SOIC、QFP、QFN、BGA、uBGA、CGA、LGA、CSP

Only a slight adjustment within ±0.05mm is allowed. Components with excessive deviation need to be returned to the supplier to avoid pin breakage caused by forced placement.

Adopt the "center support + two - end crimping" mode. The pick - and - place machine nozzle needs to contact the middle and both ends of the component simultaneously to ensure uniform stress.

The thickness needs to be reduced to 60–90μm to avoid solder paste accumulation causing bridging. It is recommended to use an electroformed stencil.

Slight adjustment (shift ≤0.1mm) is allowed before reflow soldering, but it needs to be assisted with a tweezer dipped in flux to avoid contaminating the pad.

Post - soldering is not recommended because the bottom solder joints cannot be visually inspected. The component needs to be removed and the solder paste needs to be re - printed.

Ensure that the difference in solder paste amount at both ends of the component is ≤3%, and reduce the reflow soldering heating rate to ≤1.5℃/s to reduce uneven thermal stress.

It is not recommended as it may damage the surface coating of the solder balls. Special flux (such as no - clean type) needs to be used to improve wettability.

Reduce the placement pressure to 0.05–0.1N, and delay the nozzle release time (0.2–0.5s) to avoid the deformation of solder balls under pressure.

The vacuum level needs to be ≥ - 80kPa to ensure stable adsorption of tiny components. At the same time, an anti - leakage detection sensor should be configured.

If the number of missing solder balls is ≤5% and they are non - critical pins, laser repair and ball - filling can be used; otherwise, the board needs to be scrapped.

Ceramic packages are prone to moisture absorption. They need to be baked at 150℃ for 8 hours to eliminate internal stress and reduce the moisture content to below 0.1%.

When the CTE difference > 10×10⁻⁶/℃, a slow cooling process (rate ≤1℃/s) needs to be added after reflow soldering to reduce solder joint cracking.

No. Since LGA pads have no solder balls, a flat nozzle with a pressure sensor is required to ensure uniform placement pressure.

The gold - plating layer needs to be ≥3μm, and the nickel - plating layer needs to be ≥5μm. Otherwise, excessive contact resistance may easily lead to signal attenuation or thermal failure.

The center of the nozzle needs to be aligned with the center of gravity of the component (deviation ≤0.01mm), and the component posture detection function of the pick - and - place machine should be enabled.

Elastic support pins (Shore hardness 60–70) are required to avoid component displacement caused by substrate bending.

Lens stains will cause a lead recognition error >0.02mm. It needs to be cleaned with absolute ethanol once a week.

SAM (Scanning Acoustic Microscopy) is used to detect the delamination at the solder joint interface. The delamination area should be ≤10% of the pad area.

Flip chips require precise control of the alignment of solder balls and bumps (accuracy ≤±0.002mm), and the underfill process needs to be used.

It can achieve solder - paste - free welding, with a solder joint void rate <5%, and is suitable for high - reliability scenarios (such as military products).

It uses laser beams to directly manipulate components (accuracy ≤±0.001mm), without the need for mechanical nozzles, and is suitable for nanoscale packaging.

It can simulate the placement process in real - time, predict the stress distribution of components, and optimize parameters in advance to reduce the risk of solder joint failure.

Add local air - cooling devices (temperature controlled at 23±2℃), and at the same time, shorten the exposure time of components after opening (≤30 minutes) to avoid exacerbating solder ball oxidation.

① The PCB needs to be baked at 120℃ for 4 hours before solder paste printing; ② Components should be put into production immediately after opening, and a dehumidifier (RH≤40%) should be configured in the equipment.

Residual solder needs to be cleaned with a desoldering braid, and oxides need to be removed by plasma cleaning to ensure that the surface roughness Ra of the pad is ≤1.6μm.