How to Judge the Acceptance of PCB Quality
Which Color Circuit Board Sells the Most Expensive
Method to Solve the Noise Interference of Power Supply on High-frequency PCB Board
Disassembly Skills of Chip Components on PCB
What Factors Should Be Considered in the Selection of High-frequency PCB CCL
How to Place Special Components during PCB Layout
What Are the Functions of Capacitors in Circuits?
Testing Techniques for Common Electronics Components
What to do if There is a Short Circuit on the PCB
Desoldering Principles and knowhow during PCBA Processing
Black Oxidation of the Inner Layer of the Multilayer PCB
How to Ensure the High-performance Design of PCB
What Is the Printing Process of SMT Solder Paste?
PCB without fiducial mark, Is There Any Way to do SMT for It
What Are the Benefits of Reserving Break-up Tab for PCB Production
How Does SMT Affect PCB Production Time and Speed It Up
Classification of PCBs from three aspects
Common Problems and Solutions for Dry Film pasting during PCB Manufacturing process
Several Elements to Inspect after PCB Design
What is a halogen-free circuit board?
What Do Capacitive Coupling and Decoupling Mean?
What Are the Differences Between PCB Paste Mask and Solder Mask?
How PCBA Is Packaged and Shipped
How long can PCBA finished products be stored?
What Are the Differences and Relations Between PCB, PCBA, and SMT?
PCB Baking Specifications
PCB "Solder Mask Tenting" and "Solder Mask Opening"
Five reasons for PCB deformation and six solutions
Importance of first article inspection of PCBA board
Temperature zone standard for SMT reflow soldering
Small and medium volume PCB manufacturers in China
The main reason for PCBA cleaning
For power filter, the more capacitors, the better?
What does PCBA programming mean?
Content of PCB incoming testing
What conditions must be met for PCB circuit board soldering?
What is Blind via and Buried via
PCBA Manufacturers Temperature and Humidity Sensitive Components Management
Why choose Shenzhen SMT processing factory?
How long does it take to calculate the quotation for PCBA manufacturing?
Introduction of PCB design clearance requirements
Explanation of BOM, DIP, SMT, SMD
Introduction of the process of PCBA prototype
How to prevent pseudo soldering or cold soldering defects in PCBA manufacturing?
Factors that affect the Price of FPCB
What information is required for SMT processing at PCBA factory?
Skills of using 0ohm resistor in PCB design
How to select a PCBA manufacturer
SMT processing solder joint quality inspection
Characteristics difference between immersion gold PCB and gold plating PCB
Common malfunctions of Circuit Board Caused by Moisture
A Few Rules about PCB Panelization
Compare of multi-layer PCB with single/double layer PCB
Why do we need to introduce so many subdivided GND
Difference between immersion gold boards and gold plating boards
Aluminum PCB structure
Classification of different GND in circuit
Why PCB baking is necessary during manufacturing process
The handle and precautions of OSP board in SMT process
How to choose capacitors for filter decoupling
How to choose filter capacitor for switching power supply
5 database need for SMT process
Function of three-terminal capacitor
Introduction of PCB OSP surface treatment
Method of inspecting the quality of SMT by step
How to find the short point between VCC and GND
Difference between 850nm and 940nm infrared LED
Component layout of PCB SMT DFM
Pad shape influence on the strength and reliability of the soldering joints
The difference between high temperature solder paste and low temperature solder paste
Introduction to manual welding processing
Manual visual inspection in PCBA processing
Characteristics of the conformal coating process
Difference between hardware engineers and software engineers
PCBA processing operation rules
China PCB upstream materials has continued to soar
Difference between serial buses and parallel buses
The key points of quality control in PCBA processing
Common causes of solder beading during SMT process
Analysis of the advantages and disadvantages of HASL PCB surface
Requirements for layout of components during SMT assembly
Selection of electronic components and CCL for PCBA
Performance and appearance quality inspection of components.
Quality and Reliability of SMT Chip Processing and Production
Coupling and decoupling function of capacitor
Two methods to connect digital ground and analog ground
Common sense in SMT process

The main reason for PCBA cleaning

What is the purpose of PCBA cleaning, and why do we need to conduct PCBA cleaning?

1. Appearance and electrical performance requirements

The most intuitional impact of contaminants on PCBA is the appearance of PCBA. If it is placed or used in a high temperature and humid environment, it may absorb moisture and the residue may turn white. Due to the widespread use of leadless chips, micro BGA, chip-scale packaging (CSP) and 0201 components in components, the distance between components and circuit boards is decreasing, the size of circuit boards is getting smaller and smaller, and the assembly density is increasing. In fact, if the halide is hidden under the component or cannot be cleaned at all, locally cleaning may lead to catastrophic consequences due to the release of the halide. This can also cause dendrites to grow, which can lead to short circuits. Improper cleaning of ionic contaminants can cause many problems: low surface resistance, corrosion, and conductive surface residues will form dendritic distributions (dendrites) on the surface of the circuit board, causing partial short circuits in the circuit.

The main threats to the reliability of military electronic equipment are tin whiskers and intermetallic compounds. This problem has always existed. Tin whiskers and intermetallic compounds will eventually cause short circuits. In a humid environment with electricity, if there is too much ion contamination on the components, it may cause problems. For example, due to the growth of electrolytic tin whiskers, the corrosion of the conductor, or the reduction of insulation resistance, the lines on the circuit board will be short-circuited.

Improper cleaning of non-ionic contaminants can also cause a series of problems. It may lead to poor adhesion of the circuit board soldermask, poor contact of the pins of the connector, poor resist of physical interference, and poor adhesion of the conformal coating to moving components and plugs. At the same time, non-ionic pollutants may also envelop the ionic pollutants in them, and may envelop and bring in other residues and other harmful substances. These are issues that cannot be ignored.

2. Conformal coating needs

To make the coating of the Conformal coating reliable, the surface cleanliness of the PCBA must meet the requirements of the IPC-A-610E-2010 level III standard. Resin residues that are not cleaned off before surface coating can cause delamination of the protective layer or cracks in the protective layer; activator residues may cause electrochemical migration under the coating, leading to the coating crack and failure of protection. Studies have shown that cleaning of PCBA can increase the coating adhesion rate by 50%.

3. Non-cleaning also needs to be cleaned

According to the current standard, the term "non-clean" means that the residue on the circuit board is chemically safe, will not have any effect on circuit board, and can be left on the circuit board. Corrosion testing, surface insulation resistance (SIR), electro-migration and other special testing methods are mainly used to determine the halogen/halide content, so as to determine the safety of non-clean solder paste after assembly. However, even using low solids ratio non-clean fluxes, there will still be more or less residues. For products with high reliability requirements, residues or other contaminants are not allowed to be on the circuit board. For military applications, even require cleaning of non-clean assembled PCBAs.