Aluminum base board PCB ABC

What is the aluminum base board PCB?

Aluminum base pcb is an unique metal-based CCL, aluminum PCB is with good thermal conductivity, electrical insulation and mechanical processing performance.

Characters of aluminum base PCB:

● Aluminum base PCB surface with a mount technology (SMT)

● Aluminum base PCB has good heat dissipation in the circuit design

● Aluminum core pcb can reduce the temperature, increase power density and reliability, extend product life

●Aluminum board PCB can reduce size, lower hardware and assembly costs

●Aluminum substrate PCB can replace ceramic substrates board, to obtain better mechanical endurance.

PCB aluminum structure

Aluminum PCB copper clad is a metal circuit board materials, composed with copper foil, insulation layer and the metal substrate, its structure is divided into three layers:

Circuit layer: same with general PCB CCL, copper foil thickness could be 1oz to 10oz.

Insulation: insulation layer is a layer materials with low thermal resistance, thickness from 0.003 "to 0.006”, is the key technology of aluminum core board, has received UL certification.

Base layer: is metal substrate, usually aluminum or copper. Aluminum circuit boards and traditional FR4 laminated sheet

PCB aluminum board consist of circuit layer, insulation layer and metal core .Circuit layers (copper foil CCL) is usually formed after printed circuit etching, which make each components connected. In general, the circuit layer requires a great currency loading ability, that needs thicker foil, usually 35μm ~ 280μm.

Insulation layer is the core point of PCB aluminum board. It is usually filled by a special ceramic special polymer, with feature of thermal resistance, excellent viscoelastic properties, heat resistant and aging-resistant, could withstand mechanical and thermal stresses.  Insulation layer of IMS-H01, IMS-H02, LED-0601 and other high-performance aluminum plate PCB use such technology, which enable it with an extremely excellent thermal properties and high electrical insulation strength.

Metal substrate is the support part of aluminum board, which requires a high thermal conductivity. Usually use aluminum core, sometimes also copper core (copper core pcb can provide better thermal conductivity), suitable for drilling, punching, cutting and other conventional machining. Compared with other PCB material, it has its own advantages, suitable to SMT surface mount assembly process, no radiator, much smaller, excellent heat dissipation, good insulation properties and mechanical performance.

PCB aluminum board applications:

1. Audio device: input, output amplifiers, balanced amplifiers, audio amplifiers, preamplifiers, power amplifiers, etc.

2. Power supply: switching regulator, DC / AC converter, SW regulator and so on.

3. Communication Electronic Equipment: Electric high-frequency amplifier, filtering, transmitter circuits.

4. Office Automation Equipment: motor drives.

5. Car: Electronic regulator, igniter, power controller.

6. Computer: CPU boards, floppy drives, power devices.

7. Power Modules: solid state relay inverter, rectifier bridges.

PCBA Manufacturing process flow

PCBA Assembly Process Flow from Agile Circuit Co., Ltd

Basic Knowledge about Single Sided PCB, Double Sided PCB and Multi-layer PCB

Single Sided PCB, Double Sided PCB and Multi-layer PCB

1. What is a single sided PCB?

Single sided pcb is the basic simple PCB, parts is layouted on one side and the circuit is on the other side. As there is only layer conductor, it is called single sided pcb (Single-sided pcb or one layer pcb. It is restricted in the circuit design (because there is only one side conductor, and no cross permitted, each line must have its own path), so it is more frequently used in the early printed circuits pcb.

Single sided PCB diagram mainly use network printing (Screen Printing) .That is to print resist on the bare copper, etch and then print solder mask, finally punching to finish parts plated hole and profile. In addition, some small amount of various products usually use

photoresist to pattern circuit.

2. What is the double-sided PCB?

 What is double sided PCB (2 layers circuit pcb)? How to identify a board is double-sided and what is double-sided circuit board? These questions may be fuzzy for green hands new engaged in printed circuits filed. It is frequently heard single sided board, double sided pcb, multilayer pcb, aluminum pcb, impedance pcb board, FPC circuits board etc..But usually they couldn't be distinguished. Today we will lead these new friends learn about how to confirm double layer pcb.

