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Specifying BOM substitutions / alternatives with Contract Manufacturer (CM)
Specifying BOM substitutions / alternatives with Contract Manufacturer (CM)
BOM/OPL parts help before PCB fabControlling the number of devices manufactured by a licensed manufacturerGeneral rules to define a part for BOM and Assembly files.PCB Assembly: Specifying Jumper Configuration For Assembly HouseWhy put unpopulated components on a BOM?
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$begingroup$
I fear this question may be opinion based but I think it has some value to the general community - because this falls into the end of the design phase.
When working with a CM, they may have better pricing due their volume and as a design method, should you allow the CM to make changes to the BOM (provided you specify which components may be substituted) or is it industry practice to allow specify the components and alternatives and that's it ?
pcb-assembly manufacturing
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
$endgroup$
add a comment
|
$begingroup$
I fear this question may be opinion based but I think it has some value to the general community - because this falls into the end of the design phase.
When working with a CM, they may have better pricing due their volume and as a design method, should you allow the CM to make changes to the BOM (provided you specify which components may be substituted) or is it industry practice to allow specify the components and alternatives and that's it ?
pcb-assembly manufacturing
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
$endgroup$
$begingroup$
I would ask them for their recommendations for you to approve, or see if they'll share their price list with you so that you can use that to guide your design. Keep in mind that manufacturers often have short time horizons: in my experience most manufacturing types will tell you what prices are right now, and won't even understand the concept of "what will be cheap next year?" (but there are good ones out there who can occasionally lift their eyes from the trail one day ahead, and look into the future a bit).
$endgroup$
– TimWescott
8 hours ago
$begingroup$
I think it's fairly common to allow "generic" for non-critical parts (in less critical products anyway). If you really want to trim cost you should consider a cost cutting redesign that opens it up a bit more than just substitution. A CM may be able to suggest alternative chips etc.
$endgroup$
– Spehro Pefhany
8 hours ago
$begingroup$
@TimWescott good point. Definitely something to keep in mind. When you have your initial component selected (pre board layout), would you go to them and ask them at this point - or do you wait until you know your project is good and ready (prototyped , tested etc..) ?
$endgroup$
– efox29
8 hours ago
$begingroup$
@SpehroPefhany that's what has happened where they would suggest things. What I would like is to create the necessary environment for them to find alternatives for us and right now, I don't think we do that - which is the reason for the question.
$endgroup$
– efox29
8 hours ago
$begingroup$
It really depends on what your quantities are and who the manufacturer is. If I want to go for low price, I usually kit things myself
$endgroup$
– Voltage Spike
7 hours ago
add a comment
|
$begingroup$
I fear this question may be opinion based but I think it has some value to the general community - because this falls into the end of the design phase.
When working with a CM, they may have better pricing due their volume and as a design method, should you allow the CM to make changes to the BOM (provided you specify which components may be substituted) or is it industry practice to allow specify the components and alternatives and that's it ?
pcb-assembly manufacturing
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
$endgroup$
I fear this question may be opinion based but I think it has some value to the general community - because this falls into the end of the design phase.
When working with a CM, they may have better pricing due their volume and as a design method, should you allow the CM to make changes to the BOM (provided you specify which components may be substituted) or is it industry practice to allow specify the components and alternatives and that's it ?
pcb-assembly manufacturing
pcb-assembly manufacturing
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
asked 8 hours ago
efox29efox29
8,3086 gold badges36 silver badges82 bronze badges
8,3086 gold badges36 silver badges82 bronze badges
$begingroup$
I would ask them for their recommendations for you to approve, or see if they'll share their price list with you so that you can use that to guide your design. Keep in mind that manufacturers often have short time horizons: in my experience most manufacturing types will tell you what prices are right now, and won't even understand the concept of "what will be cheap next year?" (but there are good ones out there who can occasionally lift their eyes from the trail one day ahead, and look into the future a bit).
$endgroup$
– TimWescott
8 hours ago
$begingroup$
I think it's fairly common to allow "generic" for non-critical parts (in less critical products anyway). If you really want to trim cost you should consider a cost cutting redesign that opens it up a bit more than just substitution. A CM may be able to suggest alternative chips etc.
$endgroup$
– Spehro Pefhany
8 hours ago
$begingroup$
@TimWescott good point. Definitely something to keep in mind. When you have your initial component selected (pre board layout), would you go to them and ask them at this point - or do you wait until you know your project is good and ready (prototyped , tested etc..) ?
