6 ms·

> On the one hand, the resistors used in these SSDs are too big for the circuit board, causing weak connections I am an electronics / PCB hobbyist and I can't

> On the one hand, the resistors used in these SSDs are too big for the circuit board, causing weak connections I am an electronics / PCB hobbyist and I can't for the life of me figure out how they came to such a weird conclusion. What does this even mean? Larger components will have more surface area at the joint and should be stronger than a smaller component > On the other hand, the soldering material used to attach these resistors is prone to forming bubbles and breaking easily, according to Häfele. Never heard of solder doing this - it seems more likely to me that the solder wasn't reflowed properly in manufacturing. What's more is that the component pictured is a capacitor. The only conclusion I can draw here is that the guy has no clue what he's talking about

bravo22 3y ago
The most charitable way I can read their statement is that the resistors are too large for the pad, and along with poor solder material it forms a weak joint which breaks over time. I have a hard time accepting that because there is not a lot of heat on that line nor is there a lot of physical stress, like constant vibration on SSDs.
- nrp 3y ago
  These SSDs are tiny. The controllers can easily get up to 80C during sustained writes, so there could be mechanical stress from thermal cycling. (Source: we also make small USB-interfaced high-speed storage devices and do a range of reliability testing for stuff like this)
  - bravo22 3y ago
    On the SSD chip sure. This looks like a resistor on the data line. The resistor would certainly not get to reflow temp.
jchw 3y ago
Does seem a bit strange, but the original article[1] in German, translated using Google Translate, reads as follows: > “It's definitely a hardware problem. It is a design and construction weakness . The entire soldering process of the SSD is a problem,” says Häfele. A hard drive has components that need to be soldered to the circuit board. “The soldering material used, i.e. the solder, creates bubbles and therefore breaks more easily.” > “In addition, the components used are far too large for the layout intended on the board,” says Häfele, explaining the technical problems: “As a result, the components are a little higher than the board and the contact with the intended pads is weaker. All it takes is a little something for solder joints to suddenly break.” It sounds like what they're saying is that the solder pads are too small for some of the components. Not sure about what they're saying about the solder though. [1]: https://futurezone.at/produkte/sandisk-ssd-ausfaelle-western-digital-attingo-datenrettung-problem-hardware/402664391 https://futurezone.at/produkte/sandisk-ssd-ausfaelle-western...
- jeffbee 3y ago
  > It sounds like what they're saying is that the solder pads are too small for some of the components The converse is also possible. Instead of being a design flaw with the pads too small for the component, it could be that a larger component was substituted during manufacturing. Even terrible freeware EDA packages have design rules that will flag improper solder pad layouts, so it seems like what might have happened is the physical part does not resemble its model.
  - exmadscientist 3y ago
    > Even terrible freeware EDA packages have design rules that will flag improper solder pad layouts No, they don't. EDA software doesn't really know what size the terminations are. It knows how big the pad itself is, and is very good at keeping those out of trouble, but it doesn't know what size the solderable area is. You might tell it, or give it a 3D model, but make a mistake there and you're right back here. As well, there are so many different kinds of terminations (pop quiz: what kind are these?) that even if it does know what size they are, it doesn't necessarily know what size or shape the pad should be. Also the CM will totally edit this stuff and not tell you. Which they're not supposed to do, and are probably better at if you're a huge customer, but they still do it. EDA sure doesn't know about that.
    - deleted 3y ago
      [deleted]
- exmadscientist 3y ago
  > Not sure about what they're saying about the solder though. There's more than one solder alloy in use. There's more than one class of solder alloy in use. Some are easier to use, some are harder to use. Some are high-performance, low-tolerance, some are low-performance, high-tolerance. Some are expensive, some are cheap. The most troublesome family is SnBi. These are relatively new. They have a big "greenwashing" problem in that they solder at lower temperatures, which is "environmentally friendly" (and cheaper to run). Also the base metal is dirt cheap. (Wonder why manufacturers are interested?) It's also very, very brittle. It also happens to be a low-temperature alloy... so it's much easier to get hot enough to desolder during operation. Lots of trouble all around and in general a very high field failure rate. Not recommended... oh wait but it's cheap and greenwashable. Sigh.
nurple 3y ago
