What price would you put on miscellaneus small components? - Page 1
Forum section: electronics / general

author: mORAV
author_rank: Contributor
timestamp: April 08, 2025, 07:05:18 am
content: I recently started working in a cost engineering job, and I mostly take phisical PCBs, create a BOM, and look for the lowest prices for the components (from official manufacturers).We have a few things I can critique about this methodology, particularly regarding how we treat small components.Basically, for the components "not worth identifying," we assign the following values based on size:0.005€ for passive components under 1206 (3.0x1.5mm)0.015€ for passive components under 2010 (5.0x2.5mm)0.04€ for passive components around 2512 (6.3x3.2mm) labeled resistors and unlabeled "large" ceramic capacitors0.015€ for small diodes < 3.5x1.5mm0.015€ for small active components with fewer than 3 pins (e.g., SOT-23)0.02€ for small active components with more than 4 pins (e.g., SO8)Do you think it is a good rule of thumb?

author: mORAV
author_rank: Contributor
timestamp: April 08, 2025, 07:06:28 am
content: Oh right, important detail to add: we work mostly on automotive parts so nothing too advanced

author: SMTech
author_rank: Frequent Contributor
timestamp: April 08, 2025, 07:49:10 am
content: Assuming we're talking about the line cost on the BOM....Automotive can imply the BOM stipulates you need to choose the automotive versions of even very generic parts, they might not be advanced but they cost more.By the time you have identified the size and shape of a component from its part number you probably have a screen price anyway why stop there.You can't rely on all passives being cheap, you need other checks before you make such assumtions. You can assume all 1% tolerance resistors of a given size and wattage in standard values are similar in price. Step outside that and things can vary wildly. With your methodology, the 2ppm 1206 resistor one of our clients specifies would seriously upset your accountant as it costs £15-£25 depending on who you are lucky enough to find it in stock with.I'm afraid there's no way to assume a BOM cost for Semis unless you also build in familiarity with device types manufacturer and volume. A boring signal diode is likely cheap, an ESD protection diode is not.Lastly you also need to take into account MOQs for parts according to supplier or the assemblers requirement, this heavily depends on scale but is very significant if you only order in 100s or less.

author: mORAV
author_rank: Contributor
timestamp: April 08, 2025, 08:14:21 am
content: For the other components i tend to filter for AEC-Q200[Automotive Grade] (it helps in reducing the number of possible matches too)And the estimate we give is in the order of 10.000s to 100.000s of PCBs (1.000-2000 is the smallest batch we estimate)The cost is surprisingly not too different for automotive specific part vs generic as far as experience goes

author: thm_w
author_rank: Super Contributor
timestamp: April 08, 2025, 09:27:43 pm
content: You would know better than anyone here if the list is right or not, since you have the experience.Though I would say this one sounds off:Quote from: mORAV on April 08, 2025, 07:05:18 amPrice I think is higher, and 2512 caps even higher still.

author: SMTech
author_rank: Frequent Contributor
timestamp: April 09, 2025, 07:47:59 am
content: Quote from: thm_w on April 08, 2025, 09:27:43 pmI think your volume makes this even more dangerous. Larger volumes suggest smaller margins, combined with the fact you are employing a dedicated cost engineer suggests every line needs to be validated. As manufacturer of smaller volumes we still price every line on a BOM and then build in a margin for fluctuation, as I said before, with care you can make such an assumption about very standard resistors (within reason). Everything other component type frankly invalid or risky, do the work get it right. If you are a big enough fish, your systems can extract pricing directly from supplier APIs. Or there's Ciiva etc, either doing the work is the only real answer and can reveal surprising savings

author: tszaboo
author_rank: Super Contributor
timestamp: April 09, 2025, 07:53:27 am
content: It's actually your job now to know the prices of those components.Meaning you need to RFQ those. Yes, even the small ones.

