Modern microcircuits are becoming ever smaller, and their installation is becoming denser. Soldering of such devices is available to people with skillful hands who are not afraid of painstaking work with the installation of boards.
Necessary
Soldering station with hot air gun, solder paste, stencil, flux, braid, tweezers, insulating tape, soldering iron, alcohol, alcohol canin, solder
Instructions
Step 1
Soldering the BGA packages Mark the place where the microcircuit is attached to the board with risks if the board does not have a silkscreen marking its position. Unsolder the microcircuit from the board. Hold the hair dryer perpendicular to the board. The air temperature in it is no more than 350 ° C, the air speed is low, the desoldering time is no more than a minute. Try not to overheat the circuit, do not heat it in the center, direct the air to the edges.
Step 2
Apply alcohol powder to the area of the board where the microcircuit was and heat. Clean the area with rubbing alcohol. Do the same with the microcircuit.
Step 3
Using a heated soldering iron and braid, remove the remnants of the old solder from the microcircuit and the board. Proceed carefully - do not damage the tracks on the board and the microcircuit. Secure the microcircuit in the stencil with electrical tape, so that the holes of the stencil line up with the contacts. Using a spatula or finger, apply solder paste to the stencil by rubbing it into the holes. While holding the stencil with tweezers, melt the paste using a hot air gun at no more than 300 ° C. Hold the hair dryer perpendicular to the stencil. Allow the stencil to cool until the solder solidifies. Hold the stencil with tweezers.
Step 4
Remove the tape from the stencil and heat it with a hair dryer until the solder paste flux melts. Please note - the temperature should be no more than 150 ° C, do not overheat. Separate the stencil from the microcircuit. If everything was done correctly, you should get rows of even, identical balls of solder on the microcircuit. Apply some flux to the board.
Step 5
Install the microcircuit on the board, carefully and accurately aligning the contacts on the board with the solder balls on the microcircuit, taking into account the previously applied marks, or by silk-screening. Heat the microcircuit with a hair dryer at a temperature not exceeding 350 ° C until the solder melts. Then the microcircuit will be precisely set in place under the influence of surface tension forces.
Step 6
Soldering leadless microcircuits such as LGA or MLF For this operation it is also better to use a blow dryer, but if you are a virtuoso of soldering, then try to carry it out using a regular soldering iron. However, a hairdryer is still more convenient. When designing a board for a microcircuit, try to create such configurations of tracks so that when the microcircuit is soldered to them, the latter does not install crookedly.
Step 7
Apply flux to the board (best of all, ASAHI WF6033 or glycerin-hydrazine) and use a heated soldering iron to apply solder to the board tracks in the area where the microcircuit will be installed. Thoroughly rinse off the remaining flux with alcohol. Exactly using the same technology, apply solder to the contacts of the microcircuit and just as carefully remove the remaining flux. Apply no-clean flux (ASAHI brand QF3110A or alcohol monofilm) to the board and chip.
Step 8
Carefully place the microcircuit on the board (it should adhere slightly due to the layer of flux). Heat the microcircuit with a soldering hair dryer (temperature no more than 350 ° C). After the solder has melted, the microcircuit will accurately fit onto the contacts under the action of surface tension forces. Remove flux residues with alcohol.