$endgroup$
– efox29
8 hours ago
$begingroup$
@SpehroPefhany that's what has happened where they would suggest things. What I would like is to create the necessary environment for them to find alternatives for us and right now, I don't think we do that - which is the reason for the question.
$endgroup$
– efox29
8 hours ago
$begingroup$
It really depends on what your quantities are and who the manufacturer is. If I want to go for low price, I usually kit things myself
$endgroup$
– Voltage Spike
7 hours ago
add a comment
|
$begingroup$
I would ask them for their recommendations for you to approve, or see if they'll share their price list with you so that you can use that to guide your design. Keep in mind that manufacturers often have short time horizons: in my experience most manufacturing types will tell you what prices are right now, and won't even understand the concept of "what will be cheap next year?" (but there are good ones out there who can occasionally lift their eyes from the trail one day ahead, and look into the future a bit).
$endgroup$
– TimWescott
8 hours ago
$begingroup$
I think it's fairly common to allow "generic" for non-critical parts (in less critical products anyway). If you really want to trim cost you should consider a cost cutting redesign that opens it up a bit more than just substitution. A CM may be able to suggest alternative chips etc.
$endgroup$
– Spehro Pefhany
8 hours ago
$begingroup$
@TimWescott good point. Definitely something to keep in mind. When you have your initial component selected (pre board layout), would you go to them and ask them at this point - or do you wait until you know your project is good and ready (prototyped , tested etc..) ?
$endgroup$
– efox29
8 hours ago
$begingroup$
@SpehroPefhany that's what has happened where they would suggest things. What I would like is to create the necessary environment for them to find alternatives for us and right now, I don't think we do that - which is the reason for the question.
$endgroup$
– efox29
8 hours ago
$begingroup$
It really depends on what your quantities are and who the manufacturer is. If I want to go for low price, I usually kit things myself
$endgroup$
– Voltage Spike
7 hours ago
$begingroup$
I would ask them for their recommendations for you to approve, or see if they'll share their price list with you so that you can use that to guide your design. Keep in mind that manufacturers often have short time horizons: in my experience most manufacturing types will tell you what prices are right now, and won't even understand the concept of "what will be cheap next year?" (but there are good ones out there who can occasionally lift their eyes from the trail one day ahead, and look into the future a bit).
$endgroup$
– TimWescott
8 hours ago
$begingroup$
I would ask them for their recommendations for you to approve, or see if they'll share their price list with you so that you can use that to guide your design. Keep in mind that manufacturers often have short time horizons: in my experience most manufacturing types will tell you what prices are right now, and won't even understand the concept of "what will be cheap next year?" (but there are good ones out there who can occasionally lift their eyes from the trail one day ahead, and look into the future a bit).
$endgroup$
– TimWescott
8 hours ago
$begingroup$
I think it's fairly common to allow "generic" for non-critical parts (in less critical products anyway). If you really want to trim cost you should consider a cost cutting redesign that opens it up a bit more than just substitution. A CM may be able to suggest alternative chips etc.
$endgroup$
– Spehro Pefhany
8 hours ago
$begingroup$
I think it's fairly common to allow "generic" for non-critical parts (in less critical products anyway). If you really want to trim cost you should consider a cost cutting redesign that opens it up a bit more than just substitution. A CM may be able to suggest alternative chips etc.
$endgroup$
– Spehro Pefhany
8 hours ago
$begingroup$
@TimWescott good point. Definitely something to keep in mind. When you have your initial component selected (pre board layout), would you go to them and ask them at this point - or do you wait until you know your project is good and ready (prototyped , tested etc..) ?
$endgroup$
– efox29
8 hours ago
$begingroup$
@TimWescott good point. Definitely something to keep in mind. When you have your initial component selected (pre board layout), would you go to them and ask them at this point - or do you wait until you know your project is good and ready (prototyped , tested etc..) ?
$endgroup$
– efox29
8 hours ago
$begingroup$
@SpehroPefhany that's what has happened where they would suggest things. What I would like is to create the necessary environment for them to find alternatives for us and right now, I don't think we do that - which is the reason for the question.
