On Monday, June 21, 2021 at 5:56:09 PM UTC-7, gnuarm.del...@gmail.com wrote:> On Monday, June 21, 2021 at 7:43:38 PM UTC-4, Ed Lee wrote: > > On Monday, June 21, 2021 at 4:34:38 PM UTC-7, gnuarm.del...@gmail.com wrote: > > > Yeah, that's why I let assembly houses handle my boards. > > Yes, for production, but i need to do it by hand myself for prototype. > > > > I am going to push some pins out for prototype, in order to expand the pads by 50 mils. > I don't really understand what you are doing. Many people solder gull wing devices like SOPs, SSOPs, TSSOPs and QFPs by hand quite easily. I have no idea why you need to bend pins to use any of those. What are your concerns?Sorry, i mean pushing out the pins on the circuit board, not the chip. You can look at it as Six-In-Line Package (the center goes into a ZIF 40), with columns at: _____550__450__350___350___450__550 (distance from center, in mils) This allows around 10 mils for extended pads for the TQFP 100. For prototype, i am pushing out the second and fifth columns by 30 mils. _____555__480__350___350___480__550 This allows around 40 mils for extended pads. ______XL___LW____L_____R____RW___XR____|_______B/B____ _1_____________Key____5v_______________|____B12____5v _2_____________3v3___Gnd_______________|____B13___Gnd _3_____________-*-____D2_______________|____B14___3v3 _4______________B7____D1_______________|____B15___B10 _5___Key________B8___C12____D0__Gnd____|_____A8____B2 _6___-*-___B9___E0___C10___C11__-*-____|_____A9____B1 _7___-*-___E1___A1____A6___-*-__-*-____|____A10____B0 _8___-*-___E3_______________B5__-*-____|____A11____A7 _9____E4__C13______________A10__-*-____|____A12____A6 10___C14___OI_______________C7___A9____|____A15____A5 11____OO___C2______________D12___C6____|_____B3____A4 12____C3___VA______________B15__D11____|_____B4____A3 13____A0__-*-______________B13__B14____|_____B5____A3 14___Gnd__3v3___A3____A2___-*-__Gnd____|_____B6____A1 15____A7___C4___A6___B11___E15__B10____|_____B5____A0 16____VB___E7___B1___E12___E10__48v____|_____B8_____R 17_____________ B2___E14_______________|_____B9___C15 18_____________ B0___E13_______________|_____5v___C14 19_____________Gnd___3v3_______________|____Gnd___C13 20______________VB___48v_______________|____3v3____VB> > The cost of setup is not so much that machine assembly of prototypes is really cost prohibitive. I think I am typically charged $200 or so. I suppose they might charge a bit more for the unit cost if you are only building a half dozen or so. One house all but refused to hand assemble three of a test fixture with SMD components. This was 13 years ago and I think they still had equipment to facilitate the hand insertion of DIPs in PCBs by shining a light where the chip should go. They said the labor was cost prohibitive. > > Sometimes it is hard for an engineer to understand the issues of an assembly house, particularly the difference between what a motivated engineer can do and what an hourly worker is willing to do.I only need a handful to test it out first. Will ask how much they would charge. It should be cheaper if they can do it by hand without custom made stencil.
SMD footprints
Started by ●June 19, 2021
Reply by ●June 21, 20212021-06-21
Reply by ●June 22, 20212021-06-22
On Monday, June 21, 2021 at 10:00:07 PM UTC-4, Ed Lee wrote:> On Monday, June 21, 2021 at 5:56:09 PM UTC-7, gnuarm.del...@gmail.com wrote: > > On Monday, June 21, 2021 at 7:43:38 PM UTC-4, Ed Lee wrote: > > > On Monday, June 21, 2021 at 4:34:38 PM UTC-7, gnuarm.del...@gmail.com wrote: > > > > Yeah, that's why I let assembly houses handle my boards. > > > Yes, for production, but i need to do it by hand myself for prototype. > > > > > > I am going to push some pins out for prototype, in order to expand the pads by 50 mils. > > I don't really understand what you are doing. Many people solder gull wing devices like SOPs, SSOPs, TSSOPs and QFPs by hand quite easily. I have no idea why you need to bend pins to use any of those. What are your concerns? > Sorry, i mean pushing out the pins on the circuit board, not the chip. > > You can look at it as Six-In-Line Package (the center goes into a ZIF 40), with columns at: > > _____550__450__350___350___450__550 (distance from center, in mils) > This allows around 10 mils for extended pads for the TQFP 100. > > For prototype, i am pushing out the second and fifth columns by 30 mils. > _____555__480__350___350___480__550 > This allows around 40 mils for extended pads. > > ______XL___LW____L_____R____RW___XR____|_______B/B____ > _1_____________Key____5v_______________|____B12____5v > _2_____________3v3___Gnd_______________|____B13___Gnd > _3_____________-*-____D2_______________|____B14___3v3 > _4______________B7____D1_______________|____B15___B10 > _5___Key________B8___C12____D0__Gnd____|_____A8____B2 > _6___-*-___B9___E0___C10___C11__-*-____|_____A9____B1 > _7___-*-___E1___A1____A6___-*-__-*-____|____A10____B0 > _8___-*-___E3_______________B5__-*-____|____A11____A7 > _9____E4__C13______________A10__-*-____|____A12____A6 > 10___C14___OI_______________C7___A9____|____A15____A5 > 11____OO___C2______________D12___C6____|_____B3____A4 > 12____C3___VA______________B15__D11____|_____B4____A3 > 13____A0__-*-______________B13__B14____|_____B5____A3 > 14___Gnd__3v3___A3____A2___-*-__Gnd____|_____B6____A1 > 15____A7___C4___A6___B11___E15__B10____|_____B5____A0 > 16____VB___E7___B1___E12___E10__48v____|_____B8_____R > 17_____________ B2___E14_______________|_____B9___C15 > 18_____________ B0___E13_______________|_____5v___C14 > 19_____________Gnd___3v3_______________|____Gnd___C13 > 20______________VB___48v_______________|____3v3____VBI have no idea what any of the above means. It's incomprehensible in Google Groups.> > The cost of setup is not so much that machine assembly of prototypes is really cost prohibitive. I think I am typically charged $200 or so. I suppose they might charge a bit more for the unit cost if you are only building a half dozen or so. One house all but refused to hand assemble three of a test fixture with SMD components. This was 13 years ago and I think they still had equipment to facilitate the hand insertion of DIPs in PCBs by shining a light where the chip should go. They said the labor was cost prohibitive. > > > > Sometimes it is hard for an engineer to understand the issues of an assembly house, particularly the difference between what a motivated engineer can do and what an hourly worker is willing to do. > I only need a handful to test it out first. Will ask how much they would charge. It should be cheaper if they can do it by hand without custom made stencil.Of course you only need a few now, but you will need to pay the setup when you do go to production and if you have no changes it's already done. There are places that will make your boards and assemble it for very little, like JLCPCB. Are you using parts they can't supply? I know they won't assemble anything they don't sell. -- Rick C. ++ Get 1,000 miles of free Supercharging ++ Tesla referral code - https://ts.la/richard11209