Strictly speaking, double sided circuit board is a kind of very important PCB. It is widely used. To recognize a double-sided PCB board is also very simple. After you understand what is single layer pcb, two side pcb is the extension of one side pcb. When a single side circuit is not enough, it will need to go to the opposite side. There will be conductor/line on both two sides. Two Layer pcb with another feature is that it have PTH vias. Simply speaking, double sided pcb is with two-sided traces, top layer and bottom layer.

Some may ask a pcb with double side traces, but only one side electronic components, is double layer board or single layer? The answer is obvious, such board is double-sided, just assembly component at one side( component sides).

3. What is multi-layer pcb

How to identify a pcb board is multi layer or not? What character does multi-layer circuit pcb board have? What kind of printed circuit boards pcb is multi layers pcb? What is multi-layer pcb used for? Let's check it.

Multilayer pcb is as the name implies, that is PCB boards with more than two layers, for example, four layers, six layers, eight layers, etc. Since it is double-sided multiple, then they have many common features with double layers pcb: more than two layers conductive traces, separated by insulating material between the layers, and the layer between the conductive traces must connected through drilling, lamination as required .The advantage of multilayer circuit boards is with multi layer conductive wire, high density drilling, the volume will be relatively small and the weight is relatively light accordingly. The high density line reduces the space of components which means more reliable. As there are more layers circuits, it will be flexible for PCB design / layout. And it plays the role of impedance speed transmission circuit forming. Except these advantages, multi-layer circuit boards also have its disadvantage, such as higher cost, long production time, difficult testing etc.

However, these deficiencies of multi layers printed circuits do not affect their use. Multi-layer printed circuit boards is the result of the development of electronic technology to high-speed, multi-function, high-capacity, small size. With the continuous development of electronic technology, especially extensive application of large-scale and ultra large scale integrated circuit, multi-layer circuit pcb with more requirement on fine line width, small aperture through , blind and buried vias, high aperture ratio in developing high-density, high-precision, high layer to meet the needs of the market. Due to the high-speed circuits need for computer and aerospace industries, improve the packing density, smaller discrete components in size is necessary. Together with the rapid development of microelectronics, electronic equipment volume is reducing, and weight is losing. As single layer and double layer printed pcb are with available space constraints, it is difficult to improve further in assembly or mounting density. Therefore, it is necessary to consider the use of more than double layers printed circuit pcb, which lead to the appearance of multi-layer circuit boards.

Process control of Castellated/Plated Half Holes PCB

Abstract: With the continuous development of electronic products, customer with more diverse requirements on PCB edge plated half-hole. While the quality of edge PCB plated half hole affects assembly and use directly. This article introduce processing techniques and control methods through second profiling, second drilling to make plated half-hole on the PCB edge.

Key words: Plated Half Hole pcb,second profile; second drilling; plated half-hole PCB, circuit boards edge half PTH,Edge-plated PCB,Edge PCB board with half through holes

1. Introduction:
It has been already mature technology to do PCB boards with PTH half-Moon Through Hole
in the edge, but it is still a challenge at how to control the quality for PCB edge plated half-hole after profiling, such as hole wall copper thorn cocked, residual. Those kinds of PCB with a whole row of plated half-hole on the edge usually characterized by relatively small individuals, used for PCB onboard, as sub-PCB for mother board. ThoseThrough Plated Half-Hole used to connect with mother board and components pins. If these semi-plated hole with residual copper, there may cause unsteady soldering, insufficient solder or even short between two foots when plug-in in PCB assembly manufacturing. This paper focuses on the problem encounter on production of PCB edge half PTH hole and the way to control.

2. Processing principle:
Either drilling or milling process, the rotation direction of SPINDLE is clockwise. When the machining tool reach point A, the hole wall copper layer of point A are closely linked with base layer, which avoid hole wall separated from the copper layer when extension, and the same time make assure no copper crooked and residue. While machining tool reach point B, because of copper attached to the hole wall, with no support of A schematic diagram, the tool forward running, the copper layer will curl with the cutter rotating under the external force to produce copper stab tilt, residues.