$endgroup$
– efox29
8 hours ago
$begingroup$
@SpehroPefhany that's what has happened where they would suggest things. What I would like is to create the necessary environment for them to find alternatives for us and right now, I don't think we do that - which is the reason for the question.
$endgroup$
– efox29
8 hours ago
$begingroup$
It really depends on what your quantities are and who the manufacturer is. If I want to go for low price, I usually kit things myself
$endgroup$
– Voltage Spike
7 hours ago
$begingroup$
It really depends on what your quantities are and who the manufacturer is. If I want to go for low price, I usually kit things myself
$endgroup$
– Voltage Spike
7 hours ago
add a comment
|
2 Answers
2
active
oldest
votes
$begingroup$
This is exactly why a BOM doesn't normally specify a manufacturer and part number directly. Instead, the BOM references in-house part numbers, and each in-house part number has an AVL (approved vendors list) associated with it. This level of indirection allows you to add (or remove, if necessary) manufacturers and their specific part numbers to the in-house number without having to update every BOM that uses that part. And it allows your purchasing department (or that of a CM) to pick the vendor that they prefer for whatever reason from that list.
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
$endgroup$
$begingroup$
ah! I was wondering why some larger companies had their own part numbers!
$endgroup$
– efox29
7 hours ago
$begingroup$
@dave tweed: can you elaborate on what that AVL might look like? Does it list a specific part number for each manufacturer?
$endgroup$
– Dwayne Reid
7 hours ago
$begingroup$
@DwayneReid: Yes. For each in-house part there is a list of (manufacturer, part number) pairs, where the part number is the specific number or code you would enter on an order form for that manufacturer. If you mostly order through a distributor like Digi-Key or Mouser, you would use their order code, and let them worry about the manufacturer's specific part number.
$endgroup$
– Dave Tweed♦
7 hours ago
add a comment
|
$begingroup$
For critical components (and obvious for unique components) I provide the manufacturer, manufacturer's part numbers and also provide Farnell/Mouser numbers (since i already used those making the prototypes) and other info, but still inform the CM the manufacturer and manufacturer's part numbers are leading.
For some components I also provide alternatives, still using manufacturer + manufacturer's part numbers.
For less relevant components, like standard decoupling caps, resistors etc, I only provide their value, tolerance being smaller than X, voltage rating being greater than X, and package size, and inform the CM that are free to pick components within these constraints.
I conclude my mail with an explicit statement that their suggestions for alternatives for any component are very welcome, but that these are only approved by a written confirmation (and updated BOM which contains that alternative as well).
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
$endgroup$
$begingroup$
We do this as well in our BOM lists - manufacturer AND distributor part numbers for all parts that are critical to have exactly right. For generic caps and resistors, we note value, size, voltage rating higher than, tolerance better than, and mark them as "Multiple manufacturers". Note that sometimes, caps and resistors can be critical too!
$endgroup$
– Araho
6 hours ago
$begingroup$
Before we had this procedure, we once found a CM replacing a mosfet with an alternative with almost exactly the same part number, exactly the same Vds,max, rdson, threshold, etc. Still, this alternative blow up when applying 120% of the default input voltage. Issue: the original mosfet appeared beyond the SOA, even at default input voltage. The original mosfet allowed for exceeding the SOA by a huge margin, the alternative had a smaller margin... Basicly a wrong design, but a nice anecdote compoments with exactly the same basic characteristics/ratings can still fail as alternative.
$endgroup$
– Huisman
6 hours ago
$begingroup$
@Huisman interesting point on the SOA.
$endgroup$
– efox29
5 hours ago
$begingroup$
@Huisman that might have happened even with the same part number, I suspect... no guarantee a second batch/bin/wafer of chips would tolerate the same SOA violation
$endgroup$
– mbrig
7 mins ago
add a comment
|
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
This is exactly why a BOM doesn't normally specify a manufacturer and part number directly. Instead, the BOM references in-house part numbers, and each in-house part number has an AVL (approved vendors list) associated with it. This level of indirection allows you to add (or remove, if necessary) manufacturers and their specific part numbers to the in-house number without having to update every BOM that uses that part. And it allows your purchasing department (or that of a CM) to pick the vendor that they prefer for whatever reason from that list.
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
$endgroup$
$begingroup$
ah! I was wondering why some larger companies had their own part numbers!
$endgroup$
– efox29
7 hours ago
$begingroup$
@dave tweed: can you elaborate on what that AVL might look like? Does it list a specific part number for each manufacturer?
