What are the steps of pcba manufacturing?

What is pcba? pcba is a process of assembling components onto a blank PCB board. Through the following article introduction, you can get a complete understanding of the PCBA manufacturing process.

PCB prototyping

Before mass production can begin for any given product, it is necessary to create samples in order to fully understand potential problems and develop solutions. The steps involved in PCB prototyping are as follows:

1. BOM and Gerber file verification

These files contain a list of all components required for PCB assembly, and it is crucial to verify the accuracy of all materials prior to the start of the prototyping process. Experienced engineers carefully examine board design, component samples and BOM before initiating assembly.

2. PCB and SMT Stencil Manufacturing

If you are engaged in one-stop PCB assembly, the PCB manufacturing company will also produce the PCBs. During PCB production, SMT stencils for PCB assembly are also manufactured. The duration of PCB production is dependent on the complexity of the circuit boards.

3. PCBA First Piece Testing

A comprehensive test is performed on the first assembled board to ensure that all functions are normal. If issues are identified, engineers will address them as quickly as possible. Various testing equipment will be used during this process, and a testing report will be provided upon completion. Assuming that all tests are normal, batch production may commence following customer approval.

PCBA mass production manufacturing steps

PCB mass production manufacturing steps are as follows:

1、Programming and adjusting the bonder

In accordance with the sample BOM patch location map provided by the customer, the coordinates of the location of the patch components to do the procedure. Then with the customer provided by the SMT patch processing information for the first piece.

2、Printing solder paste

The solder paste will be printed on the pads of the PCB board with a stencil that needs to be soldered to the SMD of electronic components to prepare for the welding of components. The equipment used is the screen printing machine (printing machine), located at the front of the SMT SMT processing line.

3、SPI

Standard solder paste thickness ranges from 0.09mm to 0.15mm, and the solder paste must cover the PCB pads completely. The PCB comes in the SPI machine, and the machine detects if the solder paste thickness and shape are qualified for PCB assembly.

4、Patching

The electronic components SMD will be accurately mounted on the fixed position of the PCB. The equipment used is the mounting machine, which is located behind the screen printing machine in the SMT production line.

SMD machine is divided into high speed machine and general purpose machine

High-speed machine: used to paste the components with large and small pin pitch

General purpose machine: paste pin pitch small (pin dense), large volume of components.

5、High temperature solder paste melting

The main is the solder paste through high temperature melting, cooling the electronic components SMD and PCB board firmly welded together, the equipment used for reflow oven, located in the SMT production line behind the placement machine.

6、AOI testing

After reflow soldering, the PCBAs have to go through the AOI machine. A camera automatically scans the PCBA. And the AOI machine collects images, compares the tested solder joints with the set-up parameters in the database, checks out the defects on the PCB by image processing, and marks the defects on the screen. If there are defects, a quality control technician marks the defects on the circuit boards for maintenance.

The above is the automatic SMT assembly, and below is the THT assembly line. THT assembly is done manually.

7、Through-Hole (PTH) Assembly

PTH assembly is the process of mounting PTH components on PCBAs. PTH components have much longer pins than SMDs, and the pins have to go through the PCB through-holes. This operation is quite simple and is usually done manually.

8、 Wave Soldering

After the PTHT assembly, there is still space between the PTH pins and the PCBA, and wave soldering fills the space and connects the PTH components tightly to the PCBA.

The PCBAs go through a pre-heater to warm up and then go through the wave soldering oven. In the oven, the liquid tin fills the space between the PTH pins and the PCBA. When the PCBA leaves the oven, the tin cools down and solidifies. In this way, the PTH components are connected firmly to the PCBA.

9. Visual Inspection

The manual inspection check focuses on the following items: whether there have been any changes to the version of the PCBA; whether the customer requires the use of substitute materials or components of a specified brand or plate; whether the direction of IC, diode, transistor, tantalum capacitor, aluminum capacitor, switch, and other components with direction is correct; defects after welding including short circuit, open circuit, false parts, and false welding.

10. PTH Rework

This step mainly involves trimming the pins of some products that are too long. The technician will trim the PTH legs to 1-2mm long. Another technician uses a soldering iron to repair the PCBA if there are any places that are not soldered properly.

11. PCBA Function Test

Use the PCBA function tester to test the assembled PCBA, mainly testing the current, voltage, capacitance, and other aspects of the product’s value.

12. Thermal Aging Test

The PCBAs are placed in a thermal chamber to be powered on for about 250 hours without interruption. All the PCBAs should follow the ECIA – EIA-364-17 standard.

13. Packaging

The tested products will be packed separately. The general packaging materials used are anti-static bubble bags, static cotton, and blister trays. Two main ways of packaging are used: the first is to use anti-static bubble bags or static cotton in rolls for separated packaging, which is currently the most common way of packaging; the second is to custom design blister trays according to the size of the PCBA. The PCBA is then placed in the blister tray for open packaging, mainly for PCBA boards with more sensitive or vulnerable SMD components.

Choose Leadsintec as Your PCBA Partner

If you have PCBA manufacturing and processing needs, Leadsintec is an excellent choice. We can provide a one-stop PCB manufacturing and processing service for our customers. Our products include intelligent devices, medical products, aerospace, military and other fields. We provide PCBA manufacturing services to customers from all over the world.