请问有谁能说说铁佛龙是怎样焊接的??

sqqd.12

我们做线路板设备的,有时用到铁佛龙这个材料,不过由于焊接技术的不成熟,使用时有很大的局限性,在三维上看能不能找到一些好的解决方法!

hanjixian

聚四氟乙烯在熔点以上(380℃)其黏度仍有1010～1011Pa·s，即使加高温度也只会分解而不流动，因此对聚四氟乙烯材料的焊接区别于其他热塑性塑料。聚四氟乙烯的焊接有热压焊和热风焊两种，热压焊接是将焊接的两片PTFE材料加热至高于熔点，在不太大的压力下，将两片材料压合在一起。热风焊接是用与聚四氟乙烯性能相仿的熔融加工的氟塑料如四氟乙烯-全氟烷基能乙烯基醚共聚物(PFA)作焊条，用热空气将焊条与待焊的聚四氟乙烯同时加热、加压，使聚四氟乙烯材料通过焊条连接在一起。

lihui98765

? 基本不能焊...2楼说的只针对膜...厚点就不行了..
能具体说说电路板哪边要用PTFE? 如果是加工PTFE电路板..怎么会需要焊接的?

lihui98765

查了下..还是可以焊的..把资料给你..
16.4 Welding and Joining
1 Q. E! d. Q! f. o7 KThe bonding techniques involving adhesives are
, }' q$ A0 k% z5 \! Hnormally suitable for applications where the fluoropolymer
6 Q* k- A5 p5 z7 y( [  o$ _+ Ldoes not carry large loads such as those
experienced by chemical processing equipment.
Welding or adhesiveless joining is a method by which
parts for load-bearing applications are manufactured.
The load could consist of temperature, chemical corrosion,
and force. This method also known as welding
# I, S' ^* P, k  l) H& n$ L) Gor joining allows economical fabrication of complex
4 ^# w! G& p& k! cparts by joining individual components.
( j3 t4 m( v3 x  wIt is possible to obtain a good bond between fluoropolymers
' `) M" s4 r* {1 G* Rthemselves, without the use of adhesives,
by application of heat and pressure. Pressure can help
drive the molten polymer into the pores of the substrate.
Bond strength is dependent on the mechanical
interlocking that is achieved by the adhesion mechanism,
) z: ?. f' v7 a( ^/ Q( \improving with increased surface roughness of
6 p4 w: D9 C$ p# r7 ^; Qthe substrate. Examples of parts made by this technology
include glass cloth-backed polytetrafluoroethylene
5 a5 p3 y5 g1 \0 ]- U9 h  Tsheet, or multi-ply circuit board and coated
aluminum or copper sheet. Achieving this type of
bonding is more complex with polytetrafluoroethylene
than melt processible polymers. PTFE does not flow
6 d) t# R3 h# k* M7 K, ^after melting due to its extremely high viscosity.
It is possible to achieve adhesiveless bonding using
/ C- I! S8 S- U; E' l0 gstandard PTFE in special applications where the
7 i9 F* k. L! m+ Mpolymer can be heated to a temperature well above its
  w  q5 }# d# @, q/ umelting point. It can then be forced under pressure
- ?+ ?% o, ]( d3 \into the substrate surface. These polymers are not
: }' f. P" n: g: J# ]suitable for applications where the geometry of the
( Q( @1 _+ q! F. H8 c4 R0 M$ u6 qjoining objects must be preserved, contact surfaces
6 ?  u" ]3 F) E0 N5 Tare smooth, or the objects being bonded are too large.
+ ~. e, ?! j. n5 ?4 @1 _1 dIn such cases, a different type of polytetrafluoroethylene
3 m! s! M2 s$ j# p- C* Xis required.
Polytetrafluoroethylene for these applications is
. I" [4 {# i, }& g# lknown as “modified” which refers to the presence of
a small amount of a second perfluorinated monomer,
known as a modifier, in its structure. The modifier
3 u: j$ Q  T) Y" [6 m3 [molecule always contains a pendent group. The
, ]1 ~8 ^) a. n( b* Xpreparation method of this type of PTFE has been described
in Ch. 5. Its commercial grades have been
described in Ch. 6.
5 O. K6 z8 o( |; NHow does it work? A simple explanation is offered
  q3 Q* {: f. t/ z. zhere, based on the author’s own experience. The
modification reduces the molecular weight of the polymer,
) z8 D/ X( |0 D. A0 wwhich in turn reduces its melt viscosity. Lower
4 Z. }, ~9 [2 F) O9 h8 c# umelt viscosity increases the mobility of the polytetrafluoroethylene
chains. This facilitates diffusion and
entanglement of polymer chains at the bonding interface.
0 d/ a0 ^6 P$ y$ s* sThe pendent group of the modifier disrupts the
crystals of PTFE, thus preventing excessive crystallization.
Crystallinity which is too high results in poor
mechanical properties such as poor tensile and flex
properties. An optimally modified PTFE has good
mechanical properties in addition to weldability.
Welding can be achieved using PTFE made by
+ Y) m0 V+ X- Wdispersion or suspension polymerization. Most applications
' q$ I9 B8 p. W2 Hinvolve welding of parts made from granular
resins (suspension polymer). Dispersion polymerized