$endgroup$
– Dwayne Reid
7 hours ago
$begingroup$
@DwayneReid: Yes. For each in-house part there is a list of (manufacturer, part number) pairs, where the part number is the specific number or code you would enter on an order form for that manufacturer. If you mostly order through a distributor like Digi-Key or Mouser, you would use their order code, and let them worry about the manufacturer's specific part number.
$endgroup$
– Dave Tweed♦
7 hours ago
add a comment
|
$begingroup$
This is exactly why a BOM doesn't normally specify a manufacturer and part number directly. Instead, the BOM references in-house part numbers, and each in-house part number has an AVL (approved vendors list) associated with it. This level of indirection allows you to add (or remove, if necessary) manufacturers and their specific part numbers to the in-house number without having to update every BOM that uses that part. And it allows your purchasing department (or that of a CM) to pick the vendor that they prefer for whatever reason from that list.
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
$endgroup$
$begingroup$
ah! I was wondering why some larger companies had their own part numbers!
$endgroup$
– efox29
7 hours ago
$begingroup$
@dave tweed: can you elaborate on what that AVL might look like? Does it list a specific part number for each manufacturer?
$endgroup$
– Dwayne Reid
7 hours ago
$begingroup$
@DwayneReid: Yes. For each in-house part there is a list of (manufacturer, part number) pairs, where the part number is the specific number or code you would enter on an order form for that manufacturer. If you mostly order through a distributor like Digi-Key or Mouser, you would use their order code, and let them worry about the manufacturer's specific part number.
$endgroup$
– Dave Tweed♦
7 hours ago
add a comment
|
$begingroup$
This is exactly why a BOM doesn't normally specify a manufacturer and part number directly. Instead, the BOM references in-house part numbers, and each in-house part number has an AVL (approved vendors list) associated with it. This level of indirection allows you to add (or remove, if necessary) manufacturers and their specific part numbers to the in-house number without having to update every BOM that uses that part. And it allows your purchasing department (or that of a CM) to pick the vendor that they prefer for whatever reason from that list.
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
$endgroup$
This is exactly why a BOM doesn't normally specify a manufacturer and part number directly. Instead, the BOM references in-house part numbers, and each in-house part number has an AVL (approved vendors list) associated with it. This level of indirection allows you to add (or remove, if necessary) manufacturers and their specific part numbers to the in-house number without having to update every BOM that uses that part. And it allows your purchasing department (or that of a CM) to pick the vendor that they prefer for whatever reason from that list.
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
answered 7 hours ago
Dave Tweed♦Dave Tweed
136k11 gold badges172 silver badges295 bronze badges
136k11 gold badges172 silver badges295 bronze badges
$begingroup$
ah! I was wondering why some larger companies had their own part numbers!
$endgroup$
– efox29
7 hours ago
$begingroup$
@dave tweed: can you elaborate on what that AVL might look like? Does it list a specific part number for each manufacturer?
$endgroup$
– Dwayne Reid
7 hours ago
$begingroup$
@DwayneReid: Yes. For each in-house part there is a list of (manufacturer, part number) pairs, where the part number is the specific number or code you would enter on an order form for that manufacturer. If you mostly order through a distributor like Digi-Key or Mouser, you would use their order code, and let them worry about the manufacturer's specific part number.
$endgroup$
– Dave Tweed♦
7 hours ago
add a comment
|
$begingroup$
ah! I was wondering why some larger companies had their own part numbers!
$endgroup$
– efox29
7 hours ago
$begingroup$
@dave tweed: can you elaborate on what that AVL might look like? Does it list a specific part number for each manufacturer?
$endgroup$
– Dwayne Reid
7 hours ago
$begingroup$
@DwayneReid: Yes. For each in-house part there is a list of (manufacturer, part number) pairs, where the part number is the specific number or code you would enter on an order form for that manufacturer. If you mostly order through a distributor like Digi-Key or Mouser, you would use their order code, and let them worry about the manufacturer's specific part number.
$endgroup$
– Dave Tweed♦
7 hours ago
$begingroup$
ah! I was wondering why some larger companies had their own part numbers!
$endgroup$
– efox29
7 hours ago
$begingroup$
ah! I was wondering why some larger companies had their own part numbers!
