Electronics manufacturing in China - what to expect? (part two)
In the first part, we mainly considered the potential organizational difficulties encountered in the production of experimental and industrial batches of electronics in China. Now let's talk more about technical and technological problems.
So, we need to go through four stages:
1. Make printed circuit boards.
2. Purchase components (so-called BOM - bill of materials).
3. Mount the components on the board (soldering).
4. Check the performance and quality of products.
What you need to pay attention to at each stage?
Here we are usually waiting for a relative minimum of surprises. The developer (it is the developer! Otherwise you can get some unpleasant surprises when converting from files, for example, .pcb) preparing gerberas (files in the Gerber format), the factory makes a multi-layer printed circuit board, everyone is happy. Occasionally there are surprises (for example, once they ran into mirrored boards), but the manufacturer corrects all its jambs without talking, this is the norm for Chinese factories.
By the time the production of a batch of multilayer (four or more layers, double-layer ones are made less than a week), the boards usually take from 10 days to three weeks. Oddly enough, by experience, the timing is inversely proportional to the size of the factory. Those. the larger ones do it faster, the smaller ones do it more slowly.
Sometimes specific requirements arise for boards - specific values ​​of wave resistance, thickness of conductors, or there blind holes made by a laser. Then you need to clarify whether this factory can do it? Now here, in one of the projects, the factory must provide us with the test protocol for boards for the characteristic impedance of specific tracks. Not everyone will do this, so with specific requirements, the search for the performer may be delayed.
The most problematic part. Actually, if the Chinese make you a turnkey card, i.e. the performer is complex, it is at this stage that he will receive from you the greatest amount of money for his work (it happens - up to 50-100% of the cost of parts), and this is not just so. Buying a few hundred items - the work itself is quite complicated, and here two more special factors interfere: accessibility and quality of components.
Not all (even relatively ordinary) components can be “on the stock” from suppliers. And if it is some kind of rarity - you are trapped. For development or prototyping, our (Russian) engineers select those components that can be purchased in their homeland, and they are not particularly concerned with price and mass, and much more with the quality and reputation of the manufacturer. So it turns out that the prototype memory is used by Micron, the processors are TI, and the connectors are Samtec. In our experience, the most problems arise, oddly enough, with connectors. In one project, to produce 1000 units of production, it was necessary to purchase 6000 rather specific connectors. And it turned out oh, how not easy! No, of course, there is always the option “to order at the factory and wait for two months”, but for some reason it suits few people. Therefore, we have to buy in parts from different suppliers, look for markets, etc. Often, even at the BOM negotiation stage, we propose to change something - sometimes analogs are cheaper and much more accessible. If the Chinese are doing all the production on a turnkey basis, the problem with the availability of components is somewhat aggravated by the fact that factories usually work with a limited number of their “proven” suppliers. They will not search for you throughout the market, but simply inform you about the delay and will calmly wait for the necessary details to appear with regular partners.
As for the quality of components, then we must be extremely careful. A lot of fakes, remarked chips, and just a marriage. In most cases, problems arise when purchasing retail lots (from a few to several dozen of the same name), but just recently, for example, we encountered the case when in a sealed coil (5000 pieces) with capacitors of 47 ÎĽF, the real capacity was 37 ÎĽF. Before that, there was a case with a completely unworkable batch (2500 pieces) of microcontroller chips. Representatives of the supplier arrived at the factory, surprised them, brought another coil - the same garbage! Apologized, returned the money. Chips had to be purchased elsewhere. And if all of them (2500 pieces!) Had already been managed to be mounted?
Another subtlety: parts are supplied in coils / strips / boxes, etc. Suppose you need 1800 parts of a name, and in the coil - 2500 pieces. You have a choice: buy a whole coil and put off unused parts for the future, or purchase exactly 1800 pieces, but at a slightly different price. There were cases when 100 parts and 2500 (whole coil) cost the same money. And this, in principle, is clear: if the supplier drags you a part of the coil, how long will he have to wait for the buyer who wants to purchase the rest?