If the correct amount of pad is not exposed at the edge of the part, the solder will have nowhere to form a fillet which is critical to its physical attachment. Solder is not glue, and even with more pad contact beneath this is a physically weaker connection which often results in tombstones like pictured in TFA. If you read the integration documents for these packages, you'll see that they distinctly specify the requirements for these margins. Probably the length is the more important axis and may be what he was referring to when saying "large". I've seen this be a problem particularly during the "chip shortage" where jellybean parts like these capacitors have the weakest specs in a design, meaning unilateral substitutions can happen at many points in the design/mfg pipeline. Indeed brittle solder is a real phenomenon which is often easily visible in hand soldered joints that we call "cold" joints. Formation of bubbles can happen for a number of reasons, but IME it's the result of low quality solder or flux/cleaning. The organic compounds gasify in the heat and form an internal structure similar to bread. ETA: an interesting paper exploring the cause and minimization of voiding in the reflow process. Particularly, the decrease in thermal conductivity in voided solder can critically contribute to its failure in high-heat operational environments. https://www.circuitinsight.com/pdf/controlling_voiding_mechanisms_reflow_soldering_process_ipc.pdf https://www.circuitinsight.com/pdf/controlling_voiding_mecha...
exmadscientist 3y ago
> Larger components will have more surface area at the joint and should be stronger than a smaller component Larger components are also, well, larger, and have much bigger forces on them. For ceramic capacitors you need to avoid shearing and torquing as the body of the capacitor is very brittle and a small crack means a dead part, possibly dead short. Big ceramics are dangerous to use as they have a high failure rate. I personally won't use anything larger than a 1210. Some of my colleagues think I'm nuts and should stop at 0805, but I think the flexible terminations available these days make 1210 viable. At least in medium volumes, I don't ship SSDs! > I can't for the life of me figure out how they came to such a weird conclusion What I see when I look at this is they have a part with a 5-sided termination (typical MLCC capacitor with metallized cap) but they have a footprint that only gets fillets on 1 of those 5 sides (typical would be 3). This is common for resistors... but resistors (a) have only 3-sided terminations anyway and (b) are made of robust alumina bodies, not fragile ceramics. So someone either got dumb with the footprint library or more likely overly aggressive to pack things in, not appreciating what MLCCs really need to be happy. I don't think it's part size changes, because the fillets along the length dimension that are visible look about right in size.
- mips_r4300i 3y ago
  My gut feel was also cracked MLCC ceramics from thermal expansion or shock. I've seen some 1206s shear right off a pcb from merely mechanical shock to the PCB, not the cap directly. When I use them I try to orient them parallel with any PCB bending forces, but they are still fragile.
onetimeuse92304 3y ago
I am electronics / PCB hobbyist and I can definitely see how their explanation can be true. I can't say it is, but I can see how it could be. If you design a PCB for a given size of the resistor but then decide to use larger resistors without redesigning the pads, you may have reflow problems and weak joints. This is simply due to the fact, that the components are positioned due to surface tension during reflow process (they are pulled into place as the solder melts). If the pads are for smaller components, there will be too little solder for larger surface and weight of the component and working at a wrong angle to pull it into place causing potentially higher rate of failure. > What's more is that the component pictured is a capacitor. And that means what? From the picture I can tell that there is very little solder between component and the pad. Potentially too little to hold the component well in place. > The only conclusion I can draw here is that the guy has no clue what he's talking about Maybe he does, maybe he doesn't. Have you considered a possibility you are not an expert either?
- eaasen 3y ago
  As someone who designs circuit boards professionally, the explanation is clearly lacking. There might be a thermal issue or there might not be. There is nothing conclusive in the pictures either way. What I do see is the following: 1. Underfill (the brownish-tan smooth material surrounding the components towards the bottom of the picture) around the IC, which is typically done to make parts more mechanically robust. 2. No evidence of overheating on any of the thermal interface material that is left stuck to most of the components and no evidence of overheating on the PCB or the components themselves. 3. Completely insufficient evidence to declare a soldering issue. The way to prove this one way or another is x-ray inspection to look for voids in the solder or a mechanical cross-section of the suspect solder joints. While this certainly could actually be the problem, I see insufficient evidence to conclude one way or another. Manufacturers don’t put underfill under a part unless it’s required through testing or experience with similar package types in prior designs since it adds cost, additional process steps and makes it a PITA or impossible to rework any bad components in the area. As to the pad size/shape, there are three general classes of design defined by the IPC (standards body that deals with PCBs and PCB assemblies). Depending on how space constrained your design is, there are different recommended pad designs for passive components like these. They might be using one of the tighter spacing guidelines, but if their process is well controlled, it can be perfectly fine for the design life of the product. If you want to see small pad layouts done well, look at an iPhone logic board. If you want to know more about pad design for SMT parts, search for IPC-7352
