Setting of temperature curve of reflow soldering

Setting of temperature curve of reflow soldering

Reflow soldering temperature curve according to a set temperature curve is the key to ensure the welding

quality, real-time temperature curve and the curve of solder paste temperature rising slope and the peak

temperature should be basically the same. 2 - 1 - 160 C / s. If the temperature of the slope is too fast,

on the one hand to make components and PCB heating too, the vulnerability of bad components and

cause PCB deformation. On the other hand, the speed of evaporation of flux solder paste is too fast,

easy to spill out of metal components, produce solder. Peak temperature is generally set at than the

melting point of solder paste metal high 30-40 DEG C (for example 63Sn / 37Pb solder paste melting

point for 183 0C, peak temperature should be set at 215 DEG C), the reflux time /. The peak temperature

is low or the reflux time is short, the welding is not sufficient, serious when can cause the solder paste

does not melt. The peak temperature is too high or too long back time, easy to cause the metal powder

oxidation, affect the welding quality; even damage components and printed boards.

The basis for setting the temperature curve of reflow soldering:

1 according to the temperature curve using solder paste set. Temperature curves of different temperature

curves with different content of metal solder paste should be provided in accordance with the paste

supplier to carry out a set of specific products of reflow soldering temperature curve.

2 according to the PCB plate material, thickness, whether the multilayer board, the size of the setting.

3 according to the surface of the components of the assembly of the density, the size of the components,

as well as BGA, CSP and other special components for setting up.

4. In addition, according to the specific equipment Sui Kuang, such as heating zone length, heating source

material, reflux welding furnace structure and the way of heat conduction and other factors set. Hot air

(return) stove and infrared (reflux) furnace has the very big difference, infrared furnace is mainly radiation

conduction. The utility model has the advantages of high thermal efficiency, large temperature gradient,

easy temperature control curve; double-sided welding, PCB, the temperature is easy to control; the

disadvantage is uneven temperature. Due to the requirement of the device line on the same block PCB.

5 according to the actual position of the temperature sensor to determine the setting temperature of the

temperature region, if the temperature sensor position in the heating temperature, the temperature is

higher than the actual temperature of 30 degrees celsius.

6 according to the size of the exhaust air. General reflow soldering furnace has specific requirements for

the exhaust air volume, but the actual exhaust air due to various reasons sometimes change, determine

the temperature curve of a product, due to the consideration of exhaust air, and time measurement.