heat well. Alumina has high thermal conductivity. It is 20-30 W/mK. Consider thickness too. It ranges from 0.2 to 2.4 mm. Check flammability rating. Use UL94 V-0 for safety. This ensures safe circuit card assembly. - Solder Alloys
SAC305 is a popular alloy. It has 96.5% tin. It also has 3% silver and 0.5% copper. Its melting point is 217-220°C. For lead-free, use Sn99Ag0.3Cu0.7. This melts at 217-219°C. These have good wetting.
They form reliable joints. Consider tensile strength too. It is around 50-60 MPa. Check elongation at break. This should be 30-40%. This ensures good ductility in circuit card assembly. - Surface Finishes
Immersion gold is popular. It provides a flat surface. This is ideal for fine-pitch. The gold layer is thin. It is 0.05-0.1 μm thick. HASL is cost-effective. It uses a tin-lead alloy. It has good solderability.
This is for through-hole parts. Consider OSP or ENEPIG too. You need to check shelf life. Also, check solderability and compatibility. This is important for your circuit card assembly process. - Thermal Interface
TIMs improve heat transfer. They have a conductivity of 1-5 W/mK. These fill air gaps. This reduces thermal resistance. Silicone TIMs are flexible. They conform to surfaces. PCMs absorb heat.
They have high latent heat. This is around 200 J/g. Consider thickness too. Also, check BLT and thermal cycling. This ensures good thermal management in circuit card assembly. - Adhesives
Epoxy adhesives are strong. They have high lap shear strength. This is 20-30 MPa. Their Tg is 150-175°C. Acrylic adhesives are good. They have good peel strength. This is 10-15 N/mm.
UV adhesives cure fast. They cure in 10-30 seconds. They have high shear strength. Consider viscosity and working time. Also, check service temperature. This helps choose the right adhesive for circuit card assembly.
Quality Control and Testing in the Circuit Card Assembly Process
- ICT (In-Circuit Test)
ICT uses fixtures. Fixtures have many points. Points contact the circuit card assembly. Check for opens. Also check for shorts. Measure resistance. Resistance is 0-100 ohms. Check capacitance.
Capacitance is pF to µF. Check inductance, too. Inductance is nH to mH. Check diodes. Diodes have forward voltage. This is 0.7V for silicon. Look for reverse leakage. This is in nA. Verify placement and values. Examine solder joints. The circuit card assembly must be good. - Flying Probe
Flying probes move. Probes use an X-Y axis. Servo motors control movement. Contact test points. The circuit card assembly has 20-50 points. Check for opens and shorts. Measure resistance. Resistance is milliohms to megaohms. Measure capacitance. Capacitance is picofarads to microfarads.
Test inductance. Inductance is nanohenries to millihenries. This method helps low-volume production. Production means 1-100 units. This also helps prototypes. ICT fixtures are costly.
Fixtures have high NRE costs. Flying probes use four wires. Four wires give accurate readings. Handle varying pitches. Pitches are 0.4mm to 1.27mm. - X-Ray Inspection
X-ray inspection uses X-rays. X-rays are 0.1-10 MeV. Inspect the circuit card assembly. See hidden solder joints. Find these in BGAs. BGAs are ball grid arrays. Also find them in QFNs. QFNs are quad-flat no-leads packages. Check component placement. Placement is within multi-layer boards.
Boards have 4-12 layers. Find voids in solder. This method is non-destructive. Ensure quality. Find hidden defects. Defects include head-in-pillow. Also solder bridging. And misalignment.
You cannot see these. X-ray systems use tubes. Tubes create images. Images have high-resolution. Resolution is 1-5 µm. - Functional Testing
Functional testing uses power. Power the circuit card assembly. Simulate real work. Verify voltages. Voltages are 0-5V, 12V, ±15V. Measure current. Current is mA to A. Check signals.
Signal integrity is in MHz. Check data speeds. Data rates are in Gbps. This testing uses JTAG. JTAG tests digital circuits. Use oscilloscopes. Oscilloscopes analyze analog signals. Confirm the circuit card assembly works. It works according to the design. - Burn-In
Burn-in uses temperatures. Temperatures are 50-125°C. Also use voltages. Do this for 24-168 hours. Stress the parts. Find early failures. Failures are like infant mortality. Infant mortality happens in semiconductors. Use burn-in chambers. Chambers control everything.
Control temperature and humidity. Control voltage levels. Simulate harsh conditions. Ensure reliability. Reduce failures. Reduce failures for important uses. Important uses are in space or medical devices.
Advanced Techniques for Optimizing Circuit Card Assembly Process
- HDI
HDI utilizes microvias (0.15 mm). And blind vias connect layers to circuit board. This allows smaller, complex designs. You can use higher density components. For example, 0402 resistors and 0201 capacitors. Blind vias connect surface to inner layers. Thus, increasing space for routing.
This minimizes PCB size (e.g., 100 mm x 50 mm). Ultimately, improving circuit card assembly efficiency. And reducing costs by 20%. - Blind Vias
Blind vias connect surface to inner layer. But they do not go through the entire board. This allows more compact designs. And reduces board size (e.g., 80 mm x 60 mm).