$endgroup$
– efox29
7 hours ago
$begingroup$
@dave tweed: can you elaborate on what that AVL might look like? Does it list a specific part number for each manufacturer?
$endgroup$
– Dwayne Reid
7 hours ago
$begingroup$
@dave tweed: can you elaborate on what that AVL might look like? Does it list a specific part number for each manufacturer?
$endgroup$
– Dwayne Reid
7 hours ago
$begingroup$
@DwayneReid: Yes. For each in-house part there is a list of (manufacturer, part number) pairs, where the part number is the specific number or code you would enter on an order form for that manufacturer. If you mostly order through a distributor like Digi-Key or Mouser, you would use their order code, and let them worry about the manufacturer's specific part number.
$endgroup$
– Dave Tweed♦
7 hours ago
$begingroup$
@DwayneReid: Yes. For each in-house part there is a list of (manufacturer, part number) pairs, where the part number is the specific number or code you would enter on an order form for that manufacturer. If you mostly order through a distributor like Digi-Key or Mouser, you would use their order code, and let them worry about the manufacturer's specific part number.
$endgroup$
– Dave Tweed♦
7 hours ago
add a comment
|
$begingroup$
For critical components (and obvious for unique components) I provide the manufacturer, manufacturer's part numbers and also provide Farnell/Mouser numbers (since i already used those making the prototypes) and other info, but still inform the CM the manufacturer and manufacturer's part numbers are leading.
For some components I also provide alternatives, still using manufacturer + manufacturer's part numbers.
For less relevant components, like standard decoupling caps, resistors etc, I only provide their value, tolerance being smaller than X, voltage rating being greater than X, and package size, and inform the CM that are free to pick components within these constraints.
I conclude my mail with an explicit statement that their suggestions for alternatives for any component are very welcome, but that these are only approved by a written confirmation (and updated BOM which contains that alternative as well).
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
$endgroup$
$begingroup$
We do this as well in our BOM lists - manufacturer AND distributor part numbers for all parts that are critical to have exactly right. For generic caps and resistors, we note value, size, voltage rating higher than, tolerance better than, and mark them as "Multiple manufacturers". Note that sometimes, caps and resistors can be critical too!
$endgroup$
– Araho
6 hours ago
$begingroup$
Before we had this procedure, we once found a CM replacing a mosfet with an alternative with almost exactly the same part number, exactly the same Vds,max, rdson, threshold, etc. Still, this alternative blow up when applying 120% of the default input voltage. Issue: the original mosfet appeared beyond the SOA, even at default input voltage. The original mosfet allowed for exceeding the SOA by a huge margin, the alternative had a smaller margin... Basicly a wrong design, but a nice anecdote compoments with exactly the same basic characteristics/ratings can still fail as alternative.
$endgroup$
– Huisman
6 hours ago
$begingroup$
@Huisman interesting point on the SOA.
$endgroup$
– efox29
5 hours ago
$begingroup$
@Huisman that might have happened even with the same part number, I suspect... no guarantee a second batch/bin/wafer of chips would tolerate the same SOA violation
$endgroup$
– mbrig
7 mins ago
add a comment
|
$begingroup$
For critical components (and obvious for unique components) I provide the manufacturer, manufacturer's part numbers and also provide Farnell/Mouser numbers (since i already used those making the prototypes) and other info, but still inform the CM the manufacturer and manufacturer's part numbers are leading.
For some components I also provide alternatives, still using manufacturer + manufacturer's part numbers.
For less relevant components, like standard decoupling caps, resistors etc, I only provide their value, tolerance being smaller than X, voltage rating being greater than X, and package size, and inform the CM that are free to pick components within these constraints.
I conclude my mail with an explicit statement that their suggestions for alternatives for any component are very welcome, but that these are only approved by a written confirmation (and updated BOM which contains that alternative as well).
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
$endgroup$
$begingroup$
We do this as well in our BOM lists - manufacturer AND distributor part numbers for all parts that are critical to have exactly right. For generic caps and resistors, we note value, size, voltage rating higher than, tolerance better than, and mark them as "Multiple manufacturers". Note that sometimes, caps and resistors can be critical too!
