1. Custody of solder paste
(1) Solder paste of a long time, its solder component and flux ingredients are separated, and it must be stirred when used.
(2) Solder paste is typically stored in a low temperature environment, so it must be placed at room temperature before opening the solder paste, and "Turn", even if the temperature of the solder paste is raised to room temperature. This time is about 2 to 3 hours. If you don't have "Turn", you will be opened. Like many refrigerated things, the water vapor in the air will condense and attach it to the solder paste, so that the solder paste is moist, conjunction, and then accept heat, so that moisture is rapidly vaporized. The method that causes the solder to scatter, severely time base to damage the components but is not available to the heating, so that the solder paste returns to room temperature, and the rapid temperature rise will cause the solder cream to the welding, which affects the welding effect.
(3) After opening, it is sustainable for 4 to 6 hours at room temperature. However, over time, because the component is volatilized, the viscosity is increased, and the extension is deteriorated, and it is easy to adhere to the mask plate. Therefore, the total time from the solder paste to the use should be specified in accordance with the type and environmental conditions of the solder paste.
(4) If you want to store, you should use a low-temperature storage method. Low temperature storage can stably store for 6 months.
2. Slimming of solder paste
After the solder paste is used, there is often a collapse collapse collapse of the line graphic, and the survival blur is performed around the graphic, which is due to the dispersion of the solder powder in the solder paste, and the particle size of the powder is uneven.
Therefore, during the use of solder paste, after "Temping", the solder paste is needed, so that the flux is uniformly distributed between the solder and the brazing, and gives full play to various properties.
If the powder of the solder is spherical, the size of the size is also consistent, the solder paste is inclusted, and the collapsed collapse and the infiltration phenomenon after use. A certain solder paste must be selected when printing precision patterns.
The solder powder can be produced by a jet. This method can effectively control the size and shape of the powder.
3. Generation of solder balls
When welding, the substrate is scattered with a large size solder ball, and sometimes splashes to the component of the component, so that the device cannot be removed during cleaning. Due to vibration, etc., due to vibration, it causes short circuit. At the same time, these high temperature solder particles are also melted from the protective layer of the solder on the substrate, and then secured thereto and cannot be removed.
Producing a solder ball is a major disadvantage of solder paste, the main reason is:
(1) Use the front temperature storage cream to be low-temperature, if the temperature is not used to rise to room temperature, the solder paste itself should heat the heat, and the solder will evaporate the absorbed moisture, resulting in a solder particles. In addition, if the melting temperature rises too fast, the solder particles are also splash.
(2) The surface layer of the solder powder is oxidized, and the thermal energy of cohesion with other particles is not obtained during welding, and the large and small solder ball remains in the substrate.
Current electron-level solder paste is used in the manufacture of the device and the mixed integrated circuit. It will also play a positive role in the welding of microelectronic components.
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