author: mORAV
author_rank: Contributor
timestamp: April 09, 2025, 02:09:18 pm
content: Quote from: tszaboo on April 09, 2025, 07:53:27 amWell, it's been 2 months since I’ve been here, and I'm a little doubtful about the system, which is partly why I’m asking here.I was told to take 50-60% off the price I find on the big websites like Mouser. (I found that for large volumes, 30% is the maximum realistic discount I’m willing to put my sign on based on some production costs from suppliers)

author: mORAV
author_rank: Contributor
timestamp: April 09, 2025, 02:22:54 pm
content: Quote from: thm_w on April 08, 2025, 09:27:43 pmFor one project, I tried to find the cost of the 2010 (5.0x2.5mm) resistors on the board, and they were all in the 1.6 to 2.0 cent range. So, the 1.5c we used was close, considering that we group even smaller ones together.I would like to provide better estimates because a lot of things seem off to me.We are not the cost department of a manufacturing organization. We are a consulting agency that provides data for clients to order assemblies of multiple components from manufacturing companies (electronic, plastic, metal). The PCBs are ridicolusly cheap compared to other components.As far as I know, the PCB part is fairly new, and only I and an older engineer are working on it (he was hired a little over a year ago).Quote from: tszaboo on April 09, 2025, 07:53:27 amThis was one of my proposal but they said that a lot of companies won't even bother as we don't directly buy anything.I'm working on how to make this work

author: tszaboo
author_rank: Super Contributor
timestamp: April 09, 2025, 03:02:23 pm
content: Quote from: mORAV on April 09, 2025, 02:09:18 pmDiscount from those retail websites might work OK.Quotations are better, because you have a law binding document allowing you, or your customer to purchase parts at a certain price for a certain project.You cannot put a nominal price on an small active part, it just doesn't work that way. It might be a logic gate, or a 22 GHZ amplifier. Same goes for passive parts BTW, the same footprint might be a generic resistor or a high current shunt made from Aluminium Nitride, which costs 10000 times more.

author: mORAV
author_rank: Contributor
timestamp: April 09, 2025, 03:41:29 pm
content: Quote from: tszaboo on April 09, 2025, 03:02:23 pmAre you talking about the 50% or the 30% discount from retail websites? (I'm talking about Mouser, Digikey, Farnel, etc)I totally agree with you, but what can you do when you have the board in your hands, no other information, and no labels on the components?Even if I wanted to do some advanced reverse engineering, I don't think it's worth the time.Basically, if we get a quote really wrong, the producer will come to us and say, 'Hey, that’s way below what we pay,' and we’ll adjust the price and the estimate accordingly.But usually, our clients are quoted 50, we say the whole board costs 23 to produce, and they settle somewhere in between.If we give more information to our clients, they can get a lower price from the producers. Everyone wants to get a cut, and unless you provide proof, no one is negotiating in good faith.We once had to inflate a quote a lot because a big wig settled a contract for 110, but a reasonable price would have been well under 50.

author: Rat_Patrol
author_rank: Frequent Contributor
timestamp: April 09, 2025, 11:32:28 pm
content: Passives are pretty easy to get your usual brand of that has all the values you use/need (say Bournes resistors) and they are mostly the same where you could spot check the price on the most expensive value per quote. Same with caps (which have different costs than resistors).I would never blanket "all 1206 and smaller are $xxx" and call it a day, unless you really pad the numbers up. Somebody is either going to pay too much, lose money, or have an unhappy customer when they get the "real" total for the job and they have to pay more than expected.

author: thm_w
author_rank: Super Contributor
timestamp: April 09, 2025, 11:44:43 pm
content: QuoteWell you can tell them your estimate would be better with a BOM, otherwise there is always a chance it will be far off.If the board has 100 of these caps:https://octopart.com/search?q=C2220C664K1GLCAUTOYou've estimated $4 but the real cost is going to be $400.I assume you can't just sub out parts to whatever you want?

author: mORAV
author_rank: Contributor
timestamp: April 10, 2025, 08:10:09 am
content: Quote from: Rat_Patrol on April 09, 2025, 11:32:28 pmWe try to aim for the scenario where 'someone is going to pay just a little too much,' and everyone tends to be happy with that outcome.You have to be right every time so you have to overestimate the cost. It’s still way lower than whatever proposal the producer gives us.For example, sometimes I could have made the boards myself as a random person on PCBWay for half the quote I was given.I was looking on how to have a wuote directly from the producers of the components because i assume that's the quote the producer of the board will use.

author: mORAV
author_rank: Contributor
timestamp: April 10, 2025, 08:17:41 am
content: Quote from: thm_w on April 09, 2025, 11:44:43 pmWell, that could happen, and if it does, we blame the producer for not providing us with all the necessary information.Let me give you an example: I’m currently working on a board with around 400 components, and we were given the BOM with only the names of the major active components (8 components, around 20 out of the total 400).For the rest, I’ll assume reasonably cheap components. We tend to quote Philips capacitors and Bourns inductors if possible because you can't obeject them