$endgroup$
– Araho
6 hours ago
$begingroup$
Before we had this procedure, we once found a CM replacing a mosfet with an alternative with almost exactly the same part number, exactly the same Vds,max, rdson, threshold, etc. Still, this alternative blow up when applying 120% of the default input voltage. Issue: the original mosfet appeared beyond the SOA, even at default input voltage. The original mosfet allowed for exceeding the SOA by a huge margin, the alternative had a smaller margin... Basicly a wrong design, but a nice anecdote compoments with exactly the same basic characteristics/ratings can still fail as alternative.
$endgroup$
– Huisman
6 hours ago
$begingroup$
@Huisman interesting point on the SOA.
$endgroup$
– efox29
5 hours ago
$begingroup$
@Huisman that might have happened even with the same part number, I suspect... no guarantee a second batch/bin/wafer of chips would tolerate the same SOA violation
$endgroup$
– mbrig
7 mins ago
add a comment
|
$begingroup$
For critical components (and obvious for unique components) I provide the manufacturer, manufacturer's part numbers and also provide Farnell/Mouser numbers (since i already used those making the prototypes) and other info, but still inform the CM the manufacturer and manufacturer's part numbers are leading.
For some components I also provide alternatives, still using manufacturer + manufacturer's part numbers.
For less relevant components, like standard decoupling caps, resistors etc, I only provide their value, tolerance being smaller than X, voltage rating being greater than X, and package size, and inform the CM that are free to pick components within these constraints.
I conclude my mail with an explicit statement that their suggestions for alternatives for any component are very welcome, but that these are only approved by a written confirmation (and updated BOM which contains that alternative as well).
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
$endgroup$
For critical components (and obvious for unique components) I provide the manufacturer, manufacturer's part numbers and also provide Farnell/Mouser numbers (since i already used those making the prototypes) and other info, but still inform the CM the manufacturer and manufacturer's part numbers are leading.
For some components I also provide alternatives, still using manufacturer + manufacturer's part numbers.
For less relevant components, like standard decoupling caps, resistors etc, I only provide their value, tolerance being smaller than X, voltage rating being greater than X, and package size, and inform the CM that are free to pick components within these constraints.
I conclude my mail with an explicit statement that their suggestions for alternatives for any component are very welcome, but that these are only approved by a written confirmation (and updated BOM which contains that alternative as well).
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
edited 6 hours ago
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
answered 6 hours ago
HuismanHuisman
5,0012 gold badges5 silver badges30 bronze badges
5,0012 gold badges5 silver badges30 bronze badges
$begingroup$
We do this as well in our BOM lists - manufacturer AND distributor part numbers for all parts that are critical to have exactly right. For generic caps and resistors, we note value, size, voltage rating higher than, tolerance better than, and mark them as "Multiple manufacturers". Note that sometimes, caps and resistors can be critical too!
$endgroup$
– Araho
6 hours ago
$begingroup$
Before we had this procedure, we once found a CM replacing a mosfet with an alternative with almost exactly the same part number, exactly the same Vds,max, rdson, threshold, etc. Still, this alternative blow up when applying 120% of the default input voltage. Issue: the original mosfet appeared beyond the SOA, even at default input voltage. The original mosfet allowed for exceeding the SOA by a huge margin, the alternative had a smaller margin... Basicly a wrong design, but a nice anecdote compoments with exactly the same basic characteristics/ratings can still fail as alternative.
$endgroup$
– Huisman
6 hours ago
$begingroup$
@Huisman interesting point on the SOA.
$endgroup$
– efox29
5 hours ago
$begingroup$
@Huisman that might have happened even with the same part number, I suspect... no guarantee a second batch/bin/wafer of chips would tolerate the same SOA violation
$endgroup$
– mbrig
7 mins ago
add a comment
|
$begingroup$
We do this as well in our BOM lists - manufacturer AND distributor part numbers for all parts that are critical to have exactly right. For generic caps and resistors, we note value, size, voltage rating higher than, tolerance better than, and mark them as "Multiple manufacturers". Note that sometimes, caps and resistors can be critical too!
$endgroup$
– Araho
6 hours ago
$begingroup$
Before we had this procedure, we once found a CM replacing a mosfet with an alternative with almost exactly the same part number, exactly the same Vds,max, rdson, threshold, etc. Still, this alternative blow up when applying 120% of the default input voltage. Issue: the original mosfet appeared beyond the SOA, even at default input voltage. The original mosfet allowed for exceeding the SOA by a huge margin, the alternative had a smaller margin... Basicly a wrong design, but a nice anecdote compoments with exactly the same basic characteristics/ratings can still fail as alternative.
