CHIPTRONIKS , A Division of VD Intellisys is Authorized Distributor of JOVY SYSTEMS BGA REWORK STATIONS in India . For more details visit http://www.bga-rework.in or call 09971004998
BGA Rework Station
BGA is short for Ball Grid Array. It is a kind of package method which use organic carrier in IC. It has the following features:
1. Small package area.
2. Greater functions and more pins
3. Self-centerize while PCB puddle welding, easy to put on tin.
4. More reliable.
5. Good conductivity and low overall cost. Memory which applies BGA can enlarge the memory capacity by 2 to 3 times while the volume of memory remains the same. Compared with TSOP, BGA is much smaller and better at radiating and conducting electricity.
Types of BGA
According to the encapsulation material, BGA can be classified into the following types:
CCBGA（Ceramic Column BGA）
(Chip Scale Package or MBGA)
Features of BGA
Compared with QFP, BGA has the following features:
I/O terminal space is big (eg. 1.0mm, 1.27mm, 1.5mm), and it can accommodate more I/O.
More reliable package, low rate of welding defects and welding spot durable.
Paraposition of QFP is usually observed with naked eyes. When the pin space is smaller than 0.4mm, it is hard to paraposition and weld. While the pin space of BGA is bigger, by applying the paraposition-amplification device.
Easy to paraposition and weld.
The welding coplanarity of BGA is better than QFP, because solder can make up the flat error between BGA and PCB after melting.
Good electrical property. The pins are small, the self-inductance and mutual inductance of the conductivity is low, and the frequency characteristic is good.
The tension between solder points produces good self-centration effect in solder-reflow, allowing 5% error of patch precision.
Compatible with original SMT mount technology and machines. The original screen printer machine, mounter and solder-reflow machine all can be used.
BGA Rework Process
Most of the semiconductor device’s heat-resistant temperatures are between 240°C and 600 °C. Therefore, the control of the temperature and uniformity are very important to BGA rework systems. BGA rework process as follows:
Printed Circuit Board and BGA preheating: Printed Circuit Board and BGA’s preheating is meant to wipe off the moisture. (If the moisture was little, this step can be omitted)
Remove BGA: If the BGA will not be reused, and the PCB can endure high temperature, we can use high temperature (shorter heating period) to remove it.
Clean the pad: Pad cleaning is mainly clearing the solder paste and scaling powder remained on the surface of PCB after BGA removal. For that process, it must use standard cleaning agent. To ensure the reliability of the BGA solders, generally we cannot use the remained solder paste in the pad, and we must clear away the used solder paste, except that solder balls reform on the BGA. Because of the small size of BGA, especially CSP (or μBGA smaller), it is always difficult to cleaning the pad, so when reworking CSP, it needs to use Rinse-free Flux if the space around CSP is very small.
Lay on BGA Flux Paste: Laying solder paste on the PCB has important influence on the result of BGA Rework. It is convenient to lay solder paste on the PCB by selecting mould matched with BGA. For CSP, there are three solder pastes for choice, including flux paste, clean-free and water-soluble. If we choose the flux paste, the reflow time should be longer, if choose the clean-free solder paste, reflux temperature should be lower. Mounting: The main purpose of mounting to make every BGA solder align to the PCB pad with special equipment. Hot air reflows: Hot air reflow soldering is the key to the whole BGA Rework.
The curve of reflow soldering of BGA Rework should be similar with the original soldering one. Hot air reflow soldering curve can be divided into four zones, including preheat zone, heating zone, recirculation zone and cooling area. These four zones’ temperature and time parameter can be set respectively, when it connects with the computer, these programs can be saved and transferred at any moment.
In reflow soldering process, we must choose the right heating temperature and time of different zones; at the same time, we should notice the heating speed. Commonly, the maximal heating rate is not more than 6℃/s before 100℃, and the maximal heating rate is not more than 3℃/s after 100℃. In the cooling zone, the maximal cooling rate is not more than 6℃/s, because both of the exorbitant heating rate and cooling rate may cause damage to PCB and BGA, which sometimes cannot be observed by unaided eyes. For different BGA and different solder pastes, we should choose different heating temperature and time. For example, reflux temperature of CBGA BGA should be higher than that of PBGA…choose the higher reflux temperature. For no clean solder paste, its activity is lower than non-no clean solder paste, so the soldering temperature should not be too high, and the soldering time should not be too long, so as to prevent the oxidation of solder particle.
In hot air reflow soldering, the bottom of PCB board should be heated. There are two purposes for this kind of heating. First, avoid the warping and deformation in one-side heated PCB board; second, shorten the time of the solder paste melting. For the dimension pad of BGA rework, this kind of heating on the bottom of PCB is especially important. There are two ways of heating on the bottom of BGA rework equipment. One of them is hot air heating, and the other is infrared ray heating. The advantage of hot air heating is the homogeneous heating, which common Rework Techniques suggest to adopt this way of heating. What opposite with it is the disadvantage of infrared ray’s inhomogeneous heating.
We should choose the right hot air reflux suction nozzle. The hot air reflux nozzle is non-contact heating, which depend on the high temperature air current make every solder of joint on BGA melt synchronously. For that reason, it ensures the steady temperature circumstance in the whole of reflux process, and it protects the adjacent parts from damaging by the convective hot air’s regeneration.
In order to ensure the validity of BGA Rework Station, the installation should meet the following requirements.
Away from inflammable and explosives
Away from water and other liquids
Ventilated, dry place
Stable and flat, free from tremor
No heavy objects on the controlling box
Not affected by airflow of air conditioner, heater or ventilator
Leave a space of 30cm or more behind the rework station for the upper part to move and rotate
Bga Power supply:
Use a power supply with little fluctuations in voltage