Questions tagged [manufacturing]

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10
votes
3answers
1k views

What are some reasons for hand painted dots on chips?

I've seen lots of products with hand painted dots or markings on chips, what do they often mean? Obviously I understand everybody has their own reasons but could it be an industry common practice for ...
1
vote
6answers
111 views

Electrically isolate bottom side of a PCB

I have a 4-layer board with no parts on the bottom side, the bottom-side solder mask fully covers all vias. I want to stick the board with a double-side adhesive foil on the metal bottom side of a ...
0
votes
1answer
57 views

How to read Diode Numbering System

How do I read diode numbers. I read that the numbering system for US diodes is the JEDEC system. But I don't think the JEDEC system applies to diode numbers after 1N. Everywhere I look I cant only ...
7
votes
1answer
113 views

How is the asymmetry of a Schottky diode obtained?

A Schottky diode is constructed with two metal conductors bonded to a doped semiconductor. One of the metal-semiconductor junctions is a Schottky contact, and the other metal-semiconductor junction is ...
0
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2answers
47 views

How would you connect a light dependent resistor / photoresistor/ CdS cell at a right angle to a surface mount board?

My project uses light dependent resistors (aka photoresistors or CdS cells). All the ones I can find for sale from the usual suppliers are through hole type. ie. they have two wire legs. The PCB I'm ...
2
votes
4answers
252 views

Best practice for wire harnesses in a BOM

Ive started a new job at a startup and am working on a BOM for a box build with a couple of PCBs and wire harnesses inside. Im in a bit of an impasse about how best to define wire harnesses in the BOM....
0
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1answer
44 views

Need help understanding how motors, sensors and other components of a prototype design factor into certifications for industry sale [closed]

I have built a prototype and I now need to create a production prototype that I can use as my template for a small 10-15 product unit batch order. I am in the United States where I plan to market ...
0
votes
1answer
72 views

Do Professional Manufacturers Violate IPC Standards?

I lay out simple boards using BGA packages and often ignore my EDA tool's courtyards. I know these courtyards are set by IPC standards to allow for good design, but then I look at boards like the ...
2
votes
1answer
134 views

Accuracy of manufactured photocells (LDR) with respect to light intensity

I was looking through photocell (photoresistors) datasheets, like for instance the NORPS-12, especially the graphic on resistance value versus light intensity. In no datasheet could I find information ...
0
votes
2answers
64 views

How to bond PCB and metal for high power RF boards

I want to bond a PCB (2 layer & 0.6mm thickness) to a metal (copper & 4mm thickness.) Could anyone help me with the process of bonding it? There is a power amplifier that has to be soldered ...
10
votes
3answers
1k views

What exactly makes small quantity PCB production costly compared to large quantity PCB production?

The per-PCB cost of manufacturing a small number of PCB is 10 times or more compared to the per-PCB cost of manufacturing a large number of PCBs. So what is it exactly that adds to the cost? People ...
2
votes
2answers
91 views

Bed-of-nails testing of ethernet signals

I'm designing a BON testing fixture for a complex board (multiple processors, fpga, memory, etc). One of the items to test is an external ethernet connection (1Gb). In the current design, the ethernet ...
10
votes
2answers
161 views

Why are the heatproof composites used for semiconductor packages never used for coil formers, connectors and switches?

It is very hard to destroy the material normally used for "plastic" IC and transistor packages with IR or hot air soldering tools, unless you apply a measure of heat that would reliably ...
1
vote
0answers
41 views

How to Design method to Program & Calibrate a Panel of PCBs

I'm designing a sensor-package PCB which needs to be programmed and calibrated while still in a panel of 10. I'd like to avoid a large bed-of-nails type setup for this step so that the panel can ...
0
votes
0answers
35 views

Quintic QN8007B RoHS information?

We are planning to use the Quintic QN8007B FM transmitter in our new design because it is quite cheap and has I2S interface. I believe this chip is no longer produced, but it is possible to get hold ...
0
votes
0answers
28 views

Reducing Thermal Pad Size Below Official Footprint - Can It Create Manufacturability Problems?

I'm using a DP83867 Ethernet chip by Texas Instruments in an S-PQFP-G64, 10 x 10 mm package, the mechanical dimension and its recommended footprint are shown at the end of the question. As shown, the ...
4
votes
6answers
1k views

Is it hard to do 2 sided SMD PCB in oven?