$endgroup$
– Huisman
6 hours ago
$begingroup$
@Huisman interesting point on the SOA.
$endgroup$
– efox29
5 hours ago
$begingroup$
@Huisman that might have happened even with the same part number, I suspect... no guarantee a second batch/bin/wafer of chips would tolerate the same SOA violation
$endgroup$
– mbrig
7 mins ago
$begingroup$
We do this as well in our BOM lists - manufacturer AND distributor part numbers for all parts that are critical to have exactly right. For generic caps and resistors, we note value, size, voltage rating higher than, tolerance better than, and mark them as "Multiple manufacturers". Note that sometimes, caps and resistors can be critical too!
$endgroup$
– Araho
6 hours ago
$begingroup$
We do this as well in our BOM lists - manufacturer AND distributor part numbers for all parts that are critical to have exactly right. For generic caps and resistors, we note value, size, voltage rating higher than, tolerance better than, and mark them as "Multiple manufacturers". Note that sometimes, caps and resistors can be critical too!
$endgroup$
– Araho
6 hours ago
$begingroup$
Before we had this procedure, we once found a CM replacing a mosfet with an alternative with almost exactly the same part number, exactly the same Vds,max, rdson, threshold, etc. Still, this alternative blow up when applying 120% of the default input voltage. Issue: the original mosfet appeared beyond the SOA, even at default input voltage. The original mosfet allowed for exceeding the SOA by a huge margin, the alternative had a smaller margin... Basicly a wrong design, but a nice anecdote compoments with exactly the same basic characteristics/ratings can still fail as alternative.
$endgroup$
– Huisman
6 hours ago
$begingroup$
Before we had this procedure, we once found a CM replacing a mosfet with an alternative with almost exactly the same part number, exactly the same Vds,max, rdson, threshold, etc. Still, this alternative blow up when applying 120% of the default input voltage. Issue: the original mosfet appeared beyond the SOA, even at default input voltage. The original mosfet allowed for exceeding the SOA by a huge margin, the alternative had a smaller margin... Basicly a wrong design, but a nice anecdote compoments with exactly the same basic characteristics/ratings can still fail as alternative.
$endgroup$
– Huisman
6 hours ago
$begingroup$
@Huisman interesting point on the SOA.
$endgroup$
– efox29
5 hours ago
$begingroup$
@Huisman interesting point on the SOA.
$endgroup$
– efox29
5 hours ago
$begingroup$
@Huisman that might have happened even with the same part number, I suspect... no guarantee a second batch/bin/wafer of chips would tolerate the same SOA violation
$endgroup$
– mbrig
7 mins ago
$begingroup$
@Huisman that might have happened even with the same part number, I suspect... no guarantee a second batch/bin/wafer of chips would tolerate the same SOA violation
$endgroup$
– mbrig
7 mins ago
add a comment
|
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$begingroup$
I would ask them for their recommendations for you to approve, or see if they'll share their price list with you so that you can use that to guide your design. Keep in mind that manufacturers often have short time horizons: in my experience most manufacturing types will tell you what prices are right now, and won't even understand the concept of "what will be cheap next year?" (but there are good ones out there who can occasionally lift their eyes from the trail one day ahead, and look into the future a bit).
$endgroup$
– TimWescott
8 hours ago
$begingroup$
I think it's fairly common to allow "generic" for non-critical parts (in less critical products anyway). If you really want to trim cost you should consider a cost cutting redesign that opens it up a bit more than just substitution. A CM may be able to suggest alternative chips etc.
$endgroup$
– Spehro Pefhany
8 hours ago
$begingroup$
@TimWescott good point. Definitely something to keep in mind. When you have your initial component selected (pre board layout), would you go to them and ask them at this point - or do you wait until you know your project is good and ready (prototyped , tested etc..) ?
$endgroup$
– efox29
8 hours ago
$begingroup$
@SpehroPefhany that's what has happened where they would suggest things. What I would like is to create the necessary environment for them to find alternatives for us and right now, I don't think we do that - which is the reason for the question.
$endgroup$
– efox29
8 hours ago
$begingroup$
It really depends on what your quantities are and who the manufacturer is. If I want to go for low price, I usually kit things myself
$endgroup$
– Voltage Spike
7 hours ago