ESD test

 I have heard a lot of complaints about ESD damages on keyboards. Today TVS diodes work excellently, so we do not hear such complaints nowadays. But ESD is still a severe threat for the product quality. I tested Nanaju prototype by IEC 61000-4-2:2008 standard.

The result is, it passed for level 3 (contact discharge: 6 kV, air discharge: 8 kV), and failed for level 4 in air discharge (15 kV).

I will analyze the failure mode, but I think that the ESD immunity of Nanaju will not become much better. The design does not allow bigger / more components nor larger track gap. Nanaju will not be super tolerant to ESD, sorry.

Corrugated box and cushion

I am working on packing material now. End-user products require packing material. Without dedicated packing material, the shipping cost becomes expensive, and the product can be damaged on its way.

Matrix FPC sample arrived

 

The outline works as expected. Now I am checking the electronic design.

I will try ESD test with this prototype.

Keypad rubber sample arrived

 Nanaju has a keypad on the left side. The material is silicone. I got the sample today:

The printing is a bit rotated. I will fix the problem in the product.

The keypad works as a function keypad if without modifier keys. With Layer key, it works as a PIN pad. We often make it oppositely. But digits appear consecutively in many cases. Function key input does not occur so consecutively. To reduce down/up effort of Layer key, the keypad works as a function keypad if without modifier keys.

Nanaju keycap set design in progress

 

The design concept is retrofuture of 1980s.

We have seen quite a lot of visuals of retrofuture of 1950-1970s. But time flies. We should make retrofuture of 1980s now.

The battle of FPC design

 Now I am battling with matrix FPC design of Nanaju.

What is so difficult? Please see the photo below. This is P2PPCB design:

Hand wiring is quite flexible. P2PPCB Composer F360 can generate wiring diagram and we just follow the diagram to assemble. But FPC is not very flexible like hand wiring:

The black sheet is PVC and the outline is cut by a cutting machine (Silhouette Portrait 4). A matrix FPC should be made with exact dimensions to fit the keyboard frame. I can imagine an automating software tool for this work, but making such tool requires several months, I guess. So I bought a cutting machine and I am battling with the overlooklings and misunderstandings of myself.

Recent Proceedings (Oct. 2025)

 This is the latest prototype of Nanaju:

Now it has USB 2.0 hub.

I gave up the idea of embedded scroll slider. Just placing a discrete trackpad on the left is far much better. 

The number pad becomes ITU-T E.161-like layout. It is for OTP input, not for tax return. It also works as function keys.

Layer selector switch moves into the back. The knob interferes the fingers if it is placed around the number pad.

I almost beleive that I has removed every bad ideas from Nanaju. Now I am struggling with FPC design.

The Nanaju keycap set will go on sale with two types; dye-sub and laser printing.