Blind vias are used with through-hole components. Like connectors (e.g., SMA, SMB) and ICs (e.g., BGA, QFP). They have size limits (0.2 mm to 0.5 mm). Also, they require controlled depth drilling (e.g., 0.8 mm). This is important for circuit card assembly. - Buried Vias
Buried vias connect two inner layers. They do not extend to the surface. This increases routing density. And reduces through-hole vias. Buried vias are used in HDI PCBs.
With multiple layers (e.g., 8-layer PCB). They have smaller size limits (0.1 mm to 0.3 mm). And require laser drilling. The aspect ratio is crucial. It is typically between 8:1 and 10:1 for circuit card assembly. - Embedded Components
Embedded components place passive parts inside. Like capacitors (e.g., 0603, 0402) and resistors (e.g., 0805, 0603). This reduces board size. And improves electrical performance.
By shortening signal paths. Embedding minimizes inductance. And improves signal integrity. Especially at higher frequencies (e.g., > 1 GHz). This technique is for RF modules. And microwave circuits in circuit card assembly. - Flexible Circuits
Flexible circuits use polyimide or polyester base materials. For circuit card assembly in dynamic applications. They allow bending and folding. Enabling three-dimensional designs.
Flexible circuits use thinner copper. Typically, 0.5 oz to 2 oz (17.5 µm to 70 µm). And specialized connectors (e.g., ZIF, FPC). You find them in wearable devices. Also, in medical implants and automotive electronics.
Reducing Costs in Your Circuit Card Assembly Process
- Reducing Costs: Lean manufacturing helps save money. For example, use surface-mount devices. 0402 resistors and 0603 capacitors reduce costs. These small parts fit easily on the board. Automated machines place 15,000 components per hour. Choose FR4 for circuit board. FR4 has a Tg of 130°C. This material is strong and affordable.
- Supply Chain: A good supply chain saves money. Order 10,000 capacitors at once. This lowers the price. Find suppliers with fast delivery. You can reduce storage space. Look for high-quality parts. These have a low defect rate. This reduces faulty circuit card assembly.
- Inventory: Managing inventory saves money. Track parts like resistors. Use FIFO to organize them. Software can help manage inventory. You can order the right number of parts. Store parts in the right way. This prevents damage. Good inventory helps circuit card assembly.
- Waste Reduction: Reducing waste saves money. Use the right amount of solder paste. A stencil printer helps with this. It has an accuracy of ±25µm. Recycle extra materials. Use a solder recovery system. Use efficient machines. This saves energy during circuit card assembly.
- Negotiation: Negotiation saves money. Talk to suppliers about prices. Ask for a discount for large orders. Compare prices from different places. Ask about contracts. This can help you save money on circuit card assembly.
FAQs
Q: How To Make Circuit Card Assembly Last Longer?
A: To make circuit card assembly last longer, use FR408. This PCB laminate has a high Tg. Its glass transition temperature is 190°C. Also, choose components carefully. These should have tight tolerances. For example, ±0.1% is good. And consider the temperature range.
Components should operate from -55°C to +150°C. Next, apply conformal coating. You can use acrylic or silicone. A thickness of 50-75µm is best. This protects against moisture. Finally, remember ESD protection. Use ESD mats and wrist straps. These have 1MΩ resistance.
Q: Manual Vs. Automated Assembly? Which Is The Best?
A: For high-volume production, consider automated assembly. This is best for over 10,000 units per month. Automated assembly uses pick-and-place machines. These machines have ±25µm accuracy. They place fine-pitch components. Examples include 0.4mm QFPs.
Conversely, manual assembly is good for low volume. This means under 100 units per month. You would use soldering irons. These have temperature control up to 480°C. Manual assembly is also good for large components. These might be 20mm connectors. Or they could be 100µF capacitors. Ultimately, consider your needs. Choose the best assembly method for you.
Q: What’s RoHS Compliance In Circuit Card Assembly?
A: RoHS compliance means using lead-free solder. One example is SAC305 alloy. It has a melting point of 217°C. Its tensile strength is 50MPa. RoHS also affects components. They must have lead-free platings.
ENIG is one type of plating. It has 0.05-0.1µm of gold. The nickel layer is 3-6µm thick. Furthermore, all materials must be safe. This includes PCB laminates. It also includes solder masks. No hazardous substances are allowed. These include lead and mercury. RoHS aims to protect the environment.
Q: Can I Do Circuit Card Assembly Myself?
A: Circuit card assembly requires equipment. Firstly, you need a reflow oven. It needs a peak temperature of 245°C. The ramp rate should be 1-3°C per second. Secondly, you need a soldering iron. It needs temperature control. It should go up to 450°C.
You will also need a hot air station. This helps remove components. You need skills too. Soldering is one skill. You need to know through-hole and surface mount. Component identification is important.
You must read datasheets. Finally, handle ESD-sensitive devices carefully. These can be damaged by 100V. If this seems difficult, use a professional. They can help you avoid damage.
Conclusion
You can optimize your circuit card assembly process. Use the right materials and techniques. This improves quality and reduces costs. Visit LHD-PCB for more information. We offer expert advice and services.
