Why capacitors?

A few weeks ago, we proud­ly announced that we had start­ed pro­duc­tion of capac­i­tors in high-vol­ume. But why the fuss about capac­i­tors? After all, it is a severe­ly price-pres­sured and already cheap com­mod­i­ty. And why is Smoltek’s divi­sion for the semi­con­duc­tor indus­try, Smoltek Semi, doing this? A capac­i­tor is not a semi­con­duc­tor! And what’s the plan for the future? All this is the sub­ject of this week’s blog post.

One of the toughest markets in the world

Yes, capac­i­tors are a com­mod­i­ty. Yes, capac­i­tors are cheap (they cost apiece just a frac­tion of a dol­lar). And yes, capac­i­tors are under severe price pres­sure from the big boys.

So what on earth makes a small com­pa­ny up in the north, not yet prof­itable, bet on what must be one of the tough­est mar­kets in the world?

The answer is two-fold­ed: The know-how to solve one of the elec­tron­ic indus­try’s biggest prob­lems in the con­tin­ued devel­op­ment of increas­ing­ly pow­er­ful small devices. And the busi­ness oppor­tu­ni­ty that comes with that know-how.

Let’s unpack what this means, start­ing with the busi­ness opportunity.

Why all the fuss about capacitors?

Every device that con­tains chips also con­tains capac­i­tors. Your smart­watch, smart­phone, smart speak­er; your tablet, lap­top, and desk­top com­put­ers; your tv, stereo sys­tem, and robot vac­u­um clean­er. Every elec­tron­ic gad­get you own. The same applies to larg­er sys­tems like cars, med­ical devices, and indus­tri­al-process controllers.

In short, capac­i­tors can be found every­where. They are omnipresent. And there is a colos­sal demand for them. Every year, more than a whop­ping one tril­lion capac­i­tors are pro­duced worldwide.

Smoltek aims to grab a slice of that pie.

Huge market

It sounds like the hubris of a start­up when Smoltek claims to be able to cut even a slice of the pie. But it’s any­thing but hubris.

As you know, we have part­nered with YAGEO, the world’s third-largest man­u­fac­tur­er of pas­sive com­po­nents like capac­i­tors. With our know-how and YAGEO’s sales and dis­tri­b­u­tion chan­nels, we aim to joint­ly cap­ture one-third of the capac­i­tor mar­ket for the pre­mi­um seg­ment of mobile phones except iPhones.

Of course, Apple knows what we have to offer, but we don’t pur­sue them for now. They are work­ing close­ly with a com­peti­tor, and we believe they will not jump ship any time soon. 

We esti­mate that our address­able mar­ket buys between 3.5 and 4.5 bil­lion capac­i­tors each year. So even if the price apiece is only a frac­tion of a dol­lar, the over­all sales impact is impressive.

Not a semiconductor

It may seem strange that Smoltek focus­es on an elec­tron­ic com­po­nent that is not a semi­con­duc­tor. But there is a per­fect rea­son for that. I have already hint­ed at what it is:

Capac­i­tors are an absolute neces­si­ty for dig­i­tal inte­grat­ed cir­cuits of semi­con­duc­tors to work.To explain why, we need to go down the rab­bit hole of the inner work­ings of inte­grat­ed cir­cuits and capac­i­tors. If you don’t like the won­der­land of elec­tron­ics, skip this part and go straight to the last ques­tion: What’s the endgame?

Still here?

Good! Let’s fol­low the White Rabbit.

Transients

Although semi­con­duc­tors can be used for more than just dig­i­tal inte­grat­ed cir­cuits, dig­i­tal inte­grat­ed cir­cuits, or chips for short, are what we’re talk­ing about here. A chip con­sists of tran­sis­tors that act as elec­tri­cal switch­es. Each tran­sis­tor rep­re­sents a bit – a num­ber that can be one or zero. A tran­sis­tor turns on pow­er to rep­re­sent the val­ue one and turns off pow­er to rep­re­sent the val­ue zero.

Turn­ing the pow­er on and off can affect near­by devices. You may have expe­ri­enced that the lights in your home blink when you turn on or off a ket­tle or oth­er elec­tri­cal appli­ance that draws a lot of pow­er. This is because the rapid change in pow­er demand cre­ates a short-lived pulse, called a tran­sient, which prop­a­gates from the appli­ance, through the wiring, to the lights. The same hap­pens when tran­sis­tors in a chip turn pow­er on and off.

