What are the causes of PCBA patch processing? PCBA processing manufacturers PCBA chip processing and production process, due to the impact of operational errors, it is easy to cause PCBA patch defects, such as air welding, short circuit, erection, missing parts, tin beads, lame, floating height, wrong parts, cold welding, Reverse, anti-white reversal, offset printing, component damage, tin less, poly tin, gold finger tin, overflow glue, etc., need to analyze these defects, improve, improve product quality. Analysis of Causes of PCBA Chip Processing Defects First, air welding

- Sep 27, 2019-

What are the causes of PCBA patch processing?

PCBA processing manufacturers PCBA chip processing and production process, due to the impact of operational errors, it is easy to cause PCBA patch defects, such as air welding, short circuit, erection, missing parts, tin beads, lame, floating height, wrong parts, cold welding, Reverse, anti-white reversal, offset printing, component damage, tin less, poly tin, gold finger tin, overflow glue, etc., need to analyze these defects, improve, improve product quality.

Analysis of Causes of PCBA Chip Processing Defects

First, air welding

1, solder paste activity is weak;

2, the steel mesh opening is not good;

3, copper or platinum spacing is too large or large copper stickers small components;

4, the blade pressure is too large;

5, the component feet are not flat (warped, deformed);

6, the reheating zone of the reflow furnace is heating up too fast;

7, PCB copper platinum is too dirty or oxidized;

8, PCB board contains water;

9, the machine is placed offset;

10, solder paste printing offset printing;

11, the looseness of the machine clamp rail causes the placement offset;

12, MARK point due to misalignment caused by component misalignment, resulting in welding empty;

Second, short circuit

1. The distance between the wire mesh and the PCB is too large, causing the solder paste to be printed too thick and short;

2, the component placement height is set too low, can not squeeze the solder paste, causing a short circuit;

3, the heating furnace is heating too fast;

4, caused by component placement offset;

5, the steel mesh opening is not good (thickness is too thick, the lead opening is too long, the opening is too large);

6, the solder paste can not bear the weight of the component;

7, the deformation of the steel mesh or scraper causes the solder paste to print too thick;

8, solder paste activity is strong;

9, the empty paste sealing tape is rolled up to cause the peripheral component solder paste to be printed too thick;

10, the return vibration is too large or not horizontal;

Third, upright

1, copper and platinum on both sides of different sizes produce uneven tension;

2, preheating heating rate is too fast;

3, the machine is placed offset;

4, the thickness of the solder paste printing is not uniform;

5, the temperature distribution in the reflow furnace is not uniform;

6, solder paste printing offset printing;

7, the machine track splint is not tight, resulting in placement offset;

8, the nose is shaking;

9, the solder paste activity is too strong;

10, the furnace temperature is not set correctly;

11, the spacing between copper and platinum is too large;

12, MARK point misoperation caused the Yuan Qu

Fourth, the missing pieces

1, vacuum pump carbon sheet vacuum is not enough, resulting in missing parts;

2, the nozzle is blocked or the nozzle is defective;

3, improper detection of component thickness or poor detector;

4, the placement height is improper;

5, the nozzle is too large or not blowing;

6, the nozzle vacuum is not set properly (for MPA);

7, the shaped component is placed too fast;

8, the tracheal head is very fierce;

9, the valve seal is worn;

The surface of the reflow oven rail has components on the foreign matter wiping board;

Fifth, tin beads

1, reflow soldering preheating is insufficient, heating up too fast;

2, the solder paste is refrigerated, the temperature is not complete;

3, the solder paste absorbs the splash (the indoor humidity is too heavy);

4, too much water on the PCB board;

5, adding excess diluent;

6, the steel mesh opening design is improper; 7, tin powder particles are not uniform.

Sixth, offset

1, the positioning reference point on the board is not clear

2. The positioning reference point on the board is not aligned with the reference point of the template.

3. The fixed clamping of the circuit board in the printing machine is loose. The positioning thimble is not in place.

4, the optical positioning system of the printing press is faulty

5, the solder paste lacks the template opening and does not match the board design file.

In order to improve the defects of the PCBA patch, it is necessary to carry out rigorous inspections on all aspects to prevent the problems of the previous process from flowing into the next process as little as possible.

The above is the industry consultation provided by smt patch processing factory Shenzhen Pengzexiang Technology Co., Ltd., I hope to help you! Please contact us if necessary: http://www.oem-pcb.com pcb@sunsoartech.com

 


Previous:The basic process components of SMT include Silk screen (or dispensing), placement (curing), spi, reflow soldering, cleaning, inspection, rework. Next:Analysis of common problems in SMT patch In the SMT chip processing factory, we often talk about some common problems, such as short-circuiting of chip components, solder balls on solder pads, and solder joints. We find some of the common reasons for these common problems in SMT placement processing from the following common reasons. If you find something wrong or supplemented, please ask.