3. The types of half-hole PCB circuits

4.Processing problems & improving methods:
Gernally, there are 4 types half hole printed circuits, which suitable for two ways:
4.1 Type one and type two are large plated half-hole spacing electronic circuits, second milling on the positive and negative:
Due to half hole spacing of these two types castellated circuits board is bigger than 3mm, first milling process could complete CS layer half hole plating, and then the second milling process will complete SS side plating. In the positive and negative processing, PCB board edge with two different separate stress points. The finished half-plated-hole is smooth and tidy by this way. This way is also relatively simple and easy to guarantee the quality.
4.2 Type three and type four Edge Plated PCB are with the diameter of half hole less than 0.8mm, and spacing of the center between two holes is about 1mm , and the space of two adjacent rows no bigger than 2.5mm. For the processing of these types printed circuit pcb, we need to consider space of each half-hole and part of two sides. If it encounters following problems, there may appear micro connection problem.
4.2.1 Problem analysis and improvement measures:
① Design :  In the original design, half-palted hole space is only 0.56mm, and pad clearance of each half hole is only 0.15mm
In the producing process, the cutter cuts hole edge directly, when the cutter wearing, the pads may flanging. At the same time, the pad space is too small, which will cause failure micro-connection of pads.
Improved design: change the two rows cooper connection as hole ring and increase 0.05mm to space of half-hole pad pitch. And in order to ensure the width of half plated hole the same time, we do the following improvement: reduce pads width 0.025mm only for Half-Moon Through Hole pad parts close to (B position), keep the width of rest of the pad, which could ensure the pad pitch increase to 0.20mm (C position).
② Support PCB : As the half hole is drilled on the PTH edge, the half hole of the bottom circuit board may with hole flanging if there is no enough support when the drill bit drilling. So the bottom PCB board using in the second drilling couldn’t be ignored. It must be changed after each second drilling to make sure enough support for drilling and reduce the copper side flips.
③ Choose the drill: Normal drill bit may appear biased drilling, break when drilling the PTH hole, slot drill is more suitable for processing such circuit pcb.
④ If the second drilling made as the whole PCB board processing, there may be irregular harmomegathus, which will lead to inconsistent for each array.

Improvement measures:

In order to avoid irregular harmomegathus in the production lead to the inconsistency of each array after second drilling, the producing process flow nee to adjust:
Original process: Sawing →inner layer →lamination→drilling →PTH→plating→outer layer →soldermask → silkscreen→ENIG→second drilling→profile
Improved process: Sawing→inner layer →lamination→drilling →PTH→ plating→outter layer→solder mask →silkscreen→ENIG→first machining (outer profile)→second drilling→second machining(inner tank )
If using a single Plated Through Half Hole PCB board processing secondary drilling and secondary machining after process changes, the operation time for putting up and down PCB board will increase. In order to reduce operation time, we use second drilling combination panel, that is design it as single PCB compensation, repanelizing according to the requirement ,every time to put up PCB is still the original imposition PCB board. Because it is single PCB board compensated output data , it could avoid inconsistency shown in Figure 7 due to printed pcb material irregular harmomegathus.

4.2.2 Result of implementation:

The quality of half plating hole achieve desired level through improvement in design principle, manufacturing processes and optimization of processing methods , which assure the final quality of half PTH hole circuit PCB. And the four corners and the middle of whole board circuit keep the same.

5. Conclusion

(1) Through engineering design optimization and spacing pads increasing, pads micro flange connection between the pads was eliminated.

(2) Though PCB the frequency of bottom PCB usage, copper edge flips is prevented.

(3) Through improving the process, panel way, PCB board inconsistent due to PCB material irregular harmomegathus is solved

In actual manufacturing, we need to make overall analysis and improvement from the 4M1E perspective to make sure to improve plated half-hole processing technology  and promote overall quality finally .