The aluminum substrate is a metal-based copper clad laminate with good heat dissipation function. Generally, the single panel is composed of a three-layer structure, which is a circuit layer (copper foil), an insulating layer and a metal base layer. Also used for high-end use is designed as a double panel, the structure is circuit layer, insulation layer, aluminum base, insulation layer, circuit layer. A very small number of applications are multi-layer boards, which can be made of ordinary multi-layer boards combined with an insulating layer and an aluminum base.
The surface of the power device is mounted on the circuit layer, and the heat generated by the device is quickly conducted to the metal substrate through the insulating layer, and then the heat is transferred from the metal substrate to dissipate heat from the device (see Figure 2).
Compared with the conventional FR-4, the aluminum substrate can minimize the thermal resistance, and the aluminum substrate has excellent heat conduction performance; compared with the thick film ceramic circuit, its mechanical properties are extremely excellent.
In addition, aluminum substrates have the following unique advantages:
Meet RoHs requirements;
More suitable for SMT process;
Extremely effective treatment of thermal diffusion in the circuit design, thereby reducing module operating temperature, extending service life, increasing power density and reliability;
Reduce the assembly of heat sinks and other hardware (including thermal interface materials), reduce product size, reduce hardware and assembly costs; optimize power circuit and control circuit combination;
Replace the fragile ceramic substrate for better mechanical durability.
Line layer
The circuit layer (usually using electrolytic copper foil) is etched to form a printed circuit for assembly and connection of the device. Compared to the conventional FR-4, the same thickness and the same line width allow the aluminum substrate to carry higher currents.
2. Insulation
The insulating layer is the core technology of the aluminum substrate, and mainly functions as bonding, insulation and heat conduction. The aluminum substrate insulation layer is the largest thermal barrier in the power module structure. The better the thermal conductivity of the insulating layer, the more favorable the diffusion of heat generated during the operation of the device, the more favorable it is to reduce the operating temperature of the device, thereby improving the power load of the module, reducing the volume, extending the life, and improving the power output. .
3. Metal base layer
What kind of metal is used for the insulating metal substrate depends on the thermal expansion coefficient, thermal conductivity, strength, hardness, weight, surface state and cost of the metal substrate.
1. Audio equipment: input, output amplifier, balanced amplifier, audio amplifier, preamplifier, power amplifier, etc.
2. Power supply equipment: switching regulator `DC/AC converter `SW regulator, etc.
3. Communication electronic equipment: high frequency amplifier <filtering appliance` reporting circuit.
4. Office automation equipment: motor drives, etc.
5. Car: Electronic regulator `igniter` power controller, etc.
6. Computer: CPU board `floppy disk drive` power supply unit, etc.
7. Power module: Inverter 'solid relay' rectifier bridge and so on.
8. Lighting fixtures: With the promotion of energy-saving lamps, aluminum substrates used in LED lamps have also begun to be applied on a large scale.
1, the process of cutting materials
Picking - cutting
2, the purpose of the material
Cut large sizes of incoming material into the required size for production
3, precautions for cutting materials
1The first piece of material is checked for the first piece size
2 pay attention to aluminum scraping and copper scraping
3 pay attention to the edge layering and edging
b) drilling1, the process of drilling
Selling nails - drilling - inspection board
2, the purpose of drilling
Positioning the plate for drilling provides assistance for subsequent production processes and customer assembly
3. Precautions for drilling
1 Check the number of holes and the size of the holes
2 avoid the scratching of the sheet
3 check the surface of the aluminum surface, the hole deviation
4 timely inspection and replacement of the drill
5 drilling is divided into two stages, one drill: after drilling, the hole is a peripheral tool hole;
Two drills: tool hole in the unit after solder mask
c) Dry/wet film imaging1, dry / wet film imaging process
Grinding plate - film - exposure - development
2, dry / wet film imaging purposes
Presenting the parts needed to make the line on the sheet
3, dry / wet film imaging considerations
1 Check if there is an open circuit after development
2 Whether there is deviation in the development alignment to prevent the generation of dry film
3 Pay attention to the bad line caused by the surface wipe
4 There should be no air residue during exposure to prevent poor exposure
5 After the exposure, it should be still for more than 15 minutes before developing.
d) Acidic/alkaline etching1. Acid/alkaline etching process
Etching - film removal - drying - inspection board
2. Acid/alkaline etching purpose
After the dry/wet film is imaged, the required line portion is retained, and the excess portion other than the line is removed.
3, acidic / alkaline etching considerations
1 Note that the etching is not clean, excessive etching
2 pay attention to line width and line fine
3 copper surface is not allowed to have oxidation, scratching phenomenon
4 retreat the film to be cleaned
5) silk screen soldering resistance, characters1, silk screen soldering, character flow
Silk screen - pre-bake - exposure - development - characters
2, silk screen soldering, the purpose of the character
1 anti-welding: protect the circuit that does not need to do solder, prevent tin from entering the short circuit
2 characters: play a role
3, silk screen soldering, character notes
1 Check the board for any rubbish or foreign objects
2 Check the cleanliness of the stencil
3 After silk screen printing, pre-bake for more than 30 minutes to avoid bubbles on the line.
4 pay attention to the thickness and uniformity of silk screen
5 Pre-baked plate should be completely cooled to avoid sticking to the film or destroying the gloss of the ink surface.
6 The ink is placed face down when developing
VI) V-CUT, seesaw1, V-CUT, the process of the seesaw
V-CUT - seesaw - tear protective film - in addition to the front
2, V-CUT, the purpose of the seesaw
1V-CUT: The single PCS line is cut with a small portion of the entire PNL plate for easy packaging and removal.
2 锣 board: remove the excess part of the board
3, V-CUT, the considerations for the seesaw
Pay attention to the size of V during the 1V-CUT process, the defects of the edges, burrs
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3 Finally, avoid scratching the board when removing the front.
Seven) test, OSP1, test, OSP process
Line test - withstand voltage test - OSP
2, testing, the purpose of OSP
1 line test: check if the completed line is working properly
2 withstand voltage test: test whether the completed line can withstand the specified voltage environment
3OSP: Let the line be better soldered
3, testing, OSP considerations
1 How to store qualified and non-conforming products after how to distinguish after testing
2 after the OSP is placed
3 to avoid damage to the line
Eight) FQC, FQA, packaging, shipping1, the process
FQC - FQA - Packaging - Shipping
2. Purpose
1FQC confirms the product
2FQA sampling verification
3 package and ship to customers according to requirements
3, pay attention
1FQC pays attention to the confirmation of the appearance during the visual inspection, making a reasonable distinction
2FQA really checks and verifies the inspection standard of FQC
3 to confirm the number of packaging, to avoid mixing, wrong board and packaging damage
Aluminum substrate storage conditions
Aluminum substrates are generally stored in a dark, dry environment. Most aluminum substrates are prone to moisture, yellowing and blackening. Generally, they should be used within 48 hours after vacuum packaging.
Aluminum substrate assembly method
The aluminum substrate assembly method eliminates the need for heat sinks, assembly fixtures, cooling fans, and other hardware used in conventional assembly. This structure enables automatic assembly and significantly reduces assembly costs.
Aluminum substrate related articles recommended:
A text to understand the thermal conductivity standard of aluminum substrates
Interpretation of aluminum substrate pcb production specifications and design rules
Summary of knowledge points for rapid proofing of aluminum substrates
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