3 W0 [3 ]: N4 \& Y7 t9 EPTFE is also used for application such as wire
9 p& `( p, }( I7 }coating. A thin (50–100 μm) tape of the “modified”
polytetrafluoroethylene is wrapped around the conductor
followed by sintering. The layers of the tape
$ b: h+ J2 I- {- [/ |/ eadhere to each other and form a solid insulation, due
to its good interlayer adhesion, around the conductor
at the completion of sintering cycle.
6 O: a! U( F$ [2 k# q7 E' R; |16.4.1 Welding Technique
  z5 t, E2 R5 V  @; d+ L7 @2 kQuality of a welded area is defined by the strength
2 ^! l- N8 [$ K! B( F) gof the bond. One of the ways to measure bond strength
) a6 [4 E# G) ]6 n  x8 ?" `  ais to cut a microtensile bar specimen in such a way
2 p8 j7 s5 X4 |* v0 ]3 ithat the weld line would fall near its center (Fig. 16.5).
Tensile strength and elongation can be determined by
& D, J9 R- B* i7 P# B, a  Uextensiometry. Weld factor is defined by Eq. 16.1 as
* @6 E2 s7 J; d  @" ~the ratio of tensile strength of the welded specimen
(Tw) to the tensile strength of the material (Tp). The
) H6 ~  b6 N* U' r: P6 `weld factor is defined for the weakest polymer, if two
% M8 K& |# z" _+ h: c' ldifferent polymers are welded together.
( N! r, U3 {& R" m) j9 bThree variables are significant in welding a given
modified PTFE part: welding temperature, pressure
/ w7 e) p+ R' Gand time. Optimal combinations of these three pa
rameters must be found for successful welding of parts.
Temperature should be well above the melting point
(320–330°C), typically in the range of 360–380°C.
Little pressure is required to weld the parts after reaching
/ U$ e; N. A' C1 w$ M  xgel state. Less than 350 kPa, and often less than
35 kPa, pressure is required for welding. It is normally
not possible to trade higher welding pressure
for lower temperature and vice versa. Time, the third
variable of the process, is dependent on the size and
shape of the part. The actual weld time, defined as
4 d" R4 R5 G- I( Gtime at the final temperature, is of the order of 1–2
0 D! X+ r% n1 a$ z% m6 t5 A$ fminutes. It often takes a great deal longer to heat up
* b  n$ o7 L* g# r* Ethe part to the welding temperature. High heating rates
. N6 j5 ]& O& W5 W# Bdo not accelerate the process due to the low thermal
3 O) ^+ u4 p. u# |- b& Uconductivity of PTFE. Heat rates similar to those of
2 O5 k6 p  b+ E$ S, t8 dsintering cycles of preforms can be expected.
' ?0 ~9 y5 ]7 S6 gThe mating surfaces should be smooth and uniform
. ~7 X# M/ n& r3 A3 F$ Band free from any contamination. Unsintered
0 R( s0 u7 K' d. Q/ bpreforms and sintered parts of modified polytetrafluoroethylene
can be welded. Sintering and welding can
. P6 m( g1 w6 ], ~3 }be combined. Parts can often be stacked up in the
4 |0 K/ o9 i& Csintering oven without additional pressure. A weld
factor of one can be routinely obtained in the combined
! g+ G3 U& a1 H: X! d' p& Cprocess. A higher pressure is required for welding
! l: P. e( d& v; _/ p; n$ Xsintered parts to counteract the residual stresses,
% A* O% e2 p, |7 owhich tend to move the parts upon release. It is important
7 H/ ]1 [& x: B% Z8 N4 ]to cool the welded parts slowly to minimize
stresses stored in the part. Figure 16.6 illustrates a
2 }0 q3 K) T  T% B  i2 Ndevice for hot-tool welding films and sheets.
! B6 S7 s: T) f! k6 vFigure 16.7 shows a comparison of the stressstrain
curves of a conventional and a modified PTFE
# n/ f" e! \1 U0 Pfor the original and welded material. The weld line in
' S0 H  ], z% ~+ jconventional PTFE when welded to itself, at best, fails
9 U, C: u5 j5 Aat very low strains. In the case of modified resin
( u, H- [, d5 d9 X2 jwelded to itself, the weld factor attains value of 0.80–
0.85. Weld factors for welding of conventional and
modified PTFE have been reported in the range of
% Y" X7 a/ ?5 o% X6 y/ |0.66–0.87.[13]
; W; b! a2 f3 V8 G/ jAnother method is welding with the help of a PFA
(melt processable) rod. In this case, the conventional
2 g9 V6 ~0 c- {# T1 p+ ?or modified PTFE is heated by hot air near the seam
7 A5 O5 G" D& R, \2 s8 u/ yuntil it is in gel state. The PFA rod is molten and used
# o0 E2 X2 I3 `: s2 j6 mto fill the seam.