Let's take a closer look at the chip on board. We try our best to explain the definition, application, functions and packaging of pcb chip.
First, the COB attaches the semiconductor integrated circuit to the PCB. The Chip on Board IC is semi-exposed. The second step is to attach the wire to the surface of the PCB. Chip on board assembly is the process of mounting bare semiconductor on PCB chip or substrate using conductive or non-conductive epoxy. chip on board ic usually use gold ball bonding or aluminum wedge bonding for electrical connection. For applications that require very high thermal and electrical conductivity, we have a variety of semi-sintered epoxy resins that can be used for chip-on-board assembly.
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Pcb chip technology uses adhesives to connect semiconductor chips directly to the PCB substrate. By wire bonding it to an existing circuit pattern on the board, it is then packaged. Chip on board takes surface mount technology (SMT) to its extreme. The essential difference between COB (chip on board) and SMT is: COB (chip on board) usually involves high lead count, active devices and does not require ceramic or molded plastic external device packaging.
An unpackaged integrated circuit (IC) is mounted on a laminate substrate and signal conditioning or support circuits. When the IC is connected to the corresponding substrate interconnection by gold wire bonding, an electrical connection is formed. A junction coating material can then be applied on top of the chip to protect the chip and wire bonds.
The expansion machine is used to uniformly expand the entire LED chip film provided by the manufacturer so that the tightly arranged LED die attached to the film's surface is pulled apart to facilitate the thorn crystal.
Place the expanded crystal ring on the backing machine surface where the silver paste layer has been scraped and put the silver paste on the back. Some silver paste. Suitable for bulk LED chips. Use a dispensing machine to spot an appropriate amount of silver paste on the PCB printed circuit board.
Put the crystal expansion ring prepared with silver paste into the piercing crystal holder. And the operator will pierce the LED chip on the PCB with a piercing pen under the microscope.
Put the pierced PCB printed circuit board in a thermal cycle oven and let it stand for some time. After the silver paste is cured, take it out (not for a long time, otherwise the coating of the LED chip will be yellowed, that is, oxidized. Cause difficulties). If there is LED chip bonding, the above steps are required; if there is only IC chip bonding, the above steps are canceled.
Use a dispenser to put an appropriate amount of red glue on the IC position on the PCB. And then use an anti-static device to correctly place the IC die on the red glue or black glue.
Put the glued die in a thermal cycle oven on a large flat heating plate and let it stand at a constant temperature for a while, or it can be cured naturally (a longer time).
The aluminum wire bonding machine is used to bridge the chip (LED die or IC chip) with the aluminum wire of the corresponding pad on the PCB board; that is, the inner lead of the COB is welded.
Use special inspection tools (different equipment for COB for other purposes, simply high-precision stabilized power supply) to inspect the COB board and re-repair the unqualified board.
A glue dispenser is used to place an appropriate amount of the prepared AB glue on the bonded LED die. And the IC is packaged with black glue and then packaged in appearance according to customer requirements.
Put the sealed PCB printed circuit board into a thermal cycle oven and let it stand at a constant temperature. Different drying times can be set according to requirements.
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