PCB & MCPCB – Best Technology

Generally there are two methods to do PCB outline, routing and punching.

Routing is suit for those simple boards with simple outline. But it is easy to cause burr on the edge. Also, if don’t make the tooling holes well, the boards may be easy moving while routing, which cause to the outline crooked.-

So, If you need the outline more precision and nice, the best way is to custom a tool for punching, in such way, the outline shape is very exact and no so much burr on the edge. It is used for those boards in big panel with small boards, special outline as well as high precision boards. Punching also can speed up the production lead time.  But for such way the cost is expensive than routing.

FR1 is basically the same as FR2. FR1 has a higher TG of 130^oC instead of 105^oC 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 120^o and 130^oC, 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.

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.

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.

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.