How to solve the mounting failure of SMT production line
(1) Observe the degree of failure phenomenon
(2) Summarize the environment and conditions for the occurrence of undesirable phenomena, etc.
①Whether it occurs on a specific component;
②Whether it occurs in a specific batch;
③Whether it occurs on a specific machine;
④Whether it happened at a specific moment;
(3) Analyze when the patch failure occurred during the A-E process shown in Figure 5.10
Generally, the faults after placement are mostly found in the final inspection. Therefore, in order to correctly determine where a fault occurs in the A-E process, it is necessary to check at a specific time. The most important thing is to accurately grasp the fault characteristics, and then take corrective measures.
The following is an analysis of common typical faults and their treatment in the process of component placement, as well as placement quality control countermeasures.
(1) Detection and elimination of abnormal absorption of components
When a fault occurs, it is necessary to grasp the fault phenomenon in order to find the cause and eliminate it. The most effective method is to check and eliminate item by item according to the block diagram shown in Figure 5.11.
① Unfavorable phenomena: a. Unable to absorb components; b. Standing pieces of components; c. Recognizing abnormalities.
② Occurrence occasion: a. Whether it occurs on a specific component; b. Whether it occurs on a specific batch; c. Whether it occurs on a specific machine; d. Whether it occurs at a specific time.
Reasons related to components: a. The components are stuck to the bottom tape; b. The shape of the component taping hole is irregular; c. The component shape is not good; d. The component taping hole is too large, and the component rolls; e. The bottom of the component taping hole is not flat; f. The bottom surface of the component has oil stains.
Small chip components such as 1005 are more likely to be directly affected by the above phenomenon, so special attention is required. To judge whether the braid is in good condition, you can peel off the top tape and overturn the carrier tape. If the chip component can fall off freely, it is in good condition; otherwise, it is bad.
Mechanical reasons. When there is no problem with the components, check the machine, focusing on the suction nozzle (mounting head) and the component supply mechanism.
a. When there is a problem with the suction nozzle (sticker head), check the related suction nozzle (sticker head): (a) Whether the suction nozzle is abnormal; (b) Whether the vacuum air circuit is normal; (c) Whether the vacuum valve is normal. If the dust in the factory is heavy and paper-packaged components are used, the suction nozzles and filters are more likely to be contaminated and must be cleaned regularly.
b. When confirming that it is the problem of the component supply mechanism, check the corresponding parts: (a) whether the tape packaging component is installed incorrectly; (b) whether the top tape is peeled off well; (c) whether the absorption component data is correct.