Gerber Files

The list of files for a board design will include:

silkscreen

component placements

solder screen paste files for surface mount applications

drill drawings

solder mask files

panel drawings

pad master, etc.

 

The newer Gerber format RS-274X, also known as X-Gerber or Extended Gerber, includes the aperture information into the file headers. With embedded apertures, this makes every X-Gerber file complete as to how each PCB layer should look. However, there are still problems with the interpretation of these files, such as on polygons, or the question of which file to use for which layer. Gerber file extensions are often .GBR, .GBX, .PHD, .SPL or .ART. Sometimes extensions such as .TOP and .BOT are used instead.

 

Some common XGerber extensions are:

 

    * .GBL - Gerber Bottom Layer
    * .GTL - Gerber Top Layer
    * .GBS - Gerber Bottom Solder Resist
    * .GTS - Gerber Top Solder Resist
    * .GBO - Gerber Bottom Overlay
    * .GTO - Gerber Top Overlay
    * .GBP - Gerber Bottom Paste
    * .GTP - Gerber Top Paste
    * .GKO - Gerber Keep-Out Layer
    * .GM1 - Gerber Mechanical 1
    * .GM2 - Gerber Mechanical 2
    * .GPT - Gerber Top Pad Master
    * .GPB - Gerber Bottom Pad Master

1U的高度

1U是一个表示高度的名词 1U=1.75 英寸=4.445厘米

U是一种表示服务器外部尺寸的单位，是unit的缩略语，详细尺寸由作为业界团体的美国电子工业协会（EIA）决定

服务器的宽（48.26cm＝19英寸）与高（4.445cm的倍数）。由于宽为19英寸，所以有时也将满足这一规定的机架称为"19英寸机架"。

1U就是4.445cm，2U则是1U的2倍为8.89cm

也就是说所谓"1U的PC服务器"，就是外形满足EIA规格、厚度为4.445cm的产品。设计为能放置到19英寸机柜的产品一般被称为机架服务器。

<from: http://www.nacona.cn/1u_article_2.htm>