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Aluminum PCB

Definition edit
The aluminum substrate is a metal-based copper-clad board with good heat dissipation function. Generally, a single panel is composed of a three-layer structure, which is a circuit layer (copper foil), an insulating layer, and a metal base layer. For high-end use, there are also double-panel designs with circuit layers, insulation layers, aluminum bases, insulation layers, and circuit layers. Very few applications are multilayer boards, which can be made by laminating ordinary multilayer boards with insulating layers and aluminum substrates.
The LED aluminum substrate is the PCB, which is also the meaning of the printed circuit board, but the material of the circuit board is aluminum alloy. In the past, the material of our general circuit board was glass fiber, but because the LED generates heat, the circuit board for LED lamps is The aluminum substrate can conduct heat quickly. The circuit boards for other equipment or electrical appliances are still glass fiber boards!
How it works
The power device is surface-mounted on the circuit layer. The heat generated during the operation of the device is quickly conducted to the metal base layer through the insulating layer, and then the heat is transferred by the metal base layer to achieve heat dissipation of the device
Aluminum substrate production
Compared with the traditional FR-4, the aluminum substrate can minimize the thermal resistance and make the aluminum substrate have excellent thermal conductivity; compared with the thick film ceramic circuit, its mechanical properties are extremely excellent.
In addition, the aluminum substrate has the following unique advantages:
Meet RoHs requirements;
More suitable for SMT process;
In the circuit design scheme, heat diffusion is extremely effectively treated, thereby reducing the module operating temperature, extending the service life, and improving power density and reliability;
Reduce the assembly of radiators and other hardware (including thermal interface materials), reduce product size, reduce hardware and assembly costs; optimize the combination of power circuits and control circuits;
Replace fragile ceramic substrates for better mechanical durability.
The circuit layer (usually using electrolytic copper foil) is etched to form a printed circuit, which is used to realize the assembly and connection of the device. Compared with the traditional FR-4, with the same thickness and the same line width, the aluminum substrate can carry a higher current.
Comparison of copper foil current carrying capacity between aluminum substrate and FR-4
Comparison of copper foil current carrying capacity between aluminum substrate and FR-4
Insulation
The insulation layer is the core technology of the aluminum substrate, which mainly plays the functions of bonding, insulation and heat conduction. The aluminum substrate insulation is the largest thermal barrier in the power module structure. The better the thermal conductivity of the insulation layer, the more favorable it is to spread the heat generated during the operation of the device, and the lower the operating temperature of the device, so as to increase the power load of the module, reduce the volume, extend the life, and increase the power output .
Metal substrate
What kind of metal is used for the insulating metal substrate depends on the comprehensive consideration of the thermal expansion coefficient, thermal conductivity, strength, hardness, weight, surface state and cost of the metal substrate.
In general, considering the conditions such as cost and technical performance, aluminum plate is an ideal choice. Available aluminum plates are 6061, 5052, 1060 and so on. If there are higher requirements for thermal conductivity, mechanical properties, electrical properties and other special properties, copper plates, stainless steel plates, iron plates and silicon steel plates can also be used.
Aluminum substrate sheet
Aluminum substrate sheet
Features edit
Aluminum substrate (metal-based heat sink (including aluminum substrate, copper substrate, iron substrate)) is a low-alloyed Al-Mg-Si series high-plasticity alloy plate (see the figure below for structure), which has good thermal conductivity and electrical insulation Compared with the traditional FR-4, the aluminum substrate uses the same thickness and the same line width. The aluminum substrate can carry a higher current. The aluminum substrate can withstand voltages up to 4500V and the thermal conductivity is greater than 2.0. Aluminum substrates are the main industry.
● Using surface mount technology (SMT);
Street light aluminum substrate
Street light aluminum substrate
● Extremely effective treatment of thermal diffusion in circuit design schemes;
● Reduce product operating temperature, improve product power density and reliability, and extend product life;
● Reduce product volume, reduce hardware and assembly costs;
● Replaces fragile ceramic substrates for better mechanical durability. structure
Aluminum-based copper clad board is a metal circuit board material composed of copper foil, thermally conductive insulation layer and metal substrate. Its structure is divided into three layers:
Cireuitl.Layer circuit layer: It is equivalent to the copper-clad board of ordinary PCB, and the thickness of the copper foil of the circuit is loz to 10oz.
DielcctricLayer insulation layer: The insulation layer is a layer of low thermal resistance thermally conductive insulating material. Thickness: 0.003 “to 0.006″ inches is the core technology of aluminum-based copper clad laminates, which has obtained UL certification.
BaseLayer: It is a metal substrate, usually aluminum or copper. Aluminum-based copper clad laminates and traditional epoxy glass cloth laminates.
PCB materials have incomparable advantages compared to other materials. Suitable for surface mount SMT technology of power components. No heat sink is needed, the volume is greatly reduced, the heat dissipation effect is excellent, and the good insulation performance and mechanical performance.
