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Shelf Life of Assemblied PCB's

Bernard Mulcahy

#10357

Shelf Life of Assemblied PCB's | 30 July, 1999

I have been asked to supply a maximum shelf life for our assemblied PCB's. I realise this is dependent on so many factors- temperature, humidity, no of layers etc. But does anyone have a formulae for calculating shelf life, or does anyone know of a std that gives some sort of guideline ? Many Thanks

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DL

#10358

Re: Shelf Life of Assemblied PCB's | 30 July, 1999

| I have been asked to supply a maximum shelf life for our assemblied PCB's. I realise this is dependent on so many factors- temperature, humidity, no of layers etc. But does anyone have a formulae for calculating shelf life, or does anyone know of a std that gives some sort of guideline ? | Many Thanks |

Bernard,

I looked around and came up with this. There is nothing that I can locate. Most PCBs have a product life designed into them. For example military assemblers design boards to last 50 years, others for example toy manufacturers design boards to last for a year or two. You can possibly obtain more info from your own copy of the ISO manual or call a few of your suppliers your incoming parts have Shelf life & Storage Info on the packing slip or else where on the carton. We personnally do not store our PCB's they are built to order and shipped The Hyper - Link Below may also help you.

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#10359

Re: Shelf Life of Assemblied PCB's | 3 August, 1999

| | I have been asked to supply a maximum shelf life for our assemblied PCB's. I realise this is dependent on so many factors- temperature, humidity, no of layers etc. But does anyone have a formulae for calculating shelf life, or does anyone know of a std that gives some sort of guideline ? | | Many Thanks | | | | Bernard, | | I looked around and came up with this. There is nothing that I can locate. Most PCBs have a product life designed | into them. For example military assemblers design boards to last 50 years, others for example toy manufacturers design boards to last for a year or two. You can possibly obtain more info from your own copy of the ISO manual or call a few of your suppliers your incoming parts have Shelf life & Storage Info on the packing slip or else where on the carton. We personnally | do not store our PCB's they are built to order and shipped | The Hyper - Link Below may also help you. | | Bernard: You customer poses a curious question. I assume it�s some military wonk, but with the Brits, who knows?

Shelf life calculations could be a subset of reliability calculations with zero voltage applied and a benign (??) environment. Here�s what I suggest:

1 Poke around the Reliability Analysis Center (http://rac.iitri.org/) to see if they talk about shelf life. I seem to recall that they have an "answer guy" posting area. 2 Do a MIL-HDBK-217, Reliability Prediction of Electronic Equipment study on the board.

my2�

Dave F

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#10360

Re: Shelf Life of Assemblied PCB's | 3 August, 1999

| | I have been asked to supply a maximum shelf life for our assemblied PCB's. I realise this is dependent on so many factors- temperature, humidity, no of layers etc. But does anyone have a formulae for calculating shelf life, or does anyone know of a std that gives some sort of guideline ? | | Many Thanks | | | | Bernard, | | I looked around and came up with this. There is nothing that I can locate. Most PCBs have a product life designed | into them. For example military assemblers design boards to last 50 years, others for example toy manufacturers design boards to last for a year or two. You can possibly obtain more info from your own copy of the ISO manual or call a few of your suppliers your incoming parts have Shelf life & Storage Info on the packing slip or else where on the carton. We personnally | do not store our PCB's they are built to order and shipped | The Hyper - Link Below may also help you. | | Bernard: You customer poses a curious question. I assume it�s some military wonk, but with the Brits, who knows?