londons_explore 3y ago
It reads to me more like the journalist writing the article summarized a technical report badly.
sheepshear 3y ago
> What does this even mean? It means you should click through to look at the pictures in the original article.
bunnie 3y ago
Hard to tell from appearance only but my initial impression is that's an inductor, not a capacitor. The circuit looks like a switching power regulator. The capacitors would be beige with silver ends, this one looks like an over molded inductor, similar to [1], and is used as the main power inductor in a buck regulator. If this is an inductor, my gut reaction is it has an insufficient current rating for the application and it is overheating. Inductors have a bunch of loss mechanisms that contribute to heating. Depending on the type of metal used to build the core, it can 'hard saturate' and effectively walk itself off a cliff once the current draw gets too high. At some point, it gets hot enough to desolder itself from the circuit board. It's possible they did not see this in validation because the power draw of SSDs depend heavily on the work load and process variations in the chips; erase current can have a fairly wide variation. fwiw, voiding of solder joints is a problem. The solder is applied as a paste - fine particles of metal solder suspended in solder flux. During reflow the flux evaporates and leaves the metal behind, but if the process isn't tuned right bubbles of gas can be trapped in the joint. This can lead to reliability problems. It can also increase the effective thermal resistance to the circuit board, which for tiny components like this can often be the primary path for heat removal during normal operation. [1] https://www.digikey.com/en/products/detail/pulse-electronics/ADCC002016121R5MC1/19200518 https://www.digikey.com/en/products/detail/pulse-electronics...
- Scoundreller 3y ago
  The article says: > the problem lies in hardware, not firmware, which could explain the lack of corrective firmware updates for those models and SanDisk's continued silence about the source of the issues. But I'd guess a firmware update that slowed down the erase process could let it cool down. But the performance hit. Are they not using charge pumps and these are some of the first SSDs upgraded to on-board inductored boost convertors? These messes could be solved if system power supplies had a 20V rail instead of requiring tiny devices to make it. Maybe an integrated manufacturer (hi apple) will spec out proprietary SSDs like this one day. Charge pumps are cheap and small, but not as efficient (ie: HEAT!): > By using the boost converter with the optimized inductor, the energy during write-operation of the proposed 1.8-V 3D-SSD is decreased by 68% compared with the conventional 3.3-V 3D-SSD with the charge pump. https://dl.acm.org/doi/10.1145/1594233.1594253 https://dl.acm.org/doi/10.1145/1594233.1594253 2023 paper: > One of the main causes is the on-die charge pump circuit, which has a low conversion efficiency and induces high heat generation. > Using the in package boost converter, we show that the power consumption can be reduced by up to 39% while the temperature rise can be reduced by 50%. https://ieeexplore.ieee.org/document/10145971 https://ieeexplore.ieee.org/document/10145971
RantyDave 3y ago
But there was something in the article about epoxy - so potentially the components are glued down with a conductive epoxy instead of being actually soldered. Why you do this? Don't know. But it would explain why the solder is losing the plot.
Taniwha 3y ago
It looks to me like some glued on covering has been removed here, which in turn could have pulled the components off (could still be weak solder joints) rather than it being a manufacturing problem - the components don't look too big for the pads to me Most modern manufacturing lines have manual and automatic (vision system) inspections that would detect badly soldered or toombstoned components like the ones shown here.
negative_zero 3y ago
This is something that is in my area of expertise, and your suspicions are correct. Solder can "bubble" but this is a line process issue that is easily picked up even in old AOI systems (automatic optical inspections) from 10-15 years ago. To be frank, this article to me, reads like piece put together by somebody who has no idea what they're on about to generate publicity for their company. Nothing to see here.
tyingq 3y ago
"Too big" could mean the pads on the circuit board were made for a smaller component, and now with the larger one, there's less overlap and direct contact from the pads on the board and the contacts on the component.

