Mezzanine connectors have been an important enabling technology for 1U packaging. Several electronic functions can conveniently fit into a 1U box. If you recall from previous posts, the vertical dimension in industry standard racks is based on “Rack Units” or multiples of 1.75 in. Somewhere along the way, the Rack Unit (RU) got shortened to just “U.”
因此，1U或1.75英寸。高盒子设计为19英寸。机架架构已成为电子产品中最流行的形式之一，尤其是在电信和通常使用标准19英寸的计算机系统中。架子。
Stacked and ganged cages on the motherboard provide maximum IO density for 1U boxes. Image courtesy of Molex.
In order to maximize the amount of electronic content in the 1U form factor, mezzanine connectors are used in most 1U boxes. Basically, if one row of IO connectors is on the primary card, a second level of IO connectors can be placed on a mezzanine card positioned above the primary card with the IO connectors protruding from the front of the box.
An alternative to mezzanine cards is to use double deck connector blocks of four, six, or eight connectors or cages in one assembly. These are most often found in boxes that support high volumes of industry standard interconnects, notably Ethernet where stacked connector blocks are commonly available for modular jacks and cages for pluggable interconnects like SFP (Small Form Pluggable) or QSFP (Quad Small Form Pluggable.) If you are a major router builder, you will use truckloads of these standard connectors.
但是，有一个公司的世界使1U外形的盒子中的盒子希望能够以许多不同的方式自定义前面板布局。这使他们能够为每个系统提供许多不同的系统型号，并为每个型号提供专门服务。对于这种应用，夹层是答案。堆叠的连接器有时确实在努力处理最高速度互连。借助夹层溶液，芯片可以在IO连接器后面，有可能在堆叠的连接器上具有显着的信号完整性优势。
If you choose the right mezzanine connector, much is possible, as seen in the following images.
1U Box with flexible IO mezzanine cards can be Gigabit Ethernet jacks or 10 Gb SFP or QSFP. Illustration courtesy of Cleaver Brinkerhoff.
这些夹层卡可以是完整的底盘宽度，也可以是较小的夹层卡，提供适量的应用程序所需的IO类型。这种方法使设备制造商可以为其每个系统配置使用正确的构件。他可以容纳各种IO配置；例如：使用相同的主卡，以太网，Infiniband或其他旧版IO连接器可容纳旧的客户以及前瞻性客户。更新主卡后，如果保留相同的夹层连接器，则仍然可以使用所有现有的IO卡。
这些夹层连接器可以是简单的两排配置，例如IEEE 1386，但更有可能是Array连接器，通常带有数百个引脚来容纳IO夹层卡上的任何功能。连接行业现在提供大量的解决方案。以下是有关如何为您的应用程序选择合适的建议的一些建议：
如果将夹层放置在1U空间的顶部，则在下面有更多有用的空间，用于电子和冷却功能。注意电缆连接器闩锁在满载的底盘中工作。插图由切肉刀布林克霍夫提供。
•主要板和夹层板之间的距离可能是最好的起点。您可能需要在最佳方法上选择板以优化冷却，并为散热器等高层组件提供空间。
• Next parameter is probably the number of differential pairs that will be needed. Keep in mind not only the current requirements, but also potential future uses of the mezzanine card and connector. For example, you may want to have more pins than you need today to allow for future applications that are not yet defined
• By the way, also pay attention to air flow in your box. You need to make sure you are not creating a wall that blocks airflow. The mezzanine connector should be oriented so that maximum airflow is possible (put the narrow end of the connector in the direction of the airflow.)
•考虑一下您现在以及将来可能需要的速度。您将需要使用几代主机卡重复使用IO夹层板。您绝对不想重新构造系统，只是为了适应更高的速度IO，因为您没有预料到这一点。您会发现，高速夹层的价格不超过低速版本。将来应用程序的较高速度方面的错误
• Consider the routing pattern in the PCB (printed circuit board). In general terms, the more pairs within a column in the connector, the more layers that will be needed to route out. Sometimes you can route both ways, but for mezzanine connectors, it is typical to route one way from the connector to connect to the chip. For this reason, array mezzanine connectors typically are available in 2-pair and 4-pair variants, requiring one layer per pair to route out.
• Lastly, think about what termination you will want. SMT is common with BGA (Ball Grid Array) connectors. The process has been finely tuned at the major contract manufacturers so that high yields are common with SMT BGA connectors with low heights.
• In high stack height applications, press fit mezzanine connectors can have an advantage. They are rugged and can tolerate more abuse than a comparable BGA version, especially when the mezzanine board will experience forces that might break a solder joint. In the 1U form factor, it is common to place the boards as far apart as possible in the box, with a mezzanine between. This works out to be a distance of 38-42 mm depending on metal work. One typical tall mezzanine application is in 1U blade servers where the high speed signals travel from the CPU (Central Processor Unit) up to the mezzanine card where a chip converts the protocol to one that is best for the backplane (Ethernet, for example.)
I think you will find that judicious use of mezzanine connectors can enable you to create a box that can be simple today, allow lots of enhancement capabilities, and can also be future-proof to ensure long product life cycles. By the way, mezzanines can also preventa a lot of “Woops” events by avoiding a complete redesign by just adding a mezzanine card with the upgrade.
Mezzanine connectors are your friends.
帖子Mezzanine connectors in 1U packaging are your friendsappeared first onConnector Tips.
Filed Under:Connector Tips,Connectors (electrical) • crimp technologies