Troublesome transients

To make mat­ters worse, tran­sis­tors on a chip turn on or off simul­ta­ne­ous­ly. They do so at the beat of a clock that ticks bil­lions of times every sec­ond. Each tran­sis­tor con­tributes a lit­tle to what adds up to a sig­nif­i­cant tran­sient. This tran­sient will prop­a­gate from the chip to oth­er chips and com­po­nents if not addressed. That can dis­rupt (and even destroy) the elec­tron­ics, with dev­as­tat­ing consequences.

Not only that. Tran­sients rush­ing through the pow­er-feed­ing tracks make them act as trans­mit­ting anten­nas that send out radio waves. Oth­er tracks act as receiv­er anten­nas that pick up the radio waves and con­vert them into elec­tric­i­ty. This way, the pulse is trans­mit­ted wire­less­ly from the sup­ply tracks to oth­er tracks. Tracks that may trans­mit ones and zeros that are at risk of flip­ping. Again, the con­se­quences can be devastating.

Why capacitors are a necessity for semiconductors

To pre­vent these dev­as­tat­ing con­se­quences, mit­i­gat­ing out­go­ing and incom­ing tran­sients is nec­es­sary. This is where capac­i­tors come into play. When a capac­i­tor is used for this pur­pose, it’s called a decou­pling capac­i­tor.

You can think of a decou­pling capac­i­tor as a shock absorber for the volt­age sup­ply to the chip. Quick volt­age changes, both upward and down­ward, are smoothed out and become much small­er. They do this by absorb­ing and releas­ing ener­gy as the sup­ply volt­age fluctuates.

Some capac­i­tors are light­ning-fast at absorb­ing the ener­gy but can­not absorb much. Oth­ers are slow­er but can absorb more. There­fore, sev­er­al capac­i­tors are often need­ed to pro­tect a chip. A sin­gle smart­phone proces­sor today typ­i­cal­ly has eight decou­pling capacitors.

That’s why capac­i­tors are nec­es­sary for semi­con­duc­tors and the semi­con­duc­tor indus­try. How­ev­er, the decou­pling capac­i­tors must be as close to the chip as pos­si­ble for it to work.

Why capacitors need to be close to the chip

In an ide­al world, capac­i­tors respond light­ning-fast to pow­er surges, but in real­i­ty, they don’t. The rea­son is spelled par­a­sitic induc­tance.

Induc­tance refers to the prop­er­ty of an elec­tri­cal con­duc­tor by which a quick change in cur­rent flow­ing through it induces (hence the name) a volt­age that oppos­es this change, effec­tive­ly slow­ing the rate at which cur­rent can change.

Unin­ten­tion­al and unwant­ed induc­tance is said to be par­a­sitic. Par­a­sitic induc­tance is every­where, even in the wires between the capac­i­tor and the chip. The longer the wires, the more induc­tance and the greater the resis­tance to sud­den changes. That is the oppo­site of what we want to achieve.Thus, keep­ing the wires between a decou­pling capac­i­tor and its chip as short as pos­si­ble is essen­tial. Ide­al­ly, the capac­i­tor should be inside the chip. But the next best thing for decou­pling capac­i­tors is to sit between sol­der balls under the chip. Such a capac­i­tor is called a land-side capac­i­tor (LSC).

Why capacitors need to be thin

It should be pret­ty obvi­ous why land­side capac­i­tors must be small. They com­pete with the sol­der balls for space on the under­side of the chip. The typ­i­cal length and width of a capac­i­tor vary between half and a few millimeters.

They must also be thin because the dis­tance between the chip and the cir­cuit board is small­er than the diam­e­ter of the sol­der balls. Com­mon­ly, for com­put­er chips, the sol­der balls are only 0.5 or 0.4 mil­lime­ters in diameter.

In pre­mi­um smart­phones, the require­ments are much tougher than that. They require ultra-thin capac­i­tors. We are talk­ing about tens of microm­e­ters instead of millimeters.

Challenges with ultra-thin capacitors

When the thick­ness of a land-side capac­i­tor gets down to 80 microm­e­ters, 60 microm­e­ters, or even 40 microm­e­ters, many prob­lems start to creep up.