')
At once I will say - in no case subscribe to "wave soldering"! Yes, now it is rare, but you never know. Let it be better to solder with your hands - it will also be cheaper.
If you ever will be in Shenzhen at any electronics assembly factory, you will surely boast of your "production" - long rooms with tables in several rows, behind which hundreds of peasants from yesterday's are sitting with soldering irons.
This is "our" factory, where we made boards for Virt2Real .
Horror. Any manual soldering is a significant risk. Equally likely both underheating and overheating. Due to the fact that everyone is trying to meet the requirements of RoHS, they are almost always soldered with high-temperature lead-free solders. Those. soldering iron temperature - about 400 degrees. The power is quite enough to kill some delicate quartz-type detail with an awkward movement (oh, how the Chinese love to solder quartz with their hands! Just some kind of mania).
On the left you can see a nefig drop of lead-free (!) Solder, with which the metal body (!!) of quartz (!!!) was attached to the board. Half of the quartz in the circulation went into the garbage. It was not we who did it, it was so once done for us ... Until we switched to self-service.
Well, the highest quality (but also the most expensive) method is, of course, surface mounting by automata. There is almost no marriage here.
Every customer we ask to provide the methodology and requirements for product testing. We are extremely interested to have as little marriage as possible (the Chinese will redo everything, if that, but it’s no pleasure to carry products across the border to and fro). It’s very rarely possible to avoid marriage completely, but if the customer ordered a 100% (and not selective) test and gave a normal technique (rather than “energize and make sure that the LED lights up”), in most cases of marriage is less than one percent, and they are all associated with defective parts. Agree, out of 1000 memory microcircuits, a two-three may well turn out to be a marriage ...
Service "independent audit" of production in China is very well developed. So do not neglect this opportunity, in order to avoid unpleasant surprises already on our side of the border.
Today we shipped the next batch of boards to the Chinese factory-assembler of our partner. 3000 sets, 9000 boards. Marriage - 12 units (replaced already). In total, this is already the fourth delivery to this factory, i.e. We have already made 36,000 boards for this project. Life abounds.
So, we need to go through four stages:
1. Make printed circuit boards.
2. Purchase components (so-called BOM - bill of materials).
3. Mount the components on the board (soldering).
4. Check the performance and quality of products.
What you need to pay attention to at each stage?
1. Manufacturing of printed circuit boards
Here we are usually waiting for a relative minimum of surprises. The developer (it is the developer! Otherwise you can get some unpleasant surprises when converting from files, for example, .pcb) preparing gerberas (files in the Gerber format), the factory makes a multi-layer printed circuit board, everyone is happy. Occasionally there are surprises (for example, once they ran into mirrored boards), but the manufacturer corrects all its jambs without talking, this is the norm for Chinese factories.
By the time the production of a batch of multilayer (four or more layers, double-layer ones are made less than a week), the boards usually take from 10 days to three weeks. Oddly enough, by experience, the timing is inversely proportional to the size of the factory. Those. the larger ones do it faster, the smaller ones do it more slowly.
Sometimes specific requirements arise for boards - specific values ​​of wave resistance, thickness of conductors, or there blind holes made by a laser. Then you need to clarify whether this factory can do it? Now here, in one of the projects, the factory must provide us with the test protocol for boards for the characteristic impedance of specific tracks. Not everyone will do this, so with specific requirements, the search for the performer may be delayed.
2. Purchase BOM
The most problematic part. Actually, if the Chinese make you a turnkey card, i.e. the performer is complex, it is at this stage that he will receive from you the greatest amount of money for his work (it happens - up to 50-100% of the cost of parts), and this is not just so. Buying a few hundred items - the work itself is quite complicated, and here two more special factors interfere: accessibility and quality of components.
