After multiple rounds of stirring, the viscosity of solder paste exhibits a non-linear trend of first decreasing and then increasing. In the initial stage, the shear action breaks the gel structure, enhancing the fluidity of the stirred solder paste. Continuous stirring, however, causes flux volatilization and agglomeration of metal particles, leading to an irreversible increase in solder paste viscosity. This pattern directly affects printing accuracy and the rate of missing prints.

Excess solder causes excessive solder paste on the bottom pads of BGA packages, which not only leads to surface defects such as solder ball splashing and bridging, but more importantly, significantly increases the probability of void formation. Especially in large-sized BGA devices, the void rate may exceed the 25% acceptable threshold specified in IPC-A-610E. Jiajinyuan's measured data shows that for every 0.02mm the solder paste thickness exceeds the standard value of 0.13mm, the average void area ratio increases by 7.3%. The root cause is that excessive solder paste obstructs the escape channels for flux gas during the reflow phase.

The incompatibility of solder paste with PCBs featuring different surface finishes is a root cause o

In the ball mounting process, the size, shape and taper of stencil apertures directly affect the consistency of solder ball formation. Actual measurements by Jia Jinyuan show that 0.35mm circular apertures with 8° single-sided taper can keep the diameter fluctuation of over 95% of solder balls within ±0.015mm. Combined with the parameter set of squeegee pressure 0.3MPa and release speed 25mm/s, it significantly reduces defects such as missing balls and bridging balls.

The nitrogen reflow process significantly improves solder joint wettability and oxidation suppression in the soldering of thick copper boards and high-frequency boards. Especially for thick copper substrates of 2oz or above, which have large heat capacity and slow heating, when paired with JJY dedicated solder paste, the void rate can be stably controlled within 8%. Meanwhile, it prevents thermal delamination of high-frequency dielectric layers. This process has been batch-verified on multiple production lines for military products and base station RF modules.

Dip soldering is a core process for high-volume PCBA pin soldering. The composition, melting point, and oxidation control of wave soldering solder bars directly determine solder joint wettability and cold solder joint rate. Jia Jinyuan wave soldering solder bars can maintain a solder wave height deviation of ≤0.3 mm and a solder dross generation rate of less than 1.2% during 8 consecutive hours of production, significantly reducing fixture rework frequency.

The volatilization rate of solder paste flux directly affects the wettability, void rate, and bridging risk of solder paste joints. Excessively fast volatilization can easily lead to insufficient solder paste collapse and cold solder joints, while excessively slow volatilization leaves residual flux that causes splashing and solder balls. Based on 20 years of practical SMT production line data from Jiajinyuan, this paper analyzes the cascading impact of the actual volatilization behavior of solder paste flux under different temperature zone settings on the formation of solder paste joints.

Jia Jinyuan provides free solder sample testing and sample mailing services. All solder sample tests are conducted synchronously on real SMT placement lines and wave soldering production lines, covering mainstream packages such as 0201 to QFN48. The measured yield data can be traced back to the furnace temperature curve and AOI original image of each batch. The solder sample test results are directly related to the customer's existing stencil opening, reflow soldering temperature setting and flux compatibility.

X-Ray inspection precisely identifies the geometric contours of internal voids in solder joints and automatically calculates their percentage of the total pad area. Combined with standard thresholds from IPC-A-610 or JEDEC (e.g., BGA void area ratio ≤25%), it directly determines whether a product is qualified, significantly reducing manual misjudgment rates. It has already enabled batch closed-loop control of high-reliability products such as IGBT modules and QFN packaged devices on Jiajinyuan's SMT production line.

Circuit board soldering covers core processes such as SMT placement, wave soldering, and manual soldering, each of which imposes stringent requirements on solder paste printing accuracy, temperature profile control, flux selection, and PCB board deformation tolerance. Production line tests by Jia Jinyuan show that for 0.3mm pitch QFN devices, a reflow soldering peak temperature deviation exceeding ±2℃ causes cold solder joints, while insufficient wave soldering fixture press-in depth below 0.15mm leads to through-hole solder joint climb height falling below the 0.75mm standard value.

