6 Replies Latest reply on Oct 31, 2019 12:47 AM by XinghaoZ_26

Hi

When checking PCB layout, two numbers are unknown,

Could you explain which is right?

In some cases 1.21mm, Which is right?

2. Pin17 and the edge length of the module are listed as 1.93mm,

ă€€but if Pad Pitch is calculated at 1.22mm, I think it is 1.92mm.

Thanks

Yang

• 1. Re: [CYBT-343026-01] About PCB Layout

There will be a small finite error difference in the actual position of the pads during production printing. This is the reason why these numbers are often quoted with a +/- error.

1) Pad pitch is defied as the distance between two adjacent pad centers. Use 1.22mm as stated in datasheet.

2) Use 1.93mm as calculated from the datasheet

• 2. Re: [CYBT-343026-01] About PCB Layout

I understand what you mean.

But the customer asked, if Module width is 15.50, the below value, which priority is higher.

1, Pad pitch is 1.22mm. 1.92mm

2, Pad pitch is 1.21mm (6-7pin, 18-19pin).1.93mm

• 3. Re: [CYBT-343026-01] About PCB Layout

Then I think you can go with (1).

Assuming that you indeed make a mistake on the location of Pin17, the error is negligible ((1.93-1.92)/1.92). The

reflow contact is still going to be good.

• 4. Re: [CYBT-343026-01] About PCB Layout

The error is caused by the unit conversion. We use mil as the unit when drawing the PCB layout. When convert it to mm, it will cause some error. You can refer to the distance with mil unit or download and refer to the .dxf file. 3D MODEL FILES FOR EZ-BLE/EZ-BT MODULES - KBA218122

• 5. Re: [CYBT-343026-01] About PCB Layout

I checked CYBT-343026-01 ME Drawing.dxf file.

Pad pitch is 1.21mm (6-7pin, 18-19pin).

• 6. Re: [CYBT-343026-01] About PCB Layout

The actual distance between two pads is 48mil. There is some error when convert from mil to mm. You can copy the package in the kit board and use it directly.https://www.cypress.com/documentation/development-kitsboards/cybt-343026-eval-ez-bt-module-arduino-evaluation-board