As far as I am aware, and please correct me. If we have a 2-sided PCB with SMD components on the top and also bottom, first we shall put components on the top side and solder them and then on the ...
0
votes
0answers
84 views

How does manufacturer determine initial tolerance for capacitors?

Short version: I understand resistor initial tolerance is commonly obtained through sorting process where manufacturer only picks resistor that has resistance within the advertised initial tolerance. ...
48
votes
6answers
15k views

Why don't we make CPUs with 1000s of layers to make use of space in the third dimension?

I am wondering why don't we make processors such as CPUs with 1000s of stacked layers to make use of space in the third dimension now that we have three-dimensional transistors. To be clear I'm ...
1
vote
2answers
90 views

Finding manufacturer of product based on certifications

I really do not know where to ask this question so I am starting here. If you believe there is a better place let me know and I will gladly move post. I bought an induction cooktop from amazon and ...
1
vote
1answer
165 views

Why have the same chip in the same package, but with a different number of pins?

STMicroelectronics offers the following two accelerometer chips. The LIS2DW in a 14 pin LGA package The LIS2DW12 in a 12 pin LGA package These two chips are functionally equivalent and have the same ...
1
vote
1answer
64 views

Do I need to Reduce the Width of a Power Trace for Thermal Relief When it's Passing Through a Pin on the Chip?

I'm routing a PCB. Currently, all power traces are 20 mils. A QFP chip on the board requires multiple voltage rails to operate, I found the easiest solution is passing a power trace through a pin on ...
1
vote
0answers
131 views

Unknown logo on FGS25N120ANTD IGBTs. Which semiconductor manufacturer is this?

I bought 5 FGS25N120ANTD IGBTs from my local vendor a while back. I was unable to identify the manufacturer, based on the logo. Can somebody help me out?
1
vote
0answers
95 views

Thermal reliefs for via-in-pad under BGA?

I'm doing the layout of a high-speed (Multi gigabit) system based on an FPGA with more than a thousand BGA pads and 0.8mm pitch on a 10-layer board. I'm using via in pads that will be copper-filled ...
0
votes
2answers
60 views

Is infrared photoemission from silicon used in IC manufacturing diagnostics?

In the video Why all solar panels are secretly LEDs (and all LEDs are secretly solar panels) a silicon photovoltaic cell from a calculator is purposefully damaged and then a 36 V bias is applied. When ...
0
votes
1answer
50 views

How do you make custom THT (through-hole) connectors?

I have a project that requires a connector that is no longer manufactured which would interface with an old device. For prototyping, I have been salvaging this connector from old peripherals that used ...
12
votes
4answers
3k views

What is the minimum die area of a chip?

Silicon chips are made by slicing up wafers; in general, the fewer transistors a design needs, the smaller the area it needs, so the more chips you get out of a wafer, and the lower the cost per chip. ...
10
votes
1answer
2k views

Which is better - components on both sides or components on one side of the PCB?

I am working on a PCB design. 50k PCBs will be produced. SMD components: 100 Through-hole components: 25 I need to minimize PCB size. There are no high-speed signals or sensitive signals in the ...
0
votes
0answers
42 views

Creating random PCB ID via manufacturing process

I often purchase prototype PCBAs on the order of five to twenty pieces and need to uniquely identify them sans software. I usually just whip out a permanent marker and label ...
1
vote
1answer
57 views

Hi Pot / Dielectric Pass/Fail Recording

I just graduated last year with an Electrical Engineering degree. Currently pursuing a Masters's Degree, so I am fairly new to design. We have several HiPot Testers we use on the manufacturing line. ...
2
votes
1answer
88 views

Providing Schematics to a Contract Manufacturer?

A contract manufacturer mentioned the types of the files that they need in order to build and assemble boards. He indicated that they need the schematics along with gerbers, drill files, bom etc.. Is ...
6
votes
2answers
512 views

Specifying BOM substitutions / alternatives with Contract Manufacturer (CM)

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 ...
2
votes
1answer
78 views

Is it possible to manufactrure a stencil for this paste-mask using the usual stencil making methods?