FPC soldering has extremely stringent requirements for halogen residue, wettability, and residue insulation of solder paste. Jiajinyuan halogen-free solder paste strictly controls bromine and chlorine content below 900ppm, leaving no corrosive ion residue after reflow, while maintaining excellent slump resistance and 0.3mm fine-pitch printing stability. It has been successfully applied to high-end product lines exported to the EU, Japan, and South Korea, such as automotive camera modules and foldable screen hinge FPCs.

To address the challenge of cleaning residual stains on solder paste boards, it is necessary to simultaneously optimize solder paste selection and process parameters. While no-clean solder paste reduces cleaning pressure, it is more sensitive to stencil apertures and reflow environments. In contrast, traditional solder paste paired with cleaning requires chemical compatibility between the cleaning agent and solder paste residues. The cleaning effectiveness of solder paste is directly influenced by its metal content, rosin system, and activator type.

RoHS solder SGS testing certification is a mandatory threshold for export-oriented EU electronic assembly production lines. Jiajinyuan RoHS solder has passed SGS's full set of heavy metal and organic substance testing, with all six items—lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers—meeting the standards. Customs clearance documents include the original SGS report, Declaration of Conformity, Material Safety Data Sheet, and batch factory inspection records, and the complete set of documents can be directly used for customs declaration and customer factory audits.

Loss of temperature and humidity control in the SMT printing workshop will cause fluctuations in solder paste viscosity, leading to defects such as insufficient solder, solder bridging, and misalignment. Jiajinyuan solder paste has the most stable viscosity under an environment of 22℃±2℃ and 45%RH±5%RH. When the temperature difference exceeds 3℃ or the humidity deviation exceeds 8%RH, the printing defect rate will rise. Process control must be achieved through closed-loop monitoring and zoned humidity control.

Domestic solder covers wire diameters from 0.3mm to 3.0mm, all temperature ranges (183℃~227℃) for both leaded and lead-free variants, and three flux systems: rosin, no-clean, and water-washable. It is compatible with multiple scenarios including high-speed SMT printing, wave soldering, dip soldering, and manual touch-up soldering. The Jiajinyuan series has a measured wetting angle ≤35°, bridging rate below 0.08%, and residual ion content <0.5μg/cm2. No adjustment to stencil apertures or reflow temperature profile is required when switching materials on the production line.

This article elaborates on the actual industry fluctuation logic of solder paste unit purchase price and minimum order quantity, explains the price composition in combination with different brands, metal contents and packaging specifications, clarifies that production line verification requirements and process parameters must be provided for solder paste sample applications, points out that the conventional solder paste procurement cycle is 5 to 12 working days, and urgent orders can be shortened to 3 days, but inventory and logistics routes must be confirmed simultaneously.

When performing rework soldering on FPC flexible boards, traditional solder paste requires a peak temperature above 235°C, which easily causes substrate blistering, copper foil peeling, or cover film cracking. In contrast, low-temperature solder paste reduces the reflow peak to 180°C ± 5°C, significantly lowering thermal stress while ensuring wetting, spreading, and solder joint strength. It is a key solder paste selection strategy that balances reliability and yield in precision rework of flexible printed circuits.

Consumer electronics solders must balance low melting point, high wettability, and low corrosivity of residues. Especially in high-density PCBA soldering for mobile phone earphones and similar devices, Jia Jinyuan SN96.5AG3.0CU0.5 solder has been experimentally measured to have a wetting angle of <25° on 0.3mm pitch BGA and 0201 components, with the post-reflow ICT test defect rate stably controlled within 80ppm.

Silver-plated board soldering is a critical step in the SMT process where abnormalities such as pad blackening, poor wetting, and excessively thin IMC layers are prone to occur. Based on actual production line cases from Jia Jinyuan, this article focuses on the dependence of silver-plated board soldering on the quality of PCB silver surface treatment, and provides a detailed explanation of practical key points such as silver layer thickness control, OSP residue impact, reflow profile adaptation, and stencil aperture compensation.

First Article Inspection is the first gate of the quality defense line on the SMT production line. Standardized execution of First Article Inspection and complete archiving of original records can not only quickly locate the process source of batch defects, but also provide tamper-proof process evidence during customer complaints or internal audits, truly realizing full-link quality traceability from placement and reflow to AOI.