What’s the difference for FR1, FR2, FR3 and FR4 materials?

August 12th, 2016

FR1 is basically the same as FR2. FR1 has a higher TG of 130oC instead of 105oC for FR2. Some laminate manufacturers who produce FR1 may not produce FR2 since the cost and usage are similar and it is not cost effective for having both.

FR3 is also basically FR2. But instead of phenolic resin it uses an epoxy resin binder.

 

FR4 (FR = Flame Retardent )is a glass fiber epoxy laminate. It is the most commonly used PCB material. 1.60 mm (0.062inch). FR4 uses 8 layers glass fiber material. The maximum ambient temperature is between 120o and 130oC, depending on thickness.

In China FR4 is the most widely used PCB base material, next is FR1 then FR2. But FR1 and FR2 are usually used for 1-layer PCBs because they are not good for passing through holes. FR3 is not recommended to building multi-layer PCBs. FR4 is the best selection. FR4 is widely used because it is good to make from one- layer to multi-layer PCBs. With only FR4, PCB companies can make all kinds of PCBs, which leaves the management and quality control much easier, and eventually it can reduce the cost!

 

Form the analysis above it is obvious that FR4 is the best selection to make PCBs in market. Some materials may be cheaper but it can only be used to make one-layer boards, and the reliability of the boards made by these materials is not good. So they are only used for one-layer and very simple boards.

Can my PCB don’t make solder mask for both side?

August 12th, 2016

Of course PCB can make no solder mask on both side, just make sure the solder mask layer (GTS& GBS) on your Gerber file is empty, or let us know you don’t want to make solder mask while quoting or before production, then we won’t make solder mask on both side, just print the circuits as you want.

Can make different solder mask thickness on top and bottom side?

August 12th, 2016

It’s okay to make different solder mask on top or bottom side only. Such as 50um on top side and 20um on bottom side. For 2 OZ board, the area without trace, solder mask thickness can be 40-50um, and after three or four times printing, developing, drying, the thickness of solder mask over copper trace can also reach up to 40-50um.

What is PCB Gerber file?

August 12th, 2016

The Gerber format is an open 2D binary vector image file format. It is the standard file used by printed circuit board (PCB) industry software to describe the printed circuit board images: copper layers, solder mask, legend, etc.

Gerber files should be inside a .rar or.zip archive with standard file extensions:
Extension                       Layer

  • pcbname.GTL                 Top Copper
  • pcbname.GTS                 Top Soldermask
  • pcbname.GTO                 Top Silkscreen
  • pcbname.GBL                 Bottom copper
  • pcbname.GBS                 Bottom Soldermask:
  • pcbname.GBO                 Bottom Silkscreen:
  • pcbname.TXT                  Drills
  • pcbname.GML/GKO        *Board Outline:
  • 4 layer board also need
  • pcbname.GL2                   Inner Layer2
  • pcbname.GL3                   Inner Layer3

Notes: Gerber file must be RS-274X format.  Drill file(pcbname.TXT) should be Excellon format.
PCB Outline is required.

Gerber file is used for manufacturing process.

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.