The chip hot press welding process is divided into two kinds according to the shape of the inner lead after press welding:
Ball welding (butt welding) and pin welding. Both kinds of welding need to heat the metal frame of the welded chip and the hollow splicer respectively (the temperature of the former is 350 ~ 400℃, the latter is 150 ~ 250℃), and add appropriate pressure to the splicer.
First, the gold wire segment protruding from the bottom through the hollow splitter is cut by hydrogen and oxygen flame or high pressure to form a round ball, which is pressed into the aluminum welding area on the chip under the splitter. When welding with this method, the welding area is large, the lead deformation is moderate and uniform, which is a more ideal welding form.
Then the split knife is lifted, the gold wire is pulled to the other end (that is, corresponding to the welding area to be connected on the lead frame), and the downward pressure is applied for welding, and the welding spot formed is called pin welding.
Note on welding chip:
1, for the lead is gold-plated silver treatment of integrated circuits, just wipe the lead with alcohol.
2, for the CMOS circuit that shorted the leads in advance, the short route can not be cut off before welding, and should be cut off after welding.
3, the staff should wear the anti-static bracelet on the anti-static workbench for welding operations, the workbench should be clean and tidy.
4, handheld integrated circuit, should hold the outer package of the integrated circuit, can not touch the lead.
5, welding, should use 20W internal heat type soldering iron, and the soldering iron must be reliably grounded.
6, welding, each lead welding time can not exceed 4s, continuous welding time can not exceed 10s.
7, to use a low melting point of the flux, the general flux melting point should not exceed 150℃.
8, for the MOS tube, the installation should be first S pole, then G pole and finally D pole in the order of welding.
9. When installing the heat sink, the mounting surface should be wiped with alcohol first, and then coated with a layer of silicone, and the fastening screws should be installed after the leveling.
10, directly weld the integrated circuit to the circuit board, the detonation sequence is: ground end → output end → power end → input end sequence.
Extended data
Chip welding processes can be divided into two categories:
① Low melting point alloy welding method: the welding materials used are gold-silicon alloy, gold-gallium alloy, indium lead-silver alloy, lead-tin silver alloy, etc.
② Bonding method: Using low temperature silver paste, silver mud, epoxy resin or conductive adhesive to weld the chip.
In plastic packages of integrated circuits, low temperature (below 200℃) silver paste, silver mud or conductive adhesive is often used for chip welding in the form of bonding. In addition, during sintering (that is, baking after the chip is glued to the silver paste), the atmosphere and temperature depend on the type of silver paste used.
Low temperature silver paste is mostly sintered in the air, the temperature is 150 ~ 250℃; The high temperature silver slurry is protected by nitrogen, and the sintering temperature is 380 ~ 400℃.