I have this footprint from the KI-CAD footprint library (LFCSP-32-1EP_5x5mm_P0.5mm_EP3.1x3.1mm_ThermalVias). The paste-mask shows several circular paste areas under the thermal pad. The separation ...
1
vote
1answer
49 views

LoRa and Manufacturing Technology

Which manufacturing technology do the LoRa (Semtech SX1276) belong to? Is it a CMOS based chip?
1
vote
1answer
68 views

Decreasing manufacturing variance in analogue designs

I'm designing some modular sensors for my company's internal testing. Most are analogue, with a sensor (PT100, current shunt, pressure transducer etc), some interfacing (REF200 based PT100 circuit for ...
2
votes
1answer
106 views

PCB Thickness Variability

How much variability is there in the thickness of a standard PCB? Let's say I order a 1.6mm FR-4 board. Will the actual thickness range 1.5mm-1.7mm? 1.4mm-1.8mm? 1.59mm-1.61mm? What is the (...
0
votes
1answer
65 views

Manufacturable technology for force-sensitive button

I'm hoping to hear your perspectives on which force-sensing technologies would be most reliably and inexpensively manufactured at volume. The application is a pressure-sensitive button, as are found ...
11
votes
7answers
2k views

Do manufacturers try make their components as close to ideal ones as possible?

I was wondering what developments are done on electrical components today. Do manufacturers try to make the electrical components they sell as close to the ideal model as possible? So for example, is ...
0
votes
0answers
70 views

How to prevent solder getting into through hole during HASL process?

I think this is an easy enough question - I just don't know how to effectively search for the answer. I have a PCB that came back and the programming header is plugged with solder. This most likely ...
3
votes
1answer
49 views

SMD Stencil Material Choice

We are planning to purchase a stencil for our LED boards. This will be my first stencil purchase so I don't have much idea about a good or bad one. The inquiries I received typically suggest two ...
1
vote
4answers
1k views

Soldering one PCB to another with 90 degrees angle

I want two PCB's to be soldered with each other in 90-degrees style. I think that the base PCB should have a slot with the width equals to the top board thickness. The top board should have a flange ...
0
votes
0answers
69 views

Why wierd capacitance values [duplicate]

Why are capacitors available with values like 378 µfarad and 0.22 farad which have prime numbers like 11 and 7 in factorization instead of values like 375 µfarad and 0.2 and 0.25 farad ...
2
votes
1answer
161 views

Problems with doping semiconductor materials in 7nm technology

As you know, semiconductor technology is going to reach 7nm lithographic precision soon. Which means that the smallest segment length on a semiconductor die can be as short as 7nm. After making some ...
22
votes
6answers
4k views

Writable area on a PCB

I would like to create an area on my PCB where you can write on with a pen. Is this possible, and if so how should I do it?
10
votes
1answer
1k views

'Pick and place' feature in connectors

I am looking to source a four-pin, 1.0 mm pitch, vertical JST connector -- either BM04B-SRSS-TB(LF)(SN) or BM04B-SRSS-TBT(LF)(SN). The latter has an extra 'Pick and Place' feature in Digikey. I can'...
0
votes
2answers
299 views

Reed Switch Failure Modes

I've been playing with these through hole reed switches: MDSR-4-12-23. It has been my experience so far that you have to be very careful in handling them, including when bending the leads to 90 degree ...
4
votes
1answer
204 views

Designing for Low Cost China Manufacturing [closed]

I have designed a few boards on a consulting basis. Some of them have been manufactured in China in +10k unit volumes. One of the complains I have gotten from my clients is my boards can be a bit ...
7
votes
3answers
3k views

What is this small unconnected solder blob on this PCB?

There's a small solder blob in the middle of this one-sided PCB (a switch-mode power supply), surrounded by unmasked board. The blob is 1.5mm in diameter, and the non-masked area is 4mm in diameter. ...
5
votes
2answers
878 views

Usefull 0402 and 0603 solderbridge footprints compatible with machine manufacturing?

I am currently in process of my eagle library cleanup, and came up with the idea to create a footprint similar to the one from nucleo boards. Those pads are meant to be easily bridged by just solder ...
1
vote
2answers
610 views

Do any commercial products use dead bug construction? [closed]

I'm talking about connecting electronic components without using a PCB. Soldering such an assembly is pretty fast if you have a jig holding the components in place. (The examples below are laid out ...