PCBA Tech - Common problems and solutions during PCBA processing

Common problems and solutions during PCBA processing

SMT patch processing is the core technology in the SMT process, and the speed of patch processing often restricts the production line's capacity.

An SMT placement processing production line must have at least one high-speed placement machine for placing regular-size components and a multi-function placement machine for placing special-size components. Various problems are always encountered in the process of SMT patch processing. The editor of Zhongke Circuit Board Factory will introduce to you the causes and solutions of these common problems.

1. PCBA processing poor wetting

Phenomenon: During the soldering process, there is no reaction between the substrate solder area and the metal after the solder is infiltrated, resulting in less soldering or missing soldering.

Reason analysis:

(1) During wave soldering, there is gas on the surface of the substrate, and poor wetting is also prone to occur.

(2) When the residual metal in the solder exceeds 0.005%, the flux activity will decrease and poor wetting will also occur.

(3) The surface of the welding area is contaminated, the surface of the welding area is stained with flux, or the surface of the chip component has generated metal compounds. Will cause poor wetting. Such as sulfide on the surface of silver and oxide on the surface of tin will cause poor wetting.

Solution:

(1) Strictly implement the corresponding welding process;

(2) The surface of PCB circuit boards and components should be cleaned;

(3) Choose suitable solder, and set reasonable soldering temperature and time.

2. Tombstone

Phenomenon: One end of the component does not touch the pad and stands upright or the touched pad is upright.

Reason analysis:

(1) It is related to the wettability of solder paste;

(2) The shape of electronic components is easy to produce tombstones;

(3) The temperature rises too fast during reflow soldering, and the heating direction is uneven;

(4) The wrong solder paste is selected, there is no preheating before soldering, and the size of the soldering area is selected incorrectly.

Solutions for PCBA processing:

1. Set the printing thickness of solder reasonably;

2. Reasonably formulate the temperature rise of the reflow soldering zone;

3. Store and retrieve electronic components as required;

4. Reduce the surface tension of the component ends when the solder melts;

5. The PCB circuit board needs to be preheated to ensure uniform heating during soldering.