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

What Are the Differences Between PCB Paste Mask and Solder Mask?

What Are the Differences Between PCB Paste Mask and Solder Mask?

Introduction to Solder Mask
Solder mask, which refers to the part of the board to be painted with Solder resist. In fact, solder mask uses negative film output, so after the shape of the solder mask is mapped to the board, it is not painted with solder mask, but the copper is exposed. Usually in order to increase the thickness of the copper, make solder mask open to remove the solder resist, and then add tin to increase the thickness of the copper wire.

Requirements for solder mask
The solder mask is quite vital in controlling soldering defects in reflow soldering. PCB designers should minimize the spacing around the pads.

Although many process engineers would rather separate all pad features on the board with solder mask, the pin spacing and pad size of fine-pitch components require special considerations. Although solder mask openings that are not partitioned on the four sides QFP may be acceptable, it may be more difficult to control the solder bridges between the component pins. For the solder mask of BGA, many companies provide a kind of solder mask that does not touch the pads, but covers any features between the pads to prevent solder bridges. Most surface mounted PCBs are covered with solder mask, but if the thickness of solder mask coating is greater than 0.04mm, the application of solder paste may be affected. Surface mounted PCBs, especially those using fine-pitch components, all require a low-profile photosensitive solder mask.

Solder mask materials must be used through liquid wet process or dry film lamination. Dry film solder mask materials are supplied in a thickness of 0.07-0.1mm, which can be suitable for some surface mounted products, but this material is not recommended for fine-pitch applications. Few companies provide dry films that are thin enough to meet the fine-pitch standards, but there are a few companies that can provide liquid photosensitive solder mask materials. Generally, the solder mask opening should be 0.15mm larger than the pad. This allows a gap of 0.07mm on the edge of the pad. Low-profile liquid photosensitive solder mask materials are economical and are usually specified for surface mounted applications, providing precise feature sizes and gaps.

PCB stencil

Introduction to paste mask
The paste mask is used for soldering SMD packaging and corresponds to the pads of SMD components. In SMT processing, usually, use a steel plate, laser holes on the steel corresponding to the PCB component pads, and apply solder paste on the steel plate. When the PCB is under the steel plate, the solder paste leaks, and it happens that every pad can be stained with solder. Therefore, the solder paste layer usually should not be larger than the actual pad size, preferably less than or equal to the actual pad size.

The role of solder mask and paste mask
The solder mask is mainly to prevent the PCB copper foil from being directly exposed to the air and play a protective role.

The paste mask is used to make stencil for the stencil factory, and the stencil can accurately put the solder paste on the SMD pads that need to be soldered when printing solder paste.

PCB solder paste layer

The differences between PCB paste mask and solder mask
Both layers are used for soldering. It does not mean that one is soldered and the other is coated with solder resist, but:

1. The solder mask layer means to opening on the whole piece of solder mask solder resist, the purpose is to allow soldering;

2. By default, the area without solder mask layer must be covered with solder resistor;

3. The paste mask is used for soldering SMD components.