Can we make groove on Ceramic PCB?

August 12th, 2016

Yes, we can make groove on Ceramic PCB. But the technology to make groove is different from FR4 PCB, MCPCB.

As you know, FR4 PCB, MCPCB, the substrate is rigid, so we can rout to get the groove, but ceramic PCB is fragile, so we can not use rout on the Ceramic substrate. Normally, we use laser cutting to make the holes on Ceramic PCB, you may think we should use layer cutting, but it is not available, because if use laser, then it will be cutting through. So to make a tool is necessary, that’s correct, we make a tool to form the groove at the substrate stage.

What is DCB PCB?

August 12th, 2016

DCB is abbreviation of Direct Bonding Copper. It is an electrical composites with high thermal conductivity and high dielectric strength. Which formed by the copper foil and the ceramic substrate suffering high temperature melting and diffusion process in an inert gas. In power electronics industry, the DCB promoted module package chip interconnect technology development and stimulate power electronics products towards on high power density, multi-set, high-performance low-cost.

The advantage of DCB PCB:

  • the copper foil and ceramic can be bonded directly, which have good thermal conductivity, usually thermal conductivity of aluminum -DBC is 24 ~ 28 W / (m K), AlN-DBC is 170 ~ 220 W / (m · K).
  • The stability of ceramic substrate makes DCB has a very excellent insulation properties under various conditions.
  • Coefficient of thermal expansion close to the silicon enables semiconductor chip which soldered on board to avoid the stress caused by temperature changes, therefore can greatly extend the life of semiconductor products.
  • Can process all types of graphics and lines like PCB, and strong current conducting capabilities make it easy to achieve board-on-chip interconnection function, the maximum carrying capacity will be up to 100 amps / millimeter.

The application of DCB

  • Energy-saving control of appliances.
  • Energy-saving control of industrial electrical.
  • The transportation of wind, solar and other new energy.
  • New type solar panels.

Parameters of DCB

Name Unit Test Conditions Parameters
Insulation resistance   ≥1
Insulation voltage VAC(.RMS) 1min ≥3000
Tensile strength kN/cm2   ≥5
Peel strength N/mm   ≥6
Thermal conductivity W/m.k Indoor 20℃ 24~28
Thermal expansion coefficient 1×10-6/℃ 50~200℃ ≤7.4
Adaptable of temperature range   -40~+200
Hydrogen embrittlement temperature   400

 

The flatness tolerance value of DCB

DCB diagonal Length L (mm) 200~250 150~200 110~150 80~110 60~80 40~60 20~40 <20
Tolerance value (mm) ≤1.0 ≤0.8 ≤0.6 ≤0.4 ≤0.2 ≤0.1 ≤0.05 ≤0.03

 

 

Parameters of ceramic substrate

 

Name Unit Test Conditions Parameters
Al2O3 content %   ≥96
Insulation voltage kV/mm   ≥12
Permittivity   25℃  1MHz ≥9.2
The dielectric loss tangent   25℃  1MHz ≤3×10-4
Thermal conductivity W/m.k Indoor 20℃ ≥22
Thermal expansion coefficient 1×10-6/℃ 20℃~500℃ ≤6.7
Density g/cm3   ≤3.7

What is the X-out board?

August 12th, 2016

X-out board means that the boards are not qualified. The trace may damage during the production. Normally we will do some obvious mark to distinguish the X-out board.

When we make the boards in panel, it will be easy to have X-out board, and what’s more, when we panel several pieces board in a panel, there will be more pieces for X-out board.

Some of the SMT manufacture didn’t accept the X-out board, since it will influence the production efficiency.

But this kind of circuit board and can’t absolutely avoid in the process, so even the plate number, the more the number of circuit board factory scrap will be, the more relative costs will increase.

So circuit board manufacturers hope that the less number of plate, the better, because it can avoid the loss of X – board, the sheep wool or out, of course, if the board factory has been unable to overcome the loss of X – board, the final price will respond to the customer.

What is the PCB flying probe test?

August 12th, 2016

Flying probe test is a check PCB electric function method (one of the short circuit test). Flying probe tester is for component layout density, layer number, wiring density, small distance of measuring points of PCB (printed circuit board), a kind of testing instrument, the insulation of the main test circuit board and conduction values.

The advantages include: rapid test development; Low cost test method; Fast conversion flexibility; and in the prototype stage for designers to provide rapid feedback.

The disadvantages include: Because of easy programming, to within a few hours test prototype assembly, and test the low yield of UUT without typical fixture development costs, flying probe test can solve many problems in production environment. But not all production test problem can be solved by using the probe automatically.

Through Via

August 12th, 2016

This is also one of the simplest holes, because when production as long as the use of bit or laser light directly do circuit board drilling, all costs are relatively cheap. Through vias are the oldest and simplest via configurations originally used in 2-4 layer PCB designs. Since the signals originate and terminate from the outer layers of the PCB, there are no stubs. In multi-layer PCB applications, they are an inexpensive way to eliminate the resonance effects caused by stubs where other mitigation techniques are not practical or are too expensive.

Vias make electrical connections between layers on a printed circuit board. They can carry signals or power between layers. For backplane designs, the most common form of vias use plated through hole (PTH) technology. They connect the pins of connectors to inner signal layers. A PTH via is formed by drilling a hole through the layers to be connected and then copper plating it.

