How to solder circuit boards? And how does BGA stand for? These two frequently asked questions are answered by the bgacenter masters during soldering courses. From English-ball grid array, that is, an array of balls that looks like a grid. Solder balls are applied to the chip through a stencil, then a stream of hot air melts the solder itself and the correct shape of the contacts is formed.
And the soldering process consists of a certain sequence of actions, observing which we get a high-quality connection. But there are a large number of nuances, for which they come to study. Starting from what angle and at what distance from the Board to keep the nozzle of the hair dryer, temperature modes of dismantling and mounting chips, which side to start the blade. And many other subtleties that the current master of the service center may know. And the one who can confirm their level of completed repairs.
90 % of the repair success rate depends on the correct disassembly of the chips. It is at this stage that it is important not to tear off the nickels and damage the chip with high temperature. And begin soldering the chip, with the removal of the compound.
Compound – a polymer resin, usually black or brown, used in the manufacture of phone system boards. Purpose of the compound:
The most important chips, such as: CPU, BB_RF, EEPROM, NAND Flash, Wi-Fi in the factory after installation, are filled with compound. And before you perform dismantling, you need to clear the perimeter of the resin.
1. Carefully inspect the Board for previous repairs.
2. Perform diagnostics and make the necessary measurements.
3. Prepare the Board for soldering, remove protective screens, stickers. Disconnect and remove the coaxial cable. Attach the motherboard to the appropriate holder.
4. Remove the compound around the chip being disassembled. The temperature on the hair dryer is 210-240 degrees Celsius.
5. Install heat sinks. The place of installation of heat sinks depends on the location of the soldered chip.
6. Use a hair dryer to warm up the Board for a few seconds. Thus, we increase the temperature of the Board, so that the
flux spreads evenly.
7. Apply FluxPlus, or any other non-flushing flux, to the surface of the chip.
8. Direct the hot air flow to the soldered element. The temperature during disassembly is 340 degrees Celsius. How do I know that the solder has melted and it’s time to remove the chip from the Board? There are several ways to do this:
9. Prepare the contact platform. For this:
10. The Board is prepared for the installation of a serviceable chip.
The General principle of soldering is as follows: due to the surface tension created when the solder melts, the chip is fixed relative to the contact pad on the system Board. The soldering temperature of bga chips on iPhone boards is 320-350 degrees Celsius.
Preparation of the chip:
To reduce the time when the Board is exposed to high temperatures, the Board is heated. We recommend the STM 10-6 monoblock PCB heater. Stable maintenance of the set temperature over the entire area of the heating element contributes to uniform heating of the entire motherboard (depends on the heater model). And another advantage over other thermostats is a convenient universal mounting system.
On the market represented a huge number of manufacturers of fluxes. Bga center uses the widely used FluxPlus. Pay attention to the date of manufacture and expiration date of the flux. The advantages of flux-gel:
Purpose of the Quick 861DE ESD Lead station-soldering (dismantling and installation) BGA chips and SMD components. Advantages of this station:
What can be improved in the design of the station is the temperature control not by buttons, but by rotating controllers, as on the Quick 857D (W)+.
PS-900 METCAL-induction soldering system. The power of the soldering iron 60 W is enough to work with multilayer boards of modern electronics. The experience of phone repair engineers with this soldering iron is 4 years. What are the distinctive features of the PS-900:
For the novice master on repair of phones, a good option would be a microscope СМ0745. Binocular microscope with a focal length of 145 mm (when installing a Barlow scattering lens). Purpose of the lens system, increasing the focal length while maintaining the working area.
The advantage СМ0745:
For soldering iPhone boards, mainly used solder balls with a diameter of 0.2 mm. Usually delivered in a glass container, 10,000 balls in each jar.
Composition of solder balls:
After performing the soldering work, make sure that the BGA soldering is performed efficiently. Control is performed in several ways:
For more information about verification methods, read the following article.