The first chal­lenge that man­u­fac­tur­ers face is capac­i­tance. This is the abil­i­ty to save ener­gy. It is nec­es­sary to cre­ate suf­fi­cient capac­i­tance in the small area avail­able with­out mak­ing the capac­i­tor too high.

Anoth­er chal­lenge for man­u­fac­tur­ers is to cre­ate ultra-thin capac­i­tors that are not so brit­tle that they can­not be han­dled indus­tri­al­ly with­out breaking.

A third chal­lenge is the strength of mate­ri­als. One tech­nique used today is to fill etched trench­es in sil­i­con sub­strates with an insu­lat­ing mate­r­i­al. How­ev­er, there are lim­i­ta­tions in how deep these trench­es can be and how tight­ly they can be placed.

Fourth, last but not least, these chal­lenges make the research and devel­op­ment of ever-thin­ner capac­i­tors more com­plex and their pro­duc­tion more expensive.

This is where Smoltek’s CNF-MIM capac­i­tors enter the stage.

What makes CNF-MIM capacitors unique

We expect CNF-MIM capac­i­tors to have high­er capac­i­tance than a deep trench sil­i­con capac­i­tor (the clos­est com­peti­tor) of the same length, width, and height.

In addi­tion, the CNF-MIM capac­i­tor is expect­ed to meet real-world require­ments with fly­ing col­ors: excel­lent capac­i­tance sta­bil­i­ty, high break­down volt­age, low leak­age cur­rent, and low series resis­tance and inductance.

To top it off, CNF-MIM capac­i­tors aimed at high-end device seg­ments are expect­ed to be cheap­er to pro­duce, so we can com­pete on price and still have a good mar­gin for capacitors.

The endgame

Is the com­mer­cial­iza­tion and mass pro­duc­tion of CNF-MIM capac­i­tors the endgame of Smoltek’s explo­ration in the semi­con­duc­tor territory?

No.

CNF-MIM capac­i­tors are just one of many appli­ca­tions in the semi­con­duc­tor field for which car­bon nanofibers can be used. If you’ve been around for a while, you might remem­ber SmolTIM, SmolIN­CO, and SmolIN­PO. Our patent-pro­tect­ed solu­tions for heat dis­si­pa­tion inside chips, inter­posers with built-in decou­pling capac­i­tors and rein­forced con­nec­tion points for mul­ti­ple dies, and sol­der balls with ultra-fine pitch (down to 5 micrometers).

How­ev­er, we chose CNF-MIM capac­i­tors because it was pret­ty obvi­ous busi­ness-wise. There is an immi­nent need for ultra-thin capac­i­tors, and the mar­ket is vast.

Our patents pro­tect the oth­er tech­nolo­gies, so we can safe­ly focus on launch­ing sales and rolling out mass pro­duc­tion of CNF-MIM capac­i­tors. Once it is up and run­ning, we can return to the oth­er tech­nolo­gies and con­sid­er which one to bring to the mar­ket next.

Unequivocal proof of concept

Anoth­er ben­e­fit of start­ing with pro­duc­ing CNF-MIM capac­i­tors is that it offers unequiv­o­cal proof for foundries that our tech­nol­o­gy works in their environments.

Foundries are the fac­to­ries that make the semi­con­duc­tor itself. They are arguably the most expen­sive fac­to­ries humans have ever built. Each costs sev­er­al bil­lion US dol­lars. Thus, their own­ers and investors don’t take any risks. They can’t afford it.

It is too risky for them to insert Smoltek’s car­bon nanofiber grow­ing tech­nol­o­gy into their CMOS chip man­u­fac­tur­ing process with­out proof that it works.

Now they get that proof.

The same tech­nol­o­gy used by foundries makes the CNF-MIM capac­i­tors. Of course, with the addi­tion of our car­bon nanofiber growth tech­nol­o­gy. And that’s the point. Our tech­nol­o­gy works with theirs with­out caus­ing any problems.

Over to you

Well, that’s pret­ty much all there is to know about why we chose capac­i­tors as the first com­mer­cial­ized appli­ca­tion of car­bon nanofibers.

What do you think of the blog post? Was it too long? Too tech­ni­cal? Or maybe just right? Some­thing you have missed? Head over to LinkedIn and leave a comment.