Questions on creating pins

Community PCB Design
1

I am creating a package for an LCC 68 in Eagle.

The datasheet is at: http://uploading.com/files/BZWGN2SR/lcc68.pdf.html

or http://ece.utah.edu/~nagaraju/lcc68.pdf

I have two questions regarding this:

  1. In order to create the pins what is the layer I should use. Is it just using a pad layer(layer 17) with a solder protect layer around it OR i should use a SMD?

  2. If i need to use the SMD, how should I change the shape to the one required?

2

Since i don’t wanna wait 100+ seconds for the download in the link, i suggest a quick read of Sparkfun’s [tutorial.

Contains everything you will likely need, anything else, check the EAGLE manual.

The package in the second link is a simple part to start with.

Out of interest, may i ask what component you are using that has a package in the link?](Beginning Embedded Electronics - 10 - SparkFun Electronics)

3

In the second download link(http://ece.utah.edu/~nagaraju/lcc68.pdf), you dont have to wait for 100+ seconds.

I have read through the tutorial before, but it illustrates creating a package which has pin shapes of rectangular. However, the shape of the pins required for me are different. So I was creating the pins/pads.

I started with layer 17, but I saw some examples which used the SMD part, hence i am getting confused. I am newbie to PCB design and dont have much idea of it, but my initial understanding was that I would need a layer17 and a solder protect layer for creating a pad.

Any inputs would be really helpful.

I have a custom designed IC on the package…

4

Nice.

  1. The pads you would use are rectangular

  2. When in the package editor, use the “smd” tool

  3. The pad size i would use is around .07" by .025 - .03"

  4. You should ask the package manufacturer for the recommended land layout (ie. how big the pads should be)

5

Thanks a lot for the quick replies…

The pads are rectangular!!! that comes as a surprise… http://ece.utah.edu/~nagaraju/lcc68.pdf Certianly the pad has a arc shape at the top of the rectangle. Clarify I am wrong

Again I dont know what is the land layout?

6

The edges of the package have edge plated castellations…

Sparkfun use some on their BlueTooth modules, [heres a good example.

Land layout/Land Pattern information usually contains the shape of the package, pad size,

stencil opening sizes and pad orientation and position relative to a point on the package.](http://www.sparkfun.com/commerce/product_info.php?products_id=8474)

7

Ya, the pad does not have to be the exact same shape as the pad on the chip. Those things are great to solder as well, since the solder goes right into the groove.

8

Ohh that saves a lot of my effort :smiley:

@FartingMonkey92. I did not understand how you arrived at the dimension for the pad.

As i see it, the longer dimension is 0.05’’ and that includes the arc, and you suggest 0.07’'.

I was of the opinion that either it should be 0.05’’ or 0.041’‘(0.05’‘-0.009’',the radius of the arc). Please clarify

And I understand the other dimension be 0.025’’

Thanks

Manohar

9

It depends on the process you will use to assemble the boards, on a hotplate/reflow oven, you could use close dimensions for the pads.

If you were hand soldering it, you need extra length on the pads to get the soldering iron on to.

The pad length must include the castellation for a strong solder joint.

Heres another [example, see how the module is mounted to the PCB and why you need the extra pad length to gain a good solder fillet?

As i said earlier, get the land layout/land pattern from the package manufacturer, it will tell you all you need to know. :wink:](Bluetooth Modem - BlueSMiRF Gold (Old-School) - WRL-00582 - SparkFun Electronics)