Difference for normal TG and high TG?

August 12th, 2016

General Tg board for more than 130 degrees, high Tg generally greater than 170 degrees, medium Tg is greater than 150 degrees.

Usually TG of 170 ℃ or more PCB PCB, called high TG PCB.

When increases TG for the substrate, the PCB board cane withstand heat resistance, moisture resistance, chemical resistance, resistance to stability characteristics will improve and enhance. The higher the TG values, plate temperature resistant performance is good, especially in the lead-free process, high TG application is very popular. High TG means high heat resistance.

The difference for normal TG and high TG is:

under the hot circumstance, especially after moisture absorption heat, its material mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, thermal expansion differences between various conditions such as high Tg products bright sun better than ordinary PCB substrate material.

PCB solder mask ink

August 12th, 2016

PCB solder mask ink

PCB solder resist ink is mainly used in circuit board, also called PCB inks, prevent short circuit caused by soldering pulling, at the same time it also has excellent Electrical Performance, Chemical performance. Moisture proof, mould proof, salt fog resistance.

PCB solder mask ink main functions are as follows:
(1)Prevent physical disconnection of the circuit conductors;
(2)Welding process, to prevent short circuit because of the bridging;
(3)Only in part must be welding welding, to avoid solder waste;
(4)Reduce copper pollution of welding groove;
(5)To prevent from dust, moisture and other external environment factors causing deterioration of insulation, corrosion;
(6)High insulation, made it possible to high density change of the circuit。

The function advantage of the PCB

August 12th, 2016

The board of the PCB itself is by the material of insulation and heat insulation, and is not easy to bend into. PCB appearance and development of the unique features of the printed circuit board, brought significant reform to the electronics industry, greatly promote the upgrading of electronic products. This is because the printed circuit board PCB has many unique functions and advantages:

See following tips:

  1. Printed circuit board PCB is a good consistency, it can be used in a standardized design, conducive to the production of automation and mechanization of welding equipment, improve the productivity.
  1. Printed circuit board PCB equipment parts have good mechanical properties and electrical properties, make electronic equipment unit combination, make the whole piece after assembly and debugging of printed circuit board as spare parts, is advantageous for the whole products swaps and maintenance. It is because of the above advantages of PCB, printed circuit board PCB has been very widely used in the manufacture of electronic products, without a printed circuit board PCB, there is no rapid development of modern electronic information industry. Familiar with the basic knowledge of printed circuit board PCB, master the basic design method and the printed circuit board PCB production process, understand the production process is the basic requirement of electronic technology study.
  1. Printed circuit board PCB advantage is to achieve electrical connection between the various components in the circuit, instead of the complex wiring, reducing the workload of traditional mode of connection, simplifying the electronic products assembly, welding, commissioning work.
  1. Printed circuit board PCB is narrowed the equipment volume, reduces the product cost, improve the quality and reliability of electronic equipment.

Why the PCB have test point?

August 12th, 2016

The test point is designed to test the components of the PCB if they meet the specifications and solder mask or not. For example, if we want to check a resistance on the circuit board if have any problem, the easiest way which is use the universal meter to measure the both ends of PCB. But if there have a large number of PCBs, it is hard to use the universal meter to test each components are correct or not one by one. So we can use the automated test machine of ICT(In-Circuit-Test) to test, which is designed by probe (normally called “needle Bed (Bed – Of – Nails)” fixture). This test machine can test all the circuit of components on the PCB at the same time. Then through the way of program control to measure the characteristics of the components. Generally speaking, the PCB only need to take around 1-2 minutes to finishih the testing. The testing time are depending on the components’quantity, the time will be more longer with the more components.

But if the probe contact with the components or solder pads on the PCB directly, it will damage some components easily. So the engineers design the “test point” on the PCBs, which is designed the additional parts to elicit a pair of round on the both ends of components, and there is no solder mask. It can contact these small test points directly and measure the components by the probe.

Generally speaking, the hole of PCB have PTH, blind via hole and buried hole.

August 12th, 2016

Generally speaking, the hole of PCB have PTH, blind via hole and buried hole.

One of the most common is Plating Through Hole (PTH),  the criteria of judging whether the hole is PTH, you can focus the PCB on the lamp, the light hole is PTH. During production, it can use the drill or laser to drilling the hole of PCB. So it is the most simple tpye of hole, and the cost are more cheaper than onters. But there also has some layer of PCB doesn’t need this hole, because it will take up some place of PCB.

The outermost layer of Blind Via Hole is connected to the adjacent inner’s plating hole, and the hole call “blind” since it can’t see the opposite. The production of blind hole is in order to make full use of space with the PCB circuit layers. This manufacture method should pay more attention to the depth(Z axis) of hole, almost no one in this way since the inner hole will be difficult to plate. And we can drill the hole of the connected circuit layer in advance when they in other layers and then stick up, but it needs  precision positioning and contrapuntal device.

The internal layers’ connection but without conducting any circuit layer to the outer layer of PCB, which called the buried hole. This process cannot be completed by the way of stick up the drilling hole, it has to drill the hole in each layer. After bonding inner layer, it needs to plate firstly and then stick up all layers. Since it will spend more time to process than the PTH and Blind hole, so it will be more expensive. Finally, the production of buried hole just suitable for the HDI PCB, in order to enlarge the space of each layer for PCB.