Shelf life calculations could be a subset of reliability calculations with zero voltage applied and a benign (??) environment. Here�s what I suggest:

1 Poke around the Reliability Analysis Center (http://rac.iitri.org/) to see if they talk about shelf life. I seem to recall that they have an "answer guy" posting area. 2 Do a MIL-HDBK-217, Reliability Prediction of Electronic Equipment study on the board.

my2�

Dave F

reply »


DL

#10361

Re: Shelf Life of Assemblied PCB's | 3 August, 1999

| | | I have been asked to supply a maximum shelf life for our assemblied PCB's. I realise this is dependent on so many factors- temperature, humidity, no of layers etc. But does anyone have a formulae for calculating shelf life, or does anyone know of a std that gives some sort of guideline ? | | | Many Thanks | | | | | | | Bernard, | | | | I looked around and came up with this. There is nothing that I can locate. Most PCBs have a product life designed | | into them. For example military assemblers design boards to last 50 years, others for example toy manufacturers design boards to last for a year or two. You can possibly obtain more info from your own copy of the ISO manual or call a few of your suppliers your incoming parts have Shelf life & Storage Info on the packing slip or else where on the carton. We personnally | | do not store our PCB's they are built to order and shipped | | The Hyper - Link Below may also help you. | | | | | Bernard: You customer poses a curious question. I assume it�s some military wonk, but with the Brits, who knows? | | Shelf life calculations could be a subset of reliability calculations with zero voltage applied and a benign (??) environment. Here�s what I suggest: | | 1 Poke around the Reliability Analysis Center (http://rac.iitri.org/) to see if they talk about shelf life. I seem to recall that they have an "answer guy" posting area. | 2 Do a MIL-HDBK-217, Reliability Prediction of Electronic Equipment study on the board. | | my2� | | Dave F

Bernard,

I asked around and found out this. The shelf life of a manually assembled PCB is 5-7 years. A wave soldered PCB has endless shelf life (provided you save it from dust and moisture). PCBs get absolute in terms of technology and not in terms of life of their components. This was provided to me as a matter of fact. However, I always require HARD documention from someone I've never meet or have no way of gauging their knowledge. The link below is where I was looking. There is a Tech-GURU there. However I'm waiting for him to email me with hard core Documentation, cause I want to know too. |

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#10362

Re: Shelf Life of Assemblied PCB's | 4 August, 1999

| | | | I have been asked to supply a maximum shelf life for our assemblied PCB's. I realise this is dependent on so many factors- temperature, humidity, no of layers etc. But does anyone have a formulae for calculating shelf life, or does anyone know of a std that gives some sort of guideline ? | | | | Many Thanks | | | | | | | | | | Bernard, | | | | | | I looked around and came up with this. There is nothing that I can locate. Most PCBs have a product life designed | | | into them. For example military assemblers design boards to last 50 years, others for example toy manufacturers design boards to last for a year or two. You can possibly obtain more info from your own copy of the ISO manual or call a few of your suppliers your incoming parts have Shelf life & Storage Info on the packing slip or else where on the carton. We personnally | | | do not store our PCB's they are built to order and shipped | | | The Hyper - Link Below may also help you. | | | | | | | | Bernard: You customer poses a curious question. I assume it�s some military wonk, but with the Brits, who knows? | | | | Shelf life calculations could be a subset of reliability calculations with zero voltage applied and a benign (??) environment. Here�s what I suggest: | | | | 1 Poke around the Reliability Analysis Center (http://rac.iitri.org/) to see if they talk about shelf life. I seem to recall that they have an "answer guy" posting area. | | 2 Do a MIL-HDBK-217, Reliability Prediction of Electronic Equipment study on the board. | | | | my2� | | | | Dave F | | Bernard, | | I asked around and found out this. The shelf life of a manually assembled PCB is 5-7 years. A wave soldered PCB has endless shelf life (provided you save it from dust and moisture). PCBs get absolute in terms of technology and not in terms of life of their components. This was provided to me as a matter of fact. However, I always require HARD documention | from someone I've never meet or have no way of gauging their knowledge. The link below is where I was looking. There is a Tech-GURU there. However I'm waiting for him to email me with hard core Documentation, cause I want to know too. | | | | So DL, what if the board that you're storing has:

* NiCd battery? * Adhesives that are affected by UV? * Thin HASL coating that will convert to intermetalic under normal storage conditions in a year?

Don't those things affect shelf life differently? What are the assumptions of the shelf lives you quote?

Dave F

Dave F

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