Tips to find cheaper MLCCs? - Page 1
Forum section: electronics / projects

author: MildInductor
author_rank: Regular Contributor
timestamp: July 27, 2024, 08:44:00 am
content: Hello, I am after some 4.7uF THT MLCCs from Mouser. The tolerance or voltage rating isn't really of great concern to me (so long as the voltage rating is safely over 1.8V). I am using the cap to decouple the 1.8V input of the MAX30102, as per the recommended application circuit in the datasheet. I am wondering why the caps are so expensive (around $1-2 AUD per unit in a quantity of 10)? Even the high volume pricing is still around $1 per unit. Is this really how much these caps cost or am I missing something? I do see that the SMD packages are slightly cheaper, so maybe they are priced how they are because buying a THT package isn't common?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 27, 2024, 08:52:28 am
content: Through-hole ceramic caps haven't progressed in the same way as SMDs, as nobody uses them. Check LCSC for a cheaper source

author: selcuk
author_rank: Frequent Contributor
timestamp: July 27, 2024, 08:56:36 am
content: If it is possible to use SMD you can find cheaper alternatives. The voltage is important since these MLCCs hava DC bias characteristics. They loose capacity with increasing DC bias. And the price increases if its capacity decreases less with DC voltage. So the cheapest ones may have half the capacity with your operating voltage.This one is $0.167 for 10 pcs:https://www.digikey.com/en/products/detail/samsung-electro-mechanics/CL21B106KOQNNNE/3888530Check "DC Bias Characteristics" graph on this page. Same part with the above link. It becomes 9uF at 1.8V and 7uF at 3.3V although it is rated for 16V.https://weblib.samsungsem.com/mlcc/mlcc-ec-data-sheet.do?partNumber=CL21B106KOQNNN

author: John B
author_rank: Frequent Contributor
timestamp: July 27, 2024, 09:23:45 am
content: THT versions are limited in choice and quite expensive, and to be honest, many of them look like SMD caps with legs attached to them, for 10-100x the cost.You can probably use an SMD cap if you're hand soldering to a THT footprint.Also in general, the local suppliers like element 14, mouser and digikey are quite a lot more expensive when it comes to basic passives like resistors and caps. You can save a lot getting them from LCSC, but do make sure to check the final figure including shipping to see if it's worth it in your case.

author: wraper
author_rank: Unknown
timestamp: July 27, 2024, 09:31:56 am
content: Quote from: John B on July 27, 2024, 09:23:45 amThrough hole MLCC are exactly that. They're basically SMD capacitors with terminals soldered on and dipped into protective compound.

author: MildInductor
author_rank: Regular Contributor
timestamp: July 27, 2024, 10:18:31 am
content: Thanks everyone, that helps me understand. I wasn't aware of the DC bias characteristics of MLCCs. I'll research it some more.

author: ifonlyeverything
author_rank: Regular Contributor
timestamp: July 27, 2024, 12:49:42 pm
content: Quote from: MildInductor on July 27, 2024, 08:44:00 amIf this is just for hobby use you can buy no-name Chinese through hole ceramic capacitors on eBay for cheap. They aren't characterized with data sheets so be mindful of things like DC bias limitations, but with that said they've always worked just fine for me.https://www.ebay.com/itm/362970704964

author: ebastler
author_rank: Super Contributor
timestamp: July 27, 2024, 12:59:44 pm
content: Quote from: MildInductor on July 27, 2024, 08:44:00 amThe MAX30102 is only available as an SMD part anyway, right? So why would you use THT capacitors with it? (If you plan to use the MAX30102 on one of those little breakout boards, I believe those already provide supply decoupling -- passives on the bottom of the PCB.)

author: mawyatt
author_rank: Super Contributor
timestamp: July 27, 2024, 10:37:42 pm
content: Some might this useful.https://www.eevblog.com/forum/projects/ceramic-capacitor-behavior/Best,

author: Smokey
author_rank: Super Contributor
timestamp: July 27, 2024, 11:13:46 pm
content: If it's for hobby use, just buy the expensive caps and move on.If it's for production, use smt and reduce assembly costs.

author: MildInductor
author_rank: Regular Contributor
timestamp: July 28, 2024, 12:18:43 am
content: Quote from: ifonlyeverything on July 27, 2024, 12:49:42 pmI used to use eBay as my source for almost all passives, but I got sick of not being able to order the exact same part reliably, and not having datasheets for every component. Buying the parts on Mouser isn't ridiculously more expensive for me, so I personally prefer to do that (plus they come faster).