bravo22 3y ago

The most charitable way I can read their statement is that the resistors are too large for the pad, and along with poor solder material it forms a weak joint which breaks over time. I have a hard time accepting that because there is not a lot of heat on that line nor is there a lot of physical stress, like constant vibration on SSDs.

nrp 3y ago
These SSDs are tiny. The controllers can easily get up to 80C during sustained writes, so there could be mechanical stress from thermal cycling. (Source: we also make small USB-interfaced high-speed storage devices and do a range of reliability testing for stuff like this)
- bravo22 3y ago
  On the SSD chip sure. This looks like a resistor on the data line. The resistor would certainly not get to reflow temp.

jchw 3y ago

Does seem a bit strange, but the original article[1] in German, translated using Google Translate, reads as follows: > “It's definitely a hardware problem. It is a design and construction weakness . The entire soldering process of the SSD is a problem,” says Häfele. A hard drive has components that need to be soldered to the circuit board. “The soldering material used, i.e. the solder, creates bubbles and therefore breaks more easily.” > “In addition, the components used are far too large for the layout intended on the board,” says Häfele, explaining the technical problems: “As a result, the components are a little higher than the board and the contact with the intended pads is weaker. All it takes is a little something for solder joints to suddenly break.” It sounds like what they're saying is that the solder pads are too small for some of the components. Not sure about what they're saying about the solder though. [1]: https://futurezone.at/produkte/sandisk-ssd-ausfaelle-western-digital-attingo-datenrettung-problem-hardware/402664391 https://futurezone.at/produkte/sandisk-ssd-ausfaelle-western...

jeffbee 3y ago
> It sounds like what they're saying is that the solder pads are too small for some of the components The converse is also possible. Instead of being a design flaw with the pads too small for the component, it could be that a larger component was substituted during manufacturing. Even terrible freeware EDA packages have design rules that will flag improper solder pad layouts, so it seems like what might have happened is the physical part does not resemble its model.
- exmadscientist 3y ago
  > Even terrible freeware EDA packages have design rules that will flag improper solder pad layouts No, they don't. EDA software doesn't really know what size the terminations are. It knows how big the pad itself is, and is very good at keeping those out of trouble, but it doesn't know what size the solderable area is. You might tell it, or give it a 3D model, but make a mistake there and you're right back here. As well, there are so many different kinds of terminations (pop quiz: what kind are these?) that even if it does know what size they are, it doesn't necessarily know what size or shape the pad should be. Also the CM will totally edit this stuff and not tell you. Which they're not supposed to do, and are probably better at if you're a huge customer, but they still do it. EDA sure doesn't know about that.
  - deleted 3y ago
    [deleted]
exmadscientist 3y ago
> Not sure about what they're saying about the solder though. There's more than one solder alloy in use. There's more than one class of solder alloy in use. Some are easier to use, some are harder to use. Some are high-performance, low-tolerance, some are low-performance, high-tolerance. Some are expensive, some are cheap. The most troublesome family is SnBi. These are relatively new. They have a big "greenwashing" problem in that they solder at lower temperatures, which is "environmentally friendly" (and cheaper to run). Also the base metal is dirt cheap. (Wonder why manufacturers are interested?) It's also very, very brittle. It also happens to be a low-temperature alloy... so it's much easier to get hot enough to desolder during operation. Lots of trouble all around and in general a very high field failure rate. Not recommended... oh wait but it's cheap and greenwashable. Sigh.

