How to choose solder paste and flux in SMT patch?

There are many factors that can affect the final quality of the SMT patch, such as: the quality of the patch components, the quality of the pads of the pcb circuit board, solder paste, solder paste printing, the placement accuracy of the placement machine, Furnace temperature curve adjustment for reflow soldering, etc. So, author from qihe smt pick and place machine tell you about the most commonly used auxiliary materials in SMT patches: how to choose solder paste and flux?

Distinguish product positioning and differentiate treatment

aThe product has high added value and high stability requirements, so choose high-quality solder paste (R-grade).

b If it is exposed to the air for a long time, anti-oxidation (RA grade) is required.

c For low-end products and consumer goods, those who do not have high requirements for product quality, choose solder paste (RMA) with similar quality and low price.

Device material and PCB pad material

aThe solder paste of 63Sn/37Pb should be selected if the material of the PCB pad is lead tin-plated.

b Devices with poor solderability should use 62Sn/36Pb/2Ag.

Different choices of different processes

a Lead-free process generally chooses Sn-Ag-Cu alloy solder.

bNo-clean products choose weak corrosive no-clean solder paste.

Welding temperature

aThe soldering of thermal devices with poor high temperature resistance should choose low melting point solder paste containing Bi.

bHigh temperature components must choose high melting point solder paste.

There are many factors that can affect the final quality of the SMT patch, such as: the quality of the patch components, the quality of the pads of the pcb circuit board, solder paste, solder paste printing, the placement accuracy of the placement machine, Furnace temperature curve adjustment for reflow soldering, etc. So, author from qihe smt pick and place machine tell you about the most commonly used auxiliary materials in SMT patches: how to choose solder paste and flux?

As the requirements for environmental protection standards are getting higher and higher, the selection of smt chip processing auxiliary materials such as solder paste also has corresponding environmental protection grade requirements, and the application of more lead-free solder paste and no-clean solder paste is becoming more and more popular and applied.

The above is the author from qihe smt pick and place machine wants to sharing with you. If there is some inappropriate content .I hope you can leave a message to tell me and communicate with each other.
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FAQ for smt pick and place machine

WHAT IS SMT pick and place machine？

SMT (Surface Mounted Technology) is a comprehensive system engineering technology, which covers substrates, design, equipment, components, assembly processes, production accessories and management. When it comes to SMT pick and place machines, the automatic SMT production line requires automatic loading and unloading machine, automatic solder paste printing machine, placement machine, reflow soldering machine, AOI inspection equipment, connecting table, etc. For these SMT assembly line equipment, Qihe SMT can offer you machines in prototype SMT line, small SMT production line, mass production SMT line at low SMT line cost. Contact us now if you are interested.

WHAT IS SMT ASSEMBLY LINE？

With the development of technology, future electronic products will be lighter, smaller and thinner. Traditional assembly technology can no longer meet the requirements of high-precision and high-density assembly. A new type of PCB assembly technology-SMT (Surface Mount Technology) has emerged. SMT Assembly is the use of automated machines to assemble electronic components on the surface of the circuit board. Its density, high speed, standardization and other characteristics occupies an absolute advantage in the field of circuit assembly technology. In addition, SMT assembly has a wide range of uses.

WHAT IS SMT PROCESS？

There are mainly three steps in SMT assembly line process flow： solder paste printing, components placement and reflow soldering.

Solder Paste Printing

Its function in SMT line process is to print the solder-free paste on the pads of the PCB to prepare for the soldering of the components. The equipment used is a screen printing machine, located at the forefront of the SMT production line.

Components Placement

Its function is to accurately install the surface mount components on the fixed position of the PCB. The equipment used is a placement machine, located behind the screen printing machine in the SMT production line.

Reflow Soldering

Its function in SMT manufacturing line is to melt the solder paste so that the surface mount components and the PCB board are firmly bonded together. The equipment used is a reflow oven, located behind the placement machine in the fully automatic SMT production line.