SMT Solder Paste Printing Parameters and Viscosity Evaluation Methods
Optimize solder paste print volume and yield by maintaining area ratios above 0.66, controlling squeegee force, and verifying viscosity stability.
3d SPI Metrology
Measurement Process
Automated volumetric analysis of deposited solder paste provides the primary method for evaluating print quality before the assembly moves to the pick and place stage. This 3d spi metrology utilizes structured light or laser triangulation to determine height across every discrete pad in a layout. It establishes the base reference through zero point calibration on the bare laminate.
The resulting profile calculates volume by integrating the height data across the aperture area. Success relies on high resolution sensors that distinguish between individual paste peaks and the board surface.
Height Calculation
The triangulation sensors capture shifts in light patterns to identify vertical displacement of the paste from the substrate. In 3d spi metrology calculations, the system ignores common board warpage by constantly reevaluating the local coordinate frame. Measurements are expressed in micrometers.
A sensor tracks the reflection angles to map the topography of the deposit. This depth information allows for detection of insufficient heights that signal impending joint failure.
Detection Capability
Identification of bridging and excessive volume prevents costly rework after the reflow oven has solidified the connections. If 3d spi metrology returns a high value, the printer likely failed to maintain adequate separation between the blade and the stencil. Rapid identification allows operators to stop production for stencil cleaning immediately.
Scrap rates drop when volume discrepancies are caught before component placement occurs.