nurple 3y ago

If the correct amount of pad is not exposed at the edge of the part, the solder will have nowhere to form a fillet which is critical to its physical attachment. Solder is not glue, and even with more pad contact beneath this is a physically weaker connection which often results in tombstones like pictured in TFA. If you read the integration documents for these packages, you'll see that they distinctly specify the requirements for these margins. Probably the length is the more important axis and may be what he was referring to when saying "large". I've seen this be a problem particularly during the "chip shortage" where jellybean parts like these capacitors have the weakest specs in a design, meaning unilateral substitutions can happen at many points in the design/mfg pipeline. Indeed brittle solder is a real phenomenon which is often easily visible in hand soldered joints that we call "cold" joints. Formation of bubbles can happen for a number of reasons, but IME it's the result of low quality solder or flux/cleaning. The organic compounds gasify in the heat and form an internal structure similar to bread. ETA: an interesting paper exploring the cause and minimization of voiding in the reflow process. Particularly, the decrease in thermal conductivity in voided solder can critically contribute to its failure in high-heat operational environments. https://www.circuitinsight.com/pdf/controlling_voiding_mechanisms_reflow_soldering_process_ipc.pdf https://www.circuitinsight.com/pdf/controlling_voiding_mecha...

exmadscientist 3y ago

> Larger components will have more surface area at the joint and should be stronger than a smaller component Larger components are also, well, larger, and have much bigger forces on them. For ceramic capacitors you need to avoid shearing and torquing as the body of the capacitor is very brittle and a small crack means a dead part, possibly dead short. Big ceramics are dangerous to use as they have a high failure rate. I personally won't use anything larger than a 1210. Some of my colleagues think I'm nuts and should stop at 0805, but I think the flexible terminations available these days make 1210 viable. At least in medium volumes, I don't ship SSDs! > I can't for the life of me figure out how they came to such a weird conclusion What I see when I look at this is they have a part with a 5-sided termination (typical MLCC capacitor with metallized cap) but they have a footprint that only gets fillets on 1 of those 5 sides (typical would be 3). This is common for resistors... but resistors (a) have only 3-sided terminations anyway and (b) are made of robust alumina bodies, not fragile ceramics. So someone either got dumb with the footprint library or more likely overly aggressive to pack things in, not appreciating what MLCCs really need to be happy. I don't think it's part size changes, because the fillets along the length dimension that are visible look about right in size.

mips_r4300i 3y ago
My gut feel was also cracked MLCC ceramics from thermal expansion or shock. I've seen some 1206s shear right off a pcb from merely mechanical shock to the PCB, not the cap directly. When I use them I try to orient them parallel with any PCB bending forces, but they are still fragile.

onetimeuse92304 3y ago

I am electronics / PCB hobbyist and I can definitely see how their explanation can be true. I can't say it is, but I can see how it could be. If you design a PCB for a given size of the resistor but then decide to use larger resistors without redesigning the pads, you may have reflow problems and weak joints. This is simply due to the fact, that the components are positioned due to surface tension during reflow process (they are pulled into place as the solder melts). If the pads are for smaller components, there will be too little solder for larger surface and weight of the component and working at a wrong angle to pull it into place causing potentially higher rate of failure. > What's more is that the component pictured is a capacitor. And that means what? From the picture I can tell that there is very little solder between component and the pad. Potentially too little to hold the component well in place. > The only conclusion I can draw here is that the guy has no clue what he's talking about Maybe he does, maybe he doesn't. Have you considered a possibility you are not an expert either?

eaasen 3y ago
As someone who designs circuit boards professionally, the explanation is clearly lacking. There might be a thermal issue or there might not be. There is nothing conclusive in the pictures either way. What I do see is the following: 1. Underfill (the brownish-tan smooth material surrounding the components towards the bottom of the picture) around the IC, which is typically done to make parts more mechanically robust. 2. No evidence of overheating on any of the thermal interface material that is left stuck to most of the components and no evidence of overheating on the PCB or the components themselves. 3. Completely insufficient evidence to declare a soldering issue. The way to prove this one way or another is x-ray inspection to look for voids in the solder or a mechanical cross-section of the suspect solder joints. While this certainly could actually be the problem, I see insufficient evidence to conclude one way or another. Manufacturers don’t put underfill under a part unless it’s required through testing or experience with similar package types in prior designs since it adds cost, additional process steps and makes it a PITA or impossible to rework any bad components in the area. As to the pad size/shape, there are three general classes of design defined by the IPC (standards body that deals with PCBs and PCB assemblies). Depending on how space constrained your design is, there are different recommended pad designs for passive components like these. They might be using one of the tighter spacing guidelines, but if their process is well controlled, it can be perfectly fine for the design life of the product. If you want to see small pad layouts done well, look at an iPhone logic board. If you want to know more about pad design for SMT parts, search for IPC-7352

londons_explore 3y ago

It reads to me more like the journalist writing the article summarized a technical report badly.

