There are several method of assembly pcb ie reflow, wave soldering, machine soldering. While soldering the pcb due to soldering process and chemical itching there is green spot on pcb there will be severe blister the size of a fingernail how to fix these
These thing is happen due to vapor and gasses and this is fundamental reason between pcb subtract and solder mask. Where the traces of water vapor or gas entrained therein in a different process, when faced with high temperature welding, gas expansion led to stratification and PCB solder mask substrate, welding, pad temperature is relatively high, so the bubble first appeared in the land around it.
Following multiple reasons PCB entrained water vapor:
Pcb should be cleaned after every process either after soldering or testing going for next step, as before applying solder mask need to clean PCB, if that time drying temperature is not sufficient then vapor take place when high temperature come into contact of pcb bubble appearing in this case.
PCB before processing and storage environment is not good, high humidity, there is no drying time welding process.
water flux used in wave soldering due to moisturizer its inter thee subtract part of PCB, like near pad through hole area,wall of pads, while its come in contact of high temperature it will produce bubble
1. Need to take care of all the aspects while cleaning or soldering of PCB, PCB by 260 ℃ / 10s should not blistering.
2. Need to control humidity of manufacturing environment need to bake the pPCBsome time drive out moisturizer select high reliability materials that can withstand elevated soldering temperatures.
3. Lead free soldering having high temperature of melting point then SnPb solder .due to increase in vapor pressure with increase in temperature .as component are more sensitive to moisture, this moister introduce at the time of fabrication so for process . If left in the device, this moisture will vaporize at soldering temperature, leading to delaminating, soldering voids, and device cracking.
4. Main reason is to use conventional FR-4 which may not be withstand lead g=free reflow soldering temperature of 250. Alternatively high reliable FR4 PCB can tolerated the elevated soldering temperature.
5. PCB Board manufacture induced error can give to blistering independent of processing perspective prior to initialization a lead-free trial run, first if confirm that the board material can tolerated lead-free soldering temperature.
6. Speech reorganization system chip
7. Input can be anything like any input either microphone or loudspeaker, this one using biometric technology this technology getting very popular nowadays.
8. Voice reorganization system is a device capacity to understand the capacity to spoken capacity, when using a computer with ADC which convert the analog into digital, before speech, the first of its amplification, shaping, and then its band-pass filter, filtering out unwanted high-frequency and low-frequency ingredient,The ADC digitizes the sound wave at frequent intervals by taking some precise measurements. This sampled or digitized sound is then filtered in order to remove noise, this ensure that there is sufficient identification accuracy of the premise to reduce the amount of data processing CPU, RAM .to save space and improve speech recognition chip speed .if it is compared with sample by established, when the voice found signal with sample signal phase at the same time the chip will output the area.
9. In order to convert the speech or spoken words into a computer several task has to be performed, this sampled or digital sounds is then filtered in order to remove noise .this is also done to separate the sound in different bands of Flexible circuit board manufacturers analyze the reasons of the board components falling or tin cracking.
10. Tin cracking or component falling from flex PCB, we have to understand first why it is happening , we have to assume our all ball grid are good ,all things are good but still issue come .this is because everything is fine but due to stress in PCB or flexible PCB this situation came, thermo-mechanical and shock stresses is cumulative and manifests as voids and cracks, which propagate in number and size. Mismatch between thermal pad and ball grid array not only causes fatigue of the solder joints cracks in the laminate beneath solder pads
11. actually improved the fatigue life of the solder joints’ circuit board or BGA after reflow at high-temperature deformation This is caused by the decreased stress
12. Transferred to the solder joints during thermal cycling. However, cracking in the board
13. laminate may cause other types of failure mechanisms that endanger the integrity of the
14. Printed board assembly. Some area in the winter time due to temperature difference there is material expansion coefficient which is depended upon the change of temperature while rapidly change in temperature same time there is change in BGA and relevant pads due to mismatch of stress breakout take place.
The role of rosin electronic solder flux in PCB SMT
Normally a flux is chemical cleaning material which is used in metallurgy, flux is necessary to reduce the oxides form whenever you hot metal in contact .it also improve the quality of component placement and viscosity of component.
Why Battery Flexible PCB is higher price relatively?
Flexible PCB having their own advantage compared with rigid board, flex PCB is little bit costly then rigid and process also different, production cost set up charges are high ,flex panel production are difficult .so rigid circuit board and flexible circuit produce separately more .
A flexible battery connection method can be used to connect one end of a flexible printed circuit board (PCB) strip with a small battery cell to maximize space within a small form factor electronic device.
Compared to wire or ribbon cable a flex pcb circuit is offers customize routing path or cable connection.