The LED die substrate is mainly used as a medium for deriving thermal energy between the LED die and the system circuit board, and is combined with the LED die through a wire bonding, eutectic or flip-chip process. Based on thermal considerations, the LED chip substrates on the market are mainly ceramic substrates, which can be roughly divided into three types: thick-film ceramic substrate, low-temperature co-fired multilayer ceramic, and thin-film ceramic substrate. For high-power LED components, a thick-film or low-temperature co-fired ceramic substrate is often used as the die heat dissipation substrate, and then the LED die is combined with the ceramic substrate by gold wire. As mentioned in the introduction, this gold wire connection limits the effectiveness of heat dissipation along the electrode contacts. Therefore, both domestic and foreign manufacturers are working hard to solve this problem. There are two solutions. One is to find a substrate material with a high heat dissipation coefficient to replace alumina, which includes a silicon substrate, a silicon carbide substrate, an anodized aluminum substrate, or an aluminum nitride substrate. Among them, silicon and silicon carbide substrates are semiconductors. Characteristics, making it face a more severe test at this stage, and the anodized aluminum substrate is easily connected due to fragmentation due to the insufficient strength of the anodized oxide layer, which limits its practical application. Therefore, at this stage, The more mature and more generally accepted is the use of aluminum nitride as a heat sink substrate; however, the traditional thick film process is not suitable for aluminum nitride substrates (the material must be subjected to 850 ° C atmospheric heat treatment after silver paste printing)
Aluminum substrate for fluorescent lamps
Aluminum substrate for fluorescent lamps
, So that it has a problem of material reliability), therefore, the aluminum nitride substrate circuit needs to be prepared by a thin film process. The aluminum nitride substrate prepared by the thin film process greatly accelerates the efficiency of the heat from the LED die through the substrate material to the system circuit board, so the burden of heat from the LED die through the metal wire to the system circuit board is greatly reduced, thereby achieving high heat dissipation. Effect.
Purpose edit
Application of aluminum substrate: power hybrid IC (HIC).
Audio equipment
Input, output amplifier, balanced amplifier, audio amplifier, preamplifier, power amplifier, etc.
Power equipment
Switching regulator `DC / AC converter` SW regulator, etc.
Communication electronics
The high-frequency amplifier `filtering electrical device` reports the circuit.
Office automation equipment
Motor drivers, etc.
car
Electronic regulator `ignitor` power controller and so on.
computer
CPU board `floppy disk drive` power supply unit, etc.
Power module
Converter `solid relay` rectifier bridge, etc.
Lighting
With the promotion and promotion of energy-saving lamps, various energy-saving gorgeous LED lamps have been welcomed by the market, and aluminum substrates used in LED lamps have begun to be applied on a large scale.
Process editing
I. Opening
1. Opening process
Production process of aluminum substrate
Production process of aluminum substrate
Picking-Shearing
2. Purpose of opening
Cut large size incoming materials to the size required for production
3. Notes on opening
① Check the size of the first piece
② Pay attention to scratches on aluminum and copper
③ Pay attention to the delamination and edge of the board
Second, drilling
1. The process of drilling
Pins-Drilling-Inspection Board
2. Purpose of drilling
Positioning and drilling of plates to assist in subsequent production processes and customer assembly
3. Precautions for drilling
① Check the number of holes and the size of the holes
② Avoid scratching the sheet
③ Check the aluminum front edge and hole position deviation
④ Check and replace the drill in time
⑤ Drilling is divided into two stages, one drilling: after cutting, the holes are drilled as peripheral tool holes
Second drill: tool hole in the unit after soldering
Three, dry / wet film imaging
1.Dry / wet film imaging process
Grinding plate-film-exposure-development
2.Dry / wet film imaging purpose
Show the parts needed to make the circuit on the sheet
3.Precautions for dry / wet film imaging
① Check if the circuit is open after development
② Is there any deviation in the alignment of development to prevent the occurrence of dry film fragmentation?
③ Pay attention to the poor circuit caused by the board scratches.
④ There should be no air residue during exposure to prevent poor exposure
⑤ Stand still for more than 15 minutes after exposure before developing
Fourth, acid / alkaline etching
1. Acid / alkaline etching process
Etching-film release-drying-inspection board
2. Purpose of acidic / alkaline etching
After the dry / wet film is imaged, the required circuit parts are retained, and the extra parts other than the circuits are removed. During acid etching, attention should be paid to the corrosion of the aluminum substrate by the etching solution;
3.Precautions for acidic / alkaline etching
① Note that the etching is not clean and the etching is excessive.
② Pay attention to line width and line thickness
③ The copper surface must not be oxidized or scratched.
④ Remove the dry film
Five, silk screen solder mask, characters
1. Silk screen solder mask and character flow
Silkscreen-Pre-bake-Exposure-Development-Character
2.The purpose of silk screen solder mask and character
① Solder protection: protect the circuits that do not need soldering, prevent tin from entering and cause short circuit
② Characters: play a role of identification
3.Precautions for silk screen solder mask and characters
① Check whether there is garbage or foreign matter on the surface
② Check the cleanliness of the screen
COB aluminum substrate
COB aluminum substrate
③ Pre-bake for more than 30 minutes after screen printing to avoid air bubbles on the line.
