Special Constraints of Medical Equipment on Circuit Board Soldering

Medical equipment PCBs must pass IEC 60601-1 safety certification, and their circuit board soldering process requires solder joints to be free of cold solder joints, bridging, and microcracks. Especially in the main board of ECG monitors, when 0201 package resistors and tantalum capacitors are coplanarly soldered, if the reflow peak temperature deviation exceeds ±2℃, it will lead to uneven thickness of the solder joint IMC layer, which in turn causes long-term aging failure. The JJY production line adopts a dual-zone independent temperature control reflow oven to stably control the temperature difference within ±1.2℃.

Fine-pitch Soldering Difficulties of 5G Communication Modules

Millimeter-wave RF modules generally use 0.3mm pitch QFN and 0.25mm pitch WLCSP packages, and their circuit board soldering puts forward stringent requirements on the dimensional accuracy of stencil openings. When the opening aspect ratio is lower than 1.2, the Solder Paste release rate drops sharply to 68%. We set the tapered opening angle of the JJY 30μm laser-cut stencil to 12°, and complete the placement within 30 seconds after printing, increasing the solder paste transfer rate to 94.7%.

High-current Pad Treatment for New Energy Vehicle PCBs

The pad area of the 12V/200A power loop in the vehicle OBC main board reaches 8.5mm², and its circuit board soldering must avoid solder collapse and copper foil peeling. We adopt a two-stage reflow strategy on the JJY SMT line: first, hold at 145℃ for 90 seconds to fully absorb heat for the large pad, then rise to a peak temperature of 235℃ and maintain for 45 seconds, ensuring complete solder wetting and controlling the IMC thickness between 3.2 and 4.1μm.

Cold Solder Risk Identification in BGA Rework

Hidden cold solder defects often occur in the main control BGA of communication base stations after rework, characterized by X-ray inspection showing clear solder ball contours but annular dark areas of more than 0.08mm at the edges. We found through actual measurement on the JJY rework station that when the hot air head is more than 12mm away from the BGA surface or the nitrogen flow rate is lower than 18L/min, the oxide film on the solder ball surface cannot be effectively reduced, resulting in a wetting angle greater than 92° and forming cold solder joints.

Flux Residue and Ionic Contamination Control

Medical imaging equipment PCBs are extremely sensitive to ionic contamination, and the residual chloride ion content after circuit board soldering must be lower than 0.78μg/cm². We select JJY no-clean ROL0 grade flux, strictly set the cleaning machine water temperature to 58℃, keep the spray pressure at 0.23MPa, and cooperate with two ultrasonic cleaning + three rinsing processes, the measured ionic contamination value is stable in the range of 0.41 to 0.63μg/cm².