Not all (even relatively ordinary) components can be “on the stock” from suppliers. And if it is some kind of rarity - you are trapped. For development or prototyping, our (Russian) engineers select those components that can be purchased in their homeland, and they are not particularly concerned with price and mass, and much more with the quality and reputation of the manufacturer. So it turns out that the prototype memory is used by Micron, the processors are TI, and the connectors are Samtec. In our experience, the most problems arise, oddly enough, with connectors. In one project, to produce 1000 units of production, it was necessary to purchase 6000 rather specific connectors. And it turned out oh, how not easy! No, of course, there is always the option “to order at the factory and wait for two months”, but for some reason it suits few people. Therefore, we have to buy in parts from different suppliers, look for markets, etc. Often, even at the BOM negotiation stage, we propose to change something - sometimes analogs are cheaper and much more accessible. If the Chinese are doing all the production on a turnkey basis, the problem with the availability of components is somewhat aggravated by the fact that factories usually work with a limited number of their “proven” suppliers. They will not search for you throughout the market, but simply inform you about the delay and will calmly wait for the necessary details to appear with regular partners.
As for the quality of components, then we must be extremely careful. A lot of fakes, remarked chips, and just a marriage. In most cases, problems arise when purchasing retail lots (from a few to several dozen of the same name), but just recently, for example, we encountered the case when in a sealed coil (5000 pieces) with capacitors of 47 ÎĽF, the real capacity was 37 ÎĽF. Before that, there was a case with a completely unworkable batch (2500 pieces) of microcontroller chips. Representatives of the supplier arrived at the factory, surprised them, brought another coil - the same garbage! Apologized, returned the money. Chips had to be purchased elsewhere. And if all of them (2500 pieces!) Had already been managed to be mounted?
Another subtlety: parts are supplied in coils / strips / boxes, etc. Suppose you need 1800 parts of a name, and in the coil - 2500 pieces. You have a choice: buy a whole coil and put off unused parts for the future, or purchase exactly 1800 pieces, but at a slightly different price. There were cases when 100 parts and 2500 (whole coil) cost the same money. And this, in principle, is clear: if the supplier drags you a part of the coil, how long will he have to wait for the buyer who wants to purchase the rest?
')
3. Installation
At once I will say - in no case subscribe to "wave soldering"! Yes, now it is rare, but you never know. Let it be better to solder with your hands - it will also be cheaper.
If you ever will be in Shenzhen at any electronics assembly factory, you will surely boast of your "production" - long rooms with tables in several rows, behind which hundreds of peasants from yesterday's are sitting with soldering irons.
This is "our" factory, where we made boards for Virt2Real .
Horror. Any manual soldering is a significant risk. Equally likely both underheating and overheating. Due to the fact that everyone is trying to meet the requirements of RoHS, they are almost always soldered with high-temperature lead-free solders. Those. soldering iron temperature - about 400 degrees. The power is quite enough to kill some delicate quartz-type detail with an awkward movement (oh, how the Chinese love to solder quartz with their hands! Just some kind of mania).
On the left you can see a nefig drop of lead-free (!) Solder, with which the metal body (!!) of quartz (!!!) was attached to the board. Half of the quartz in the circulation went into the garbage. It was not we who did it, it was so once done for us ... Until we switched to self-service.
Well, the highest quality (but also the most expensive) method is, of course, surface mounting by automata. There is almost no marriage here.
4. Quality control
Every customer we ask to provide the methodology and requirements for product testing. We are extremely interested to have as little marriage as possible (the Chinese will redo everything, if that, but it’s no pleasure to carry products across the border to and fro). It’s very rarely possible to avoid marriage completely, but if the customer ordered a 100% (and not selective) test and gave a normal technique (rather than “energize and make sure that the LED lights up”), in most cases of marriage is less than one percent, and they are all associated with defective parts. Agree, out of 1000 memory microcircuits, a two-three may well turn out to be a marriage ...
Service "independent audit" of production in China is very well developed. So do not neglect this opportunity, in order to avoid unpleasant surprises already on our side of the border.
Today we shipped the next batch of boards to the Chinese factory-assembler of our partner. 3000 sets, 9000 boards. Marriage - 12 units (replaced already). In total, this is already the fourth delivery to this factory, i.e. We have already made 36,000 boards for this project. Life abounds.
Source: https://habr.com/ru/post/213635/
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