Technical
What are the advantages and applications of flexible microcircuits?
FPC Reinforcement Types
Criteria for Classification of electronic Component Classes
Four softwares suitable for beginners to draw PCB circuit boards
What information is needed for SMT processing?
What are the advantages of small and medium batch SMT processing?
PCB related knowledge- The purpose of each layer of the PCB
How to do heat resistance testing for PCB board
Detailed explanation of rigid-flex board and IC carrier board
PCBA prototype procedure
Defects which can be detected by the SPI
What are the spacing requirements for designing PCB circuit boards?
What are the classification and advantages of PCB metal substrates?
Difference between the processing technology of 1Layer AL PCB and 2Layer AL PCB
Introduction of FPC Cable and its usage
advantages of Shenzhen SMT assembly factory
inspection items before PCB ordering
usages of ceramic substrates
main applications of PCB boards
Cost-effective PCB product services
How to check short circuit of a circuit board during manual soldering
Identify the polarity of electronic components during PCBA processing
Means Which Can Prevent Component Shifting in SMT Processing
Skills of PCB prototype manual soldering
Reasons for the shift of Components in the SMT Process
Seven Types of PCB Probes
What Should Be Paid Attention to in Layout of High-frequency PCB
Precautions for PCB CCL Selection
Advantages of LED Plant growth light
Advantages of using LED grow lights to grow industrial hemp
Detailed explanation of PCB manufacturing process and precautions
Detailed explanation of PCB manufacturing process and precautions
How to draw multilayer PCB on Altium Designer
Three basic elements of interference and how to suppression them.
Decrease interference between digital circuit and analog circuit
SMT Component Placement Process Of Parts : Manual Placement
SMT factory incoming PCB material inspection
Basic concepts commonly used in PCB design
Ideas and principles of High speed PCB layout
Component layout rules and safety distance considerations
SMT assembly process quality specification
5 points in PCB layout
Professional interpretation of SMT
Advantages and disadvantages of different PCB surface treatment
Special process in PCB prototype
Why the via hole become open after component assembly
Keep the cost of the PCB as low as possible
what are the causes of PCB board heating radiation problem
Pad size and via diameter dimensions consideration in PCB prototyping
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

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.