sheepshear 3y ago

> What does this even mean? It means you should click through to look at the pictures in the original article.

bunnie 3y ago

Hard to tell from appearance only but my initial impression is that's an inductor, not a capacitor. The circuit looks like a switching power regulator. The capacitors would be beige with silver ends, this one looks like an over molded inductor, similar to [1], and is used as the main power inductor in a buck regulator. If this is an inductor, my gut reaction is it has an insufficient current rating for the application and it is overheating. Inductors have a bunch of loss mechanisms that contribute to heating. Depending on the type of metal used to build the core, it can 'hard saturate' and effectively walk itself off a cliff once the current draw gets too high. At some point, it gets hot enough to desolder itself from the circuit board. It's possible they did not see this in validation because the power draw of SSDs depend heavily on the work load and process variations in the chips; erase current can have a fairly wide variation. fwiw, voiding of solder joints is a problem. The solder is applied as a paste - fine particles of metal solder suspended in solder flux. During reflow the flux evaporates and leaves the metal behind, but if the process isn't tuned right bubbles of gas can be trapped in the joint. This can lead to reliability problems. It can also increase the effective thermal resistance to the circuit board, which for tiny components like this can often be the primary path for heat removal during normal operation. [1] https://www.digikey.com/en/products/detail/pulse-electronics/ADCC002016121R5MC1/19200518 https://www.digikey.com/en/products/detail/pulse-electronics...

Scoundreller 3y ago
The article says: > the problem lies in hardware, not firmware, which could explain the lack of corrective firmware updates for those models and SanDisk's continued silence about the source of the issues. But I'd guess a firmware update that slowed down the erase process could let it cool down. But the performance hit. Are they not using charge pumps and these are some of the first SSDs upgraded to on-board inductored boost convertors? These messes could be solved if system power supplies had a 20V rail instead of requiring tiny devices to make it. Maybe an integrated manufacturer (hi apple) will spec out proprietary SSDs like this one day. Charge pumps are cheap and small, but not as efficient (ie: HEAT!): > By using the boost converter with the optimized inductor, the energy during write-operation of the proposed 1.8-V 3D-SSD is decreased by 68% compared with the conventional 3.3-V 3D-SSD with the charge pump. https://dl.acm.org/doi/10.1145/1594233.1594253 https://dl.acm.org/doi/10.1145/1594233.1594253 2023 paper: > One of the main causes is the on-die charge pump circuit, which has a low conversion efficiency and induces high heat generation. > Using the in package boost converter, we show that the power consumption can be reduced by up to 39% while the temperature rise can be reduced by 50%. https://ieeexplore.ieee.org/document/10145971 https://ieeexplore.ieee.org/document/10145971

RantyDave 3y ago

But there was something in the article about epoxy - so potentially the components are glued down with a conductive epoxy instead of being actually soldered. Why you do this? Don't know. But it would explain why the solder is losing the plot.

Taniwha 3y ago

It looks to me like some glued on covering has been removed here, which in turn could have pulled the components off (could still be weak solder joints) rather than it being a manufacturing problem - the components don't look too big for the pads to me Most modern manufacturing lines have manual and automatic (vision system) inspections that would detect badly soldered or toombstoned components like the ones shown here.

negative_zero 3y ago

This is something that is in my area of expertise, and your suspicions are correct. Solder can "bubble" but this is a line process issue that is easily picked up even in old AOI systems (automatic optical inspections) from 10-15 years ago. To be frank, this article to me, reads like piece put together by somebody who has no idea what they're on about to generate publicity for their company. Nothing to see here.

tyingq 3y ago

"Too big" could mean the pads on the circuit board were made for a smaller component, and now with the larger one, there's less overlap and direct contact from the pads on the board and the contacts on the component.