author: MildInductor
author_rank: Regular Contributor
timestamp: July 28, 2024, 12:32:26 am
content: Quote from: ebastler on July 27, 2024, 12:59:44 pmThe THT adapter I am using doesn't have any decoupling. This is potentially going to lead into a side tangent, but how does one look at a capacitor near the power rail of an IC and determine if it is a bypass vs decoupling capacitor? I have read a few articles about this, but I still don't really know how to differentiate them. My understanding is that a bypass capacitor is to remove noise from the power rail by sending it to ground. Whereas a decoupling capacitor acts as an energy reserve to ensure the IC always has a reliable power source, even when nearby ICs may be switching rapidly. Even with these definitions, I see some websites conflict them, and even more so with the capacitor values that one would pick to achieve either task. Perhaps someone can offer some insight?

author: AndyC_772
author_rank: Super Contributor
timestamp: July 28, 2024, 06:47:52 am
content: https://www.cawteengineering.com/design-focus-parasitic-inductance/

author: Zero999
author_rank: Super Contributor
timestamp: July 28, 2024, 10:06:16 am
content: Quote from: mikeselectricstuff on July 27, 2024, 08:52:28 amAre you sure? The last time I decapsulated one, it was just a multilayer ceramic surface mount capacitor, with leads welded/soldered to it.

author: mawyatt
author_rank: Super Contributor
timestamp: July 28, 2024, 01:41:39 pm
content: Quote from: Zero999 on July 28, 2024, 10:06:16 amSome time ago Disc Ceramics were popular, these were a circular disc of ceramic metalized on each side (analogy is circular parallel plates with ceramic dielectric in between) with leads soldered on extending radially and then covered/dipped with a durable material (sometimes a final dipping in wax for moisture sealing). To replace limited resource materials like tantalum, MLCC with a higher capacitance density due to multi-layers began taking hold causing the Disc Ceramic use to decline, and today almost extinct except for some HV applications.However, there were/are uses for TH type capacitors where the old Disc Ceramics filled the need, these are often serviced with MLCC SMD with leads soldered on each end then covered/dipped with a durable material.The cost/farad of capacitors today has dropped dramatically due to the massive personal electronics usage and the manufacturing capability to support such. Even reliability has improved as the cost dropped which seems unique to the electronics world!Best,

author: Zero999
author_rank: Super Contributor
timestamp: July 28, 2024, 03:57:31 pm
content: Ceramic disc capacitors are still made, but yes, nowadays most through hole ceramic capacitors are multilayer.Here's a data sheet showing them with values up to 470µF.https://docs.rs-online.com/e1ea/0900766b816b6808.pdf

author: Siwastaja
author_rank: Super Contributor
timestamp: July 28, 2024, 04:09:34 pm
content: Pricing of any component is inversely proportional to the popularity. Therefore, tip to find cheaper X is to make your design as typical as possible. The problem here is that everyone else uses SMD MLCCs, so even though the through hole versions seem only slightly more tedious to manufacture, they are a lot more expensive because are being manufactured in small numbers.The fix therefore is to redesign in SMD.

author: ebastler
author_rank: Super Contributor
timestamp: July 28, 2024, 04:12:48 pm
content: Quote from: Siwastaja on July 28, 2024, 04:09:34 pmOr, if it's a one-off for hobby use, just solder an 0805 SMD cap across two through-hole pads or across the VCC and GND pins of that adapter PCB.

author: Zero999
author_rank: Super Contributor
timestamp: July 28, 2024, 05:40:12 pm
content: If it's just a one-off, then why are you that bothered about cost?Regarding SMD: the larger parts are fairly easy to handle and can be easily soldered between two tracks on strip board.

author: MildInductor
author_rank: Regular Contributor
timestamp: July 30, 2024, 06:05:38 am
content: I’m not worried about cost, because I am only buying a few THT caps for breadboard prototyping. I’m just interested in the reasoning behind the pricing, which I now know. Thanks for the info everyone.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 30, 2024, 07:32:10 am
content: Datasheet:https://www.analog.com/media/en/technical-documentation/data-sheets/max30102.pdfIt's a mixed analog/digital supply, low current, for logic and bias. It's not clear what they want such a large capacitor for in the first place, but if I had to guess, it's rejection from external noise sources; use a low-noise LDO from the main 3.3V supply, and an electrolytic or polymer capacitor will suffice, no need for ceramic. If in doubt, ask the manufacturer -- or test variations yourself. Most likely consequence, poor readings: noisy, unstable, interference, etc. Even then, the S-D converter should reject noise well.The LED supply however likely needs enough capacitance to deliver peak currents. Polymer or ceramic likely is recommended there.Tim