④ Pay attention to the thickness and uniformity of silk screen
⑤ After pre-baking, the plate should be completely cooled to avoid staining the film or destroying the gloss of the ink surface.
⑥ Place the ink face down during development
Six, V-CUT, gong board
1. V-CUT, the process of gong board
V-CUT——Gong board——Tear protective film—except Pifeng
2. V-CUT, the purpose of the gong board
① V-CUT: Connect a single PCS line to the whole PNL sheet cutting with a small part connected for easy packaging and removal
② Gong board: remove excess parts from the circuit board
3, V-CUT, the matters needing attention
① Pay attention to the size of V during the V-CUT process.
② Pay attention to the burrs caused by the gong board, and the deflection of the gong knife.
③ Finally, avoid scratching the board when removing the front.
7. Testing, OSP
1. Testing, OSP process
Circuit Test-Withstand Voltage Test-OSP
2. The purpose of testing, OSP
① Line test: check whether the completed line works normally
② Withstand voltage test: check whether the completed line can withstand the specified voltage environment
③ OSP: Let the circuit be better soldered
3. Testing, OSP considerations
① How to distinguish between qualified and unqualified products after testing
② Placement after OSP
③ Avoid line damage
Eight, FQC, FQA, packaging, shipping
1. Process
FQC-FQA-Packaging-Shipping
2. Purpose
① FQC conducts full inspection and confirmation of products
② FQA spot check
③ Pack and ship to customers as required
3. Note
① During the visual inspection, FQC pays attention to the confirmation of appearance and makes a reasonable distinction.
② FQA really conducts random inspection on FQC inspection standards
③ To confirm the quantity of packaging, to avoid mixed plates, wrong plates and packaging damage [3]
Test project editing
Experimental conditions
Typical value
thickness
Performance parameter
Peel strength
Solder resistance
No layering, no foaming
Dielectric breakdown voltage
Thermal resistance
Cooked impedance
Thermal Conductivity
Surface resistance
Volume resistance
Dielectric constant
Dielectric loss
Flame resistance
※ The above thickness is only the thickness of the adhesive layer, excluding copper foil and copper plate.
structure
Insulation thickness: 75 um ±% Conductor thickness: 35um ± 10%
Metal plate thickness: 1.0mm ± 0.1mm [3]
Editing storage conditions
Aluminum substrates are generally stored in a dark, dry environment. Most aluminum substrates are prone to moisture, yellowing, and blackening. Generally, it is used within 48 hours after opening the vacuum packaging. [3]
Working principle of aluminum substrate
Working principle of aluminum substrate
Model editing
Aluminum substrates commonly used in aluminum substrates are mainly 1000 series, 5000 series, and 6000 series. The basic characteristics of these three series of aluminum materials are as follows:
①1000 series stands for 1050, 1060, 1070. 1000 series aluminum plates are also called pure aluminum plates. Among all series, 1000 series are the ones with the highest aluminum content, and the purity can reach more than 99.00%. Because it does not contain other technical elements, the production process is relatively simple and the price is relatively cheap. It is the most commonly used series in conventional industry. The majority of the circulation in the market is the 1050 and 1060 series. The 1000 series aluminum plate is based on the last two digits to determine the minimum aluminum content of this series. For example, the last two digits of the 1050 series are 50. According to the international brand naming principle, its aluminum content must be above 99.5% to be qualified products. China’s aluminum alloy technical standards (GB / T3880-2006) also clearly stipulated that the aluminum content of 1050 reached 99.5%. For the same reason, the aluminum content of the 1060 series aluminum plate must reach more than 99.6%.
②5000 series represents 5052, 5005, 5083, and 5A05 series. 5000 series aluminum plate belongs to the more commonly used alloy aluminum plate series. The main element is magnesium with a magnesium content of 3-5%. It is also called aluminum-magnesium alloy. The main features are low density, high tensile strength and high elongation. In the same area, the weight of aluminum-magnesium alloy is lower than other series, so it is often used in aviation, such as aircraft fuel tanks. In addition, it is widely used in conventional industries. Its processing technology is continuous casting and rolling, which belongs to the hot-rolled aluminum plate series, so it can be used for deep oxidation processing. 5000 series aluminum plate is one of the more mature aluminum plate series in China.
③ 6000 series Representative 6061 mainly contains two elements of magnesium and silicon. Therefore, the advantages of 4000 series and 5000 series are concentrated. 6061 is a cold-treated aluminum forged product, which is suitable for applications with high requirements on corrosion resistance and oxidation. Good workability, excellent interface characteristics, easy coating, and good processability.
6061 general characteristics: excellent interface characteristics, easy coating, high strength, good workability, strong corrosion resistance. Typical uses of 6061 aluminum: aircraft parts, camera parts, couplers, marine accessories and hardware, electronic accessories and connectors. Considering the material’s texture, hardness, elongation, chemical properties, and price, aluminum substrates are generally used in the 5052 alloy aluminum plate of 5000 series aluminum.
Category editor
Aluminum substrates can be divided according to the process: tin-sprayed aluminum substrate, alumina-based


Post time: Mar-25-2020