1. PCBA is a completed module that has been processed by PCB through SMT and DIP techniques.
2. The PCBA processing encompasses two main aspects: SMT surface assembly and DIP packaging.
3. Different surface-mounted components come with varying specifications, leading to distinct process requirements during insertion and assembly.
4. Typical methods for PCBA surface assembly include full surface assembly, single-sided mixed assembly, and double-sided mixed assembly, among others.
5. **Full surface assembly process**
6. The assembly of all surface-mounted components is referred to as full surface assembly, while the integration of both plug-in and surface-mounted components is termed hybrid assembly (mixed assembly).
7. Full surface assembly implies that both sides of the PCB are populated with surface-mounted components (SMC/SMD), and it can take the form of either single-sided or double-sided surface assembly.
8. Single-sided surface assembly utilizes a single panel, while double-sided surface assembly employs a dual panel.
Usually, there are two distinct processes:
1. Print solder paste on side B – mount components – reflow soldering – flip PCB – print solder paste on side A – mount components – reflow soldering.
2. Print solder paste on side A – mount components – dry (cure) – reflow solder on side A – (clean) – flip the PCB – print solder paste on side B (apply patch glue) – mount components – bake – reflow.
**Single-Sided Mixed Packaging Process**
Single-sided mixed packaging refers to the presence of both surface mount components (SMC/SMD) and through-hole components (THC) on the PCB. THC is typically located on the main side, while SMC/SMD can appear on either side.
1. SMC/SMD and THC on the same side:
Print solder paste – apply patch – reflow soldering – insert components – wave soldering.
**Double-Sided Mixed Installation**
Double-sided mixed installation involves SMC/SMD on both sides, with THC on the main side or potentially on both sides.
1. THC with SMC/SMD on sides A and B:
Print solder paste on side A – apply patch – reflow soldering – flip board – apply patch glue on side B – apply patch – secure components – flip board – insert components on side A – wave solder on side B.
2. Both sides A and B have SMC/SMD and THC:
Print solder paste on side A – apply patch – reflow soldering – flip board – apply patch glue on side B – apply patch – secure components – flip board – insert components on side A – wave solder on side B – insert components on side B – wave soldering.
**Factors to Consider in the PCBA Processing Workflow**
The selection process primarily depends on the assembly density of PCBA components and the capabilities of the SMT production line. When the SMT line is equipped with both reflow soldering and wave soldering, the following should be considered:
It is advisable to prioritize reflow soldering due to its advantages over wave soldering:
1. Reflow soldering does not require components to be immersed in molten solder, resulting in lower thermal shock.
2. Solder is applied only to the pads, allowing precise control over solder volume and minimizing defects like cold joints and bridging, ensuring higher reliability.
3. There is a self-positioning effect. When component placement is slightly off, surface tension of the molten solder can pull components back to the desired position as all solder ends or pins wet the pads simultaneously.
4. Generally, no impurities are introduced into the solder. When using solder paste, the composition can be closely monitored.
5. Local heating sources can be utilized, allowing different soldering processes on the same substrate.
6. The process is straightforward, leading to reduced repair workloads, conserving manpower, electricity, and materials.
Under typical mixed assembly conditions with moderate density, when SMC/SMD and THC are on the same side of the PCB, solder paste is printed on side A, followed by reflow soldering, and wave soldering on side B. When THC is on side A and SMC/SMD is on side B, a glue application and wave soldering process is adopted for side B.
In high-density hybrid assembly scenarios, where THC is minimal or absent, double-sided solder paste printing and reflow soldering can be employed, with a small quantity of THC added as needed. If a larger number of THC components are present on side A, the processing sequence will involve printing solder paste on side A, followed by reflow soldering, glue application on side B, securing components, and wave soldering.
—
Feel free to let me know if you need any further adjustments!
2. The PCBA processing encompasses two main aspects: SMT surface assembly and DIP packaging.
3. Different surface-mounted components come with varying specifications, leading to distinct process requirements during insertion and assembly.
4. Typical methods for PCBA surface assembly include full surface assembly, single-sided mixed assembly, and double-sided mixed assembly, among others.
5. **Full surface assembly process**
6. The assembly of all surface-mounted components is referred to as full surface assembly, while the integration of both plug-in and surface-mounted components is termed hybrid assembly (mixed assembly).
7. Full surface assembly implies that both sides of the PCB are populated with surface-mounted components (SMC/SMD), and it can take the form of either single-sided or double-sided surface assembly.
8. Single-sided surface assembly utilizes a single panel, while double-sided surface assembly employs a dual panel.
Usually, there are two distinct processes:
1. Print solder paste on side B – mount components – reflow soldering – flip PCB – print solder paste on side A – mount components – reflow soldering.
2. Print solder paste on side A – mount components – dry (cure) – reflow solder on side A – (clean) – flip the PCB – print solder paste on side B (apply patch glue) – mount components – bake – reflow.
**Single-Sided Mixed Packaging Process**
Single-sided mixed packaging refers to the presence of both surface mount components (SMC/SMD) and through-hole components (THC) on the PCB. THC is typically located on the main side, while SMC/SMD can appear on either side.
1. SMC/SMD and THC on the same side:
Print solder paste – apply patch – reflow soldering – insert components – wave soldering.
**Double-Sided Mixed Installation**
Double-sided mixed installation involves SMC/SMD on both sides, with THC on the main side or potentially on both sides.
1. THC with SMC/SMD on sides A and B:
Print solder paste on side A – apply patch – reflow soldering – flip board – apply patch glue on side B – apply patch – secure components – flip board – insert components on side A – wave solder on side B.
2. Both sides A and B have SMC/SMD and THC:
Print solder paste on side A – apply patch – reflow soldering – flip board – apply patch glue on side B – apply patch – secure components – flip board – insert components on side A – wave solder on side B – insert components on side B – wave soldering.
**Factors to Consider in the PCBA Processing Workflow**
The selection process primarily depends on the assembly density of PCBA components and the capabilities of the SMT production line. When the SMT line is equipped with both reflow soldering and wave soldering, the following should be considered:
It is advisable to prioritize reflow soldering due to its advantages over wave soldering:
1. Reflow soldering does not require components to be immersed in molten solder, resulting in lower thermal shock.
2. Solder is applied only to the pads, allowing precise control over solder volume and minimizing defects like cold joints and bridging, ensuring higher reliability.
3. There is a self-positioning effect. When component placement is slightly off, surface tension of the molten solder can pull components back to the desired position as all solder ends or pins wet the pads simultaneously.
4. Generally, no impurities are introduced into the solder. When using solder paste, the composition can be closely monitored.
5. Local heating sources can be utilized, allowing different soldering processes on the same substrate.
6. The process is straightforward, leading to reduced repair workloads, conserving manpower, electricity, and materials.
Under typical mixed assembly conditions with moderate density, when SMC/SMD and THC are on the same side of the PCB, solder paste is printed on side A, followed by reflow soldering, and wave soldering on side B. When THC is on side A and SMC/SMD is on side B, a glue application and wave soldering process is adopted for side B.
In high-density hybrid assembly scenarios, where THC is minimal or absent, double-sided solder paste printing and reflow soldering can be employed, with a small quantity of THC added as needed. If a larger number of THC components are present on side A, the processing sequence will involve printing solder paste on side A, followed by reflow soldering, glue application on side B, securing components, and wave soldering.
—
Feel free to let me know if you need any further adjustments!
